Patent Publication Number: US-2021177991-A1

Title: Frataxin expression constructs

Description:
REFERENCE TO SEQUENCE LISTING 
     This application incorporates by reference a “Sequence Listing” (identified below) which is submitted concurrently herewith in text file format via the U.S. Patent Office&#39;s Electronic Filing System (EFS). The text file copy of the Sequence Listing submitted herewith is labeled “INX00317PCT_ST25”, is a file of 40.298 bytes in size, and was created on Oct. 4, 2017. This Sequence Listing is incorporated by reference in its entirety herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Friedreich&#39;s Ataxia (FA) is the most common form of inheritable ataxia and affects around 1 in 50,000 people in the United States. Friedreich&#39;s ataxia is caused by a mutation in the gene coding for frataxin gene (FXN) which is present on chromosome 9. The underlying molecular pathology of FA is due to the presence of a trinucleotide GAA repeat expansion (70-1700) in the first intron of the FXN (Campuzano et al. (1996)  Hum. Mol. Genet.  6:1771-1780). The effect of this gene mutation is production of inadequate quantities of the mitochondrial protein frataxin, which appears to play an important role in iron homeostasis (Pandolfo (2008)  Archives of Neurology  65:1296-1303; Campuzano et al. (1996)  Hum. Mol. Genet.  6:1771-1780). Reduced levels of frataxin protein are associated with mitochondrial dysfunction, and lead to cell toxicity and cell death (Pandolfo (2009)  J. Neurol.  256 Suppl. 1:3-8). Heterozygote carriers of the defective gene express approximately 50% of normal frataxin protein levels and are asymptomatic; homozygous patients express 5-25% of normal frataxin levels and are symptomatic. Therefore, it is possible that modest increases in frataxin protein levels in cells in the CNS of FA patients could result in significant neurological improvements. Moreover, molecules that increase endogenous FXN levels or FXN protein replacement methods have shown promise in clinical and pre-clinical studies. As such, protein replacement via gene therapy is a compelling alternative option for therapeutic development. There is an urgent need in the art for a treatment and prevention of Friedreich&#39;s ataxia. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a polynucleotide comprising a nucleic acid molecule encoding human frataxin operably linked to control elements that direct the transcription and translation thereof. In some embodiments of the invention, the nucleic acid encodes a frataxin protein with amino acid sequence that is at least 80%, 85%, 90%, 95%, 98%, or 99% identical to SEQ ID NO:1. In some embodiments of the invention, the nucleic acid encodes a frataxin protein with amino acid sequence of SEQ ID NO:1. In some embodiments, the control elements are selected from the group consisting of a promoter, a 5′ regulatory element, a 3′ regulatory element and combinations thereof. 
     In some embodiments, the promoter is selected from the group consisting of a CMV promoter, a UBC promoter an EF1α promoter, a PGK1 promoter and a minimal frataxin promoter. In some embodiments, the 5′ regulatory element is selected from the group consisting of a GAPDH sequence, a FTH1-5′UTR, a RPL6-5′ Splice sequence, and a 5U2 sequence. In some embodiments, the 3′ regulatory element is selected from the group consisting of an SV40 early sequence, an SV40 late sequence, a synthetic 3′ regulatory element, and a human growth hormone polyadenylation sequence. 
     In a particular embodiment of the invention, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, and the control elements comprise a UBC promoter (e.g., SEQ ID NO:3), a 5U2 sequence (e.g., SEQ ID NO:4) and a human growth hormone polyadenylation sequence (e.g., SEQ ID NO:5). 
     In another particular embodiment of the invention, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, and the control elements comprise a UBC promoter (e.g., SEQ ID NO:3), a 5U2 sequence (e.g., SEQ ID NO:4) and a synthetic 3′ regulatory element sequence (SEQ ID NO:7). 
     The invention also provides a viral vector comprising the polynucleotide of the invention. In some embodiments, the viral vector is an adeno-associated viral vector. In a specific embodiment, the viral vector is AAV5. 
     The invention also provides a recombinant virion which comprises a viral vector, and wherein the viral vector comprises a nucleic acid molecule encoding human frataxin operably linked to control elements that direct the transcription and translation thereof. In some embodiments, the virion contains an adeno-associated viral vector. In certain specific embodiments, the adeno-associated viral vector is AAV5. In some embodiments, the virion comprises a nucleic acid molecule encoding a protein with the amino acid sequence of SEQ ID NO:1. 
     In some embodiments, the control elements are selected from the group consisting of a promoter, a 5′ regulatory element, a 3′ regulatory element and combinations thereof. In some embodiments, the promoter is selected from the group consisting of a CMV promoter (e.g., SEQ ID NO:13), a UBC promoter (e.g., SEQ ID NO:3) an EF1α promoter (e.g., SEQ ID NO:18), a PGK1 promoter (e.g., SEQ ID NO:17) and a minimal frataxin promoter. In some embodiments, the 5′ regulatory element is selected from the group consisting of a GAPDH (e.g., SEQ ID NO:15) sequence, a FTH1-5′UTR (e.g., SEQ ID NO:14), a RPL6-5′Splice sequence (e.g., SEQ ID NO:16), and a 5U2 sequence (SEQ ID NO:4). In some embodiments, the 3′ regulatory element is selected from the group consisting of an SV40 early sequence (e.g., SEQ ID NO:8), an SV40 late sequence (e.g., SEQ ID NO:9), a synthetic 3′ regulatory element sequence (SEQ ID NO:7), and a human growth hormone polyadenylation sequence (e.g., SEQ ID NO:5). In certain specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a human growth hormone polyadenylation sequence (SEQ ID NO:5). In other specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a synthetic 3′ regulatory element sequence (SEQ ID NO:7). 
     The invention also provides a composition comprising (a) a viral vector, wherein the viral vector comprises a nucleic acid molecule encoding human frataxin operably linked to control elements that direct the transcription and translation thereof; and (b) a pharmaceutically acceptable excipient. 
     In some embodiments, the vector is an adeno-associated viral vector. In certain specific embodiments, the adeno-associated viral vector is AAV5. 
     In some embodiments, the nucleic acid encodes a frataxin protein with an amino acid sequence that is at least 80%, 85%, 90%, 95%, 98%, or 99% identical to SEQ ID NO:1. 
     In some embodiments, the control elements are selected from the group consisting of a promoter, a 5′ regulatory element, a 3′ regulatory element and combinations thereof. In some embodiments, the promoter is selected from the group consisting of a CMV promoter (e.g., SEQ ID NO:13), a UBC promoter (e.g., SEQ ID NO:3) an EF1α promoter (e.g., SEQ ID NO:18), a PGK1 promoter (e.g., SEQ ID NO:17) and a minimal frataxin promoter. In some embodiments, the 5′ regulatory element is selected from the group consisting of a GAPDH sequence (e.g., SEQ ID NO:15), a FTH1-5′UTR (e.g., SEQ ID NO:14), a RPL6-5′Splice sequence (e.g., SEQ ID NO:16), and a 5U2 sequence (SEQ ID NO:4). In some embodiments, the 3′ regulatory element is selected from the group consisting of an SV40 early sequence (e.g., SEQ ID NO:8), an SV40 late sequence (e.g., SEQ ID NO:9), a synthetic 3′ regulatory element sequence (SEQ ID NO:7), and a human growth hormone polyadenylation sequence (e.g., SEQ ID NO:5). In certain specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a human growth hormone polyadenylation sequence (SEQ ID NO:5). In certain other specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a synthetic 3′ regulatory element sequence (SEQ ID NO:7). 
     The invention also provides a composition comprising (a) a recombinant virion and (b) a pharmaceutically acceptable excipient, wherein the recombinant virion comprises a viral vector, and wherein the viral vector comprises a nucleic acid molecule encoding a human frataxin protein with amino acid sequence that is at least 80%, 85%, 90%, 95%, 98%, or 99% identical to SEQ ID NO:1, operably linked to control elements that direct the transcription and translation thereof. In some embodiments, the virion contains an adeno-associated viral vector. In certain specific embodiments, the adeno-associated viral vector is AAV5. In some embodiments, the virion comprises a nucleic acid molecule encoding a protein with the amino acid sequence of SEQ ID NO:1. 
     In some embodiments, the control elements are selected from the group consisting of a promoter, a 5′ regulatory element, a 3′ regulatory element and combinations thereof. In some embodiments, the promoter is selected from the group consisting of a CMV promoter, a UBC promoter an EF1α promoter, a PGK1 promoter and a minimal frataxin promoter. In some embodiments, the 5′ regulatory element is selected from the group consisting of a GAPDH sequence (e.g., SEQ ID NO:15), a FTH1-5′UTR (e.g., SEQ ID NO:14), a RPL6-5′Splice sequence (e.g., SEQ ID NO:16), and a 5U2 sequence (SEQ ID NO:4). In some embodiments, the 3′ regulatory element is selected from the group consisting of an SV40 early sequence (SEQ ID NO:8), an SV40 late sequence (SEQ ID NO:9), a synthetic 3′ regulatory element sequence (SEQ ID NO:7), and a human growth hormone polyadenylation sequence (SEQ ID NO:5). In certain specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a human growth hormone polyadenylation sequence (SEQ ID NO:5). In other specific embodiments, the nucleic acid encodes a protein with the amino acid sequence of SEQ ID NO:1, the promoter is a UBC promoter (SEQ ID NO:3), and the regulatory elements are a 5U2 sequence (SEQ ID NO:4) and a synthetic 3′ regulatory element sequence (SEQ ID NO:7). 
     In some embodiments, the pharmaceutically acceptable excipient is 1×PBS, (e.g., 0.154M NaCl, 0.056M Na 2 HPO 4 , and 0.0106 M KH 2 PO 4 ) or DPBS (e.g., 0.337M NaCl, 0.027 M KCl, 0.015M Na 2 HPO 4 , and 0.0015M KH 2 PO 4 ). 
     In some embodiments, the viral vector is present at a concentration of 2.5×10 11  vg/mL, 7.5×10 11  vg/mL, or 2.5×10 12  vg/mL. 
     In some embodiments, the pH of the composition is 6.5 to 7.5; 7.0 to 7.5; 6.8 to 7.2. In some embodiments, the pH of the composition is 7.0 or 7.4. 
     The composition may further comprise empty capsids at a percentage of at most 95% cp/cp, preferably 50% cp/cp or less. 
     The invention also provides a method of treating Friedrich&#39;s Ataxia, comprising providing a pharmaceutical formulation comprising a viral vector (e.g., preferably an AAV vector such as, but not limited to an AAV5 vector), wherein the vector comprises a polynucleotide encoding a human frataxin protein and a pharmaceutically-acceptable excipient to at least one target site in the CNS of the subject in a dose of at least about 1×10 9  vg, 1×10 10  vg, 1×10 11  vg, or 1×10 12  vg, or more. In some embodiments, the dose is at least about 1×10 13  vg, 5×10 13  vg, 1.5×10 14  vg, or 5×10 14  vg. 
     In some embodiments, the target site is the CSF space; the subarachnoid space, (e.g., the cisterna magna); the brain, (e.g., the cerebroventricular space, the cerebellum, the cerebrum, the hippocampus, the interior cortex, the dorsal root ganglion, or caudate nucleus); or the spine (e.g., the lumbar spine, thoracic spine, cervical spine). In some embodiments, the active ingredient (e.g., vectors expressing frataxin, virions, viruses, rAAVs, etc.) is delivered in two injections: one in the right cerebellum and one in the left cerebellum. In some embodiments, these are two equal injections. In some embodiments, the active ingredient (e.g., vectors expressing frataxin, virions, viruses, rAAVs, etc.) are administered by injecting the cerebellum and also providing it systemically. 
     In embodiments of the methods, the pharmaceutical formulation may be administered intraparenchymally, intrathecally, intracerebroventricularly, systemically or a combination of these. In some embodiments, the pharmaceutical formulation is administered by intrathecally in equal portions to the cisterna magna and the lumbar spine. 
     In some embodiments of the method, the dose is an amount of at least 3.7×10 10  vg/g, 1.11×10 11  vg/g, or 3.7×10 11  vg/g on a brain weight basis. In some embodiments, the pharmaceutical formulation comprises a vector concentration of at least 2×10 12  vg/mL, 7×10 12  vg/mL, or 2×10 13  vg/mL. 
     In some embodiments of the method, the pharmaceutical formulation is administered as a single bolus injection of 0.1 mL to 5 mL (e.g., 3 mL or 2 mL). In other embodiments, the pharmaceutical formulation is delivered as an infusion at a rate of 0.001 mL/min to 1 mL/min, (e.g., 0.01 mL/min). 
     The invention also provides a method of treating Friedreich&#39;s Ataxia in a subject in need thereof. In some embodiments, the method comprises administering to a subject a therapeutically effective amount of a pharmaceutical composition of a virus of the invention comprising a virion to express frataxin, in a pharmaceutical carrier. The recombinant virions transduce the cells in the subject, and the nucleic acid molecule is expressed by the transduced cells at a level sufficient to ameliorate at least one symptom of Friedreich&#39;s Ataxia in the subject. 
     The symptoms of Friedreich&#39;s Ataxia may be one or more selected from the group consisting of loss of coordination in the arms and/or legs; fatigue, vision impairment, hearing loss, slurred speech, aggressive scoliosis, diabetes mellitus, hypertrophic cardiomyopathy and cardiac arrhythmia. 
     In some embodiments, frataxin is expressed in the mitochondria. In some embodiments, frataxin is expressed in the cerebellum. In some embodiments, frataxin is expressed in the hippocampus. In some embodiments, frataxin is expressed in the anterior cortex. In some embodiments, frataxin is expressed in the dorsal root ganglion. 
     In some embodiments of the method of the invention, frataxin is expressed in said subject at a level of greater than 25% of normal levels of frataxin. In other embodiments, frataxin is expressed in said subject at a level of greater than 30% of normal levels of frataxin. In still other embodiments, frataxin is expressed in said subject at a level of greater than 40% of normal levels of frataxin. In still other embodiments, frataxin is expressed in said subject at a level of greater than 50% of normal levels of frataxin. 
     In certain embodiments, a gene switch which inducibly regulates (in a dose-dependent manner) expression of frataxin is incorporated into the polynucleotide to express frataxin. The gene switch may be, for example, a RHEOSWITCH THERAPEUTIC SYSTEM® (RTS®) gene switch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1B  show the Tier 1 results for selected constructs employing the UBC promoter in undifferentiated SY5Y, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 1A  shows pg yield of FXN per μg of total protein.  FIG. 1B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 2A-2B  show the Tier 1 results for selected constructs employing the UBC promoter in FA patient fibroblasts, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 2A  shows pg yield of FXN per μg of total protein.  FIG. 2B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 3A-3B  show the Tier 2 results for selected constructs employing the UBC promoter in undifferentiated SY5Y, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 3A  shows pg yield of FXN per μg of total protein.  FIG. 3B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 4A-4B  show the Tier 2 results for selected constructs employing the UBC promoter in FA patient fibroblasts, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 4A  shows pg yield of FXN per μg of total protein.  FIG. 4B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 5A-5B  show the Tier 3 results for selected constructs employing the UBC promoter in undifferentiated SY5Y, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 5A  shows pg yield of FXN per μg of total protein.  FIG. 5B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 6A-6B  show the Tier 3 results for selected constructs employing the UBC promoter in FA patient fibroblasts, along with the Green Fluorescent Protein (GFP), CMV and Mock controls.  FIG. 6A  shows pg yield of FXN per μg of total protein.  FIG. 6B  shows fold-expression levels over mock-transfected cells. See Table 1 for construct composition. 
         FIGS. 7A-7D  show human frataxin being expressed and appropriately trafficked into the mitochondria by fluorescence images of African green monkey fibroblasts (COS-7) transfected with human Frataxin: ( FIG. 7A ) nuclei stained with DAPI, ( FIG. 7B ) mitochondria stained with MitoTracker, ( FIG. 7C ) expressed human frataxin stained with anti-human frataxin (Abcam #ab11038), and ( FIG. 7D ) co-localization of human frataxin with nuclei and mitochondria. 
         FIGS. 8A-8D  show human frataxin being expressed and appropriately trafficked into the mitochondria by fluorescence images of murine fibroblasts (NC6) transfected with human Frataxin: ( FIG. 8A ) nuclei stained with DAPI, ( FIG. 8B ) mitochondria stained with MitoTracker, ( FIG. 8C ) expressed human frataxin stained with anti-human frataxin (Abcam #ab11038), and ( FIG. 8D ) co-localization of human frataxin with nuclei and mitochondria. 
         FIGS. 9A-9B  show a western blot of FA (3816) Day 21 neurons were transduced with AAV5-human frataxin (026) at 500,000 genome copies/cell at days 5 and 7 post transduction ( FIG. 9A ) and at days 10 and 14 post transduction ( FIG. 9B ). Human frataxin was detected with an anti-human frataxin antibody (Abcam #ab11038) using standard Western blot techniques. Molecular weight markers were loaded to confirm the size of the mature frataxin protein (14.2 kDa). FA+: transduced cells; FA: non-transduced cells; Ctrl: control cells. 
         FIG. 10  shows a cartoon of the strategy of reprogramming fibroblasts to become pluripotent cells which can differentiate into various cell types for use in modeling, testing of therapies and for transplantation. 
         FIG. 11  shows the results of frataxin expression from iPSC-derived neuronal cells transformed by electroporation of a frataxin-expressing plasmid for the 024 and 026 constructs (see Table 1) as expressed by fold over mock (GFP-treated) cells. 
         FIG. 12  shows the results of frataxin expression from iPSC-derived neuronal cells transduced with frataxin-expressing AAV for the 024 and 026 AAV constructs (see Table 1) as expressed by fold over mock (GFP-treated) cells. 
         FIG. 13  shows expression of frataxin (pg FXN/mg protein) in the cerebellum of mice intraparenchymally administered AAV5-FXN-026. 
         FIG. 14  shows expression of frataxin (pg FXN/mg protein) in the cerebellum (CB), hippocampus (HPC) and anterior cortex (ACX) of mice intraventricularly administered AAV5-FXN 026. 
         FIG. 15  shows a Recombinant AAV5.hFXN Vector Map. Ubiquitin C promoter (UBC promoter), a 5′ regulatory element (5U2), unmodified hFXN cDNA (hFXN GOI), a human growth hormone polyadenylation 3′ regulatory element (hGH-poly A), and an ITR linker. The entire sequence is flanked by AAV Inverted Terminal Repeats (ITR). 
         FIG. 16  shows a Normal Human Frataxin Precursor Deduced Amino Acid Sequence SEQ ID NO:1). The underlined sequence is a peptide necessary for transportation of the frataxin protein precursor to the mitochondria. The italicized peptide must be removed to activate the protein. The fully processed, canonical frataxin protein (in bold) has 130 amino acids. The sequence is from the UniProt database: Identifier #: Q16595-1. The UniProt consortium comprises the European Bioinformatics Institute (EBI), the Swiss Institute of Bioinformatics (SIB), and the Protein Information Resource (PIR). 
         FIG. 17  shows a Schematic Overview of an AAV5.hFXN Vector Manufacturing Process. 
         FIG. 18  shows a Schematic Plasmid Map of pAAV5-hFXN DNA. 
         FIGS. 19A-19C  show a Nucleotide sequence of an AAV5-hFXN-vector: gene insert: ITR to ITR-Annotated (SEQ ID NO:19). 
         FIGS. 20A-20B  show a Nucleotide sequence of a pAAV5-hFXN plasmid (SEQ ID NO:20). 
         FIG. 21  shows a chart representing rAAV5-hFXN vector-Induced Expression of Human Frataxin in the Cerebellum of Sarsero Frataxin-Deficient Mice. rAAV5.hFXN (2 μL) was injected directly into the cerebellum (IPc, N=7 mice) or intracerebroventricular space (ICV, N=7) of FA mice at a dose of 7×10 9  vg/μL. Three FA mice were injected with AAV5.GFP (control, 2 μL) either in the cerebellum or ICV at a dose of 4×10 9  vg/μL. At 4 weeks post injection, the cerebellums were harvested. Cerebellar tissue from two untreated control mice was also harvested. Tissue lysates were analyzed for human frataxin as described above. The average expression for each treatment is shown. 
         FIG. 22  is a chart showing DNA Copies per μg Tissue from Cerebellum of swine following the biodistribution of vector using several delivery locations and devices. 
         FIG. 23  is a chart showing DNA Copies per μg Tissue from Other Brain of swine following the biodistribution of vector using several delivery locations and devices. 
         FIG. 24  is a chart showing DNA Copies per μg Tissue from Spinal Tissues of swine following the biodistribution of vector using several delivery locations and devices. 
         FIG. 25  is a chart showing DNA Copies per μg Tissue from Systemic Tissues of swine following the biodistribution of vector using several delivery locations and devices. 
         FIG. 26  is a chart showing distribution of rAAV5-FXN-026 following a single infusion into the cerebellum. Vector Genome Copies in the Cerebellum of male Yucatan swine Day 28 vs 60 (vg DNA/μg Tissue DNA). 
         FIG. 27  is a chart showing distribution of rAAV5-FXN-026 following a single infusion into the cerebellum of male Yucatan swine. Vector Genome Copies in the Brain Day 28 vs 60 (vg DNA/μg Tissue DNA). 
         FIG. 28  is a chart showing distribution of rAAV5-FXN-026 following a single infusion into the cerebellum of male Yucatan swine. Vector Genome Copies in the Spinal Cord and DRG&#39;s Day 28 vs 60 (vg DNA/μg Tissue DNA). 
         FIG. 29  is a chart showing expression of frataxin protein in tissue samples from the cerebellar cortex, the dentate nucleus, hippocampus, and the motor cortex of male Yucatan swine. Frataxin levels via ELISA. 
         FIG. 30  is a chart showing biodistribution of an AAV5 human frataxin vector AAV5-hFXN (026) following intracerebellar administration to cynomolgus monkeys. Tissue samples from the cerebellar cortex, the dentate nucleus, hippocampus, and the motor cortex were analyzed for frataxin levels via ELISA. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to the expression of human frataxin in cells and the treatment of Friedreich&#39;s Ataxia in patients in need thereof. 
     For the methods described herein, various protocols that could be used are disclosed in reference manuals such as: Current Protocols in Molecular Biology (eds. Ausubel et al., Wiley, 2004 edition) and M OLECULAR  C LONING: A  L ABORATORY  M ANUAL  (Sambrook and Russell (Cold Spring Harbor Laboratory Press, 2001, third edition). Immunoreagent-containing methods such as western blots, ELISAs, and immunoprecipitations are performed as described in: U SING  A NTIBODIES: A  L ABORATORY  M ANUAL  (Harlow and Lane Cold Spring Harbor Laboratory Press, 1999). Each of these references is incorporated herein in its entirety. 
     When the terms “one,” “a,” or “an” are used in this disclosure, they mean “at least one” or “one or more,” unless otherwise indicated. 
     The term “AAV virus” shall mean a complete virus particle, for example a wild-type (wt) AAV virus particle. An AAV virus has an AAV capsid protein coat encasing a linear, single-stranded AAV nucleic acid genome. An AAV virus is replication-incompetent (i.e., replication-defective or helper-dependent virus). An AAV virus is optionally derived from any adeno-associated virus serotype, including without limitation, AAV-1, AAV-2, AAV-3, AAV-4, AAV-5, or AAVX7. AAV viruses can have one or more of the AAV wild-type genes deleted in whole or part, preferably the rep and/or cap genes, but retain functional flanking ITR sequences. Examples of AAV viruses include, but are not limited to, AAV viruses that are available from the American Type Culture Collection (“ATCC”) under Accession Numbers 53222, 53223, 53224, 53225 and 53226. For a description of AAV viruses and their uses see, e.g., Haj-Ahmad and Graham (1986)  J. Virol.  57:267-274; Bett et al. (1993)  J. Virol.  67:5911-5921; Mittereder et al. (1994)  Human Gene Therapy  5:717-729; Seth et al. (1994) J. Virol.  68:933-940; Barr et al. (1994)  Gene Therapy  1:51-58; Berkner, K. L. (1988)  BioTechniques  6:616-629; and Rich et al. (1993)  Human Gene Therapy  4:461-476. 
     As used herein, a “virion” is a polynucleotide comprising a viral nucleic acid backbone with a gene of interest to be expressed (e.g., frataxin) and at least on regulatory element to control expression of the gene of interest. 
     The term “recombinant AAV,” a “rAAV,” a “recombinant AAV vector,” or a “rAAV vector” shall mean an infectious but replication-defective virus composed of an AAV protein shell (i.e., a capsid) encapsulating a viral vector with a gene insert different from the wild-type AAV DNA. 
     The term “inverted terminal repeat” or “ITR” shall mean a symmetrical nucleic acid sequence at either end of the genetic material of a virus. Without being bound by theory, literature reports show that ITRs aid the efficient multiplication of the AAV genome. Literature also reports ITRs ability to form a hairpin, which contributes to self-priming that allows primase-independent synthesis of a second nucleic acid strand. ITRs were also shown to aid both integration of AAV DNA into a host cell genome. ITRs need not be the wild-type nucleotide sequences, and may be altered, for example, by the insertion, deletion or substitution of nucleotides, so long as the sequences provide for functional rescue, replication and packaging. Optional nucleotide sequences of AAV ITR regions are known. See, e.g., Kotin, R. M. (1994) “Human Gene Therapy” 5:793-801; Berns, K. I. “Parvoviridae and their Replication” in  Fundamental Virology,  2nd Edition, (B. N. Fields and D. M. Knipe, eds.) 
     The term “gene insert” shall mean a nucleic acid molecule, including a portion that encodes a polypeptide. 
     The term “gene therapy” shall mean a treatment of a subject comprising the introduction, to a subject, of a normal copy of one or more defective or missing genes. 
     The term “FXN gene therapy” or “frataxin gene therapy” shall mean a treatment of a subject comprising the introduction of a normal copy of an FXN gene to a subject that has a defective FXN gene, is missing an FXN gene, has insufficient expression of an FXN Gene, or produces inadequate quantities of frataxin. 
     The term “subject,” “individual,” or “patient” shall be used interchangeably and shall mean a mammal, preferably a human in need of therapy. A subject may be any age. A subject may be an adult. A subject may be an adult aged about 18 years to about 60 years. A subject may be a child. A subject may be a minor child aged about 17 years or less. A subject may be a minor child aged about 10 years or less. A subject may be a minor child aged about 3 years or less. 
     The term “capsid” shall mean a protein coat or shell of a virus. A capsid optionally comprises one or more oligomeric structural subunits comprising proteins, optionally referred to as protomers. A capsid may optionally be surrounded by a lipid bilayer and glycoprotein envelope. In one embodiment, a capsid is an adeno-associated virus (AAV) capsid. In one embodiment, the capsid is a recombinant adeno-associated virus (rAAV) serotype-5 capsid. 
     The term “empty capsid” shall mean a virus protein coat that does not contain a vector genome. An empty capsid can be a virus-like particle in that it reacts with one or more antibodies that react with intact (e.g., vector genome carrying) virus (e.g. adeno-associated virus, AAV). In a non-limiting example, an empty AAV5 capsid retains the ability to react with one or more antibodies that bind to an AAV, such as an AAV5 or another AAV serotype. For example, an empty AAV2 capsid retains the ability to react with one or more antibodies that bind to AAV5. 
     Empty capsids may sometimes be naturally found in AAV vector preparations. Such preparations can be used in accordance with the invention. Optionally, such preparations may be manipulated to increase or decrease the number of empty capsids. For example, the amount of empty capsid can be adjusted to an amount that would be expected to reduce the inhibitory effect of antibodies. Empty capsids can also be produced independently of vector preparations, and optionally (i) added to vector preparations, or (ii) administered separately to a subject. See F. Mingozzi et al., U.S. Patent Application Publication No. 2014/0336245 “Virus vectors for highly efficient transgene delivery.” 
     The term “modified capsid” shall mean a content-modified capsid, or a capsid modified so that the capsid is unable to enter a cell. 
     The term “content-modified capsid” shall mean a capsid carrying a gene insert that is modified. Examples of gene inserts that are modified, include but are not limited to, non-coding nucleic acids. 
     The term “mutant empty capsid” shall mean an empty capsid comprising a mutation that disrupts virus receptor binding. In one embodiment, a mutant empty capsid is a non-infective mutant capsid. In another embodiment, an empty capsid can absorb an antibody but cannot enter a target cell. In another embodiment, an empty capsid can absorb a neutralizing antibody. See C. J. Aalbers, et al., “Empty Capsids and Macrophage Inhibition/Depletion Increase rAAV Transgene Expression in Joints of Both Healthy and Arthritic Mice,”  Human Gene Therapy,  2017 February; 28(2):168-1781; and Ayuso E, et al. “High AAV vector purity results in serotype- and tissue independent enhancement of transduction efficiency.”  Gene Ther  2010; 17:503-510. 
     The term “FXN gene insert” shall mean a gene insert comprising a nucleic acid sequence encoding FXN. In one embodiment, gene insert comprises a nucleic acid sequence encoding human FXN (hFXN). In one embodiment, the nucleic acid sequence encoding hFXN is an unmodified FXN cDNA. In one particular embodiment, the nucleic acid sequence encoding hFXN is a cDNA corresponding to the sequence of normal human frataxin mRNA described in Reference Sequence: NM_000144.4. (See JJ Carvajal et al., “The Friedreich&#39;s ataxia gene encodes a novel phosphatidylinositol-4-phosphate 5-kinase”  Nat. Genet.  14 (2), 157-162 (1996).) 
     The term “vector genome” or “vg” shall be broadly understood to encompass gene insert-containing vectors or virions. For convenience, “vector genomes” shall include, but shall not be limited to, gene insert-containing vectors or virions encapsulated within capsids such as AAV viruses and rAAV vectors and gene inserts, that are not encapsulated by capsids. For convenience gene insert-containing vectors or virions, that are not encapsulated by capsids include isolated gene insert-containing vectors or virions. See U.S. Pat. No. 9,598,703 “Capsid-free AAV vectors, compositions, and methods for vector production and gene delivery.” 
     For quantitative purposes, “vg” is calculated as a count of gene insert-containing vectors or virions. In one example, of a single “vector genome” or single “vg” is a single gene insert or a single capsid carrying a gene insert-containing vector or virion. In another example, one AAV5.hFXN vector particle shall mean “1 vg,” while about 5×10 14  vg shall mean about 5×10 14  AAV5.hFXN vectors. 
     The term “capsid particle” or “cp” shall be broadly understood to encompass any capsid. For convenience, the capsids may be full (e.g., encapsulating a gene insert) or empty. Capsid particles include, but not limited to, capsids carrying vector genomes (e.g., AAV viruses, and rAAV vectors), empty capsids, modified capsids, content-modified capsids, and mutant empty capsids. 
     For quantitative purposes, “cp” is calculated as a count of the total number of combined capsids carrying vector genomes (e.g., AAV viruses, and rAAV vectors, virions), empty capsids, modified capsids, content-modified capsids, and mutant empty capsids. In one example, “1 cp” shall mean one empty capsid, while about 1.76×10 12  cp shall mean about 1.76×10 12  empty capsids. In another example, a pharmaceutical formulation comprising 50% cp/cp empty capsids comprises 50 empty capsid particles per 100 total capsid particles (full and empty). In another example, a pharmaceutical formulation comprising 10% empty capsids can comprise a total of about 5.5×10 14  cp capsid particles, wherein the pharmaceutical formulation comprises about 5×10 14  vg AAV5.hFXN vectors and about 5×10 13  cp empty capsids. 
     The term “transduction” shall mean the transport of a gene to a cell by using a virus particle. 
     The term “effective amount” or “therapeutically effective amount” is an amount sufficient to affect a therapeutically beneficial or therapeutically desired result. A therapeutically effective amount can be administered in one or more administrations, applications or dosages. 
     The term “target point” or “target site” shall mean a location in the central nervous system (CNS) of a subject where the pharmaceutical formulation is administered. In one aspect, the target site is the cerebrospinal fluid (CSF) space. In one embodiment, the target site is the subarachnoid space. In another embodiment, the target site is the cerebroventricular space. In one embodiment, the target site is the brain. In another embodiment, the target site is the spine. In another embodiment, the target site is the cauda equina. A target site may optionally be the cerebrum, cerebellum, hippocampus, interior cortex, dorsal root ganglion, dentate nucleus, caudate nucleus, or cisterna magna. A target site may optionally be the sacral, lumbar, thoracic or cervical spine. The pharmaceutical formulation may be administered to one or more target sites. 
     The term “plasmid construct” shall mean a circular nucleic acid molecule that is used in combination with at least one other plasmid, to transfect a cell line in vitro to produce capsid particles. In one embodiment, the plasmid construct comprises: a nucleic acid sequence encoding hFXN (e.g., Human FXN cDNA); a Human Ubiquitin C (UBC) promoter; 5U2, which is a synthetic 5′ regulatory element derived from the second intron of the canine sarcoplasmic/endoplasmic reticulum calcium ATPase gene and the 5′ untranslated region of the bovine casein gene (U.S. Pat. No. 8,835,621); a Human Growth Hormone Poly A(hGH-Poly A); two AAV2 inverted terminal repeats (ITRs) flanking the AAV2 gene elements; and an antibiotic resistance gene. 
     As used herein, “nucleic acid,” “nucleic acid molecule,” “nucleic acid sequence,” “oligonucleotide,” “oligonucleotide sequence,” “nucleotide sequence,” “polynucleotide,” and “polynucleotide sequence” are used interchangeably and refer to the phosphate ester polymeric form of ribonucleosides (adenosine, guanosine, uridine or cytidine; “RNA molecules”) or deoxyribonucleosides (deoxyadenosine, deoxyguanosine, deoxythymidine, or deoxycytidine; “DNA molecules”), or any phosphoester analogs thereof, such as phosphorothioates and thioesters, in either single stranded form, or a double-stranded helix. Double stranded DNA-DNA, DNA-RNA and RNA-RNA helices are possible. The term nucleic acid molecule, and in particular DNA or RNA molecule, refers only to the primary and secondary structure of the molecule, and does not limit it to any particular tertiary forms. Thus, this term includes double-stranded DNA found, inter alia, in linear or circular DNA molecules (e.g., restriction fragments), plasmids, supercoiled DNA and chromosomes. In discussing the structure of particular double-stranded DNA molecules, sequences may be described herein according to the normal convention of giving only the sequence in the 5 ‘ to 3’ direction along the non-transcribed strand of DNA (i.e., the strand having a sequence homologous to the mRNA). 
     As used herein, a “recombinant DNA molecule” is a DNA molecule that has undergone a molecular biological manipulation. DNA includes but is not limited to cDNA, genomic DNA, plasmid DNA, synthetic DNA, and semi-synthetic DNA. 
     As used herein, the term “fragment” used in connection with a polynucleotide sequence (e.g. “polynucleotide fragment”) refers to a nucleotide sequence of reduced length relative to the reference nucleic acid and comprising, over the common portion, a nucleotide sequence identical to the reference nucleic acid. Such a nucleic acid fragment according to the invention may be, where appropriate, included in a larger polynucleotide of which it is a constituent. Such fragments comprise, or alternatively consist of, polynucleotides ranging in length from at least 6, 8, 9, 10, 12, 15, 18, 20, 21, 22, 23, 24, 25, 30, 39, 40, 42, 45, 48, 50, 51, 54, 57, 60, 63, 66, 70, 75, 78, 80, 90, 100, 105, 120, 135, 150, 200, 300, 500, 720, 900, 1000 or 1500 consecutive nucleotides of a nucleic acid according to the invention. 
     As used herein, the term “chimeric” means comprised of fragments that are not contiguous in their natural state. For example, a chimeric polynucleotide means a polynucleotide comprising fragments that are not contiguous in their natural state. 
     As used herein, the term “synthetic” used in connection with a polynucleotide sequence is a non-natural polynucleotide (or portion of a polynucleotide) that differs from a wild-type polynucleotide sequence. For example, a synthetic gene (or portion of a gene) may contain one or more nucleic acid sequences not contiguous in nature (chimeric sequences), and/or may encompass substitutions, insertions, and deletions and combinations thereof. 
     As used herein, “gene” refers to a polynucleotide comprising nucleotides that encode a functional molecule (e.g., a polypeptide or RNA), and includes cDNA or genomic DNA nucleic acids. It is generally understood that genomic DNA encoding for a polypeptide or RNA includes non-coding regions (i.e. introns) that are spliced from mature mRNA, and are therefore not present in cDNA encoding for the same polypeptide or RNA. “Gene” may comprise a nucleic acid fragment that expresses a specific RNA, protein or polypeptide. The “gene” may further comprise regulatory sequences preceding (5′ non-coding sequences) and following (3′ non-coding sequences) the coding sequence. The “gene” may also comprise triplex-forming oligonucleotides (TFOs). “Native gene” refers to a gene as found in nature with its own regulatory sequences. “Chimeric gene” or “recombinant gene” refers to any gene that is not a native gene, comprising regulatory and/or coding sequences that are not found together in nature. Accordingly, a chimeric gene may comprise regulatory sequences and coding sequences that are derived from different sources, or regulatory sequences and coding sequences derived from the same source, but arranged in a manner different than that found in nature. A chimeric gene may comprise coding sequences derived from different sources and/or regulatory sequences derived from different sources. “Endogenous gene” refers to a native gene in its natural location in the genome of an organism. 
     A “foreign” gene or “exogenous” gene or “heterologous” gene or “transgene” refers to a gene not normally found in the host cell or organism, but that is introduced into the host cell or organism by gene transfer. Transgenes can comprise native genes inserted into a non-native organism, or chimeric or synthetic genes. A transgene may also be a cDNA version of an endogenous gene. A transgene gene may also be an unmutated version of an endogenous mutated gene or a mutated version of an endogenous unmutated gene. A transgene gene may also be a therapeutic gene or an experimental gene such as a reporter. A transgene can be directly introduced into the target cells of a host organism, or indirectly introduced by the transfer of transformed cells, e.g. autologous cells, into the host organism. 
     As used herein, the “5′ untranslated region” or “5′UTR” of a gene is to be understood as that part of a gene which is transcribed into a primary RNA transcript (pre-mRNA) and which part is located upstream of the coding sequence. The primary transcript is the initial RNA product, containing introns and exons, produced by transcription of DNA. Many primary transcripts must undergo RNA processing to form the physiologically active RNA species. The processing into a mature mRNA may comprise trimming of the ends, removal of introns, capping and/or cutting out of individual rRNA molecules from their precursor RNAs. The 5′UTR of an mRNA is thus that part of the mRNA which is not translated into protein and which is located upstream of the coding sequence. In a genomic sequence, the 5′UTR is typically defined as the region between the transcription initiation site and the start codon. The 5′ untranslated regions (5′UTRs) of vertebrate mRNAs may be a few tens of bases to several hundred bases in length (Crowe et al., 2006 BMC Genomics 7:16). A “synthetic 5′UTR” is a non-natural 5′UTR that differs from a wild-type 5′UTR polynucleotide sequence. A synthetic 5′UTR may contain one or more nucleic acid sequences not contiguous in nature (chimeric sequences), and/or may encompass substitutions, insertions, and deletions and combinations thereof. 
     As used herein, a “splice junction,” “intron-exon splice junction,” or “splice site” are regions at the boundaries of an intron in eukaryotic pre-mRNAs recognized by the cell&#39;s splicing apparatus where two neighboring exons are joined and the intron is deleted. Splice sites are represented by conserved sequences at the 5′ and 3′ intron/exon boundaries. For the vast majority of introns, the most conserved sequences are GU flanking the 5′ end of the intron and AG flanking at the 3′ end. However, exceptions to these consensus sequences are also known such as introns with AU-AC splice sites. The 5′ splice site at an intron-exon boundary is known as a “splice donor” site. The 3′ splice site at an intron-exon boundary is known as a “splice acceptor” site. A “spliceosome” is a large ribonucleoprotein complex that serves as the cell&#39;s splicing apparatus. The spliceosome is comprised of small nuclear ribonucleoproteins (snRNP) subunits that assemble on a pre-mRNA substrate. The snRNPs are themselves comprised of small nuclear RNAs (snRNAs) and several protein subunits. During the splicing reaction, recognition of splice sites within the pre-mRNA is performed through base-pairing with snRNAs. 
     As used herein, “heterologous” DNA refers to DNA not naturally located in the cell, or in a chromosomal site of the cell. Therefore, the heterologous DNA includes a gene foreign to the cell. “Heterologous” DNA may also include a gene naturally existing in the cell, but located in a non-native location. Furthermore, a “heterologous” DNA molecule may be a DNA molecule containing a non-host DNA segment, operably linked to a host DNA segment, for example, a transcription promoter. Conversely, a heterologous DNA molecule may comprise an endogenous gene operably linked with an exogenous promoter. Further, “heterologous” may refer to a DNA molecule or fragment that is derived from a gene that does not share a common evolutionary origin with a reference DNA molecule or fragment. 
     As used herein, the term “genome” includes chromosomal as well as mitochondrial, chloroplast and viral DNA or RNA. 
     As used herein, the term “probe” refers to a single-stranded nucleic acid molecule that can base pair with a complementary single stranded target nucleic acid to form a double-stranded molecule. 
     As used herein, a DNA “coding sequence” refers to a double-stranded DNA sequence that encodes a polypeptide and can be transcribed and translated into a polypeptide in a cell in vitro or in vivo or outside a cell, e.g., in a tube, when placed under the control of appropriate regulatory sequences. “Suitable regulatory sequences” refers to nucleotide sequences located upstream (5′ non-coding sequences), within, or downstream (3′ non-coding sequences) of a coding sequence, and which influence the transcription, RNA processing or stability, or translation of the associated coding sequence. Regulatory sequences may include promoters, translation leader sequences, introns, polyadenylation recognition sequences, RNA processing site, effector binding site and stem-loop structure. The boundaries of the coding sequence are determined by a start codon at the 5′ (amino) terminus and a translation stop codon at the 3′ (carboxyl) terminus. A coding sequence can include, but is not limited to, prokaryotic, eukaryotic, or chimeric sequences, cDNA from mRNA, genomic DNA sequences, and even synthetic DNA sequences. 
     As used herein, “open reading frame” is abbreviated ORF and refers to a length of nucleic acid sequence, either DNA, cDNA or RNA, that comprises a translation start signal or initiation codon, such as an ATG or AUG, and a termination codon and can be potentially translated into a polypeptide sequence. 
     As used herein, the term “downstream” refers to a nucleotide sequence that is located 3′ to a reference nucleotide sequence. In particular, downstream nucleotide sequences generally relate to sequences that follow the starting point of transcription. For example, the translation initiation codon of a gene is located downstream of the start site of transcription. The term “upstream” refers to a nucleotide sequence that is located 5′ to a reference nucleotide sequence. In particular, upstream nucleotide sequences generally relate to sequences that are located on the 5′ side of a coding sequence or starting point of transcription. For example, most promoters are located upstream of the start site of transcription. 
     As used herein, the term “chemically synthesized,” as related to a sequence of DNA, means that the component nucleotides were assembled in vitro. Manual chemical synthesis of DNA may be accomplished using well-established procedures, or automated chemical synthesis can be performed using one of a number of commercially available machines. Accordingly, the genes can be tailored for optimal gene expression based on optimization of nucleotide sequence to reflect the codon bias of the host cell. The skilled artisan appreciates the likelihood of successful gene expression if codon usage is biased towards those codons favored by the host. Determination of preferred codons can be based on a survey of genes derived from the host cell where sequence information is available. 
     As used herein, the terms “restriction endonuclease” and “restriction enzyme” are used interchangeably and refer to an enzyme that binds and cuts within a specific nucleotide sequence within double stranded DNA. 
     As used herein, the terms “polypeptide,” “peptide,” and “protein” are used interchangeably and refer to a polymeric compound comprised of covalently linked amino acid residues. 
     As used herein, “polymerase chain reaction” is abbreviated PCR and refers to an in vitro method for enzymatically amplifying specific nucleic acid sequences. PCR involves a repetitive series of temperature cycles with each cycle comprising three stages: denaturation of the template nucleic acid to separate the strands of the target molecule, annealing a single stranded PCR oligonucleotide primer to the template nucleic acid, and extension of the annealed primer(s) by DNA polymerase. 
     As used herein, the term “homology” refers to the percent of identity between two polynucleotide or two polypeptide moieties. The correspondence between the sequence from one moiety to another can be determined by techniques known to the art. For example, homology can be determined by a direct comparison of the sequence information between two polypeptide molecules by aligning the sequence information and using readily available computer programs. Alternatively, homology can be determined by hybridization of polynucleotides under conditions that form stable duplexes between homologous regions, followed by digestion with single-stranded-specific nuclease(s) and size determination of the digested fragments. As used herein, the term “homologous” in all its grammatical forms and spelling variations refers to the relationship between proteins that possess a “common evolutionary origin,” including proteins from superfamilies (e.g., the immunoglobulin superfamily) and homologous proteins from different species (e.g., myosin light chain, etc.) (Reeck et al., (1987)  Cell  50:667). Such proteins (and their encoding genes) have sequence homology, as reflected by their high degree of sequence similarity. However, in common usage and in the present application, the term “homologous,” when modified with an adverb such as “highly,” may refer to sequence similarity and not a common evolutionary origin. 
     Accordingly, the term “sequence similarity” in all its grammatical forms refers to the degree of identity or correspondence between nucleic acid or amino acid sequences of proteins that may or may not share a common evolutionary origin (see Reeck et al., (1987)  Cell  50:667). In one embodiment, two DNA sequences are “substantially homologous” or “substantially similar” when at least about 21% (preferably at least about 50%, and most preferably at least about 75%, 90%, 95%, 96%, 97%, 98%, or 99%) of the nucleotides match over the defined length of the DNA sequences. Sequences that are substantially homologous can be identified by comparing the sequences using standard software available in sequence data banks, or in a Southern hybridization experiment under, for example, stringent conditions as defined for that particular system. Defining appropriate hybridization conditions is within the skill of the art (see e.g., Sambrook et al., 1989, infra). 
     As used herein, “substantially similar” refers to nucleic acid fragments wherein changes in one or more nucleotide bases results in substitution of one or more amino acids, but do not affect the functional properties of the protein encoded by the DNA sequence. “Substantially similar” also refers to nucleic acid fragments wherein changes in one or more nucleotide bases do not affect the ability of the nucleic acid fragment to mediate alteration of gene expression by antisense or co-suppression technology. “Substantially similar” also refers to modifications of the nucleic acid fragments of the present invention such as deletion or insertion of one or more nucleotide bases that do not substantially affect the functional properties of the resulting transcript. It is therefore understood that the invention encompasses more than the specific exemplary sequences. Each of the proposed modifications is well within the routine skill in the art, as is determination of retention of biological activity of the encoded products. 
     Moreover, the skilled artisan recognizes that substantially similar sequences encompassed by this invention are also defined by their ability to hybridize, under stringent conditions. A nucleic acid molecule is “hybridizable” to another nucleic acid molecule, such as a cDNA, genomic DNA, or RNA, when a single stranded form of the nucleic acid molecule can anneal to the other nucleic acid molecule under the appropriate conditions of temperature and solution ionic strength (see Sambrook et al., 1989 infra). Hybridization and washing conditions are well known and exemplified in Sambrook, J., Fritsch, E. F. and Maniatis, T. M OLECULAR  C LONING . A L ABORATORY  M ANUAL , Second Edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor (1989), particularly Chapter 11 and Table 11.1 therein. The conditions of temperature and ionic strength determine the “stringency” of the hybridization. 
     Stringency conditions can be adjusted to screen for moderately similar fragments, such as homologous sequences from distantly related organisms, to highly similar fragments, such as genes that duplicate functional enzymes from closely related organisms. For preliminary screening for homologous nucleic acids, low stringency hybridization conditions, corresponding to a Tm of 55° C., can be used, e.g., 5×SSC, 0.1% SDS, 0.25% milk, and no formamide; or 30% formamide, 5×SSC, 0.5% SDS. Moderate stringency hybridization conditions correspond to a higher Tm, e.g., 40% formamide, with 5× or 6×SSC. High stringency hybridization conditions correspond to the highest Tm, e.g., 50% formamide, 5× or 6×SSC. 
     Hybridization requires that the two nucleic acids contain complementary sequences, although depending on the stringency of the hybridization, mismatches between bases are possible. The term “complementary” is used to describe the relationship between nucleotide bases that are capable of hybridizing to one another. For example, with respect to DNA, adenosine is complementary to thymine and cytosine is complementary to guanine. Accordingly, the instant invention also includes isolated nucleic acid fragments that are complementary to the complete sequences as disclosed or used herein as well as those substantially similar nucleic acid sequences. 
     In one embodiment, polynucleotides are detected by employing hybridization conditions comprising a hybridization step at Tm of 55° C., and utilizing conditions as set forth above. In another embodiment, the Tm is 60° C.; in certain embodiments, the Tm is 63° C. or 65° C. 
     Post-hybridization washes also determine stringency conditions. One set of preferred conditions uses a series of washes starting with 6×SSC, 0.5% SDS at room temperature for 15 minutes (min), then repeated with 2×SSC, 0.5% SDS at 45° C. for 30 minutes, and then repeated twice with 0.2×SSC, 0.5% SDS at 50° C. for 30 minutes. Another example of stringent conditions uses higher temperatures in which the washes are identical to those above except for the temperature of the final two 30 min washes in 0.2×SSC, 0.5% SDS was increased to 60° C. Still another example of highly stringent conditions uses two final washes in 0.1×SSC, 0.1% SDS at 65° C. Hybridization requires that the two nucleic acids comprise complementary sequences, although depending on the stringency of the hybridization, mismatches between bases are possible. 
     The appropriate stringency for hybridizing nucleic acids depends on the length of the nucleic acids and the degree of complementation, variables well known in the art. The greater the degree of similarity or homology between two nucleotide sequences, the greater the value of Tm for hybrids of nucleic acids having those sequences. The relative stability (corresponding to higher Tm) of nucleic acid hybridizations decreases in the following order: RNA:RNA, DNA:RNA, DNA:DNA. For hybrids of greater than 100 nucleotides in length, equations for calculating Tm have been derived (see Sambrook et al., supra, 9.50-0.51). For hybridization with shorter nucleic acids, i.e., oligonucleotides, the position of mismatches becomes more important, and the length of the oligonucleotide determines its specificity (see Sambrook et al., supra, 11.7-11.8). 
     In one embodiment, polynucleotides are detected by employing hybridization conditions comprising a hybridization step in less than 500 mM salt and at least 37° C., and a washing step in 2×SSPE at a temperature of at least 63° C. In another embodiment, the hybridization conditions comprise less than 200 mM salt and at least 37° C. for the hybridization step. In certain embodiments, the hybridization conditions comprise 2×SSPE and 63° C. for both the hybridization and washing steps. 
     The length for a hybridizable nucleic acid is, for example, at least about 10 nucleotides. A minimum length for a hybridizable nucleic acid may be at least about 15 nucleotides; at least about 20 nucleotides; or at least 30 nucleotides. Furthermore, the skilled artisan will recognize that the temperature and wash solution salt concentration may be adjusted as necessary according to factors such as length of the probe. 
     Substantially similar nucleic acid fragments of the present invention are those nucleic acid fragments whose DNA sequences are at least 70% identical to the DNA sequence of the nucleic acid fragments reported herein. Nucleic acid fragments of the present invention include those nucleic acid fragments whose DNA sequences are at least 80%, 90%, 95%, 96%, 97%, 98%, and 99% identical to the DNA sequence of the nucleic acid fragments reported herein. 
     As used herein, the term “corresponding to” is used herein to refer to similar or homologous sequences, whether the exact position is identical or different from the molecule to which the similarity or homology is measured. A nucleic acid or amino acid sequence alignment may include spaces. Thus, the term “corresponding to” refers to the sequence similarity, and not the numbering of the amino acid residues or nucleotide bases. 
     As used herein, a “substantial portion” of an amino acid or nucleotide sequence comprises enough of the amino acid sequence of a polypeptide or the nucleotide sequence of a gene to putatively identify that polypeptide or gene, either by manual evaluation of the sequence by one skilled in the art, or by computer-automated sequence comparison and identification using algorithms such as BLAST (Basic Local Alignment Search Tool; Altschul et al., J. Mol. Biol. 215:403 410 (1993)); BLAST is publicly available on the World Wide Web. In general, a sequence of ten or more contiguous amino acids or thirty or more nucleotides is necessary in order to putatively identify a polypeptide or nucleic acid sequence as homologous to a known protein or gene. Moreover, with respect to nucleotide sequences, gene specific oligonucleotide probes comprising 20 to 30 contiguous nucleotides may be used in sequence-dependent methods of gene identification (e.g., Southern hybridization) and isolation (e.g., in situ hybridization of bacterial colonies or bacteriophage plaques). In addition, short oligonucleotides of 12 to 15 bases may be used as amplification primers in PCR in order to obtain a particular nucleic acid fragment comprising the primers. Accordingly, a “substantial portion” of a nucleotide sequence comprises enough of the sequence to specifically identify and/or isolate a nucleic acid fragment comprising the sequence. 
     As used herein, the term “percent similarity,” as known in the art, is a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, as determined by comparing the sequences. In the art, “identity” also means the degree of sequence relatedness between polypeptide or polynucleotide sequences, as the case may be, as determined by the match between strings of such sequences. “Identity” and “similarity” can be readily calculated by known methods, including but not limited to those described in: Computational Molecular Biology (Lesk, A. M., ed.) Oxford University Press, New York (1988); B IOCOMPUTING : I NFORMATICS AND  G ENOME  P ROJECTS  (Smith, D. W., ed.) Academic Press, New York (1993); C OMPUTER  A NALYSIS OF  S EQUENCE  D ATA , P ART  I (Griffin, A. M., and Griffin, H. G., eds.) Humana Press, New Jersey (1994); S EQUENCE  A NALYSIS IN  M OLECULAR  B IOLOGY  (von Heinje, G., ed.) Academic Press (1987); and S EQUENCE  A NALYSIS  P RIMER  (Gribskov, M. and Devereux, J., eds.) Stockton Press, New York (1991). Methods to determine identity are designed to give the best match between the sequences tested. Methods to determine identity and similarity are codified in publicly available computer programs. Sequence alignments and percent identity calculations may be performed using the Megalign program of the LASERGENE bioinformatics computing suite (DNASTAR Inc., Madison, Wis.). Multiple alignment of the sequences may be performed using the Clustal method of alignment (Higgins et al., CABIOS. 5:151 153 (1989)) with the default parameters (GAP PENALTY=IO, GAP LENGTH PENALTY=IO). Default parameters for pairwise alignments using the Clustal method may be selected: KTUPLE 1, GAP PENALTY=3, WINDO W=5 and DIAGONALS SAVED=5. 
     As used herein, the term “sequence analysis software” refers to any computer algorithm or software program that is useful for the analysis of nucleotide or amino acid sequences. “Sequence analysis software” may be commercially available or independently developed. Typical sequence analysis software will include, but is not limited to, the GCG suite of programs (Wisconsin Package Version 9.0, Genetics Computer Group (GCG), Madison, Wis.), BLASTP, BLASTN, BLASTX (Altschul et al.,  J. Mol. Biol.  215:403 410 (1990)), and DNASTAR (DNASTAR, Inc. 1228 S. Park St., Madison, Wis. 53715 USA). Within the context of this application it will be understood that where sequence analysis software is used for analysis, that the results of the analysis will be based on the “default values” of the program referenced, unless otherwise specified. As used herein “default values” will mean any set of values or parameters which originally load with the software when first initialized. 
     As used herein, the terms “expression” or “gene expression” refer to the process of converting genetic information encoded in a gene into RNA (e.g., mRNA, rRNA, tRNA, or snRNA) through “transcription” of the gene (i.e., via the enzymatic action of an RNA polymerase), and for protein encoding genes, into protein through “translation” of mRNA. Gene expression can be regulated at many stages in the process. “Upregulation” or “activation” refers to regulation that increases the production of gene expression products (i.e., RNA or protein), while “down-regulation” or “repression” refers to regulation that decrease production. Factors (e.g., transcription factors) that are involved in up-regulation or down-regulation are often called “activators” and “repressors,” respectively. For the purposes of the invention, a target gene may be down-regulated “post-transcriptionally” (i.e. at the level of the RNA transcript) through specific interaction with a down-regulating RNA molecule. 
     As used herein, the term “Transcriptional and translational control sequences” refer to DNA regulatory sequences, such as promoters, enhancers, terminators, and the like, that provide for the expression of a coding sequence in a host cell. 
     The term “ecdysone receptor-based,” with respect to a gene switch, refers to a gene switch comprising at least a functional part of a naturally occurring or synthetic ecdysone receptor ligand binding domain and which regulates gene expression in response to a ligand that binds to the ecdysone receptor ligand binding domain. Examples of ecdysone-responsive systems are described in U.S. Pat. Nos. 7,091,038 and 6,258,603. In one embodiment, the system is the RHEOSWITCH THERAPEUTIC SYSTEM® (RTS®), which contains two fusion proteins, the DEF domains of a mutagenized ecdysone receptor (EcR) fused with a Gal4 DNA binding domain and the EF domains of a chimeric RXR fused with a VP16 transcription activation domain, expressed under a constitutive promoter. 
     As used herein, the term “operably linked” refers to the association of nucleic acid sequences on a single nucleic acid fragment so that the function of one is affected by the other. For example, a promoter is operably linked with a coding sequence when it is capable of affecting the expression of that coding sequence (i.e., that the coding sequence is under the transcriptional control of the promoter). Coding sequences can be operably linked to regulatory sequences in sense or antisense orientation. 
     As used herein, “vector” refers to any vehicle for the cloning of and/or transfer of a nucleic acid into a host cell. A vector may be a replicon to which another DNA segment may be attached so as to bring about the replication of the attached segment. A “replicon” refers to any genetic element (e.g., plasmid, phage, cosmid, chromosome, virus) that functions as an autonomous unit of DNA replication in vivo, i.e., capable of replication under its own control. The term “vector” includes both viral and non-viral vehicles for introducing the nucleic acid into a host cell in vitro, ex vivo or in vivo. The term “vector” may also include minicircle DNAs. For example, the vector may be a plasmid without bacterial DNA sequences. The removal of bacterial DNA sequences which are rich in CpG regions has been shown to decrease transgene expression silencing and result in more persistent expression from plasmid DNA vectors (see e.g., Ehrhardt, A. et al. (2003)  Hum. Gene Ther.  10: 215-25; Yet, N. S. (2002)  Mol. Ther.  5: 731-38; Chen, Z. Y. et al. (2004)  Gene Ther.  11: 856-64). The term “vector” may also include transposons such as Sleeping Beauty (Izsvak et al. (2000)  J. Mol. Biol.  302:93-102), or artificial chromosomes. 
     A large number of vectors known in the art may be used to manipulate nucleic acids, incorporate response elements and promoters into genes, etc., or transfer a nucleic acid into a host cell. Possible vectors include, for example, plasmids or modified viruses including, for example bacteriophages such as lambda derivatives, or plasmids such as pBR322 or pUC plasmid derivatives, or the Bluescript vector. Larger vectors such as artificial chromosomes (bacteria (BAC), yeast (YAC), or human (HAC)) may be used to accommodate larger inserts. For example, the insertion of the DNA fragments corresponding to response elements or promoters into a suitable vector can be accomplished by ligating the appropriate DNA fragments into a chosen vector that has complementary cohesive termini. Alternatively, the ends of the DNA molecules may be enzymatically modified or any site may be produced by ligating nucleotide sequences (linkers) into the DNA termini. Such vectors may be engineered to contain selectable marker genes that provide for the selection of cells transfected or transformed with the vector. A recombinant vector comprising a polynucleotide according to the invention may include one or more origins for replication in the cellular hosts in which their amplification or their expression is sought, markers or selectable markers. 
     As used herein, the term “selectable marker” refers to an identifying factor, usually an antibiotic or chemical resistance gene, that is able to be selected for based upon the marker gene&#39;s effect, i.e., resistance to an antibiotic, resistance to a herbicide, colorimetric markers, enzymes, fluorescent markers, and the like, wherein the effect is used to track the inheritance of a nucleic acid of interest and/or to identify or select a cell or organism that has inherited the nucleic acid of interest. Examples of selectable marker genes known and used in the art include: genes providing resistance to ampicillin, streptomycin, gentamycin, kanamycin, hygromycin, bialaphos herbicide, sulfonamide, and the like; and genes that are used as phenotypic markers, i.e., anthocyanin regulatory genes, isopentanyl transferase gene, and the like. 
     As used herein, the term “reporter gene” refers to a nucleic acid encoding an identifying factor that is able to be identified based upon the reporter gene&#39;s effect, wherein the effect is used to track the inheritance of a nucleic acid of interest, to identify a cell or organism that has inherited the nucleic acid of interest, and/or to measure gene expression induction or transcription. Examples of reporter genes known and used in the art include: luciferase (Luc), fluorescent proteins such as green fluorescent protein (GFP), chloramphenicol acetyltransferase (CAT), beta-galactosidase (LacZ), beta-glucuronidase (Gus), and the like. Selectable marker genes may also be considered reporter genes. 
     As used herein, the term “plasmid” refers to an extra-chromosomal element often carrying a gene that is not part of the central metabolism of the cell, and usually in the form of circular double-stranded DNA molecules. Such elements may be autonomously replicating sequences, genome integrating sequences, phage or nucleotide sequences, linear, circular, or supercoiled, of a single- or double-stranded DNA or RNA, derived from any source, in which a number of nucleotide sequences have been joined or recombined into a unique construction which is capable of introducing a promoter fragment and DNA sequence for a selected gene product along with appropriate 3′ untranslated sequence into a cell. 
     As used herein, a “cloning vector” refers to a “replicon,” which is a unit length of a nucleic acid, e.g., DNA, that replicates sequentially and which comprises an origin of replication, such as a plasmid, phage or cosmid, to which another nucleic acid segment may be attached so as to bring about the replication of the attached segment. Cloning vectors may be capable of replication in one cell type and expression in another (“shuttle vector”). The term “expression vector” refers to a vector, plasmid or vehicle designed to enable the expression of an inserted nucleic acid sequence following transformation into a host cell. The cloned gene, i.e., the inserted nucleic acid sequence, is usually placed under the control of control elements such as a promoter, a minimal promoter, an enhancer, or the like. Initiation control regions or promoters, which are useful to drive expression of a nucleic acid in the host cell are numerous and familiar to those skilled in the art. 
     Examples of eukaryotic vectors include, but are not limited to, pW-LNEO, pSV2CAT, pOG44, pXTl and pSG available from Stratagene; pSVK3, pBPV, pMSG and pSVL available from Amersham Pharmacia Biotech; and pCMVDsRed2-express, pIRES2-DsRed2, pDsRed2-Mito, pCMV-EGFP available from Clontech. Many other vectors are well-known and commercially available. 
     For example, useful vectors, which comprise molecular insertion pivots for rapid insertion and removal of elements of gene programs, are described in U.S. Published Patent Application No. 2004/0185556, U.S. patent application Ser. No. 11/233,246 and International Published Application Nos. WO 2005/040336 and WO 2005/116231. 
     As used herein, the terms “promoter” and “promoter sequences” are used interchangeably and refer to a DNA sequence capable of controlling the expression of a coding sequence or functional RNA. In general, a coding sequence is located 3′ to a promoter sequence. Promoters may be derived in their entirety from a native gene, or be composed of different elements derived from different promoters found in nature, or even comprise synthetic DNA segments. It is understood by those skilled in the art that different promoters may direct the expression of a gene in different tissues or cell types, or at different stages of development, or in response to different environmental or physiological conditions. 
     Promoters that cause a gene to be expressed in most cell types at most times are commonly referred to as “constitutive promoters.” Promoters that cause a gene to be expressed in a specific cell type are commonly referred to as “conditional promoters.” Non-limiting examples of conditional promoters are “cell-specific promoters” or “tissue-specific promoters.” Promoters that cause a gene to be expressed at a specific stage of development or cell differentiation are commonly referred to as “developmentally-specific promoters” or “cell differentiation-specific promoters.” Promoters that are induced and cause a gene to be expressed following exposure or treatment of the cell with an agent, biological molecule, chemical, ligand, light, or the like that induces the promoter are commonly referred to as “inducible promoters” or “regulatable promoters.” Non-limiting examples of the inducible promoters are a TetO inducible promoter, heat shock protein promoter, metallothionein promoter, growth hormone promoter, and MMTV-LTR promoter. It is further recognized that since in most cases the exact boundaries of regulatory sequences have not been completely defined, DNA fragments of different lengths may have identical promoter activity. 
     The promoter sequence is typically bounded at its 3′ terminus by the transcription initiation site and extends upstream (5′ direction) to include the minimum number of bases or elements necessary to initiate transcription at levels detectable above background. Within the promoter sequence will be found a transcription initiation site (conveniently defined for example, by mapping with nuclease S1), as well as protein binding domains (consensus sequences) responsible for the binding of RNA polymerase. 
     A coding sequence is “under the control” of transcriptional and translational control sequences in a cell when RNA polymerase transcribes the coding sequence into mRNA, which is then trans-RNA spliced (if the coding sequence contains introns) and translated into the protein encoded by the coding sequence. 
     Termination control regions, i.e., terminator or polyadenylation sequences, may also be derived from various genes native to the preferred hosts. Optionally, a termination site may be unnecessary, however, it can be included. In one embodiment of the invention, the termination control region may be comprised or be derived from a synthetic sequence, synthetic polyadenylation signal, an SV40 late polyadenylation signal, an SV40 polyadenylation signal, a bovine growth hormone (BGH) polyadenylation signal, viral terminator sequences, or the like. 
     As used herein, the term “transfection” refers to the uptake of exogenous or heterologous RNA or DNA by a cell. A cell has been “transfected” by exogenous or heterologous RNA or DNA when such RNA or DNA has been introduced inside the cell. The transfected RNA or DNA can be integrated (covalently linked) into chromosomal DNA making up the genome of the host cell. “Transformation” refers to the transfer of a nucleic acid fragment into the genome of a host organism, resulting in genetically stable inheritance. 
     As used herein, the terms “modulate” and “modulates” mean to induce, reduce or inhibit nucleic acid or gene expression, resulting in the respective induction, reduction or inhibition of protein or polypeptide production. 
     As used herein, “RNA transcript” refers to the product resulting from RNA polymerase-catalyzed transcription of a DNA sequence. When the RNA transcript is a perfect complementary copy of the DNA sequence, it is referred to as the primary transcript or it may be a RNA sequence derived from post-transcriptional processing of the primary transcript and is referred to as the mature RNA. “Messenger RNA (mRNA)” refers to the RNA that is without introns and that can be translated into protein by the cell. “cDNA” refers to a double-stranded DNA that is complementary to and derived from mRNA. “Sense” RNA refers to RNA transcript that includes the mRNA and so can be translated into protein by the cell. 
     “Stuffer sequences” comprised of non-coding polynucleotides ranging from 1001 to 3000 bp to ensure optimal genome packaging size for AAV, may be incorporated into the viral vectors of the invention. 
     The invention provides polynucleotides comprising a nucleic acid sequence encoding a frataxin protein. As used herein, a “frataxin protein” refers to a polypeptide that has the biological activity of frataxin and has an amino acid sequence that is at least 80% identical to the human frataxin sequence shown in SEQ ID NO:1. In some embodiments, the polypeptide has an amino acid sequence that is at least 85% identical to SEQ ID NO:1. In other embodiments, the polypeptide has an amino acid sequence that is at least 90% identical to SEQ ID NO:1. In other embodiments, the polypeptide has an amino acid sequence that is at least 95% identical to SEQ ID NO:1. In other embodiments, the polypeptide has an amino acid sequence that is at least 96%, 97%, 98%, or 99% identical to SEQ ID NO:1. In some embodiments, the polypeptide has the amino acid sequence of SEQ ID NO:1. The nucleic acids encoding the frataxin protein may be that shown in SEQ ID NO:2 or any sequence that encodes SEQ ID NO:1 that differs from SEQ ID NO:2 due to the degeneracy of the genetic code. Nucleic acids that encode the variants of the frataxin protein may be a nucleic acid that encodes a polypeptide has an amino acid sequence that is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to SEQ ID NO:1. 
     Nucleic Acid Molecules 
     Frataxins 
     Friedreich&#39;s Ataxia (FRDA) is linked to a deficiency of frataxin (FXN), a mitochondrial protein involved in iron-sulfur cluster synthesis. The frataxin proteins that are useful in the invention are full-length frataxin proteins, functional truncations, functional variants and functional analogues. By “functional” it is meant that the frataxin used in the invention retains frataxin activity sufficient to alleviate at least one symptom of Friedreich&#39;s ataxia. The frataxin protein sequence preferably contains a portion at the N-terminus that directs the protein for translocation into the mitochondria. Mitochondrial localization sequences (also called “transit peptides”) are known in the art. The frataxin localization sequence is amino acids 1-41 of SEQ ID NO:1. This sequence could be substituted by other mitochondrial translocators whose sequences are known in the art. SEQ ID NO:1 shows the frataxin preproprotein for which amino acids 1-41 constitute the transit peptide, amino acids 42-210 constitute the proprotein, and amino acids 56-210 constitute the mature protein. 
     In a detailed study of the frataxin protein, Faraj et al. investigated the structural-functional relationship of the C-terminal region (CTR) or frataxin and the effect of alterations on the stability of the frataxin protein (Faraj, S. E. et al. (2014)  FEBS J.  281(15):3397-3419) (incorporated by reference herein in its entirety). Faraj et al. found that a certain mutant with a L198R mutation or a complete truncation from 81-193 was sufficient to cause Friedreich&#39;s ataxia. Other mutants such as a L203C mutation increased the stability of the protein. In another study for her Master&#39;s Thesis for Texas A&amp;M University (2013), Melissa Thorstad found that FXN β4 and β5 sheets residues Q153, W155, and R165 were implicated as vital for SDU binding, and residues N146, Q148, Q153, and W155 appeared to be essential for SDU activation. Thus, functional frataxin proteins of use in the invention include those that maintain the structure and stability of the frataxin CTR, one example being the L203C variant. In general, the frataxin protein that is useful in the invention has an amino acid sequence is at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to that of SEQ ID NO:1 provided that certain residues, including a transit peptide and pro-sequence (amino acids 42-55 of SEQ ID NO:1), and Q153, W155, R165, N146, Q148, Q153, and W155, are included. Such frataxin proteins may be determined by one of skill in the art using the methods of Faraj et al. and assessing stability and structure of the CTR, and maintaining critical residues as described by Faraj and Thorstad. 
     Promoters 
     Promoters, which are useful to drive expression of a nucleic acid in the desired host cell are numerous and familiar to those skilled in the art. Virtually any promoter capable of driving expression of the polynucleotide encoding frataxin can be used in an expression vector, including but not limited to, viral promoters, bacterial promoters, animal cell promoters, mammalian cell promoters, synthetic promoters, constitutive promoters, tissue-specific promoters, pathogenesis or disease related promoters, developmental specific promoters, inducible promoters, and light regulated promoters. Animal and mammalian promoters known in the art include, but are not limited to, the SV40 early (SV40e) promoter region, the promoter contained in the 3′ long terminal repeat (LTR) of Rous sarcoma virus (RSV), the promoters of the E1A or major late promoter (MLP) genes of adenoviruses (Ad), the cytomegalovirus (CMV) early promoter, the herpes simplex virus (HSV) thymidine kinase (TK) promoter, a baculovirus IE1 promoter, an elongation factor 1 alpha (EF1) promoter, a phosphoglycerate kinase (PGK1) promoter, a ubiquitin (UBC) promoter, an albumin promoter, the regulatory sequences of the mouse metallothionein-L promoter and transcriptional control regions, the ubiquitous promoters (HPRT, vimentin, (x-actin, tubulin and the like), the promoters of the intermediate filaments (desmin, neurofilaments, keratin, GFAP, and the like), the promoters of therapeutic genes (of the MDR, CFTR or factor VIII type, and the like), pathogenesis or disease related-promoters, and promoters that exhibit tissue specificity and have been utilized in transgenic animals, such as myelin basic protein gene control region active in oligodendrocyte cells in the brain, myosin light chain-2 gene control region active in skeletal muscle. In addition, these expression sequences may be modified by addition of enhancer or regulatory sequences and the like. In the polynucleotides of the invention, the frataxin gene is operably linked to a promoter to drive transcription of the frataxin gene. The promoter may be any known promoter that has the effect of driving transcription of the frataxin gene. In certain specific examples of such promoters include, but are not limited to a CMV promoter, a UBC promoter, an EF1α promoter, a PGK1 promoter and a minimal frataxin promoter. In specific embodiments, the polynucleotide encoding frataxin is operably linked to a UBC promoter, such as, for example that shown in SEQ ID NO:3. 
     5′ Regulatory Elements 
     In the polynucleotide comprising a frataxin gene, the polynucleotide preferably comprises at least a portion of a 5′ untranslated region (5′UTR) operably linked to the frataxin gene wherein the 5′UTR may be from any mammalian species. Non-limiting 5′UTRs which could be used include the 5′UTR from a human frataxin gene, a bovine frataxin gene, a mouse frataxin gene, a rat frataxin gene, a sheep frataxin gene, a monkey frataxin gene, a goat frataxin gene, a horse frataxin gene, a pig frataxin gene, a camel frataxin gene, a cat frataxin gene, or a dog frataxin gene. 
     In certain embodiments, at least a portion of a non-frataxin 5′UTR is used. Examples of non-frataxin 5′UTRs include, but are not limited to a glyceraldehyde 3-phosphate dehydrogenase 5′ regulatory element (GAPDH) (e.g., SEQ ID NO:15), a synthetic 5′ regulatory element (such as those described in U.S. Pat. No. 8,835,621, which is incorporated by reference herein in its entirety, including 5U2 (SEQ ID NO:4)), a 60S ribosomal protein L5 5′ regulatory element (RPL6-5′Splice) (e.g., SEQ ID NO:16), and a Ferritin heavy chain 5′ regulatory element (FTH1-5′UTR) (e.g., SEQ ID NO:14). 
     In some embodiments, the 5′UTR may be at least about 25 nucleotides in length. In other embodiments, the 5′UTR may be at least about 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 185, 190, 195, 200 or more nucleotides in length. In another embodiment, the polynucleotide fragment comprising a frataxin gene 5′UTR may represent at least about 50% of the natural 5′UTR sequence. In other embodiments, the polynucleotide fragment comprising a frataxin gene 5′UTR may represent at least about 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98% or more of the natural 5′UTR sequence. In another embodiment, the polynucleotide fragment comprising a frataxin gene 5′UTR may represent the entire natural 5′ UTR sequence. 
     3′ Regulatory Elements 
     In the polynucleotide comprising a frataxin gene, the polynucleotide preferably comprises a 3′ regulatory region operably linked to the frataxin gene, wherein the 3′ regulatory region may be from any mammalian species. In certain embodiments, the polynucleotide comprising a frataxin gene additionally comprises a 3′ regulatory element such as a human growth hormone polyadenylation signal (hGHpA) (e.g., SEQ ID NO:5), a Simian virus 40 early polyadenylation region (SV40 early) (e.g., SEQ ID NO:8), a Simian virus 40 late polyadenylation region (SV40 late) (e.g., SEQ ID NO:9), and a synthetic 3′ regulatory element (such as SEQ ID NO:7). 
     Vectors 
     Several methods known in the art may be used to propagate a polynucleotide according to the invention. Once a suitable host system and growth conditions are established, recombinant expression vectors can be propagated and prepared in quantity. As described herein, the expression vectors which can be used include, but are not limited to, the following vectors or their derivatives: human or animal viruses such as vaccinia virus or adenovirus; insect viruses such as baculovirus; yeast vectors; bacteriophage vectors (e.g., lambda), and plasmid and cosmid DNA vectors, and the like. 
     A large number of vectors known in the art may be used to manipulate nucleic acids, incorporate response elements and promoters into genes, etc. Possible vectors include, for example, plasmids or modified viruses including, for example bacteriophages such as lambda derivatives, or plasmids such as pBR322 or pUC plasmid derivatives, or the Bluescript vector. Another example of vectors that are useful in the invention is the ULTRAVECTOR® Production System (Intrexon Corp., Blacksburg, Va.) as described in WO 2007/038276. For example, the insertion of the DNA fragments corresponding to response elements and promoters into a suitable vector can be accomplished by ligating the appropriate DNA fragments into a chosen vector that has complementary cohesive termini. Alternatively, the ends of the DNA molecules may be enzymatically modified or any site may be produced by ligating nucleotide sequences (linkers) into the DNA termini. Such vectors may be engineered to contain selectable marker genes that provide for the selection of cells that have incorporated the marker into the cellular genome. Such markers allow identification and/or selection of host cells that incorporate and express the proteins encoded by the marker. 
     Viral vectors, and particularly retroviral vectors, have been used in both cells and animals. Viral vectors that can be used include, but are not limited to, retrovirus, adeno-associated virus, pox, baculovirus, vaccinia, herpes simplex, Epstein-Barr, adenovirus, geminivirus, and caulimovirus vectors. Non-viral vectors include plasmids, liposomes, electrically charged lipids (cytofectins), DNA-protein complexes, and biopolymers. In addition to a nucleic acid, a vector may also comprise one or more regulatory regions, and/or selectable markers useful in selecting, measuring, and monitoring nucleic acid transfer results (transfer to which tissues, duration of expression, etc.). 
     Vectors may be introduced into the desired host cells by methods known in the art, e.g., transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, lipofection (lysosome fusion), use of a gene gun, or a DNA vector transporter (see, e.g., Wu et al., (1992)  J. Biol. Chem.  267:963; Wu et al., (1988)  J. Biol. Chem.  263:14621; and Hartmut et al., Canadian Patent Application No. 2,012,311). 
     A polynucleotide according to the invention can also be introduced in vivo by lipofection. (Feigner et al., (1987)  Proc. Natl. Acad. Sci. USA  84:7413; Mackey et al., (1988)  Proc. Natl. Acad. Sci. USA  85:8027; and Ulmer et al. (1993)  Science  259:1745; Feigner et al. (1989)  Science  337:387). Various lipid compounds and other compositions for transfer of nucleic acids are known in the art, including, but not limited to those described in PCT Publication Nos. WO 95/18863, WO 96/17823, U.S. Pat. No. 5,459,127, WO 95/21931, WO 96/25508, and WO 95/21931. 
     It is also possible to introduce a vector in vivo as a naked DNA plasmid as described in U.S. Pat. Nos. 5,693,622, 5,589,466 and 5,580,859. 
     In certain embodiments, the polynucleotides of the invention may be incorporated into a viral vector for deliver to a subject. Non-limiting examples of viral vectors include adenoviral vectors, retroviral vectors, lentiviral vectors, herpesvirus vectors and adeno-associated virus (AAV) vectors. 
     In particular embodiments, the polynucleotides of the invention are provided in adeno-associated viral (AAV) vectors. The adeno-associated viral vector may be AAV1, AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV5, AAV5, AAVrhlO or any other serotypes of AAV that can infect humans. In certain specific embodiments, the Adeno-associated viral vector is AAV5. 
     AAV vectors are vectors derived from an adeno-associated virus serotype. AAV vectors can have one or more of the AAV wild-type genes deleted in whole or part, preferably the rep and/or cap genes, but retain functional flanking ITR sequences. AAV vectors include at least those sequences required in cis for replication and packaging (e.g., functional ITRs) of the virus. The nucleotide sequences of AAV ITR regions are known (Kotin, R M (1994)  Hum. Gene Ther.  5(7):793-801; Berns, K I “Parvoviridae and their Replication” in  VIROLOGY , 2nd Edition, (Fields, B N and Knipe, D M, eds.) New York: Raven Press; 1990b: 1743-1763). The ITRs may be derived from different serotypes so long as they are functional. The AAV expression vectors of the invention may be constructed by any means known in the art to operatively link components in the direction of transcription, (i.e., control elements including promoter, 5′UTR, the frataxin gene, and 3′ regulatory element (such as a transcriptional termination region)). 
     In one particular aspect, the invention is directed to a vector comprising AAV serotype 5 (AAV5) and a FXN gene insert. In one embodiment, the vector is a AAV5-hFXN vector comprising an rAAV5 capsid, and a complementary DNA (cDNA) sequence encoding hFXN. 
     An example of an AAV5.hFXN vector with gene insert is shown in  FIG. 15 . 
     //-ITR-UBC-5U2-hFXN GOI-hGH-Poly A-ITR Linker-ITR-//ITR-// 
     AAV2 inverted terminal repeat, 
     UBC=Human Ubiquitin C (UBC) promoter 
     5U2=Synthetic 5′ regulatory element 
     hFXN GOI=Human FXN cDNA 
     hGH-Poly A=Human Growth Hormone Poly A 
     Recombinant viruses comprising the frataxin constructs may be produced by any technique known in the art, including but not limited to transfecting packaging cells (e.g., PA317 cells, PsiCRIP cells, GPenv+ cells, 293 cells) or transient transfection with helper plasmids or viruses. Description and protocols for making replication-defective recombinant viruses may be found, for example, in WO 94/19478, WO 95/14785, WO 96/22378, U.S. Pat. Nos. 5,882,877, 6,013,516, 4,861,719, and 5,278,056. 
     In a specific embodiments of the invention, the polynucleotide comprises a nucleic acid encoding a Frataxin protein having the amino acid sequence of SEQ ID NO:1 operably linked to a UBC promoter (SEQ ID NO:3) and a 5U2 5′UTR (SEQ ID NO:4) and a synthetic 3′ regulatory element (SEQ ID NO:7). In another specific embodiments of the invention, the polynucleotide comprises a nucleic acid encoding a Frataxin protein having the amino acid sequence of SEQ ID NO:1 operably linked to a UBC promoter (SEQ ID NO:3) and a 5U2 5′UTR (SEQ ID NO:4) and an hGHpA 3′ regulatory element (SEQ ID NO:5). In certain embodiments of the invention, each of these two polynucleotides is incorporated into an AAV5 vector, thereby making two types of AAV5 vectors to express frataxin. In other particular embodiments, each of these types of AAV5 vectors to express frataxin is packaged into virions, making two types of rAAV5s for expressing frataxin, each of which may optionally be formulated into compositions of the invention. 
     Pharmaceutical Formulation 
     Optionally, the AAV5.hFXN vector is formulated in phosphate buffered saline (PBS), 1×PBS, 2×PBS, 10×PBS, Dulbecco&#39;s PBS (DPBS), or DPBS which does not comprise Magnesium or Calcium. 
     In one embodiment, the pharmaceutical formulation comprises a AAV5.hFXN vector, and 1×PBS. In another embodiment, the pharmaceutical formulation comprises a AAV5.hFXN vector, 1×DPBS, and about 200 mM NaCl. 
     In one aspect, the pharmaceutical formulation has a pH substantially similar to the pH of human cerebral spinal fluid. In one embodiment, the pharmaceutical formulation has a pH from about 6.5 to about 7.5. In another embodiment, the pharmaceutical formulation has a pH from about 6.8 to about 7.2. In another embodiment, the pharmaceutical formulation has a pH from about 7.0 to about 7.5. In another embodiment, the pharmaceutical formulation has a pH of about 7. In another embodiment, the pharmaceutical formulation has a pH of about 7.1. In another embodiment, the pharmaceutical formulation has a pH of about 7.2. In another embodiment, the pharmaceutical formulation has a pH of about 7.2. In another embodiment, the pharmaceutical formulation has a pH of about 7.4. 
     In one particular embodiment, the pharmaceutical formulation comprises AAV5.hFXN vector, 0.154M NaCl, 0.056M Na 2 HPO 4 , and 0.0106 M KH 2 PO 4 . In another particular embodiment, the pharmaceutical formulation comprises AAV5.hFXN vector, 0.337M NaCl, 0.027 M KCl, 0.015M Na 2 HPO 4 , and 0.0015M KH 2 PO 4 . 
     Examples of pharmaceutical formulations include, but are not limited to, the pharmaceutical formulations shown in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Example AAV5.hFXN Formulations 
               
            
           
           
               
               
               
            
               
                 Component 
                 Formulation 1 
                 Formulation 2 
               
               
                   
               
               
                 AAV5-hFXN 
                 2.5 × 10 11  vg/mL 
                 2.5 × 10 12  vg/mL 
               
               
                 Excipients 
                 PBS 
                 Dulbecco&#39;s PBS (no Mg, no Ca) + 
               
               
                   
                   
                 200 mM NaCl 
               
               
                 pH 
                 7.4 
                 7.0 
               
               
                   
               
            
           
         
       
     
     In one aspect, the pharmaceutical formulation comprises empty capsids at a percentage of at most about 25% to about 95% cp/cp. In some embodiments, the pharmaceutical formulation comprises empty capsids at a percentage of at most about 50% cp/cp to about 75% cp/cp. In other embodiments, the pharmaceutical formulation comprises empty capsids at a percentage of at most about 25% cp/cp to about 50% cp/cp. In some embodiments, the pharmaceutical formulation comprises empty capsids at a percentage of at most about 95% cp/cp. In some embodiments, the pharmaceutical formulation comprises empty capsids at a percentage of 0% to at most about 25% cp/cp. The ranges herein include all whole numbers between the stated numbers (e.g., 25% to 50% includes 25%, 26%, 27%, 28%, etc., up to and including 50%). In some embodiments, the pharmaceutical formulation is substantially free of empty capsids. As used herein, “substantially free” means refers to a formulation that has little or no amount of the component. “Substantially free of empty capsids” refers to a formulation that has 1% to 0% empty capsids. 
     Route of Administration; Delivery of Pharmaceutical Formulation: 
     In one aspect, the pharmaceutical formulation is administered by intrathecal (IT) delivery. In another aspect, the pharmaceutical formulation is administered by intracerebroventricular (ICV) delivery. In another aspect, the pharmaceutical formulation is administered by intraparenchymal delivery. 
     In one embodiment, the pharmaceutical formulation is administered by intraparenchymal delivery to the brain. In one embodiment, the pharmaceutical formulation is administered by intraparenchymal delivery to the cerebellum. In another embodiment, the pharmaceutical formulation is administered by intraparenchymal delivery to the cerebrum. In another embodiment, the pharmaceutical formulation is administered by intraparenchymal delivery into the dentate nucleus. In another embodiment, the pharmaceutical formulation is administered by intraparenchymal delivery into the dorsal root ganglion. 
     The pharmaceutical formulation may be administered using any suitable delivery device including, but not limited to, needle, catheter or related device. The pharmaceutical formulation may be administered using any suitable techniques known in the art, including, but not limited to, stereotactic injection (see Davidson et al., “Recombinant adeno-associated virus type 2, 4, and 5 vectors: Transduction of variant cell types and regions in the mammalian central nervous system” PNAS 97:3428-3432, 2000; and Alisky et al., “Gene therapy for amyotrophic lateral sclerosis and other motor neuron diseases”  Hum. Gene Ther.  11:2315-2329, 2000). 
     In one embodiment, the pharmaceutical formulation is administered using a single bolus injection. In another embodiment, the pharmaceutical formulation is administered using a continuous infusion. In another embodiment, the pharmaceutical formulation is administered using multiple injections. In another embodiment, the pharmaceutical formulation is administered using one injection, two injections, three injections, or four injections. 
     In one embodiment, the pharmaceutical formulation is administered bilaterally. In another embodiment, the pharmaceutical formulation is administered bilaterally. In one particular embodiment, the pharmaceutical formulation is administered as a bilateral injection to the cerebellum. 
     The pharmaceutical formulation can be delivered by manual injection, by an infusion pumps or by an osmotic pump. Non-manual injection includes, but in not limited to, convection enhanced delivery (CED). Reference is made to L. Samaranch et al., “MR-guided parenchymal Delivery of Adeno-Associated Viral Vector Serotype 5 in Non-Human Primate Brain”  Gene Therapy  (2017) 24, 253-261; and U.S. Pat. No. 9,701,984 “CNS targeting AAV Vectors and Methods of use Thereof” Both osmotic and infusion pumps are commercially available from a variety of suppliers, for example Alzet Corporation, Hamilton Corporation, Alza, Inc., Palo Alto, Calif. One non-limiting example of a syringe pump is a Pump 11 Elite Series, Harvard Pump, Harvard Apparatus Holliston, Mass. One non-limiting example of a syringe pump is a Legato™ Syringe Pump, KD Scientific Inc. Holliston, Mass. 
     Any suitable Cannulas or needle may be used. Any suitable tip style may be used. The cannula or needle may optionally include one or more tapered regions. In various embodiments, the cannula or needle may be beveled. 
     Example Spinal Needles include, but are not limited to, Pencil-Point (Pencan®—Braun; Reganesth®—Sarstedt AG; Whitacre; Sprotte) and Quincke (Spinocan®—Braun) type bevel needles. 
     Any suitable dimensions of cannula or needle may be used. Dimensions may depend on the site for implantation. For example, the width of the epidural space is only about 3-5 mm for the thoracic region and about 5-7 mm for the lumbar region. Examples of lengths of the cannula or needle may include, but are not limited to, from about 15 to 150 mm in length, for example, about 65 mm for epidural pediatric use, about 85 mm for a standard adult and about 110 mm for an obese adult patient. Example thicknesses of the cannula or needle, include, but is not limited to, from about 0.05 mm to about 2 mm. 
     Any suitable gauge of cannula or needle may be used. Examples include but are not limited to, about 14 G to about 22 G. In some embodiments, the gauge of the needle or cannula is about 18 to about 22 G. 
     Examples of ICV access devices include but are not limited to, Ommaya and Rickham reservoirs. Reference is made to J. L. Cohen-Pfeffer et al., “Intracerebroventricular Delivery as a Safe, Long-Term Route of Drug Administration”  Pediatric Neurology , Volume 67, February 2017, Pages 23-35; “Safety of Ommaya reservoirs in children with brain tumors: a 20-year experience with 5472 intraventricular drug administrations in 98 patients”  J Neurooncol.,  120 (2014), pp. 139-145; A. Desi et al., “Gibaldi&#39;s Drug Delivery Systems In Pharmaceutical Care,” American Society of Health-System Pharmacists, 2007; and Cook A M, et al., Intracerebroventricular administration of drugs. Pharmacotherapy. 2009 July; 29(7): 832-45. 
     In one another embodiment, the pharmaceutical formulation is administered by Intrathecal delivery via lumbar puncture into the CSF using the Medtronic ASCENDA™ Intrathecal Catheter delivery system. In one particular embodiment, the pharmaceutical formulation is administered by inserting a catheter to the subarachnoid space and administering ½ the dose of the pharmaceutical formulation to the lumbar and ½ the dose of the pharmaceutical formulation to the cisterna magna. 
     In one embodiment, the ASCENDA™ 8781 Intrathecal Catheter delivery system kit includes, but is not limited to: Spinal segment with inserted guide wire, Pump segment with attached sutureless pump connector, Catheter connector with 2 attached collets, 16 T-gauge introducer needle (11.4 cm) • Anchor with anchor dispenser. Length: Total catheter 139.7 cm, Spinal segment 66.0 cm, Pump segment 73.7 cm. Spinal segment: Outer diameter 1.2 mm (4 French), Inner diameter 0.5 mm, Interval marker 1 cm, Catheter tip Closed with 6 side holes. Pump segment: Outer diameter (catheter only) 1.2 mm (4 French), Inner diameter 0.5 mm (catheter only), Interval marker 1 cm interval. Catheter volume: 0.0022 mL/cm. Catheter connector: inner diameter 0.3 mm, Collet outer diameter 4.3 mm, Guide wire: outer diameter 0.5 mm, Introducer needle 16 T-gauge, 11.4 cm. Trimmable segments: Catheter connector ends of the spinal and pump segments Pump segment to spinal segment separation force &gt;10.0 N. Sutureless pump connector to pump separation force: &gt;10.0 N. 
     The pharmaceutical formulation is optionally delivered by catheter and infusion pump. Any catheter and pump combination suitable for CNS infusion is optionally used. One non-limiting example of a catheter and pump combination is the Medtronic ASCENDA™ Intrathecal Catheter delivery system. Examples of useful pumps include but are not limited to Medtronic SynchroMed®EL 18 mL, SynchroMed® II 20 mL, and SynchroMed® II 40 mL pumps. 
     In another embodiment, the pharmaceutical formulation is optionally delivered by Alcyone MEMS Cannula (AMC™, Alcyone Lifesciences, Inc., Lowel, Mass.), a dual-lumen, MR-compatible injection and aspiration neuro-ventricular cannula. In another embodiment, the pharmaceutical formulation is optionally delivered by Alcyone Pulsar intrathecal catheter. 
     Container: 
     In one embodiment, the pharmaceutical formulation is contained in a pharmaceutical-grade borosilicate glass container with a fluoropolymer lined plastic closure. Examples of fluoropolymers include, but are not limited to, polytetrafluoroethylene (PTFE) (Teflon®). polyethylenetetrafluoroethylene (ETFE). (Fluorotec®), and a copolymer of ethylene and tetrafluoroethylene (Tefzel®). In one embodiment, the closure is lined with polytetrafluoroethylene (PTFE) (Teflon®). 
     Dose: 
     Dosages of the vector depend upon factors, including but not limited to, the mode of administration, the individual subject&#39;s condition, and the particular vector delivered. 
     In one embodiment of the instant invention, the dose per subject ranges from about 1×10 10  vg to about 1×10 15  vg. In another embodiment, the dose is at least about 1×10 11  vg, at least about 1×10 12  vg, at least about 1×10 13  vg, at least about 1×10 14  vg, or at least about 1×10 15  vg. 
     In another embodiment, the dose is at least about 5×10 13  vg, at least about 1.5×10 14  vg, or at least about 5×10 14  vg. 
     In another embodiment, the dose is about 5×10 13  vg, about 1.5×10 14  vg, or about 5×10 14  vg. 
     In another embodiment, the dose is an amount of about 3.7×10 10  vg/g on a brain weight basis, about 1.11×10 11  vg/g on a brain weight basis, or about 3.7×10 11  vg/g on a brain weight basis. 
     The dose is a total dose per subject per administration over all target sites. 
     For one non-limiting example, a total dose per subject of about 5×10 13  vg includes two injections of about 2.5×10 13  vg (i.e., one 2.5×10 13  vg injection in the right half of the cerebellum and one 2.5×10 13  vg injection left half of the cerebellum). For another non-limiting example, a total dose per subject of about 1.5×10 14  vg includes two injections of about 7.5×10 13  vg (i.e., one 7.5×10 13  vg injection in the right half of the cerebellum and one 7.5×10 13  vg injection in the left half of the cerebellum). For another non-limiting example, a total dose per subject of about 5×10 14  vg includes two injections of about 2.5×10 14  vg (i.e., one 2.5×10 14  vg injection in the right half of the cerebellum and one 2.5×10 14  vg injection left half of the cerebellum). 
     For another non-limiting example, a total dose per subject of about 5×10 13  vg includes two injections of about 2.5×10 13  vg (i.e., one 2.5×10 13  vg injection at the Lumbar and one 2.5×10 13  vg injection at the cisterna magna). For another non-limiting example, a total dose per subject of about 1.5×10 14  vg includes two injections of about 7.5×10 13  vg (i.e., one 7.5×10 13  vg injection at the Lumbar and one 7.5×10 13  vg injection at the cisterna magna). For another non-limiting example, a total dose per subject of about 5×10 14  vg includes two injections of about 2.5×10 14  vg (i.e., one 2.5×10 14  vg injection at the Lumbar and one 2.5×10 14  vg injection at the cisterna magna). 
     Reference is made to D. J. Schuster, “Supraspinal gene transfer by intrathecal adeno-associated virus serotype 5 .” Front. Neuroanat.  (2014b), 8:66; S. J. Gray. “Global CNS gene delivery and evasion of anti-AAV-neutralizing antibodies by intrathecal AAV administration in non-human primates.”  Gene Ther.  2013; 20(4):450-459.; T. Federici, et al., “Robust spinal motor neuron transduction following intrathecal delivery of AAV9 in pigs,”  Gene Ther,  19(8):852, 2012; and B. Snyder, et al., “Comparison of adeno-associated viral vector serotypes for spinal cord and motor neuron gene delivery,”  Hum. Gene Ther,  22(9):1129, 2011. 
     Dose Volume: 
     In one embodiment, the pharmaceutical formulation is delivered at a dose volume ranging from about 0.1 mL to about 10 mL per target site. In another embodiment, the pharmaceutical formulation is delivered at a dose volume ranging from about 1 mL to about 5 mL per target site. In another embodiment, the pharmaceutical formulation is delivered at a dose volume ranging from about 1 mL to about 3 mL per target site. In another embodiment, the pharmaceutical formulation is delivered at a dose volume ranging from about 1.5 mL to about 2.5 mL per target site. In another embodiment, the pharmaceutical formulation is delivered at a dose volume ranging from about 1 mL to about 2 mL per target site. In one particular embodiment, the pharmaceutical formulation is delivered at a dose volume of about 1 mL per target site. In another particular embodiment, the pharmaceutical formulation is delivered at a dose volume of about 2 mL per target site. In another particular embodiment, the pharmaceutical formulation is delivered at a dose volume of about 3 mL per target site. 
     Dose Concentration: 
     In one embodiment, the pharmaceutical formulation comprises an AAV5.hFXN vector concentration of about 1×10 9  to about 2×10 13  vg/mL. In some embodiments, the AAV5.hFXN vector concentration is about 1×10 10  to about 2×10 13 . In other embodiments, the AAV5.hFXN vector concentration is about 1×10 11  to about 2×10 13 . In other embodiments the AAV5.hFXN vector concentration is about 1×10 12  to about 2×10 13  vg/mL. In another embodiment, the AAV5.hFXN vector concentration is about 2.5×10 12  to about 2×10 13  vg/mL. In other embodiments, the AAV5.hFXN vector concentration is about 5×10 12  to about 2×10 13  vg/mL. In still further embodiments, the AAV5hFXN vector concentration is about 7×10 12  to about 2×10 13  vg/mL. 
     In certain embodiments, the AAV5.hFXN vector concentration is at least about 1×10 9 , at least about 1×10 11 , at least about 2.5×10 11 , at least about 5×10 11 , at least about 1×10 12 , at least about 2×10 12 , at least about 2.5×10 12 , at least about 5×10 12 , at least about 7×10 12 , at least about 1×10 13 , or at least about 2×10 13  vg/mL. 
     In one embodiment, the pharmaceutical formulation comprises a AAV5.hFXN vector concentration of concentration of about 1×10 9  vg/mL, about 1×10 10  vg/mL, about 1×10 11  vg/mL, about 1×10 12  vg/mL, about 1×10 13  vg/mL, about 2.5×10 11  vg/mL, about 5×10 11  vg/mL, about 2×10 12  vg/mL, about 2.5×10 12  vg/mL, about 5×10 12  vg/mL, about 7×10 12  vg/mL, about 1×10 13  vg/mL, or about 2×10 13  vg/mL. 
     Rate of Administration: 
     In one embodiment, the pharmaceutical formulation is delivered as a single bolus injection over about one minute to about 10 minutes. In one embodiment, the pharmaceutical formulation is delivered as a single bolus injection over about 1 minute, to about 5 minutes. 
     In one embodiment, the pharmaceutical formulation is delivered at a rate ranging from of about 0.001 mL/min to about 10 mL/min. In another embodiment, the pharmaceutical formulation is delivered at a rate ranging from of about 0.01 mL/min to about 1 mL/min. In another embodiment, the pharmaceutical formulation is delivered at a rate ranging from of about 0.01 mL/min to about 0.1 mL/min. In another embodiment, the pharmaceutical formulation is delivered at a rate ranging from of about 1 mL/min to about 10 mL/min. In another embodiment, the pharmaceutical formulation is delivered at a rate ranging from of about 1 mL/min to about 2 mL/min. 
     In one embodiment, the pharmaceutical formulation is delivered at a rate of about 0.1 mL/min, about 0.2 mL/min, about 0.3 mL/min, about 0.4 mL/min, about 0.5 mL/min, about 0.6 mL/min, about 0.7 mL/min, about 0.8 mL/min, about 0.9 mL/min, or about 1.0 mL/min. 
     In one embodiment, the pharmaceutical formulation is delivered at a rate of about 0.01 mL/min, about 0.02 mL/min, about 0.03 mL/min, about 0.04 mL/min, about 0.05 mL/min, about 0.06 mL/min, about 0.07 mL/min, about 0.08 mL/min, about 0.09 mL/min, or about 0.1 mL/min. 
     In one embodiment, the pharmaceutical formulation, comprising a AAV5.hFXN vector concentration of 1×10 12  vg/mL, is delivered to at a dose volume of about 1 mL per target site at a rate of about 0.001 mL/min. 
     The physician of ordinary skill in the art will be able to adjust the dose either higher or lower and determine an appropriate dose/dose regimen depending upon factors such as route of administration (e.g., a systemic dose may be as much as a 2-3 log increase), timing of doses, symptom improvement (i.e., efficacy), or the individual needs of the particular patient. 
     Outcome Measures: 
     Reference is made to M. Patel et al., “Progression of Friedreich ataxia: quantitative characterization over 5 years,”  Annals of Clinical and Translational Neurology,  2016; 3(9): 684-69; D. Lynch et al. “Friedreich ataxia: effects of genetic understanding on clinical evaluation and therapy”  Arch. Neurol,  2002, 59:743-747; C. Wilson et al., “Quality of life in Friedreich ataxia: what clinical, social and demographic factors are important?”  Eur. J Neurol.  200714(9):1040-1047; G. Rance et al., “Speech perception ability in individuals with Friedreich ataxia.”  Brain.  2008131:2002-2012; A. Koeppen, “Friedreich&#39;s ataxia: Pathology, pathogenesis, and molecular genetics.”  J. Neurol. Sci.  2011, 303(1-2): 1-12; and S. R. Regner et al. “Friedreich ataxia clinical outcome measures: natural history evaluation in 410 participants”  J. Child Neurol.  2012, 27(9):1152-8. 
     Efficacy data is collected at 1, 3, 6 and 12 months post study drug administration. Efficacy is evaluated in subjects using diffusion tensor imaging and various functional outcomes (including but not limited to FARS total and FARS Neuro; evaluation of a 25-foot walk test; evaluation on a GAITRite Walkway System; evaluation using a Biodex Balance System SD; evaluation using the 9-hole peg test). Diffusion tensor imaging may be measured, for example, by T2 relaxometry of dentate nucleus and DRG and/or NAA levels and iron levels by Magnetic Resonance Imaging (MRS). 
     Pharmaceutical excipients for in vivo use, the active ingredients (e.g., vectors expressing frataxin, virions, viruses, rAAVs, etc.) described herein may be taken up in pharmaceutically acceptable carriers, such as, for example, solutions, suspensions, tablets, capsules, ointments, elixirs, and injectable compositions. Pharmaceutical compositions may contain from 0.01% to 99% by weight of the active ingredient. Compositions may be either in single or multiple dose forms. The amount of ligand in any particular pharmaceutical composition will depend upon the effective dose, that is, the dose required to elicit the desired gene expression or suppression. 
     Suitable routes of administering the pharmaceutical preparations include oral, rectal, topical (including dermal, buccal and sublingual), vaginal, parenteral (including subcutaneous, intraparenchymal, intramuscular, intravenous, intratumoral, intradermal, intrathecal intraventricular, and epidural), intravitreal, and by naso-gastric tube. In certain embodiments, the route of administration is to the CSF space; the subarachnoid space, (e.g., the cisterna magna); the brain, (e.g., the cerebroventricular space, the cerebellum, the cerebrum, the hippocampus, the interior cortex, the dorsal root ganglion, or caudate nucleus); or the spine (e.g., the lumbar spine, thoracic spine, cervical spine). In some embodiments, the active ingredient (e.g., vectors expressing frataxin, virions, viruses, rAAVs, etc.) is delivered in two injections: one in the right cerebellum and one in the left cerebellum. In some embodiments, these are two equal injections. In some embodiments, the active ingredient (e.g., vectors expressing frataxin, virions, viruses, rAAVs, etc.) are administered by injecting the cerebellum and also providing it systemically. It will be understood by those skilled in the art that the route of administration will depend upon the condition being treated and may vary with factors such as the condition of the recipient. 
     The polynucleotides of the invention for expressing frataxin (e.g., virons, AAVs, vectors, viruses, etc.) may be used to treat Friedreich&#39;s Ataxia. Administration of the polynucleotides, virions and/or compositions of the invention to a subject in need thereof ameliorates at least one symptom of Friedreich&#39;s ataxia. The symptoms of Friedreich&#39;s ataxia that can be ameliorated include, but are not limited to loss of coordination in the arms and/or legs, fatigue, vision impairment, hearing loss, slurred speech, aggressive scoliosis, diabetes mellitus, hypertrophic cardiomyopathy and cardiac arrhythmia. 
     Treatment of Friedreich&#39;s Ataxia using the constructs and compositions of the invention allow expression of frataxin in a subject at a level of at least 25% of normal expression of frataxin or greater up to normal levels (including levels that exceed normal levels, provided it causes no untoward effects). In some embodiments, the level will be at least 30% of normal. In other embodiments, the level will be at least, or greater than 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 98%, of normal levels of frataxin. In other embodiments, normal levels of frataxin are achieved. 
     Using the compositions and methods of the invention, frataxin is expressed in the mitochondria. Preferably, frataxin is expressed in the mitochondria of at least one tissue selected from the group consisting of the cerebellum, the hippocampus, the anterior cortex, and the dorsal root ganglion. 
     Gene Switch Systems 
     The gene switch may be any gene switch that regulates gene expression by addition or removal of a specific ligand. In one embodiment, the gene switch is one in which the level of gene expression is dependent on the level of ligand that is present. Examples of ligand-dependent transcription factor complexes that may be used in the gene switches of the invention include, without limitation, members of the nuclear receptor superfamily activated by their respective ligands (e.g., glucocorticoid, estrogen, progestin, retinoid, ecdysone, and analogs and mimetics thereof) and rTTA activated by tetracycline. In one aspect of the invention, the gene switch is an EcR-based gene switch. Examples of such systems include, without limitation, the systems described in U.S. Pat. Nos. 6,258,603, 7,045,315, U.S. Published Patent Application Nos. 2006/0014711, 2007/0161086, and International Published Application No. WO 01/70816. Examples of chimeric ecdysone receptor systems are described in U.S. Pat. No. 7,091,038, U.S. Published Patent Application Nos. 2002/0110861, 2004/0033600, 2004/0096942, 2005/0266457, and 2006/0100416, and International Published Application Nos. WO 01/70816, WO 02/066612, WO 02/066613, WO 02/066614, WO 02/066615, WO 02/29075, and WO 2005/108617, each of which is incorporated by reference in its entirety. An example of a non-steroidal ecdysone agonist-regulated system is the RheoSwitch® Mammalian Inducible Expression System (New England Biolabs, Ipswich, Mass.). In another aspect of the invention, the gene switch is based on heterodimerization of FK506 binding protein (FKBP) with FKBP rapamycin associated protein (FRAP) and is regulated through rapamycin or its non-immunosuppressive analogs. Examples of such systems, include, without limitation, the ARGENT™ Transcriptional Technology (ARIAD Pharmaceuticals, Cambridge, Mass.) and the systems described in U.S. Pat. Nos. 6,015,709, 6,117,680, 6,479,653, 6,187,757, and 6,649,595. 
     In one embodiment, the gene switch comprises a single transcription factor sequence encoding a ligand-dependent transcription factor complex under the control of a therapeutic switch promoter. The transcription factor sequence may encode a ligand-dependent transcription factor complex that is a naturally occurring or an artificial ligand-dependent transcription factor complex. An artificial transcription factor is one in which the natural sequence of the transcription factor has been altered, e.g., by mutation of the sequence or by the combining of domains from different transcription factors. In one embodiment, the transcription factor comprises a Group H nuclear receptor ligand binding domain. In one embodiment, the Group H nuclear receptor ligand binding domain is from an ecdysone receptor, a ubiquitous receptor (UR), an orphan receptor 1 (OR-1), a steroid hormone nuclear receptor 1 (NER-1), a retinoid×receptor interacting protein-15 (RIP-15), a liver×receptor β (LXRβ), a steroid hormone receptor like protein (RLD-1), a liver×receptor (L×R), a liver×receptor α (LXRα), a farnesoid×receptor (F×R), a receptor interacting protein 14 (RIP-14), or a farnesol receptor (HRR-1). In another embodiment, the Group H nuclear receptor LBD is from an ecdysone receptor. 
     A. Ecdysone-Based Gene Switch 
     The EcR and the other Group H nuclear receptors are members of the nuclear receptor superfamily wherein all members are generally characterized by the presence of an amino-terminal transactivation domain (AD, also referred to interchangeably as “TA” or “TD”), optionally fused to a heterodimerization partner (HP) to form a coactivation protein (CAP), a DNA binding domain (DBD), and a LBD fused to the DBD via a hinge region to form a ligand-dependent transcription factor (LTF). As used herein, the term “DNA binding domain” comprises a minimal polypeptide sequence of a DNA binding protein, up to the entire length of a DNA binding protein, so long as the DNA binding domain functions to associate with a particular response element. Members of the nuclear receptor superfamily are also characterized by the presence of four or five domains: A/B, C, D, E, and in some members F (see U.S. Pat. No. 4,981,784 and Evans, Science 240:889 (1988)). The “A/B” domain corresponds to the transactivation domain, “C” corresponds to the DNA binding domain, “D” corresponds to the hinge region, and “E” corresponds to the ligand binding domain. Some members of the family may also have another transactivation domain on the carboxy-terminal side of the LBD corresponding to “F”. 
     The following polypeptide sequence was reported as a polypeptide sequence of Ecdysone receptor (Ecdysteroid receptor) (20-hydroxy-ecdysone receptor) (20E receptor) (EcRH) (Nuclear receptor subfamily 1 group H member 1) and has the accession number P34021 in Genbank. 
     
       
         
           
               
            
               
                 Protein Sequence of the ecdysone receptor of 
               
               
                   Drosophila   melanogaster   
               
               
                 (SEQ ID NO: 10) 
               
            
           
           
               
               
            
               
                 1 
                 MKRRWSNNGG FMRLPEESSS EVTSSSNGLV LPSGVNMSPS 
               
               
                   
               
               
                   
                 SLDSHDYCDQ DLWLCGNESG 
               
               
                   
               
               
                 61 
                 SFGGSNGHGL SQQQQSVITL AMHGCSSTLP AQTTIIPING 
               
               
                   
               
               
                   
                 NANGNGGSTN GQYVPGATNL 
               
               
                   
               
               
                 121 
                 GALANGMLNG GFNGMQQQIQ NGHGLINSTT PSTPTTPLHL 
               
               
                   
               
               
                   
                 QQNLGGAGGG GIGGMGILHH 
               
               
                   
               
               
                 181 
                 ANGTPNGLIG VVGGGGGVGL GVGGGGVGGL GMQHTPRSDS 
               
               
                   
               
               
                   
                 VNSISSGRDD LSPSSSLNGY 
               
               
                   
               
               
                 241 
                 SANESCDAKK SKKGPAPRVQ EELCLVCGDR ASGYHYNALT 
               
               
                   
               
               
                   
                 CEGCKGFFRR SVTKSAVYCC 
               
               
                   
               
               
                 301 
                 KFGRACEMDM YMRRKCQECR LKKCLAVGMR PECVVPENQC 
               
               
                   
               
               
                   
                 AMKRREKKAQ KEKDKMTTSP 
               
               
                   
               
               
                 361 
                 SSQHGGNGSL ASGGGQDFVK KEILDLMTCE PPQHATIPLL 
               
               
                   
               
               
                   
                 PDEILAKCQA RNIPSLTYNQ 
               
               
                   
               
               
                 421 
                 LAVIYKLIWY QDGYEQPSEE DLRRIMSQPD ENESQTDVSF 
               
               
                   
               
               
                   
                 RHITEITILT VQLIVEFAKG 
               
               
                   
               
               
                 481 
                 LPAFTKIPQE DQITLLKACS SEVMMLRMAR RYDHSSDSIF 
               
               
                   
               
               
                   
                 FANNRSYTRD SYKMAGMADN 
               
               
                   
               
               
                 541 
                 IEDLLHFCRQ MFSMKVDNVE YALLTAIVIF SDRPGLEKAQ 
               
               
                   
               
               
                   
                 LVEAIQSYYI DTLRIYILNR 
               
               
                   
               
               
                 601 
                 HCGDSMSLVF YAKLLSILTE LRTLGNQNAE MCFSLKLKNR 
               
               
                   
               
               
                   
                 KLPKFLEEIW DVHAIPPSVQ 
               
               
                   
               
               
                 661 
                 SHLQITQEEN ERLERAERMR ASVGGAITAG IDCDSASTSA 
               
               
                   
               
               
                   
                 AAAAAQHQPQ PQPQPQPSSL 
               
               
                   
               
               
                 721 
                 TQNDSQHQTQ PQLQPQLPPQ LQGQLQPQLQ PQLQTQLQPQ 
               
               
                   
               
               
                   
                 IQPQPQLLPV SAPVPASVTA 
               
               
                   
               
               
                 781 
                 PGSLSAVSTS SEYMGGSAAI GPITPATTSS ITAAVTASST 
               
               
                   
               
               
                   
                 TSAVPMGNGV GVGVGVGGNV 
               
               
                   
               
               
                 841 
                 SMYANAQTAM ALMGVALHSH QEQLIGGVAV KSEHSTTA 
               
            
           
         
       
     
     In one embodiment, the ecdysone receptor ligand binding domain is selected from the group consisting of an invertebrate ecdysone receptor ligand binding domain, an Arthropod ecdysone receptor ligand binding domain, a Lepidopteran ecdysone receptor ligand binding domain, a Dipteran ecdysone receptor ligand binding domain, an Orthopteran ecdysone receptor ligand binding domain, a Homopteran ecdysone receptor ligand binding domain, a Hemipteran ecdysone receptor ligand binding domain, a spruce budworm  Choristoneura fumiferana  EcR ecdysone receptor ligand binding domain, a beetle  Tenebrio molitor  ecdysone receptor ligand binding domain, a  Manduca sexta  ecdysone receptor ligand binding domain, a  Heliothis virescens  ecdysone receptor ligand binding domain, a midge  Chironomus tentans  ecdysone receptor ligand binding domain, a silk moth  Bombyx mori  ecdysone receptor ligand binding domain, a squinting bush brown  Bicyclus anynana  ecdysone receptor ligand binding domain, a buckeye  Junonia coenia  ecdysone receptor ligand binding domain, a fruit fly  Drosophila melanogaster  ecdysone receptor ligand binding domain, a mosquito  Aedes aegypti  ecdysone receptor ligand binding domain, a blowfly  Lucilia capitata  ecdysone receptor ligand binding domain, a blowfly  Lucilia cuprina  ecdysone receptor ligand binding domain, a blowfly  Calliphora vicinia  ecdysone receptor ligand binding domain, a Mediterranean fruit fly  Ceratitis capitata  ecdysone receptor ligand binding domain, a locust  Locusta migratoria  ecdysone receptor ligand binding domain, an aphid  Myzus persicae  ecdysone receptor ligand binding domain, a fiddler crab  Celuca pugilator  ecdysone receptor ligand binding domain, an ixodid tick  Amblyomma americanum  ecdysone receptor ligand binding domain, a whitefly  Bamecia argentifoli  ecdysone receptor ligand binding domain and a leafhopper  Nephotetix cincticeps  ecdysone receptor ligand binding domain. 
     In another embodiment, the ecdysone receptor ligand binding domain is the  Choristoneura fumiferana  ecdysone receptor ligand binding domain, for which the amino acid sequence is set forth in SEQ ID NO:11. 
     In another embodiment, the ecdysone receptor ligand binding domain is an analog of the  Choristoneura fumiferana  ecdysone receptor ligand binding domain that retains at least 80%, 85%, 90%, 95%, 96%, 97%, 98% 99% or 100% of the in vitro  Choristoneura fumiferana  ecdysone receptor ligand binding activity of the  Choristoneura fumiferana  ecdysone receptor ligand binding domain. In vitro ecdysone receptor ligand binding assays are well known to those of ordinary skill in the art. For example, see WO 02/066612. 
     In another embodiment, the ecdysone receptor ligand binding domain analog is an ecdysone receptor ligand binding domain disclosed in WO 02/066612, US 2006/0100416, WO 05/108617 and 2005/0266457. In another embodiment, the ecdysone receptor ligand binding domain analog is the V107I/Y127E substitution mutant of the  Choristoneura fumiferana  ecdysone receptor which is set forth in SEQ ID NO: 12. 
     The DBD is characterized by the presence of two cysteine zinc fingers between which are two amino acid motifs, the P-box and the D-box, which confer specificity for response elements. These domains may be either native, modified, or chimeras of different domains of heterologous receptor proteins. The EcR, like a subset of the nuclear receptor family, also possesses less well-defined regions responsible for heterodimerization properties. Because the domains of nuclear receptors are modular in nature, the LBD, DBD, and AD may be interchanged. 
     In another embodiment, the transcription factor comprises an AD, a DBD that recognizes a response element associated with the therapeutic protein or therapeutic polynucleotide whose expression is to be modulated; and a Group H nuclear receptor LBD. In certain embodiments, the Group H nuclear receptor LBD comprises a substitution mutation. 
     The DNA binding domain can be any DNA binding domain (DBD) with a known response element, including synthetic and chimeric DNA binding domains, or analogs, combinations, or modifications thereof. In one embodiment, the DNA binding domain is selected from the group consisting of a GAL4 DBD, a LexA DBD, a transcription factor DBD, a Group H nuclear receptor member DBD, a steroid/thyroid hormone nuclear receptor superfamily member DBD, a bacterial LacZ DBD, an EcR DBD, a GAL4 DBD and a LexA DBD. 
     The transactivation domain (abbreviated “AD” or “TA”) may be any Group H nuclear receptor member AD, steroid/thyroid hormone nuclear receptor AD, synthetic or chimeric AD, polyglutamine AD, basic or acidic amino acid AD, a VP16 AD, a GAL4 AD, an NF-κB AD, a BP64 AD, a B42 acidic activation domain (B42AD), a p65 transactivation domain (p65AD), or an analog, combination, or modification thereof. 
     In another embodiment, the gene switch comprises a first transcription factor sequence, e.g., a CAP, under the control of a first therapeutic switch promoter (TSP-1) and a second transcription factor sequence, e.g., a LTF, under the control of a second therapeutic switch promoter (TSP-2), wherein the proteins encoded by said first transcription factor sequence and said second transcription factor sequence interact to form a protein complex (LDTFC), i.e., a “dual switch”- or “two-hybrid”-based gene switch. The first and second TSPs may be the same or different. In this embodiment, the presence of two different TSPs in the gene switch that are required for therapeutic molecule expression enhances the specificity of the therapeutic method (see FIG. 2 of WO 2011/119773). FIG. 2 of WO 2011/119773 also demonstrates the ability to modify the therapeutic gene switch to treat any disease, disorder, or condition simply by inserting the appropriate TSPs. 
     In a further embodiment, both the first and the second transcription factor sequence, e.g., a CAP or a LTF, are under the control of a single therapeutic switch promoter (e.g. TSP-1 in FIG. 1 of WO 2011/119773). Activation of this promoter will generate both CAP and LTF with a single open reading frame. This can be achieved with the use of a transcriptional linker such as an IRES (internal ribosomal entry site). In this embodiment, both portions of the ligand-dependent transcription factor complex are synthesized upon activation of TSP-1. TSP-1 can be a constitutive promoter or only activated under conditions associated with the disease, disorder, or condition. 
     In a further embodiment, one transcription factor sequence, e.g. a LTF, is under the control of a therapeutic switch promoter only activated under conditions associated with the disease, disorder, or condition (e.g., TSP-2 or TSP-3 in FIG. 4 in WO 2011/119773) and the other transcription factor sequence, e.g., CAP, is under the control of a constitutive therapeutic switch promoter (e.g., TSP-1 in FIG. 4 in WO 2011/119773). In this embodiment, one portion of the ligand-dependent transcription factor complex is constitutively present while the second portion will only be synthesized under conditions associated with the disease, disorder, or condition. 
     In another embodiment, one transcription factor sequence, e.g., CAP, is under the control of a first TSP (e.g., TSP-1 in FIG. 3 in WO 2011/119773) and two or more different second transcription factor sequences, e.g., LTF-1 and LTF-2 are under the control of different TSPs (e.g., TSP-2 and TSP-3 in FIG. 3 in WO 2011/119773). In this embodiment, each of the LTFs may have a different DBD that recognizes a different factor-regulated promoter sequence (e.g., DBD-A binds to a response element associated with factor-regulated promoter-1 (FRP-1) and DBD-B binds to a response element associated with factor-regulated promoter-2 (FRP-2). Each of the factor-regulated promoters may be operably linked to a different therapeutic gene. In this manner, multiple treatments may be provided simultaneously. 
     In one embodiment, the first transcription factor sequence encodes a polypeptide comprising an AD, a DBD that recognizes a response element associated with the therapeutic product sequence whose expression is to be modulated; and a Group H nuclear receptor LBD, and the second transcription factor sequence encodes a transcription factor comprising a nuclear receptor LBD selected from a vertebrate retinoid×receptor (RXR), an invertebrate RXR, an ultraspiracle protein (USP), or a chimeric nuclear receptor comprising at least two different nuclear receptor ligand binding domain polypeptide fragments selected from a vertebrate RXR, an invertebrate RXR, and a USP (see WO 01/70816 A2 and US 2004/0096942 A1). The “partner” nuclear receptor ligand binding domain may further comprise a truncation mutation, a deletion mutation, a substitution mutation, or another modification. 
     In another embodiment, the gene switch comprises a first transcription factor sequence encoding a first polypeptide comprising a nuclear receptor LBD and a DBD that recognizes a response element associated with the therapeutic product sequence whose expression is to be modulated, and a second transcription factor sequence encoding a second polypeptide comprising an AD and a nuclear receptor LBD, wherein one of the nuclear receptor LBDs is a Group H nuclear receptor LBD. In one embodiment, the first polypeptide is substantially free of an AD and the second polypeptide is substantially free of a DBD. For purposes of the invention, “substantially free” means that the protein in question does not contain a sufficient sequence of the domain in question to provide activation or binding activity. 
     In another aspect of the invention, the first transcription factor sequence encodes a protein comprising a heterodimerization partner and an AD (a “CAP”) and the second transcription factor sequence encodes a protein comprising a DBD and a LBD (a “LTF”). 
     When only one nuclear receptor LBD is a Group H LBD, the other nuclear receptor LBD may be from any other nuclear receptor that forms a dimer with the Group H LBD. For example, when the Group H nuclear receptor LBD is an EcR LBD, the other nuclear receptor LBD “partner” may be from an EcR, a vertebrate RXR, an invertebrate RXR, an ultraspiracle protein (USP), or a chimeric nuclear receptor comprising at least two different nuclear receptor LBD polypeptide fragments selected from a vertebrate RXR, an invertebrate RXR, or a USP (see WO 01/70816 A2, International Patent Application No. PCT/US02/05235, US 2004/0096942 A1 and U.S. Pat. No. 7,531,326, incorporated herein by reference in their entirety). The “partner” nuclear receptor ligand binding domain may further comprise a truncation mutation, a deletion mutation, a substitution mutation, or another modification. 
     In one embodiment, the vertebrate RXR LBD is from a human  Homo sapiens , mouse  Mus musculus , rat  Rattus norvegicus , chicken  Gallus gallus , pig  Sus scrofa domestica , frog  Xenopus laevis , zebrafish  Danio rerio , tunicate  Polyandrocarpa misakiensis , or jellyfish  Tripedalia cysophora  RXR. 
     In one embodiment, the invertebrate RXR ligand binding domain is from a locust  Locusta migratoria  ultraspiracle polypeptide (“LmUSP”), an ixodid tick  Amblyomma americanum  RXR homolog 1 (“AmaRXR1”), an ixodid tick  Amblyomma americanum  RXR homolog 2 (“AmaRXR2”), a fiddler crab  Celuca pugilator  RXR homolog (“CpRXR”), a beetle  Tenebrio molitor  RXR homolog (“TmRXR”), a honeybee  Apis mellifera  RXR homolog (“AmRXR”), an aphid  Myzus persicae  RXR homolog (“MpRXR”), or a non-Dipteran/non-Lepidopteran RXR homolog. 
     In one embodiment, the chimeric RXR LBD comprises at least two polypeptide fragments selected from a vertebrate species RXR polypeptide fragment, an invertebrate species RXR polypeptide fragment, or a non-Dipteran/non-Lepidopteran invertebrate species RXR homolog polypeptide fragment. A chimeric RXR ligand binding domain for use in the present invention may comprise at least two different species RXR polypeptide fragments, or when the species is the same, the two or more polypeptide fragments may be from two or more different isoforms of the species RXR polypeptide fragment. Such chimeric RXR LBDs are disclosed, for example, in WO 2002/066614. 
     In one embodiment, the chimeric RXR ligand binding domain comprises at least one vertebrate species RXR polypeptide fragment and one invertebrate species RXR polypeptide fragment. 
     In another embodiment, the chimeric RXR ligand binding domain comprises at least one vertebrate species RXR polypeptide fragment and one non-Dipteran/non-Lepidopteran invertebrate species RXR homolog polypeptide fragment. 
     The ligand, when combined with the LBD of the nuclear receptor(s), which in turn are bound to the response element of a FRP associated with a therapeutic product sequence, provides external temporal regulation of expression of the therapeutic product sequence. The binding mechanism or the order in which the various components of this invention bind to each other, that is, for example, ligand to LBD, DBD to response element, AD to promoter, etc., is not critical. 
     In a specific example, binding of the ligand to the LBD of a Group H nuclear receptor and its nuclear receptor LBD partner enables expression of the therapeutic product sequence. This mechanism does not exclude the potential for ligand binding to the Group H nuclear receptor (GHNR) or its partner, and the resulting formation of active homodimer complexes (e.g. GHNR+GHNR or partner+partner). Preferably, one or more of the receptor domains is varied producing a hybrid gene switch. Typically, one or more of the three domains, DBD, LBD, and AD, may be chosen from a source different than the source of the other domains so that the hybrid genes and the resulting hybrid proteins are optimized in the chosen host cell or organism for transactivating activity, complementary binding of the ligand, and recognition of a specific response element. In addition, the response element itself can be modified or substituted with response elements for other DNA binding protein domains such as the GAL-4 protein from yeast (see Sadowski et al.,  Nature  335:563 (1988)) or LexA protein from  Escherichia coli  (see Brent et al.,  Cell  43:729 (1985)), or synthetic response elements specific for targeted interactions with proteins designed, modified, and selected for such specific interactions (see, for example, Kim et al.,  Proc. Natl. Acad. Sci. USA,  94:3616 (1997)) to accommodate hybrid receptors. Another advantage of two-hybrid systems is that they allow choice of a promoter used to drive the gene expression according to a desired end result. Such double control may be particularly important in areas of gene therapy, especially when cytotoxic proteins are produced, because both the timing of expression as well as the cells wherein expression occurs may be controlled. When genes, operably linked to a suitable promoter, are introduced into the cells of the subject, expression of the exogenous genes is controlled by the presence of the system of this invention. Promoters may be constitutively or inducibly regulated or may be tissue-specific (that is, expressed only in a particular type of cells) or specific to certain developmental stages of the organism. 
     The DNA binding domain of the first hybrid protein binds, in the presence or absence of a ligand, to the DNA sequence of a response element to initiate or suppress transcription of downstream gene(s) under the regulation of this response element. 
     The functional LDTFC, e.g., an EcR complex, may also include additional protein(s) such as immunophilins. Additional members of the nuclear receptor family of proteins, known as transcriptional factors (such as DHR38 or betaFTZ-1), may also be ligand dependent or independent partners for EcR, USP, and/or RXR. Additionally, other cofactors may be required such as proteins generally known as coactivators (also termed adapters or mediators). These proteins do not bind sequence-specifically to DNA and are not involved in basal transcription. They may exert their effect on transcription activation through various mechanisms, including stimulation of DNA-binding of activators, by affecting chromatin structure, or by mediating activator-initiation complex interactions. Examples of such coactivators include RIP140, TIF1, RAP46/Bag-1, ARA70, SRC-1/NCoA-1, TIF2/GRIP/NCoA-2, ACTR/AIB1/RAC3/pCIP as well as the promiscuous coactivator C response element B binding protein, CBP/p300 (for review see Glass et al.,  Curr. Opin. Cell Biol.  9:222 (1997)). Also, protein cofactors generally known as corepressors (also known as repressors, silencers, or silencing mediators) may be required to effectively inhibit transcriptional activation in the absence of ligand. These corepressors may interact with the unliganded EcR to silence the activity at the response element. Current evidence suggests that the binding of ligand changes the conformation of the receptor, which results in release of the corepressor and recruitment of the above described coactivators, thereby abolishing their silencing activity. Examples of corepressors include N—CoR and SMRT (for review, see Horwitz et al.,  Mol Endocrinol.  10:1167 (1996)). These cofactors may either be endogenous within the cell or organism, or may be added exogenously as transgenes to be expressed in either a regulated or unregulated fashion. 
     B. Rapamycin Based Gene Switch 
     The present invention further provides a gene switch system which utilizes FK506 binding protein as the ligand-dependent transcription factor complex and rapamycin as the ligand. In one embodiment, the construct encoding the gene switch comprises: 
     (a) a first polynucleotide encoding a first chimeric protein which binds to rapamycin or an analog thereof and which comprises at least one FK506-binding protein (FKBP) domain and at least one protein domain heterologous thereto, wherein the FKBP domain comprises a peptide sequence selected from:
         (1) a naturally occurring FKBP   (2) a variant of a naturally occurring FKBP in which up to 10 amino acid residues have been deleted, inserted, or replaced with substitute amino acids, and   (3) an FKBP encoded by a DNA sequence which selectively hybridizes to a DNA sequence encoding an FKBP of (1) or (2);       

     (b) a second polynucleotide encoding a second chimeric protein which forms a complex with both (a) rapamycin or a rapamycin analog and (b) the first chimeric protein, and which comprises at least one FKBP:rapamycin binding (FRB) domain and at least one protein domain heterologous thereto, wherein the FRB domain comprises a peptide sequence selected from:
         (4) a naturally occurring FRB domain,   (5) a variant of a naturally occurring FRB domain in which up to 10 amino acid residues have been deleted, inserted, or replaced with substitute amino acids, and   (6) an FRB domain encoded by a DNA sequence which selectively hybridizes to a DNA sequence encoding an FRB of (4) or (5).       

     In this gene switch system, each of the first polynucleotide and the second polynucleotide are under the control of one or more therapeutic switch promoters as described elsewhere herein. Furthermore, in certain embodiments, at least one protein domain heterologous to the FKBP and/or FRB domains in the first and second chimeric protein may be one or more “action” or “effector” domains. Effector domains may be selected from a wide variety of protein domains including DNA binding domains, transcription activation domains, cellular localization domains and signaling domains (i.e., domains which are capable upon clustering or multimerization, of triggering cell growth, proliferation, differentiation, apoptosis, gene transcription, etc.). 
     In certain embodiments, one fusion protein contains at least one DNA binding domain (e.g., a GAL4 or ZFHD1 DNA-binding domain) and another fusion protein contains at least one transcription activation domain (e.g., a VP16 or p65 transcription activation domain). Ligand-mediated association of the fusion proteins represents the formation of a transcription factor complex and leads to initiation of transcription of a target gene linked to a DNA sequence recognized by (i.e., capable of binding with) the DNA-binding domain on one of the fusion proteins. Information regarding the gene expression system as well as the ligand is disclosed in U.S. Pat. Nos. 6,187,757; 6,649,595; 6,509,152; 6,479,653; and 6,117,680. 
     In other embodiments, the present invention provides a gene switch system which comprises polynucleotides encoding two fusion proteins which self-aggregate in the absence of a ligand, wherein (a) the first fusion protein comprises a conditional aggregation domain which binds to a selected ligand and a transcription activation domain, and (b) the second fusion protein comprising a conditional aggregation domain which binds to a selected ligand and a DNA binding domain, and (c) in the absence of ligand, the cells express a gene operably linked to regulatory DNA to which said DNA binding domain binds. Modified cells comprising the gene switch system are expanded in the presence of the ligand in an amount sufficient for repression of the gene. Ligand removal induces expression of the encoded protein that causes cell death. The nucleic acids encoding the two fusion proteins are under the control of at least one conditional promoter. The gene expression system utilizing conditional aggregation domains is disclosed in U.S. Publication No. 2002/0048792. 
     C. Prokaryotic Repressor/Operator Based Gene Switch System 
     In one embodiment, the present invention provides gene switch system comprising (a) a first polynucleotide coding for a transactivator fusion protein comprising a prokaryotic tetracycline (“tet”) repressor and a eukaryotic transcriptional activator protein domain; and (b) a second polynucleotide coding for a frataxin polypeptide, wherein said second polynucleotide is operably linked to a minimal promoter and at least one tet operator sequence. The first polynucleotide coding for a transactivator fusion protein may comprise therapeutic switch promoter as described elsewhere herein. 
     In another embodiment, the gene switch system comprises the lactose (“Lac”) repressor-operator systems from the bacterium  Escherichia coli . The gene switch system of the present invention may also comprise (a) a first polynucleotide coding for a transactivator fusion protein comprising a prokaryotic lac I repressor and a eukaryotic transcriptional activator protein domain; and (b) a second polynucleotide coding for a frataxin polypeptide, wherein said second polynucleotide is operably linked to a gene switch promoter. In the Lac system, a lac operon is inactivated in the absence of lactose, or synthetic analogs such as isopropyl-b-D-thiogalactoside. 
     Additional gene switch systems include those described in the following: U.S. Pat. No. 7,091,038; WO2004078924; EP1266015; US20010044151; US20020110861; US20020119521; US20040033600; US20040197861; US20040235097; US20060020146; US20040049437; US20040096942; US20050228016; US20050266457; US20060100416; WO2001/70816; WO2002/29075; WO2002/066612; WO2002/066613; WO2002/066614; WO2002/066615; WO2005/108617; U.S. Pat. No. 6,258,603; US20050209283; US20050228016; US20060020146; EP0965644; U.S. Pat. Nos. 7,304,162; 7,304,161; MX234742; KR10-0563143; AU765306; AU2002-248500; and AU2002-306550. 
     D. Combination of the Gene Switch Systems 
     The present invention provides nucleic acid compositions, modified cells, and bioreactors comprising two or more gene switch systems comprising different ligand-dependent transcription factor complexes which are activated by an effective amount of one or more ligands, wherein the two or more gene switch systems comprise a first gene switch and a second gene switch, both of which selectively induce expression of one or more interleukin polypeptides, upon binding to one or more ligands. Within the scope of the present invention are any numbers of and/or combinations of gene switch systems. 
     In one embodiment, the present invention provides a nucleic acid composition comprising a gene switch system which comprises:
         i. a first gene expression cassette comprising a polynucleotide encoding a first hybrid polypeptide which comprises:
           1. a transactivation domain, which activates a promoter operably associated
               with a polynucleotide encoding a frataxin polypeptide; and   
               2. a heterodimer partner domain,   
           ii. a second gene expression cassette comprising a polynucleotide encoding a second hybrid polypeptide which comprises:
           1. a DNA-binding domain, which recognizes a factor-regulated promoter operably associated with a polynucleotide encoding a frataxin polypeptide; and   2. a ligand binding domain; and   
           iii. a third gene expression cassette comprising a polynucleotide encoding a frataxin polypeptide, said third gene expression cassette comprising:
           1. an inducible promoter, which is activated by the transactivation domain of the second hybrid polypeptide; and,   2. a polynucleotide encoding said frataxin polypeptide.   
               

     In certain embodiments, the combination of two or more gene switch systems may be (1) a dual-switch ecdysone receptor based gene expression system and (2) a single-switch ecdysone receptor based gene switch. In other embodiments, the combination may be (1) a single- or dual-switch ecdysone receptor based gene switch and (2) a rapamycin based gene switch. Alternatively, the combination of gene switch systems may be two identical rapamycin based gene switch systems disclosed above. Any possible combinations of the gene switch systems are within the scope of the invention. Examples of dual-switch ecdysone systems can be found, for example, in WO 2002/29075 and US 2002/0110861. 
     E. Other Gene Switches 
     In another aspect of the invention, gene expression cassettes of the invention incorporate a cumate switch system, which works through the CymR repressor that binds the cumate operator sequences with high affinity. (SparQ™ Cumate Switch, System Biosciences, Inc.). The repression is alleviated through the addition of cumate, a non-toxic small molecule that binds to CymR. This system has a dynamic inducibility, can be finely tuned and is reversible and inducible. 
     In another aspect of the invention, gene expression cassettes of the invention incorporate a riboswitch, which is a regulatory segment of a messenger RNA molecule that binds an effector, resulting in a change in production of the proteins encoded by the mRNA. An mRNA that contains a riboswitch is directly involved in regulating its own activity in response to the concentrations of its effector molecule. Effectors can be metabolites derived from purine/pyrimidine, amino acid, vitamin, or other small molecule co-factors. These effectors act as ligands for the riboswitch sensor, or aptamer. Breaker, RR. Mol Cell. (2011) 43(6): 867-79. 
     In another aspect of the invention, gene expression cassettes of the invention incorporate the biotin-based gene switch system, in which the bacterial repressor protein TetR is fused to streptavidin, which interacts with the synthetic biotinylation signal AVITAG that is fused to VP16 to activate gene expression. Biotinylation of the AVITAG peptide is regulated by a bacterial biotin ligase BirA, thus enabling ligand responsiveness. Weber et al. (2007)  Proc. Natl. Acad. Sci. USA  104, 2643-2648; Weber et al. (2009)  Metabolic Engineering,  11(2): 117-124. 
     Additional gene switch systems which may be used as part of the present invention are well known in the art, including but not limited to those described in Auslander and Fussenegger,  Trends in Biotechnology  (2012), 31(3): 155-168, incorporated herein by reference. 
     Gene Switch Ligands 
     As used herein, the term “ligand,” as applied to gene switches (e.g., EcR based gene switches), describes small and soluble molecules having the capability of activating a gene switch to stimulate expression of a polypeptide encoded therein. The ligand for a ligand-dependent transcription factor complex of the invention binds to the protein complex comprising one or more of the ligand binding domain, the heterodimer partner domain, the DNA binding domain, and the transactivation domain. The choice of ligand to activate the ligand-dependent transcription factor complex depends on the type of the gene switch utilized. 
     Examples of ligands include, without limitation, an ecdysteroid, such as ecdysone, 20-hydroxyecdysone, ponasterone A, muristerone A, and the like, 9-cis-retinoic acid, synthetic analogs of retinoic acid, N,N′-diacylhydrazines such as those disclosed in U.S. Pat. Nos. 6,013,836; 5,117,057; 5,530,028; and 5,378,726 and U.S. Published Application Nos. 2005/0209283 and 2006/0020146; oxadiazolines as described in U.S. Published Application No. 2004/0171651; dibenzoylalkyl cyanohydrazines such as those disclosed in European Application No. 461,809; N-alkyl-N,N′-diaroylhydrazines such as those disclosed in U.S. Pat. No. 5,225,443; N-acyl-N-alkylcarbonylhydrazines such as those disclosed in European Application No. 234,994; N-aroyl-N-alkyl-N′-aroylhydrazines such as those described in U.S. Pat. No. 4,985,461; amidoketones such as those described in U.S. Published Application No. 2004/0049037; each of which is incorporated herein by reference and other similar materials including 3,5-di-tert-butyl-4-hydroxy-N-isobutyl-benzamide, 8-O-acetylharpagide, oxysterols, 22(R) hydroxycholesterol, 24(S) hydroxycholesterol, 25-epoxycholesterol, T0901317, 5-alpha-6-alpha-epoxycholesterol-3-sulfate (ECHS), 7-ketocholesterol-3-sulfate, famesol, bile acids, 1,1-biphosphonate esters, juvenile hormone III, and the like. Examples of diacylhydrazine ligands useful in the present invention include RG-115819 (3,5-Dimethyl-benzoic acid N-(1-ethyl-2,2-dimethyl-propyl)-N′-(2-methyl-3-methoxy-benzoyl)-hydrazide), RG-115932 ((R)-3,5-Dimethyl-benzoic acid N-(1-tert-butyl-butyl)-N′-(2-ethyl-3-methoxy-benzoyl)-hydrazide), and RG-115830 (3,5-Dimethyl-benzoic acid N-(1-tert-butyl-butyl)-N′-(2-ethyl-3-methoxy-benzoyl)-hydrazide). See, e.g., U.S. patent application Ser. No. 12/155,111, published as US 2009/0163592, and PCT Appl. No. PCT/US2008/006757, both of which are incorporated herein by reference in their entireties. 
     For example, a ligand for the ecdysone receptor based gene switch may be selected from any suitable ligands. Both naturally occurring ecdysone or ecdysone analogs (e.g., 20-hydroxyecdysone, muristerone A, ponasterone A, ponasterone B, ponasterone C, 26-iodoponasterone A, inokosterone or 26-mesylinokosterone) and non-steroid inducers may be used as a ligand for gene switch of the present invention. U.S. Pat. No. 6,379,945 B1, describes an insect steroid receptor isolated from  Heliothis virescens  (“HEcR”) which is capable of acting as a gene switch responsive to both steroid and certain non-steroidal inducers. Non-steroidal inducers have a distinct advantage over steroids, in this and many other systems which are responsive to both steroids and non-steroid inducers, for a number of reasons including, for example: lower manufacturing cost, metabolic stability, absence from insects, plants, or mammals, and environmental acceptability. U.S. Pat. No. 6,379,945 B1 describes the utility of two dibenzoylhydrazines, 1,2-dibenzoyl-1-tert-butyl-hydrazine and tebufenozide (N-(4-ethylbenzoyl)-N′-(3,5-dimethylbenzoyl)-N′-tert-butyl-hydrazine) as ligands for an ecdysone-based gene switch. Also included in the present invention as a ligand are other dibenzoylhydrazines, such as those disclosed in U.S. Pat. No. 5,117,057 B1. Use of tebufenozide as a chemical ligand for the ecdysone receptor from  Drosophila melanogaster  is also disclosed in U.S. Pat. No. 6,147,282. Additional, non-limiting examples of ecdysone ligands are 3,5-di-tert-butyl-4-hydroxy-N-isobutyl-benzamide, 8-O-acetylharpagide, a 1,2-diacyl hydrazine, an N′-substituted-N,N′-disubstituted hydrazine, a dibenzoylalkyl cyanohydrazine, an N-substituted-N-alkyl-N,N-diaroyl hydrazine, an N-substituted-N-acyl-N-alkyl, carbonyl hydrazine or an N-aroyl-N′-alkyl-N′-aroyl hydrazine. (See U.S. Pat. No. 6,723,531). 
     In one embodiment, the ligand for an ecdysone based gene switch system is a diacylhydrazine ligand or chiral diacylhydrazine ligand. The ligand used in the gene switch system may be compounds of Formula I 
     
       
         
         
             
             
         
       
     
     wherein
 
A is alkoxy, arylalkyloxy or aryloxy;
 
B is optionally substituted aryl or optionally substituted heteroaryl; and
 
R 1  and R 2  are independently optionally substituted alkyl, arylalkyl, hydroxyalkyl, haloalkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heterocyclo, optionally substituted aryl or optionally substituted heteroaryl;
 
or pharmaceutically acceptable salts, hydrates, crystalline forms or amorphous forms thereof.
 
     In another embodiment, the ligand may be enantiomerically enriched compounds of Formula II 
     
       
         
         
             
             
         
       
     
     wherein
 
A is alkoxy, arylalkyloxy, aryloxy, arylalkyl, optionally substituted aryl or optionally substituted heteroaryl;
 
B is optionally substituted aryl or optionally substituted heteroaryl; and
 
R 1  and R 2  are independently optionally substituted alkyl, arylalkyl, hydroxyalkyl, haloalkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heterocyclo, optionally substituted aryl or optionally substituted heteroaryl;
 
with the proviso that R 1  does not equal R 2 ;
 
wherein the absolute configuration at the asymmetric carbon atom bearing R 1  and R 2  is predominantly S;
 
or pharmaceutically acceptable salts, hydrates, crystalline forms or amorphous forms thereof.
 
     In certain embodiments, the ligand may be enantiomerically enriched compounds of Formula III 
     
       
         
         
             
             
         
       
     
     wherein
 
A is alkoxy, arylalkyloxy, aryloxy, arylalkyl, optionally substituted aryl or optionally substituted heteroaryl;
 
B is optionally substituted aryl or optionally substituted heteroaryl; and
 
R 1  and R 2  are independently optionally substituted alkyl, arylalkyl, hydroxyalkyl, haloalkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heterocyclo, optionally substituted aryl or optionally substituted heteroaryl;
 
with the proviso that R 1  does not equal R 2 ;
 
wherein the absolute configuration at the asymmetric carbon atom bearing R 1  and R 2  is predominantly R;
 
or pharmaceutically acceptable salts, hydrates, crystalline forms or amorphous forms thereof.
 
     In one embodiment, a ligand may be (R)-3,5-dimethyl-benzoic acid N-(1-tert-butyl-butyl)-N′-(2-ethyl-3-methoxy-benzoyl)-hydrazide having an enantiomeric excess of at least 95% or a pharmaceutically acceptable salt, hydrate, crystalline form or amorphous form thereof. 
     The diacylhydrazine ligands of Formula I and chiral diacylhydrazine ligands of Formula II or III, when used with an ecdysone-based gene switch system, provide the means for external temporal regulation of expression of a frataxin polypeptide of the present invention. See U.S. application Ser. No. 12/155,111, published as US 2009/0163592, filed May 29, 2008, which is fully incorporated by reference herein. 
     The ligands used in the present invention may form salts. The term “salt(s)” as used herein denotes acidic and/or basic salts formed with inorganic and/or organic acids and bases. In addition, when a compound of Formula I, II or III contains both a basic moiety and an acidic moiety, zwitterions (“inner salts”) may be formed and are included within the term “salt(s)” as used herein. Pharmaceutically acceptable (i.e., non-toxic, physiologically acceptable) salts are used, although other salts are also useful, e.g., in isolation or purification steps which may be employed during preparation. Salts of the compounds of Formula I, II or III may be formed, for example, by reacting a compound with an amount of acid or base, such as an equivalent amount, in a medium such as one in which the salt precipitates or in an aqueous medium followed by lyophilization. 
     The ligands which contain a basic moiety may form salts with a variety of organic and inorganic acids. Exemplary acid addition salts include acetates (such as those formed with acetic acid or trihaloacetic acid, for example, trifluoroacetic acid), adipates, alginates, ascorbates, aspartates, benzoates, benzenesulfonates, bisulfates, borates, butyrates, citrates, camphorates, camphorsulfonates, cyclopentanepropionates, digluconates, dodecylsulfates, ethanesulfonates, fumarates, glucoheptanoates, glycerophosphates, hemisulfates, heptanoates, hexanoates, hydrochlorides (formed with hydrochloric acid), hydrobromides (formed with hydrogen bromide), hydroiodides, 2-hydroxyethanesulfonates, lactates, maleates (formed with maleic acid), methanesulfonates (formed with methanesulfonic acid), 2-naphthalenesulfonates, nicotinates, nitrates, oxalates, pectinates, persulfates, 3-phenylpropionates, phosphates, picrates, pivalates, propionates, salicylates, succinates, sulfates (such as those formed with sulfuric acid), sulfonates (such as those mentioned herein), tartrates, thiocyanates, toluenesulfonates such as tosylates, undecanoates, and the like. 
     The ligands which contain an acidic moiety may form salts with a variety of organic and inorganic bases. Exemplary basic salts include ammonium salts, alkali metal salts such as sodium, lithium, and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases (for example, organic amines) such as benzathines, dicyclohexylamines, hydrabamines (formed with N,N-bis(dehydroabietyl)ethylenediamine), N-methyl-D-glucamines, N-methyl-D-glucamides, t-butyl amines, and salts with amino acids such as arginine, lysine and the like. 
     Non-limiting examples of the ligands for the inducible gene expression system utilizing the FK506 binding domain are FK506, Cyclosporin A, or Rapamycin. FK506, rapamycin, and their analogs are disclosed in U.S. Pat. Nos. 6,649,595 B2 and 6,187,757. See also U.S. Pat. Nos. 7,276,498 and 7,273,874. 
     The ligands described herein may be administered alone or as part of a pharmaceutical composition comprising a pharmaceutically acceptable carrier. In one embodiment, the pharmaceutical compositions are in the form of solutions, suspensions, tablets, capsules, ointments, elixirs, or injectable compositions. 
     Certain embodiments of the invention will now be described with reference to particular examples which are provided solely to illustrate the invention and should not be construed to be limiting in any way. 
     EXAMPLES 
     Certain aspects of the invention will now be described, but shall not be construed as limiting of the invention. 
     Materials and Methods Used in the Examples 
     A. Matrix Design and Design of Experiments 
     The initial Frataxin design cycle was carried out in three phases. First, parts were selected based on historical data and expert consideration and literature precedence for in vivo target cell type (DRGs). Second, the full factorial matrix was formulated. Third, D-optimal experimental design was carried out on the full factorial. This resulted in a subset of the matrix that uncovers the maximal variance and leads most rapidly to the development of a predictive model. 
     A constitutive expression matrix of ˜80 constructs, with variations in the promoter and 5′/3′ regulatory elements was designed and analyzed using Design of Experiment algorithms to reduce the number of constructs needed to adequately test for “high” and “medium” levels of FXN expression (potentially representing super-physiological and physiological levels, respectively). The FXN minimal essential 1,255 bp promoter as described in Greene et al. (2005) was included in the matrix to provide potentially physiological levels of FXN expression. Other constitutive promoters included EF1a, UBC, and PGK1. Fifty constructs were generated from the original matrix of 80. 
     The matrix was reduced to 50 vectors with additional positive, super-physiological expression controls included in the expression screen: CAG-FXN-hGHpA and CMV-5U2-FXN-hGHpA. The CMV promoter, known to be a very strong promoter, was not included in the matrix as it is known to be silenced over time in vivo (McCown et al. (1996)  Brain Res.  713:99-107; Klein et al. (1998)  Exp. Neurol.  150:183-194; Paterna et al. (2000)  Gene Ther.  7, 1304-1311; Tenenbaum et al. (2004)  J. Gene Med.  6(Suppl. 1), S212-S222). The CAG-FXN-hGHpA construct with the CAG (chicken beta-actin hybrid) promoter, also a strong promoter, was included as a comparator. The CAG promoter also contains the CMV early enhancer and the first exon and the first intron of chicken beta-actin gene, and the 5′ splice acceptor of the rabbit beta-globin gene. This hybrid promoter and other variations of it, is routinely used in AAV gene therapy applications (e.g., Flotte et al. (2011)  Hum. Gene Ther.  22:1239-1247; Maclachlan et al. (2011)  Mol. Ther.  19:326-334; Perdomini et al. (2014)  Nature Med.  20:542-547). 
     The 50 matrix vectors and controls were constructed using standard cloning techniques. The matrix vectors and controls were generated into an AAV backbone where the expression cassette was inserted between the two AAV inverted terminal repeat (ITR) sequences which are essential for packaging the genome into the selected AAV capsid serotype. Constructs also included non-coding “stiffer” sequences ranging from 1,001 bp to 2,500 bp to bring the genome size to the ˜4.2 kb which is optimal for capsid packaging. Constructs were fully sequence verified using next generation sequencing technologies, including the Nextra XT DNA preparation kit from Illumina with some modifications. A subset of these is presented herein and is listed in Table 1. 
     B. Transfection Procedures, Assays, and Analysis 
     On day 0, frozen SY5Y cells (European Collection of Cell Cultures, ECACC operated by Public Health England), Sigma Cat #94030304; Lot #13C014) were seeded in an original flask and incubated at 37° C., 5% CO 2 , saturating humidity. Separately, frozen FA fibroblasts (Coriell; Cat #GM03816) were seeded in an original flask and incubated at 37° C., at 5% CO 2 , saturating humidity. 
     On day 3, when the SY5Y and fibroblasts were at 75% confluence, the media of each flask was aspirated, and the cells were rinsed once with 10 mL DPBS (Gibco, without Calcium, Magnesium, Cat #14190), prior to resuspending them in 3 mL Trypsin-EDTA (0.25%, Gibco Cat #25200) and incubating them for 3 minutes at RT. 5 mL of media was added to neutralize trypsin in each flask. Cells were collected from each of the T75 flasks into 15 mL Falcon tubes and centrifuged at 1000 rpm in a Sorval table-top centrifuge for 5 minutes at RT. The supernates were discarded and the cells were resuspended in 2 mL of fresh medium. The cells were agitated gently to break up any clumps. Cells were then split 1:2 and 1 mL of the cell suspensions were added to 4 T75 flasks each. 
     C. Transfection 
     On day 0, 4.0×10 4  live SY5Y and FA fibroblast cells were plated in 0.4 mL medium/well of four 48-well tissue-culture treated plates. Cells were collected by aspirating and discarding the media, rinsing each flask once with 10 mL DPBS, aspirating and discarding the DPBS, resuspending the cells in 3 mL Trypsin-EDTA and incubating them for 3 minutes at RT. 5 mL of media was then added to neutralize trypsin in each flask and the cells were collected into 15 mL Falcon tubes and centrifuged at 1000 rpm in a Sorval table-top centrifuge for 5 minutes at RT. The supernates were discarded and the cells were resuspended in 2 mL fresh fibroblast medium and the cells from each of the 2 cell types were pooled (fibroblasts separately from SY5Y). The cells were agitated gently to break up any clumps. 
     Cells were counted by adding 10 μL of cell suspension to 90 μL diluted trypan blue and mixed gently before loading cells on a hemacytometer to count the cells. We obtained Live/Dead: 6.5×10 6  cells/mL of SY5Y and 1.8×10 6  cells/mL of FA fibroblasts wherein viability: 83/85=97.6% for SY5Y and 82/85=96.5% for FA fibroblasts. 
     Then 4.0×10 4  SY5Y cells and FA fibroblasts were plated into each of the wells of the 48 well plates containing 0.4 mL of fresh DMEM/F12 medium (Gibco, Cat #11320-033, supplemented with 10% heat inactivated fetal bovine serum (FBS)(Atlanta Bio, Cat # S11550H). The plates were rocked side to side and forward and backward to evenly distribute cells. The plates were incubated overnight at 37° C., at 5% CO 2 , saturating humidity. 
     For FA fibroblasts, on Day 1, cells were observed for confluency and general appearance. DNA:TransfeX (1:1) complexes for FA fibroblasts were prepared. One tube for each plasmid was labeled and there were 3 tubes for each of the plasmids. The TransfeX, plasmid DNA, and Opti-MEM I Reduced-Serum Medium (Gibco, Cat #31985-062, with L-Glutamine, w/HEPES, w/2.4 g/L NaBicarb) were warmed to room temperature and swirled gently to mix. 50 μL of Opti-MEM I Reduced-Serum Medium was pipetted into sterile microcentrifuge tubes. Appropriate volumes of plasmid DNA (0.75 μg DNA) were added per tube and mixed thoroughly by gentle pipetting. Then, 0.75 μL of TransfeX Reagent (ATCC, Cat #ACS-4005) was added to the diluted DNA mixture in each of the tubes. The TransfeX:DNA complexes were mixed thoroughly by pipetting followed by flicking the tubes. The TransfeX:DNA complexes were incubated at room temperature for 15 minutes. The tubes were centrifuged (short spin) to force all liquid to bottom of Eppendorf tubes. To add the transfection complexes to the FA fibroblasts, the complexes were distributed to the cells by adding the complexes drop-wise to different areas of the wells (50 μL of mixture to each of three triplicate wells). The culture vessels were gently rocked back and forth and from side to side to evenly distribute the TransfeX:DNA complexes and incubated for ˜72 hrs. 
     For the SY5Y cells, on Day 1, DNA:Fugene 6 (1:3) complexes were prepared. One tube for each plasmid was labeled and there were 3 tubes for each of the plasmids. The FuGene 6, plasmid DNA, and Opti-MEM I Reduced-Serum Medium were warmed to room temperature and swirled gently to mix. 50 μL of Opti-MEM I Reduced-Serum Medium was pipetted into sterile microcentrifuge tubes. Then 2.25 μL Fugene 6 Reagent (Promega, Cat #2692) was added to the media in each of the tubes and the incubated for 5 minutes. Appropriate volumes of plasmid DNA (0.75 μg DNA) were added per tube and mixed thoroughly by gentle pipetting. The transfection reagent/media/DNA complexes were mixed thoroughly by pipetting followed by flicking the tubes. The complexes were incubated at room temperature for 15 minutes. The tubes were centrifuged (short spin) to force all liquid to bottom of Eppendorf tubes. To add the transfection complexes to the SY5Y cells, the complexes were distributed to the cells by adding the complexes drop-wise to different areas of the wells (50 μL of mixture to each of three triplicate wells). The culture vessels were gently rocked back and forth and from side to side to evenly distribute the transfection complexes and incubated for ˜72 hrs. 
     On Day 4, the GFP fluorescence signal was verified (visually) and cells were lysed in cell lysis buffer (for each 10 mL of cell lysis buffer: 200 uL (50× cell extraction enhancer)+2 mL (5× cell extraction buffer)+7.8 mL (DI water, Gibco, Cat #A12873)+1 tablet Protease inhibitor/EDTA (Roche, Cat #04693159001). Briefly, supernatants from each of the wells of the four 48 well plates was aspirated and the cells were washed twice with chilled 1×PBS (all steps of the procedure performed on ice). Chilled Lysis buffer was added at 150 μL/well. The cells in each well were scraped to ensure cell lysis using the bottom of a P1000 tip. The plates with cells in lysis buffer were incubated at 4° C. on a shaker for 30 minutes. Cell lysates were collected by pipetting up and down without forming foam and add to a microfuge tube. The lysates were centrifuged at 4° C., 18,000 rpm for 20 min. The cell lysates were then transferred to a new microfuge tube and stored at −800 C until ready to use in the Frataxin ELISA (see below). 
     On Day 5, total protein concentrations of the SY5Y and the FA fibroblast cell lysates transfected with the FXN matrix was determined using the Micro BCA Assay Protocol (Pierce, Cat #23235; Lot #PK 207908) per manufacturer&#39;s instructions. 
     On Day 6, FXN contents in the FXN matrix transfected SY5Y and FA fibroblast samples was determined using the FXN ELISA (FRATAXIN Human Simple Step ELISA, Abcam ab176112) according to the manufacturer&#39;s recommendation with the exception that all the samples and Standards were diluted in 1×PBS. Briefly, reagents, working standards, and samples were prepared according to the Abcam Kit&#39;s manufacturer instructions. All materials and reagents were equilibrated to room temperature prior to use. All standards, controls and samples were run in duplicates. 
     A 50 μL aliquot of each sample or standards was added to appropriate wells. SY5Y cell lysates were diluted 1:150 and the FA Fibroblasts were diluted 1:50 based on the total protein concentration data obtained from the micro BCA assay (Pierce, Cat #23235; Lot #PK 207908) per the manufacturer&#39;s instructions. A 50 μL aliquot of the Antibody Cocktail (1× Capture Antibody plus 1× Detector Antibody provided in Frataxin ELISA kit and prepared per manufacturer&#39;s instructions) was to each well. The plate was sealed and incubated for 1 hour at room temperature on a plate shaker set to 400 rpm. Each well was washed with 3×350 μL 1× Wash Buffer PT (buffer provided in Frataxin ELISA kit and prepared per manufacturer&#39;s instructions) by aspirating or decanting from wells then dispensing 350 μL 1× Wash Buffer PT into each well. After the last wash, the plate was inverted and blotted against clean paper towels to remove excess liquid. 100 μL of TMB Substrate was added to each well and incubated for 10 minutes in the dark on a plate shaker set to 400 rpm. 100 μL of Stop Solution was then added to each well. The plate was shaken on a plate shaker for 1 minute to mix. OD at 450 nm of each well was recorded as an endpoint reading. 
     Plasmids: Construct description in Table 1. All constructs contain a stuffer ranging from 1001 to 3000 bp to ensure optimal genome packaging size for AAV. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Selected Constructs 
               
            
           
           
               
               
            
               
                   
                 Composition* 
               
            
           
           
               
               
               
               
            
               
                 No./name 
                 Promoter 
                 5′ Reg 
                 3′ Reg 
               
               
                   
               
               
                 CMV 
                 CMV 
                 5U2 
                 hGHpA 
               
               
                   
                 (SEQ ID NO: 13) 
                 (SEQ ID NO: 4) 
                 (SEQ ID NO: 5) 
               
               
                   
               
               
                 012 
                 UBC 
                 FTH1-5′UTR 
                 SV40 early 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 14) 
                 (SEQ ID NO: 8) 
               
               
                   
               
               
                 017 
                 UBC 
                 FTH1-5′UTR 
                 SV40 late 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 14) 
                 (SEQ ID NO: 9) 
               
               
                   
               
               
                 020 
                 UBC 
                 GAPDH 
                 Other 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 15) 
                   
               
               
                   
               
               
                 021 
                 UBC 
                 RPL6-5′Splice 
                 Other 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 16) 
                   
               
               
                   
               
               
                 023 
                 UBC 
                 GAPDH 
                 synthetic 3′ regulatory element 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 15) 
                 (SEQ ID NO: 7) 
               
               
                   
               
               
                 024 
                 UBC 
                 5U2 
                 synthetic 3′ regulatory element 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 4) 
                 (SEQ ID NO: 7) 
               
               
                   
               
               
                 025 
                 UBC 
                 RPL6-5′Splice 
                 synthetic 3′ regulatory element 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 16) 
                 (SEQ ID NO: 7) 
               
               
                   
               
               
                 026 
                 UBC 
                 5U2 
                 hGHpA 
               
               
                   
                 (SEQ ID NO: 3) 
                 (SEQ ID NO: 4) 
                 (SEQ ID NO: 5) 
               
               
                   
               
               
                 034 
                 PGK1 
                 GAPDH 
                 SV40 late 
               
               
                   
                 (SEQ ID NO: 17) 
                 (SEQ ID NO: 15) 
                 (SEQ ID NO: 9) 
               
               
                   
               
               
                 GFP 
                 CMV 
                 n/a 
                 unknown 
               
               
                   
                 (SEQ ID NO: 13) 
                   
                   
               
               
                   
               
               
                 Mock 
               
               
                   
               
            
           
         
       
     
     D. AAV5 Vector Manufacture 
     Viral particles, including but not limited to, viruses, vectors, virions, gene delivery vehicles, rAAVs, capsids and empty capsids, useful in the practice of the present invention, can be constructed using methods well known in the art of molecular biology. Viral vectors carrying transgenes can be assembled from polynucleotides encoding the transgene, suitable regulatory elements and elements necessary for production of viral proteins that mediate cell transduction. 
     The Biological Substance, AAV5.hFXN is a recombinant adeno-associated virus (rAAV) containing WT hFXN cDNA. The gene insert (e.g. ‘transgene’) codes for human frataxin protein precursor, the expression of which is intended to increase the amount of the mitochondrial frataxin in the treated subjects. The hFXN cDNA in the vector was chemically synthesized de novo to match the sequence of normal human frataxin mRNA described in Reference Sequence: NM_000144.4 (on the worldwide web at URL ncbi.nlm.nih.gov/nuccore/NM_000144). 
     Description of 026 Construct: 
     The major elements of the recombinant AAV5 single-stranded DNA vector are shown in  FIG. 21 . The vector elements are described in more detail in Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Description of the Single-stranded DNA Vector Elements. 
               
            
           
           
               
               
               
            
               
                 Nucleotide Bases 
                 Element Identifier 
                 Description 
               
               
                   
               
               
                  1-141 
                 ITR 
                 AAV2 inverted terminal repeat 
               
               
                 142-191 
                 not shown 
                 Restriction enzyme sites 
               
               
                 192-762 
                 UBC promoter 
                 Human Ubiquitin C (UBC)  
               
               
                   
                   
                 promoter 
               
               
                 763-784 
                 not shown 
                 Restriction enzyme sites 
               
               
                 785-964 
                 5U2 
                 Synthetic 5′ regulatory element 
               
               
                 965-970 
                 not shown 
                 Restriction enzyme site 
               
               
                  971-1609 
                 hFXN GOI 
                 Human FXN cDNA 
               
               
                 1610-1635 
                 not shown 
                 Restriction enzyme sites 
               
               
                 1636-2262 
                 hGH-Poly A 
                 Human Growth Hormone Poly A 
               
               
                 2263-2283 
                 not shown 
                 Restriction enzyme sites 
               
               
                 2284-4533 
                 ITR linker 
                 Synthetic linker 
               
               
                 4534-4451 
                 not shown 
                 Restriction enzyme site 
               
               
                 4452-4691 
                 ITR 
                 AAV2 inverted terminal repeat 
               
               
                   
               
            
           
         
       
     
     A representative example of a rAAV5.hFXN plasmid nucleotide sequence (SEQ ID NO: 20) is shown in  FIG. 20 . Embodiments of the present invention include, but are not limited to functional homologues of the rAAV5.hFXN plasmid nucleotide sequence (SEQ ID NO:20). 
     A representative example of a vector containing a gene insert is a nucleotide sequence nucleotide sequence (SEQ ID NO:19) is shown in  FIG. 19 . The sequence represents the pAAV5.hFXN plasmid from the beginning of the left ITR to the end of the right ITR. Embodiments of the present invention include, but are not limited to functional homologues of the nucleotide sequence (SEQ ID NO:19). 
     Pharmaceutical Formulation 
     The biologic product, rAAV5.hFXN vector is formulated in a sterile, buffered solution suitable for intrathecal injection. Exemplary compositions of are shown in Table 4 and Table 5. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Example Composition of AA5.hFXN Vector Product 
               
            
           
           
               
               
               
            
               
                 Component 
                 Concentration 
                 Function 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 AAV5.hFXN 
                 5 × 10 13    
                 vg/mL 
                 Active ingredient 
               
               
                 NaCl 
                 7.01  
                 gm/L 
                 Diluent of active vector that 
               
               
                 KCl 
                 0.208  
                 gm/L 
                 mimics the major chemical ionic 
               
               
                 CaCl 2   
                 0.233  
                 gm/L 
                 species, concentrations, and pH 
               
               
                 MgCl 2   
                 0.029  
                 gm/L 
                 (7.3) of human cerebral spinal 
               
               
                 Na 2 HPO 4   
                 1.10  
                 gm/L 
                 fluid 
               
               
                 NaH 2 PO 4   
                 0.329  
                 gm/L 
                   
               
               
                 H 2 O 
                 qs 1.0  
                 L 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Example Composition of AA5.hFXN Vector Product 
               
            
           
           
               
               
               
               
            
               
                   
                 Component 
                 Concentration 
                 Function 
               
               
                   
                   
               
               
                   
                 AAV5.hFXN 
                 2.5 × 10 11  vg/mL 
                 Active ingredient 
               
               
                   
                 NaCl 
                  0.154M 
                 pH (7.4) 
               
               
                   
                 Na 2 HPO 4   
                  0.056M 
                   
               
               
                   
                 KH 2 PO 4   
                 0.0106M 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Example Composition of AA5.hFXN Vector Product 
               
            
           
           
               
               
               
               
            
               
                   
                 Component 
                 Concentration 
                 Function 
               
               
                   
                   
               
               
                   
                 AAV5.hFXN 
                 5 × 10 13  vg/mL 
                 Active ingredient 
               
               
                   
                 NaCl 
                  0.337M 
                 pH (7.0) 
               
               
                   
                 KCl 
                  0.027M 
                   
               
               
                   
                 Na 2 HPO 4   
                  0.015M 
                   
               
               
                   
                 KH 2 PO 4   
                 0.0015M 
               
               
                   
                   
               
            
           
         
       
     
     Example 1 
     (A) Tier 1 Screen 
     Transfections occurred in 48 well plates in duplicate. For each construct, the cells from the two wells were pooled, assayed for total protein levels (BCA), and then assayed for FXN levels by ELISA. FXN levels were normalized to total protein content, and error bars represent ELISA assay duplicates. Shown in  FIG. 1  and  FIG. 2 , respectively, are the FXN expression levels in undifferentiated SY5Y cells and FA patient fibroblasts with constructs employing the UBC promoter. Panel A of  FIG. 1  and  FIG. 2  shows pg FXN/ng total protein. Panel B of  FIG. 1  and  FIG. 2  shows the fold FXN over mock. With only minimal exception, the UBC (SEQ ID NO:3) and EF1α (SEQ ID NO:18) promoters provided higher levels of FXN expression in SY5Y and in FA patient fibroblasts ( FIG. 2 ). 
     (B) Tier 2 Screen 
     Transfections were performed in 48 well plates in triplicate, with separate DNA/lipid prep for each well. Shown in  FIG. 3  and  FIG. 4  are results from the Tier 2 screen. FXN expression from UBC and EF1α promoter constructs (plus two minimum FXN promoter constructs not included in the first screen) were evaluated and the results grouped by 5′ regulatory elements. 
     (C) Tier 3 Screen 
     Based on the combined results from the primary (Tier 1) and secondary (Tier 2) screens, 14 FXN constructs were selected for further development. Results from the second run execution of the Tertiary (Tier 3) screen are shown below in  FIG. 5  and  FIG. 6  for both cell types. 
     Example 2 
     To demonstrate the site of expression of frataxin in cells, African green monkey fibroblasts (COS-7) or murine fibroblasts (NC6) were grown on glass coverslips under standard culture conditions. The culture medium was removed and the cells were fixed with 1 ml 3.7% formalin/phosphate buffered saline (PBS) at room temperature for 10 min. The cells were washed three times for 10 minute with 2 ml PBS and then were treated with blocking solution (1 ml 2% fetal bovine serum/0.2% Triton X-100/PBS) for 1 hour at room temperature. Following an overnight incubation at 40° C. with an anti-human frataxin antibody (1:500 dilution in blocking solution, Abcam #ab11038), the cells were washed three times for 10 minute with PBS-T (0.2% Tween 20/PBS). The cells were then incubated in the dark with 250 ul of secondary detection antibody (Alexa Fluor 488 Gt anti-Ms IgG, Thermo Fisher #A-11017) at 1:500 dilution in blocking buffer for 1 hour at room temperature. Following three 10 minute washes with PBS-T, the coverslips containing the cells were placed face-down onto microscope slides with one drop of VectaShield Hard Set with the nuclear counterstain, DAPI (Vector #H1500), and analyzed by confocal microscopy. In  FIG. 7 , Panel A, nuclei were stained with DAPI. In Panel B, mitochondria were stained with MitoTracker. Panel C shows staining with anti-human frataxin. The merged colocalization is shown in Panel D and demonstrates that Frataxin is being expressed in the mitochondria of the COS cells ( FIG. 7 ) and NC6 cells ( FIG. 8 ). 
     Example 3 
     To demonstrate that human frataxin is expressed and correctly processed in cells, the following experiment was conducted. Inducible pluripotent stem cells (iPSCs) derived from FA patients can be differentiated into cardiomyocyte and neuronal cell types, specific cell types which are affected in FA patients, and maintain reduced frataxin levels and triplet repeat instability (Liu et al. (2011)  Stem Cell Rev.  7(3):703-713; Polak et al. (2012)  J. Vis. Exp.  60:3416; Du et al. (2012)  J. Biol. Chem.  287(35):29861-29872). The neuronal cells are referred to as FA-iPSCs. FA (3816) Day 21 neurons were transduced with AAV5-human frataxin (026) at 500,000 genome copies/cell. The neurons were harvested in passive lysis buffer (Promega #E1941) with proteinase inhibitors at days 5, 7, 10, and 14 post-transduction. Total protein from the cells was isolated using sonication. The protein concentration was calculated using the Bradford method. 30 ug total protein per lane was separated by SDS-PAGE (Thermo Fisher #NW04120BOX, 4-12% NuPage). Human frataxin was detected with an anti-human frataxin antibody (Abcam #ab11038) using standard Western blot techniques. Molecular weight markers were loaded to confirm the size of the mature frataxin protein (14.2 kDa).  FIG. 9  Panel A shows day 21 neurons harvested at days 5 and 7 post-transduction (FA+) along with non-transduced cells (FA) and IPSCs derived from normal patients, which served as control cells (Ctrl).  FIG. 9  Panel B shows day 21 neurons harvested at days 10 and 14 post-transduction (FA+) along with non-transduced cells (FA) and IPSCs derived from normal patients, which served as control cells (Ctrl). The results show that human frataxin is expressed and correctly processed in the FA-AAV5 transduced cells. 
       FIG. 10  shows a schematic of the uses of stem cell therapy (adapted from “Stem Cell Therapy: A Panacea or Perturbed Claim!” (Dec. 30, 2014)(source: stemcells.uct.ac.za). 
     Example 4 
     Day 8 iPSCs were transfected with 2 μg DNA of the human frataxin DNA construct, 024 or 026, using the BioRad Gene Pulser Xcell electroporation system. Frataxin protein expression was determined after 4 days treatment (day 12 iPSCs) using the Frataxin Protein Quantity Dipstick Assay (AbCam #ab109881) and is expressed as frataxin antibody signal/mg total protein. The fold increase in the frataxin expression was calculated by dividing the mean frataxin concentration/signal in treated cells by the frataxin concentration/signal in mock control (GFP treated) cells.  FIG. 11  shows that both 024 and 026 exhibited a mean frataxin concentration/signal of greater than 3 fold and 3.5 fold, respectively. 
     Example 5 
     Day 8 iPSCs were transduced with AAV5-human frataxin (AAV5-hFXN) 024 and 026 at a multiplicity of infection (MOI) of 3.75×10 5  vector genomes (vg)/cell. Frataxin protein expression was determined after 4 days treatment (day 12 iPSCs) using the Frataxin Protein Quantity Dipstick Assay (AbCam #ab109881) and is expressed as frataxin antibody signal/mg total protein. The fold increase in the frataxin expression was calculated by dividing the mean frataxin concentration/signal in treated cells by the frataxin concentration/signal in mock control (GFP treated) cells.  FIG. 12  shows that both 024 and 026 exhibited a mean frataxin concentration/signal of greater than 2.5 fold and 3.5 fold, respectively. 
     Example 6 
     AAV5-human frataxin vector was injected directly into the cerebellum (CB) of four normal wild-type (WT) mice at a dose of 7×10 9  vg in 3 μl. At 4 weeks post injection, the cerebellum was harvested from treated mice as well as two untreated mice. Tissue lysates were analyzed for human frataxin expression using the Human Frataxin Simple Step ELISA (Abcam #176112) and normalized to pg frataxin/mg total protein.  FIG. 13  shows that greater than 30 ng and 70 ng of frataxin were detected for 024 and 026 cerebellar lysates, respectively. No expression of human frataxin was detected in the untreated animals (data not shown). 
     Example 7 
     AAV5-human frataxin vector was administered by intracerebroventricular injection into four normal wild-type (WT) mice at a dose of 7×10 9  vg in 3 At 4 weeks post injection, the cerebellum (CB), the hippocampus (HPC), and anterior cortex (ACX) were harvested from treated mice as well as from two untreated mice. Tissue lysates were analyzed for human frataxin expression using the Human Frataxin Simple Step ELISA (Abcam #176112) and normalized to pg frataxin/mg total protein. No expression of human frataxin was detected in the untreated animals (data not shown).  FIG. 14  shows that the accumulation of frataxin was greatest in the hippocampus in both 024 and 026, however, 026 showed greater than 8 fold more frataxin in the hippocampus than 024. 
     Example 8 
     Clinical Study of AAV5.hFXN Vector Gene Therapy 
     AAV5.hFXN vector is formulated in a sterile solution containing standard compendial excipients. The vector is administrated by intrathecal (IT) injection. The total dose is of 5×10 13  vg to 5×10 14  vg in a maximum volume of 10 mL, which is approximately 5% of the average cerebrospinal fluid (CSF) volume in humans of approximately 200 mL (See D. Agamanolis 2013 , Neuropathology: An illustrated interactive course for medical students and residents . Chapter 14: Cerebrospinal Fluid; Brown et al., “Molecular Mechanisms of Cerebrospinal Fluid Production. Neuroscience.” 2004, 129(4): 957-970). 
     A Phase 1, 3+3 single ascending dose study evaluates the safety of AAV5.hFXN in adult patients with FA. A single dose of AAV5.hFXN pharmaceutical formulation is administered intrathecally to successive cohorts of 3 subjects each. Three ascending doses of AAV5.hFXN are administered, with a review of safety by an independent DSMB prior to enrollment of the next higher dose level. Safety and neurological evaluations are performed periodically for 24 months post dose. Functional assessments are performed. 
     A Medtronic Model 8781 ASCENDA™ Intrathecal Catheter System that can deliver parenteral drugs to the intrathecal space is used. The Catheter System components include a Medtronic pump and the catheter system—the catheter is implanted in a sterile surgical procedure performed under general or regional anesthesia. The Catheter System is inserted at the lumbar level, where half of the dose to be administered is injected, and then the catheter is threaded to the level of the cisterna magna using guided imaging, where the remaining half of the dose is injected. 
     Three optional doses are studied. The low dose tested in the clinical trial is 5×10 13  vg. The middle dose is 1.5×10 14  vg. The high dose is 5×10 14  vg. Non-limiting Exemplary doses are shown in Table 6. 
     
       
         
           
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                   
                 Total Dose—CSF  
                 Total Dose—Brain  
               
               
                 Total Vector  
                 Volume Basis 
                 Weight Basis 
               
               
                 Dose (vg) 
                 (vg/mL) 
                 (vg/g) 
               
               
                   
               
             
            
               
                 5.0 × 10 13   
                 2.5 × 10 11   
                  3.7 × 10 10   
               
               
                 1.5 × 10 14   
                 7.5 × 10 11   
                 1.11 × 10 11   
               
               
                 5.0 × 10 14   
                 2.5 × 10 12   
                  3.7 × 10 11   
               
               
                   
               
            
           
         
       
     
     Efficacy data is collected at 1, 3, 6 and 12 months post study drug administration. Efficacy is evaluated in subjects using diffusion tensor imaging and various functional outcomes (including but not limited to FARS total and FARS Neuro; evaluation of a 25-foot walk test; evaluation on a GAITRite Walkway System; evaluation using a Biodex Balance System SD; evaluation using the 9-hole peg test). Diffusion tensor imaging may be measured, for example, by T2 relaxometry of dentate nucleus and DRG and/or NAA levels and iron levels by Magnetic Resonance Imaging (MRS). 
     Example 9 
     Treatment of Friedrich&#39;s Ataxia with AAV5.hFXN Vector Gene Therapy Intracerebellar Administration 
     A 5.0×10 13  (vg) Total Vector Dose of AAV5.hFXN vector pharmaceutical formulation (2.5×10 13  vg/mL with 1×PBS at a pH of 7.4) is administered to a 30-year-old patient with Friedreich&#39;s ataxia. The vector delivers hFXN gene into the central nervous system of the Friedrich ataxia patient. The pharmaceutical formulation is administered as a single bolus intracerebellar injection. The rate of injection is controlled by a Medtronic SynchroMed®EL 18-mL pump. The 5.0×10 13  (vg) Total Vector Dose is administered at a rate of 0.001 mL/min and at a concentration of 2.5×10 13  vg/mL. Total volume=2 mL. 
     Improved function relative to natural disease progression is observed. The increases from baseline in FARS total and FARS Neuro score improve over time and achieve statistical significance by 6 months after the procedure. Integrated analyses of the patient&#39;s FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores demonstrate statistically significant improvement in gross and fine motor skills as early as 6 months after gene therapy. A significant treatment benefit seen on motor skills generally continues to improve over time. After surgery, the patient demonstrates generally continuous increases in their FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores. Safety and neurological evaluations are performed periodically for 24 months post dose. Functional assessments are performed. In conclusion, the present disclosure using AAV viral vectors to transfer hFXN genes for treating Friedrich&#39;s Ataxia is practical and effective. 
     Example 10 
     Treatment of Friedrich&#39;s Ataxia with AAV5.hFXN Vector Gene Therapy Intracerebellar Administration 
     A 5.0×10 14  (vg) Total Vector Dose of AAV5.hFXN vector pharmaceutical formulation (2.5×10 14  vg/mL with 1×PBS at a pH of 7.4) is administered to a 30-year-old patient with Friedreich&#39;s ataxia. The vector delivers hFXN gene into the central nervous system of the Friedrich ataxia patient. The pharmaceutical formulation is administered as a single bolus intracerebellar injection. The rate of injection is controlled by a Medtronic SynchroMed®EL 18-mL pump. The 5.0×10 14  (vg) Total Vector Dose is administered at a rate of 0.01 mL/min and at a concentration of 2.5×10 14  vg/mL. Total volume=2 mL. 
     Improved function relative to natural disease progression is observed. The increases from baseline in FARS total and FARS Neuro score improve over time and achieve statistical significance by 6 months after the procedure. Integrated analyses of the patient&#39;s FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores demonstrate statistically significant improvement in gross and fine motor skills as early as 6 months after gene therapy. A significant treatment benefit seen on motor skills generally continues to improve over time. After surgery, the patient demonstrates generally continuous increases in their FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores. Safety and neurological evaluations are performed periodically for 24 months post dose. Functional assessments are performed. In conclusion, the present disclosure using AAV viral vectors to transfer hFXN genes for treating Friedrich&#39;s Ataxia is practical and effective. 
     Example 11 
     Treatment of Friedrich&#39;s Ataxia with AAV5.hFXN Vector Gene Therapy Intracerebroventricular Administration 
     A 3.5×10 12  vg Total Vector Dose of AAV5.hFXN vector pharmaceutical formulation (7×10 12  vg/mL with DPBS at a pH of 7.0) is administered to a 25-year-old patient with Friedreich&#39;s ataxia. The vector delivers hFXN gene into the central nervous system of the Friedrich ataxia patient. The pharmaceutical formulation is administered as a single bolus intracerebroventricular injection to the CSF space of the patient. The rate of injection is controlled by a Medtronic SynchroMed®EL 18-mL pump. The 3.5×10 12  vg Total Vector Dose is administered at a rate of 0.001 mL/min and at a concentration of 7×10 12  vg/mL. Total volume=0.5 mL. 
     Improved function relative to natural disease progression is observed. The increases from baseline in FARS total and FARS Neuro score improve over time and achieve statistical significance by 6 months after the procedure. Integrated analyses of the patient&#39;s FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores demonstrate statistically significant improvement in gross and fine motor skills as early as 6 months after gene therapy. A significant treatment benefit seen on motor skills generally continues to improve over time. After surgery, the patient demonstrates generally continuous increases in their FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores. Safety and neurological evaluations are performed periodically for 24 months post dose. Functional assessments are performed. In conclusion, the present disclosure using AAV viral vectors to transfer hFXN genes for treating Friedrich&#39;s Ataxia is practical and effective. 
     Example 12 
     Treatment of Friedrich&#39;s Ataxia with AAV5.hFXN Vector Gene Therapy Intrathecal Administration 
     A 5.0×10 14  (vg) Total Vector Dose of AAV5.hFXN vector pharmaceutical formulation (2.5×10 14  vg/mL with 1×PBS at a pH of 7.4) is administered to a 30-year-old patient with Friedreich&#39;s ataxia. The vector delivers hFXN gene into the central nervous system of the Friedrich ataxia patient. The pharmaceutical formulation is administered as a single bolus intrathecal injection to the CSF space of the patient. Half of the dose is administered to the patient&#39;s lumbar, and half of the dose is administered to the patient&#39;s cisterna magna. A Medtronic Model 8781 ASCENDA™ Intrathecal Catheter System with 66 cm spinal segment is implanted in a sterile surgical procedure performed under general or regional anesthesia. The Catheter System is inserted at the lumbar level, where half of the dose to be administered is injected, and then the catheter is threaded to the level of the cisterna magna using guided imaging, where the remaining half of the dose is injected. The rate of injection is controlled by a Medtronic SynchroMed®EL 18-mL pump. The 5.0×10 14  (vg) Total Vector Dose is administered at a rate of 0.01 mL/min and at a concentration of 2.5×10 14  vg/mL. Total volume=2 mL (1 mL Lumbar+1 mL cisterna magna). 
     Improved function relative to natural disease progression is observed. The increases from baseline in FARS total and FARS Neuro score improve over time and achieve statistical significance by 6 months after the procedure. Integrated analyses of the patient&#39;s FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores demonstrate statistically significant improvement in gross and fine motor skills as early as 6 months after gene therapy. A significant treatment benefit seen on motor skills generally continues to improve over time. After surgery, the patient demonstrates generally continuous increases in their FARS total and FARS Neuro, 25-foot walk test, GAITRite Walkway System, Biodex Balance System SD, 9-hole peg test scores. Safety and neurological evaluations are performed periodically for 24 months post dose. Functional assessments are performed. In conclusion, the present disclosure using AAV viral vectors to transfer hFXN genes for treating Friedrich&#39;s Ataxia is practical and effective. 
     Example 13 
     Sarsero Frataxin-Deficient Mouse Model 
     Reference is made to JP Sarsero et al., “Human BAC-mediated rescue of the Friedreich ataxia knockout mutation in transgenic mice,”  Mamm. Genome,  2004 May; 15(5):370-82. The FVB; B6.Tg(FXN); FXN-mouse model (#018299, The Jackson Laboratories) is hemizygous for the human FXN*500GAA transgene and homozygous for the frataxin knockout allele. Therefore, the mouse is null for murine frataxin and contains the human frataxin gene (with 500 GAA repeats in the first intron) inserted in Chromosome 5. The model expresses a low level of human frataxin (˜10%) that rescues lethality in mice and is similar to the frataxin reduction in humans, but does not generate any disease phenotypes characteristic of FA. 
     A. Methods 
     Mice were anesthetized with isoflurane and placed in the stereotaxic apparatus (51725D Digital Just for Mice Stereotaxic Instrument, Stoelting, Wood Dale, Ill.). An incision was made sagittally over the middle of the cranium and the surrounding skin was pushed back to enlarge the opening. Burr holes were drilled in the skull using a Dremel drill and a dental bit under stereotaxic guidance. Mice received bilateral intracerebellar injections of either 2 μL of AAV5-FXN-026 at a concentration of 7×10 12  vector genomes/mL (N=7) or AAV5-GFP (control) at a concentration of 4×10 12  vector genomes/mL (N=3) using a 10 μL Hamilton syringe with a 27-gauge blunt end needle/glass capillary. Virus was injected at 2.5 μL/min using a convention enhanced delivery method. The surgical incision was closed with nylon (Ethilon®) sutures. Alternatively, mice received bilateral intracerebroventricular injections of either 2 μL of AAV5-FXN-026 at a concentration of 7×10 12  vg/mL (N=7) or AAV5-GFP (control) at a concentration of 4×10 12  vg/mL (N=3) using a 10 μL Hamilton syringe. At 4 weeks post injection, the cerebellums were harvested. Cerebellar tissue from two untreated control mice was also harvested. Tissue lysates were analyzed for human frataxin expression using the Human Frataxin Simple Step ELISA (Abcam #176112), an assay that specifically detects human frataxin. 
     B. Results 
     Following different routes of administration of the AAV5-FXN-026 vector, the expression of frataxin protein in specific tissues was evaluated as shown in  FIG. 21 . The detectable level of endogenous frataxin protein in the cerebellum was the result of expression from the incorporated human frataxin transgene that rescues the null murine frataxin phenotype. After intraparenchymal (IPc) administration to the cerebellum, an approximately 7-fold increased expression of frataxin protein over control levels in the cerebellum was observed. Upon intracerebroventricular (ICV) administration, there was over a 4-fold increased expression of frataxin protein over control levels in the cerebellum. 
     C. Conclusions 
     AAV5-FXN-026 increased frataxin expression in the cerebellum of frataxin-deficient mice by approximately 4-fold via ICV administration and approximately 7-fold following IPc injection. The increased expression over control levels of human frataxin protein from AAV5-FXN-026 in a mouse model of FA, provides evidence that the promoter/regulatory elements in the DNA construct in AAV5-FXN-026 are functional in the complex in vivo environment. Assuming a 10% level of normal frataxin expression in this mouse model, the level of exogenous frataxin achieved following transduction would be 40-70% of normal and in a range that is asymptomatic in humans. 
     Example 14 
     Route of Administration Comparison Study in Pigs 
     Biodistribution of the test article, AAV5-FXN-026, was studied in swine using several delivery locations and devices. Five treatment groups of three male Yucatan swine underwent a surgical procedure in which the dosing site(s) (lumbar, lumbar and cisterna magna, or dentate nucleus) was accessed. The test article was administered on Day 0 via a spinal needle in the lumbar (Group 2), a Medtronic ASCENDA™ catheter in the lumbar and cisterna magna (Group 3), an Alcyone Pulsar catheter in the lumbar and cisterna magna (Group 4), a spinal needle in the dentate nucleus (Group 5), or an Alcyone MEMS cannula (AMC™) in the dentate nucleus (Group 6). The test article was administered at a dose level of 3×10 13  (Groups 2 to 4) or 3×10 12  (Groups 5 and 6) viral genomes (vg) and a dose volume of 2.2 to 2.3 or 0.12 to 0.146 mL, respectively. One animal served as the control and did not undergo a surgical procedure or treatment (Group 1). The animals were maintained for a 28±1 day recovery period. 
     Observations for morbidity, mortality, injury, and the availability of food and water were conducted twice daily for all animals. Clinical observations were conducted for all animals daily on Days −1 to 7 and weekly thereafter. Body weights were measured and recorded for all animals weekly, beginning during Week −1. Physical examinations were conducted for all animals pretest. At study termination, necropsy examinations were performed and selected tissues were analyzed for concentrations of the test article by qPCR analysis. 
     Biodistribution results were variable within and between each group. AAV5-FXN-026 levels in the area of the dentate nucleus of the cerebellum, was highest in those animals receiving direct infusion into the cerebellum (Groups 5 and 6). 
     A. Surgical Procedure 
     The test article was administered on Day 0 via a spinal needle in the lumbar (Group 2, 2.2 mL at 3×10 13  vg), a Medtronic ASCENDA catheter in the lumbar and cisterna magna (Group 3, 2.2 mL at 3×10 13  vg), an Alcyone Pulsar catheter in the lumbar and cisterna magna (Group 4, 2.2 to 2.3 mL at 3×10 13  to 3.14×10 13  vg), a spinal needle in the dentate nucleus (Group 5, 0.12 mL at 3×10 13  vg), or an Alcyone MEMS cannula (AMC™) in the dentate nucleus (Group 6, 0.13 to 0.146 mL at 2.71×10 12  to 3.04×10 12  vg). One animal served as the control and did not undergo a surgical procedure or treatment (Group 1). The animals were maintained for a 28±1 day recovery period. 
     (a). Group 2—Lumbar Injection (Spinal Needle) 
     Each animal was placed in ventral recumbency. An incision was made in the skin just caudal to L2-L3. A 14G spinal needle was advanced into the intrathecal space at L2-L3. Placement was verified by fluoroscopic imaging and/or hanging drop technique as well as back flow of cerebral spinal fluid (CSF). A fluoroscopic image of the needle placement was taken, and catheter placement was verified with a contrast injection of Omnipaque-300. The needle was flushed with 1.5 mL of saline. The test article (2.2 mL) was drawn up into a 3 cc syringe and dosed over 48 to 72 seconds. A dwell time of at least 1 minute was allowed after completion of the injection. The needle was removed, and the incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     (b). Group 3—Lumbar and Cisterna Magna Injection (Medtronic ASCENDA™, Model 8780 Catheter) 
     Each animal was placed in ventral recumbency. An incision was made in the skin just caudal to L3-L4. A 16G introducer needle was advanced into the intrathecal space at L3-L4. 
     Placement was verified by fluoroscopic imaging and/or hanging drop technique as well as back flow of CSF. A fluoroscopic image of the needle placement was taken, and catheter placement was verified with a contrast injection of Omnipaque-300. The Medtronic ASCENDA™ catheter was advanced under fluoroscopic guidance with the target of the cistema magna region. The introducer needle was withdrawn from the intrathecal space, and the catheter was flushed with 1.5 mL of saline. The test article (2.2 mL) was drawn up into a 3 cc syringe. One half of the total volume of the test article (1.1 mL) was dosed into the cistema magna over 30 seconds and flushed with 1 mL saline. The catheter was repositioned in the upper lumbar region (L1) under fluoroscopic guidance, and the second half the total volume of the test article (1.1 mL) was dosed over 30 to 45 seconds and flushed with 1 mL saline. The catheter was then removed, and the incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     (c). Group 4—Lumbar and Cisterna  Magna  Injection (Alcyone Pulsar Catheter) 
     Each animal was placed in ventral recumbency. An incision was made in the skin just caudal to L3-L4. A 16 G introducer needle was advanced into the intrathecal space at L2-L3 or L3-L4. Placement was verified by fluoroscopic imaging and/or hanging drop technique as well as back flow of CSF. A fluoroscopic image of the needle placement was taken, and catheter placement was verified with a contrast injection of Omnipaque-300. The Alcylone Pulsar catheter was advanced under fluoroscopic guidance to the cisterna magna region. The introducer needle was withdrawn from the intrathecal space, and the catheter was flushed with 1.5 mL of saline. The test article (2.2 mL) was drawn up into a 3 cc syringe. One portion of the total volume of the test article (1.1 to 1.4 mL) was dosed in to the cisterna magna over 20 to 29 seconds and flushed with 1 mL saline. The catheter was repositioned to L1 under fluoroscopic guidance, and the second half of the total volume of the test article (0.9 to 1.1 mL) was dosed over 19 to 71 seconds and flushed with 1 mL saline. The catheter was then removed, and the incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     (d). Group 5—Dentate Nucleus Injection (22 Ga Spinal Needle) 
     Each animal was placed in ventral recumbency. A midline dorsal incision was made on the dorsal surface of the skull extending to cervical region. The base of the skull was exposed, and a magnetic resonance imaging (MRI) fiducial was placed in the left occipital bone and sealed in place with bone wax. The skin incision was temporarily closed with suture, and the animal was transported to the MRI scanner for coronal and sagittal imaging of the cerebellum. Once the MRI was collected, it was uploaded to Osirix MD for targeting purposes. The animal was placed in a head immobilizer frame, and the incision was reopened. A craniotomy on the right side of the skull was performed with a burr. Based on the stereotaxic coordinates from Osirix, a 22 G 3.50 inch spinal needle (BD Spinal Needle with Quincke point) was inserted into the right cerebellum in the area of the dentate nucleus. A fluoroscopic image of the needle placement was taken, and needle placement was verified with a contrast injection of Omnipaque-300. The test article (0.15 mL) was loaded into a microbore extension set, and a 30 μL air separation bubble was placed. The remainder of the microbore extension was filled with sterile saline. The test article (0.12 mL) was infused at a rate of 10 μL/min over approximately 12 minutes. A dwell time of at least 1 minute was allowed after completion of the dose. Bone wax was placed into the burr hole. The incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     (e). Group 6—Dentate Nucleus Injection (Alcyone MEMS Cannula (AMC™)) 
     Each animal was placed in ventral recumbency. A midline dorsal incision was made on the dorsal surface of the skull extending to cervical region. The base of the skull was exposed, and an MRI fiducial was placed on the left side of skull. The skin incision was temporarily closed with suture, and the animal was transported to the MRI scanner for coronal and sagittal imaging of the cerebellum. Once the MRI was collected, it was uploaded to Osirix MD for targeting purposes. The animal was placed in a head immobilizer frame, and the incision was reopened. A craniotomy on the right side of the skull was performed with a burr. Based on the stereotaxic coordinates from Osirix, the Alcyone MEMS Cannula was inserted into the right cerebellum in the area of the dentate nucleus. A fluoroscopic image of the catheter tip placement was taken. The test article (0.13 to 0.146 mL) was infused at a rate of 10 μL/min over 13 to 14 minutes and 40 seconds. Bone wax was placed into the burr hole. The incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     B. Biodistribution Evaluations (qPCR) 
     Tissue samples (100 to 200 mg per organ) were collected from the brain, dorsal root ganglia ((DRG) (cervical, lumbar, and thoracic)), kidney (left), spinal cord (cervical, lumbar, and thoracic), spleen, and liver (left lateral lobe) of all surviving animals for analysis of the test article concentrations. For brain tissues, samples were taken from both right and left hemispheres maintaining laterality using an 8 mm circular punch; samples were taken from the region of the cerebellar cortex (to include Purkinje cell layer), dentate nucleus, hippocampus, and motor cortex. Spinal cord tissues were collected with an 8 mm circular punch from 4 to 6 mm axial segments in the area of the ventral horn to include both white and gray matter. DRG were collected as pairs consisting of left and right ganglia correlating to the spinal cord segments collected. A sufficient number of pairs of DRG from each spinal region specified were collected to obtain 100 to 200 mg of tissue. 
       FIG. 22  shows DNA Copies per μg Tissue from Cerebellum.  FIG. 23  shows DNA Copies per μg Tissue from Other Brain Areas.  FIG. 24  shows DNA Copies per μg Tissue from Spinal Tissues.  FIG. 25  shows DNA Copies per μg Tissue from Systemic Tissues. Intrathecal and intracranial administration of AAV5-FXN-026 was well tolerated in male Yucatan pigs weighing 51.0 to 55.2 kg. Biodistribution results were variable within and between each group. AAV5-FXN-026 levels in the area of the dentate nucleus of the cerebellum, was highest in those animals receiving diced infusion into the cerebellum (Groups 5 and 6). In general, injections with a 22 Ga spinal needle resulted in high cerebellar AAV5-FXN-026 levels. Intrathecal delivery, whether by a single lumbar bolus (Group 2), dosing at both the mid/lower and lumbar region with a Medtronic ASCENDA catheter (Group 3) or dosing at both the high cervical/cisterna magna and lumbar region with an Alcyone Pulsar catheter resulted in detectable levels of AAV5-FXN-026. The Alcyone Pulsar was able to be advanced to the Cl or cisterna magna level. 
     Example 15 
     Intracerebellar Tolerance and Biodistribution Study in Pigs 
     A direct injection into the dentate nucleus of pigs assessed the biodistribution of AAV5-FXN-026. Two treatment groups of three or six male Yucatan swine per group underwent a surgical procedure in which a single infusion of the test article was administered into the dentate nucleus of the cerebellum following a craniotomy of the skull. The treated animals were administered the test article on Day 0 at a dose level of 1×10 12  viral genomes (vg) (56 μL) (low-dose) or 3×10 12  vg (167 μL) (high-dose). One additional group of one male animal served as the control and did not receive test article nor underwent the surgical procedure; this animal was euthanized on Day 0 to provide control tissues. The animals were maintained for a 28±1 day or 60±4 days recovery period. 
     Observations for morbidity, mortality, injury, and the availability of food and water were conducted twice daily for all animals. Clinical observations were conducted daily on Days 1 to 7 and then weekly thereafter. Body weights were measured and recorded beginning in Week-1 and weekly during the study. Physical examinations were conducted pretest. Blood samples for clinical pathology evaluations were collected from all animals pretest. Blood samples were collected for possible future determination of the whole blood concentrations of the AAV5 antibody from all animals pretest and prior to each necropsy. Samples of cerebral spinal fluid (CSF) were collected for possible determination of CSF concentration of the AAV5 antibody pretest for Groups 2 and 3 and for all animals at each necropsy. At study termination, each animal was euthanized and a necropsy examination was conducted. Blood and selected tissues were collected for qPCR and frataxin protein analysis for all animals. Additionally, western blot analysis was conducted for the Group 1 animal and one of the Group 3 animals. 
     The results of this study found extensive and persistent distribution of AAV5-FXN-026 throughout the brain and spinal cord following a single infusion into the cerebellum. Vector Genome Copies in the Cerebellum Day 28 vs 60 (vg DNA/μg Tissue DNA) are shown in  FIG. 26 . Vector Genome Copies in the Brain Day 28 vs 60 (vg DNA/μg Tissue DNA) are shown in  FIG. 27 . Vector Genome Copies in the Spinal Cord and DRG&#39;s Day 28 vs 60 (vg DNA/μg Tissue DNA are shown in  FIG. 28 . At 28 days, the highest levels of vector genome were found in the cerebellum, the motor cortex and the dorsal root ganglia. By 60 days, AAV5-FXN-026 was still present in these tissues, although the levels decreased relative to 28 days. These results demonstrate an affinity of the AAV5 capsid for the motor neuron tracts in the CNS. AAV5-FXN-026 levels in blood went from being undetectable in most animals on day 28 to detectable in all animals on Day 60, consistent with clearance of the vector from the CNS. 
     Analyzing expression of frataxin protein, tissue samples from the cerebellar cortex, the dentate nucleus, hippocampus, and the motor cortex were collected. Frataxin levels via ELISA are shown in  FIG. 29 . Low dose animals showed variable increases over background control levels of frataxin. At Day-28 post-dose, frataxin levels increased between 1.5 (cerebellar cortex) and 6.4 (hippocampus) fold in the low dose tissues control tissues. High dose animals, at 28 and 60 days post-dose, showed frataxin levels increased approximately 2 (motor cortex) and 9 (dentate nucleus) fold over levels noted in the untreated, control tissues. These results demonstrate a persistent increase of frataxin protein production 60 days following treatment with the high dose of AAV5-FXN-026. 
     Overall this study demonstrated that following direct infusion of the test article at doses of 1×10 12  and 3×10 12  vg to the cerebellum, resulted in extensive and persistent biodistribution of the AAV5 capsid with an affinity for the motor neuron tracts. 
     Example 16 
     28-Day Intracerebellar Pilot Tolerance and Biodistribution Study in Primates 
     This study assessed the tolerance and biodistribution of an AAV5 human frataxin vector, AAV5-hFXN (026), following intracerebellar administration in cynomolgus monkeys ( Macaca fascicularis ). 
     This study was based on the current International Council on Harmonization (ICH) Harmonized Tripartite Guidelines and generally accepted procedures for the testing of pharmaceutical compounds and in accordance with the United States Department of Agriculture&#39;s (USDA) Animal Welfare Act (9 CFR Parts 1, 2, and 3) and the Guide for the Care and Use of Laboratory Animals, Institute of Laboratory Animal Resources, National Academy Press, Washington, D.C., 2011. (See “Guidance on non-clinical safety studies for the conduct of human clinical trials and marketing authorization for pharmaceuticals,” ICH M3(R2), 2009 Jun. 11 and “Preclinical safety evaluation of biotechnology-derived pharmaceuticals,” ICH S6 (R1), 1997 Jul. 16, (Addendum dated 12 Jun. 2011)). 
     Two treatment groups of three male cynomolgus monkeys per group underwent a surgical procedure in which a unilateral or bilateral infusion of the test article was administered into the dentate nucleus of the cerebellum following a craniotomy of the skull. The treated animals were administered the article on Day 1 at a dose level of 1.2×10 12  (30 μL) or 2.4×10 12  (30 μL/hemisphere) viral genomes (vg) per animal. One additional group of two male animals served as the control and received a bilateral infusion of the control article, phosphate buffered saline (PBS), pH 7.4. The animals were maintained until the Day 29±1 day necropsy. 
     Observations for morbidity, mortality, injury, and the availability of food and water were conducted twice daily for all animals. Clinical observations were conducted daily beginning on Day 1. Functional observational battery (FOB) assessments and neurological examinations were conducted prior to dosing (Day 1), 24 and 48 hours post-dose, and 7, 14, and 28 days post-dose. Body weights were measured and recorded weekly beginning on Day −1. Blood samples for clinical pathology evaluations were collected from all animals pretest and prior to necropsy. At study termination, necropsy examinations were performed and tissues were microscopically examined. Blood and selected tissues were collected for qPCR and frataxin protein enzyme-linked immunosorbent assay (ELISA) analysis. 
     The results demonstrated an affinity of the AAV5 capsid for the motor neuron tracts in the CNS. Upon analysis of brain tissue for expression frataxin protein by ELISA, at 28 days post-dose, frataxin levels increased between approximately 2 (cerebellar cortex) and 14 (dentate Nucleus) fold in test article treated animals over levels noted in the control animal tissues. Administration of the test article was associated with meningeal mononuclear cells infiltration within the meninges with occasional clustering around small meningeal vessels (perivascular). In addition, minimal perivascular mononuclear infiltrates were also noted within the brain parenchyma. Mononuclear cell infiltration is an expected non-adverse tissue response to the viral capsid. 
     In summary, the results of this study demonstrated that following direct infusion of the test article AAV5-hFXN (026) at doses of 1.2×10 12  vg and 2.4×10 12  vg to the cerebellum, extensive and persistent biodistribution of the AAV5 capsid with an affinity for the motor neuron tracts was observed. Frataxin expression was evident in the dentate nucleus and cortex regions of the cerebellum, where consistent increases in tissue frataxin levels relative to control tissues were observed. At 28 days, the highest levels of vector genome were found in the dentate nucleus and cerebellar cortex. These results demonstrated an affinity of the AAV5 capsid for the motor neuron tracts in the CNS. These results further demonstrated that intracerebellar injection of the test article at doses up to 2.4×10 12  vg are well tolerated and distributed well throughout the CNS. 
     Test Article and Control Preparation 
     The test article, AAV5-hFXN (026), was formulated at a concentration of 4×10 13  GC/mL and was warmed to between room temperature and body temperature prior to dosing. The control article was PBS, pH 7.4. 
     Animal Acquisition 
     A total of nine male cynomolgus monkeys ( Macaca fascicularis ) (approximately 3 years 10 months to 4 years 5 months of age at transfer) 
     Randomization, Assignment to Study, and Maintenance 
     Using a standard, by weight, randomization procedure, eight male animals (weighing 3.4 kg to 4.9 kg at randomization) were assigned to the study as identified in Table 8. Animals were maintained until the Day 29±1 day necropsy. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Group Assignments 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 Number 
               
               
                 Group 
                   
                   
                 Dose 
                 of Male 
               
               
                 Number 
                 Route of Administration 
                 Treatment 
                 (vg) 
                 Animals 
               
               
                   
               
               
                 1 
                 Bilateral Intracerebellar  
                 PBS, pH 7.4 
                 0 
                 2 
               
               
                   
                 Injection 
                   
                   
                   
               
               
                 2 
                 Unilateral Intracerebellar  
                 AAV5-hFXN 
                 1.2 × 10 12   
                 3 
               
               
                   
                 Injection 
                 (026) 
                   
                   
               
               
                 3 
                 Bilateral Intracerebellar  
                 AAV5-hFXN 
                 2.4 × 10 12   
                 3 
               
               
                   
                 Injection 
                 (026) 
               
               
                   
               
            
           
         
       
     
     Surgical Procedure 
     The control and test article were administered via unilateral (Group 2) or bilateral (Groups 1 and 3) intracerebellar infusion into the area of the dentate nucleus. The treated groups (Groups 2 and 3) were administered the article on Day 1 at a dose level of 1.2×10 12  (30 μL) or 2.4×10 12  (30 μL/hemisphere) viral genomes (vg) per animal. The control group (Group 1) received a bilateral infusion of the control article, phosphate buffered saline (PBS), pH 7.4. The animals were maintained until the Day 29±1 day necropsy. 
     Following induction of anesthesia, the scalp was shaved and the animal was mounted in a magnetic resonance imaging (MRI) compatible stereotaxic frame (Kopf). A baseline MRI was given to establish targets and the animal was then transported to the surgical suite. An incision was made and the skin was reflected. A craniotomy was performed with a K wire and a cannulated drill bit at the appropriate injection site(s). Based on the stereotaxic coordinates, a blunt needle (22 gauge; 3.5 inch; B&amp;D; reference number 405181) was inserted into the right (and left, for bilateral administration) cerebellum in the area of the dentate nucleus. Placement of the needle was confirmed via fluoroscopy and injection of contrast. The hub of the needle was flushed with sterile saline prior to attaching the dosing line. The control or test article (30 μL per infusion) was loaded into the microbore extension set with 30 μL of an air separation bubble. The remainder of the microbore extension was filled with sterile saline. The control or test article was infused at 10 μL/minute for 9 minutes to account for dead space in the needle. The needle was left in place for at least 2 minutes following completion of the infusion. Following removal of the needle, bone wax was placed into the drill hole and the incision was closed in standard fashion using any combination of absorbable sutures, skin staples, or skin glue. 
     Detailed Clinical Observations 
     A detailed clinical examination of each animal was performed daily during the study. On occasion, clinical observations were recorded at unscheduled intervals. The observations included, but were not limited to, evaluation of the skin, fur, eyes, ears, nose, oral cavity, thorax, abdomen, external genitalia, limbs and feet, respiratory and circulatory effects, autonomic effects such as salivation, and nervous system effects including tremors, convulsions, reactivity to handling, and unusual behavior. 
     Biodistribution Evaluations (Tissue, Blood, and Formulations) 
     Blood and tissue samples (approximately 100 to 200 mg per sample were collected from the brain (eight samples per animal), bone marrow, heart, liver, cervical lymph node, and kidney. For brain tissues, samples were taken from both right and left hemispheres, maintaining laterality. Samples were taken from the region of the cerebellar cortex (and included the Purkinje cell layer), cerebellum area of the dentate nucleus, hippocampus, and motor cortex. A section of each tissue was collected using an 8 mm punch biopsy and placed in labeled 2 mL microfuge tubes, snap-frozen in liquid nitrogen, and then placed on dry ice until stored frozen at −60 to −90° C. prior to qPCR analysis. 
     On each day of surgery, one sample (approximately 100 μL) of test article was injected through the needle and the sample was collected, placed on dry ice, and stored at −60 to −90° C. prior to qPCR analysis for test article concentration (vg/mL). 
     Tissue Collection for Frataxin Protein Analysis 
     Samples from the brain regions collected for qPCR analysis (at least 50 mg) were collected for frataxin protein ELISA analysis. Samples were taken from both right and left hemispheres maintaining laterality using a 5 mm circular punch. 
     Western Blot Analysis for Frataxin Localization in Mitochondria 
     Two additional cerebellar cortex samples (approximately 100 to 300 mg) were taken from one Group 1 (animal number 701) and all Group 3 animals for potential western blot analysis. 
     Neurologic examinations were performed by a staff veterinarian on Days 1, 2, 3, 7, 14, and 28. Cranial nerve response, peripheral sensation, and postural/behavior responses were assessed. Upon examination, all cranial nerve responses/reflexes and response to superficial pain were considered to be within normal limits. There were no test article-related effects observed among clinical pathology endpoints on Day 27 in cynomolgus monkeys administered AAV5-hFXN (026) via intracerebellar injection on Day 1 at doses of 1.2×10 12  vg or 2.4×10 12  vg. 
     There were no test article-related effects on hematology endpoints at either dose level. All apparent differences among hematology endpoints were not considered test article-related due to their negligible magnitude, lack of a dose-responsive pattern, and/or relation to expected values for biologic and procedure-related variation. 
     There were no test article-related effects on coagulation times (i.e. APTT and prothrombin times) or fibrinogen concentration at either dose level. All apparent differences among coagulation endpoints were not considered test article-related due to their negligible magnitude, lack of a dose-responsive pattern, and/or relation to expected values for biologic and procedure-related variation. 
     There were no test article-related effects on clinical chemistry endpoints at either dose level. All apparent differences among clinical chemistry endpoints were not considered test article-related due to their negligible magnitude, lack of a dose-responsive pattern, and/or relation to expected values for biologic and procedure-related variation. 
     There were no test article-related macroscopic findings; all tissues of all animals were considered within normal limits. 
     AAV5-hFXN (026)-related microscopic findings were limited to the presence of small numbers of mononuclear infiltrates in animals receiving 2.4×10 12  vg (bilateral injections) and 1.2×10 12  vg (unilateral injection, right). Mononuclear infiltrates were not observed in concurrent control animals. 
     In the majority of animals, the meningeal mononuclear cells were characterized by focal to locally extensive accumulations of small numbers of mononuclear cells within the meninges with occasional clustering around small meningeal vessels (perivascular). In addition, minimal perivascular mononuclear infiltrates were also noted within the brain parenchyma in a small number of animals (in the right cerebellar cortex and right motor cortex sections of one animal at 1.2×10 12  vg, and in the right cerebellar cortex or left motor cortex of single animals receiving 2.4×10 12  vg). The mononuclear infiltrates were associated with and/or exhibited increased IBA-1 staining/immunoreactivity. Mononuclear cell infiltration is an expected finding and is considered to be a non-adverse tissue response to the viral capsid. 
     Results and Discussion 
     Frataxin Protein Analysis 
     Tissue samples from the cerebellar cortex, the dentate nucleus, hippocampus, and the motor cortex were collected and submitted for analysis of frataxin levels ( FIG. 30 ) via ELISA. The results of this analysis found background levels of frataxin in the vehicle control animals. Frataxin levels are discussed as relative increases over background levels noted in the control animal. Animals in Group 2 received a single injection in the right cerebellar cortex and the animals in Group 3 received bilateral injections. At Day 28 post-dose, frataxin levels were noted to increase between 1.2 and 6.6 (cerebellar cortex) and 2.7 to 14.5 (dentate nucleus) fold over levels noted in the control tissues. At 28 days post-dose, frataxin levels were approximately equivalent in the hippocampus and motor cortex. These results, while variable, demonstrate a consistent increase over 28 days of frataxin protein production following treatment with the test article as either a single injection or bilateral injection in the cerebellar dentate nucleus and cerebellar cortex.