# Patent

## Title
Constructs for expressing lysosomal polypeptides

## Abstract

Provided are isolated nucleic acids for expressing lysosomal polypeptides such as lysosomal acid α-glucosidase (GAA) and vectors comprising the same. The invention provides an isolated nucleic acid encoding a chimeric polypeptide comprising a secretory signal sequence operably linked to a lysosomal polypeptide. The invention also provides an isolated nucleic acid comprising a coding region encoding a GAA and a GAA 3′ untranslated region (UTR), wherein the GAA 3′ UTR comprises a deletion therein. The invention further provides an isolated nucleic acid comprising a coding region encoding a GAA and a 3′ UTR wherein the 3′ UTR is less than about 200 nucleotides in length and comprises a segment that is heterologous to the GAA coding region. Also provided are methods of making and using delivery vectors encoding lysosomal polypeptides to produce the lysosomal polypeptide to treat subjects afflicted with a deficiency in the lysosomal polypeptide.

## Background
RELATED APPLICATION INFORMATION
This application is a continuation of U.S. application Ser. No. 10/761,530, filed Jan. 21, 2004 (abandoned), which claims the benefit of U.S. Provisional Application Nos. 60/441,789, filed Jan. 22, 2003, the entire contents of each of which are hereby incorporated by reference.


FIELD OF THE INVENTION
The present invention relates to novel nucleic acid constructs encoding lysosomal polypeptides, in particular lysosomal acid α-glucosidase, as well as methods of using the same to produce recombinant lysosomal polypeptides and to treat lysosomal polypeptide deficiencies.
BACKGROUND OF THE INVENTION
Glycogen storage disease type II (GSD II) is a classical lysosomal storage disorder, characterized by lysosomal accumulation of glycogen and tissue damage, primarily in muscle and heart (Hirschhorn, R. and Reuser, A. J. (2001) In The Metabolic and Molecular Basis for Inherited Disease (Scriver, C. R., Beaudet, A. L., Sly, W. S. & Valle, D. Eds.), pp. 3389-3419. McGraw-Hill, New York). The underlying enzyme deficiency is acid α-glucosidase (GAA). In severe, infantile GSD II progressive cardiomyopathy and myopathy lead to cardiorespiratory failure and death by 1 year of age. In milder, juvenile and adult-onset GSD II, progressive weakness and respiratory failure are disabling and death from respiratory failure occurs.
Animal models for human lysosomal acid α-glucosidase (hGAA) deficiency accurately mimic GSD II, and the efficacy of approaches to gene therapy for GSD II can be evaluated in these systems. The GAA knockout (GAA-KO) mouse model accumulated glycogen in skeletal and cardiac muscle, and developed weakness and reduced mobility (Raben, N., et al. (1998) J. Biol. Chem. 273:19086-19092, Bijvoet, A. G., et al. (1998) Hum. Mol. Genet. 7:53-62). The administration of recombinant GAA to a GAA-KO mouse demonstrated uptake of GAA by skeletal muscle, presumably through receptor-mediated uptake and delivery of GAA to the lysosomes (Bijvoet, A. G. et al., (1998) Hum. Mol. Genet. 7:1815-1824). The Japanese quail model is similar to juvenile-onset GSD II, and has been treated successfully with recombinant enzyme replacement (Kikuchi, T., et al. (1998) J. Clin. Invest. 101:827-833). Enzyme therapy has demonstrated efficacy for severe, infantile GSD II; however the benefit of enzyme therapy is limited by the need for frequent infusions and the development of inhibitor antibodies against recombinant hGAA (Amalfitano, A., et al. (2001) Genet. In Med. 3:132-138). As an alternative or adjunct to enzyme therapy, the feasibility of gene therapy approaches to treat GSD-II have been investigated (Amalfitano, A., et al., (1999) Proc. Natl. Acad. Sci. USA 96:8861-8866, Ding, E., et al. (2002) Mol. Ther. 5:436-446, Fraites, T. J., et al., (2002) Mol. Ther. 5:571-578, Tsujino, S., et al. (1998) Hum. Gene Ther. 9:1609-1616).
Administration of an adenovirus (Ad) vector encoding hGAA that was targeted to mouse liver in the GAA-KO mouse model reversed the glycogen accumulation in skeletal and cardiac muscle within 12 days through secretion of hGAA from the liver and uptake in other tissues (Amalfitano, A., et al., (1999) Proc. Natl. Acad. Sci. USA 96:8861-8866). Antibodies against hGAA abbreviated the duration of hGAA secretion with an Ad vector in liver, although vector DNA and hGAA persisted in tissues at reduced levels for many weeks (Ding, E., et al., (2002) Mol. Ther. 5:436-446). Introduction of adeno-associate virus 2 (AAV2) vectors encoding GAA normalized the GAA activity in the injected skeletal muscle and the injected cardiac muscle, and glycogen content was normalized in muscle when an AAV1-pseudotyped vector was administered with improved muscle transduction (Fraites, T. J., et al. (2002) Mol. Ther. 5:571-578). Muscle-targeted Ad vector gene therapy was attempted in the Japanese quail model, although only localized reversal of glycogen accumulation at the site of vector injection was achieved (Tsujino, S., et al. (1998) Hum. Gene Ther. 9:1609-1616).
Neonatal gene therapy may have greater efficacy than administration later in life, as evidenced by experiments in several rodent disease models. An AAV vector administered intravenously on the second day of life in β-glucoronidase deficient (Sly disease) mice produced therapeutically relevant levels of β-glucoronidase and corrected lysosomal storage in multiple tissues, including liver and kidney (Daly, T. M., et al. (1999) Proc. Natl. Acad. Sci. USA 96:2296-2300). Similarly, intramuscular injection of the AAV vector produced sustained, therapeutic levels of expression of β-glucoronidase and eliminated lysosomal storage in muscle and liver (Daly, T. M., et al., (1999) Hum. Gene Ther. 10:85-94). AAV vector DNA persisted in muscle and in transduced areas of the liver following neonatal intramuscular injection in the Sly disease mouse (Daly, T. M., et al. (1999) Hum. Gene Ther. 10:85-94). The number of AAV vector particles administered to neonatal Sly mice was approximately 100-fold less than was needed to produce therapeutically relevant levels of proteins in adult mice (Kessler, P. D., et al. (1996) Proc. Natl. Acad. Sci. USA 93:14082-14087, Herzog, R. W., et al. (1997) Proc. Natl. Acad. Sci. USA 94:5804-5809, Nakai, H., et al. (1998) Blood 91:4600-4607, Snyder, R. O., et al. (1997) Nat. Genet. 16:270-276, Koeberl, D. D., et al. (1999) Hum. Gene Ther. 10:2133-2140, Snyder, R. O., et al. (1999) Nat. Med. 5:64-70, Herzog, R. W. et al. (1999) Nat. Med. 5:56-63).
There is a need in the art for improved methods of producing lysosomal polypeptides such as GAA in vitro and in vivo, for example, to treat lysosomal polypeptide deficiencies. Further, there is a need for methods that result in systemic delivery of GAA and other lysosomal polypeptides to affected tissues and organs.
SUMMARY OF THE INVENTION
The present invention is based, in part, on the discovery of improved nucleic acid constructs for expressing lysosomal polypeptides such as GAA. One aspect of the invention provides an isolated nucleic acid encoding a chimeric polypeptide comprising a lysosomal polypeptide operably linked to a secretory signal sequence such that targeting of the lysosomal polypeptide to the secretory pathway (i.e., instead of to the lysosome) is enhanced. As another aspect, the invention encompasses isolated nucleic acids comprising a coding sequence for GAA and an “abbreviated” 3′ untranslated region (3′ UTR). The isolated nucleic acids of the invention can be used to produce recombinant lysosomal polypeptides in vitro (e.g., in cultured cells) or in vivo (e.g., in an animal or plant based protein production system or in methods of therapeutic treatment). In addition, improved (i.e., higher) titers of viral vectors encoding lysosomal polypeptides can be produced with the isolated nucleic acids of the invention.
Accordingly, as one aspect, the present invention provides an isolated nucleic acid encoding a chimeric polypeptide comprising a secretory signal sequence operably linked to a lysosomal polypeptide (e.g., GAA). Also provided is the chimeric polypeptide comprising the secretory signal sequence operably linked to the lysosomal polypeptide.
As another aspect, the present invention provides isolated nucleic acids comprising a GAA coding sequence and an “abbreviated” 3′ UTR. In one representative embodiment, the invention provides an isolated nucleic acid encoding a GAA, the isolated nucleic acid comprising: (a) a coding region encoding a GAA, and (b) an abbreviated 3′ UTR, wherein the 3′ untranslated region is a GAA 3′ UTR comprising a deletion therein (e.g., a deletion of at least 25 consecutive nucleotides), so that upon introduction into a cell, GAA polypeptide is produced at a higher level from the isolated nucleic acid as compared with GAA polypeptide production from an isolated nucleic acid comprising a full-length GAA 3′ UTR. In an exemplary embodiment, the 3′ UTR comprises a deletion in the region shown as nucleotides 3301 through 3846 of SEQ ID NO:1 (FIG. 8).
In another representative embodiment, the invention provides an isolated nucleic acid encoding a GAA, the isolated nucleic acid comprising: (a) a coding region encoding a GAA, and (b) an abbreviated 3′ UTR, wherein the 3′ UTR is less than about 200 nucleotides in length and comprises a segment that is heterologous to the GAA coding region, so that upon introduction into a cell, GAA polypeptide is produced at a higher level from the isolated nucleic acid as compared with GAA polypeptide production from an isolated nucleic acid comprising a full-length GAA 3′ UTR.
In other particular embodiments, the lysosomal polypeptide is a human polypeptide and/or the isolated nucleic acid is operatively associated with a transcriptional control element that is operable in liver cells (optionally, with a liver-specific transcriptional control element).
As additional aspects, the present invention further provides vectors (including nonviral and viral vectors, the latter including adenovirus, AAV and hybrid adenovirus-AAV vectors), cells and pharmaceutical formulations comprising the isolated nucleic acids of this invention.
As still further aspects, the present invention provides methods of making delivery vectors (e.g., viral vectors) comprising the isolated nucleic acids of this invention.
Also provided are methods of using the isolated nucleic acids, vectors, cells, and pharmaceutical formulations of the invention to treat deficiencies of lysosomal polypeptides (e.g., GAA) and to produce recombinant lysosomal polypeptides (e.g., in vitro in cultured cells or in vivo in an animal or plant-based recombinant protein expression system or for therapeutic purposes).
In illustrative embodiments, the present invention is practiced to administer an isolated nucleic acid encoding a lysosomal polypeptide such as GAA to a subject (for example, a subject diagnosed with or suspected of having a deficiency of the lysosomal polypeptide). In particular representative embodiments, an isolated nucleic acid of the invention encoding a lysosomal polypeptide can be administered to one depot tissue or organ (e.g., liver, skeletal muscle, lung and the like) and the polypeptide expressed therein at levels sufficient to result in secretion into the systemic circulation, from which the secreted polypeptide is taken up by distal target tissues (e.g., skeletal, cardiac and/or diaphragm muscle). Similarly, the isolated nucleic acid can be delivered to brain cells (e.g., to treat MPS disorders such as Sly disease), where the lysosomal polypeptide can be expressed, secreted and taken up by non-transformed or non-transduced brain cells (e.g., neurons and glial cells).
In another particular embodiment, a recombinant adeno-associated virus (AAV) vector expressing an isolated nucleic acid encoding GAA of the invention is administered to the liver of a subject having GAA deficiency, which results in GAA polypeptide production at sufficiently high levels such that GAA polypeptide is secreted from the liver and taken up by skeletal muscle and/or other tissues, which advantageously leads to a reduction in glycogen content and/or an improvement in other clinical indicia of GAA deficiency in affected tissues.
As yet a further aspect, the present invention provides the use of the isolated nucleic acids, vectors, cells and pharmaceutical formulations of the invention in the manufacture of medicaments for the treatment of lysosomal polypeptide deficiencies (e.g., GAA deficiency).
These and other aspects of the invention are described in more detail in the description of the invention set forth below.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1. Detection of hGAA following neonatal intramuscular administration of an Ad-AAV vector in GAA-KO mice. (Panel A) Western blot analysis of muscle after gastrocnemius of GAA-KO mice was injected with the Ad-AAV vector (4×1010 DRP) encoding hGAA at 3 days of age. All samples were obtained 24 weeks following vector administration. Recombinant human GAA (rhGAA) was the standard. Each lane for the indicated muscle groups represents one GAA-KO mouse. The  ̃67 kD,  ̃76 kD, and  ̃110 kD hGAA species were detected in transduced muscle as expected (Amalfitano, A., et al. (1999) Proc. Natl. Acad. Sci. USA 96:8861-8866, Ding, E., et al., (2002) Mol. Ther. 5:436-446). (Panel B) Western blot analysis of heart, liver and diaphragm following neonatal administration of the Ad-AAV vector. Each lane represents one GAA-KO mouse analyzed at the indicated time following vector administration. The samples for individual mice were loaded in the same order for the Western blot of each tissue.
FIG. 2. GAA activity and glycogen content for skeletal muscle and other tissues in GAA-KO mice following neonatal Ad-AAV vector administration. (Panel A) The hGAA activity for gastrocnemius and quadriceps at 6, 12, and 24 weeks following vector administration, and for hamstrings at 24 weeks, compared to the hGAA activity in gastrocnemius, quadriceps, and hamstrings for untreated, GAA-KO mice. The average and standard deviation are shown. The p value is indicated as follows: *<0.05, **<0.01, and ***<0.001. The number of mice (n) is shown for each time point. (Panel B) The hGAA activity for heart, liver, and diaphragm in mice following Ad-AAV vector administration, and for controls. Controls were untreated, GAA-KO mice: n=4 for heart and liver, n=5 for diaphragm. The average and standard deviation are shown for controls.
FIG. 3. Antibodies in GAA-KO mouse plasma following neonatal Ad-AAV vector administration. (Panel A) The absorbance for anti-hGAA antibodies in an ELISA of GAA-KO mouse plasma at 6 weeks following neonatal Ad-AAV vector administration (Neonatal Intramuscular Ad-AAV), and of GAA-KO mouse plasma at 6 weeks following intravenous Ad-AAV vector administration (4×1010 particles) in adult mice (Ad-AAV). Controls consisted of untreated, GAA-KO mice (Control). Each column represents the mean and standard deviation for an individual mouse. Each dilution of plasma (1:100, 1:200, and 1:400) was analyzed in triplicate. (Panel B) The titer for anti-hGAA antibodies by ELISA, representing the same mice in the same order as in FIG. 1 Panel B. Each sample was analyzed in duplicate at each dilution. (Panel C) The absorbance for anti-Ad antibodies in an ELISA of GAA-KO mouse plasma for the same samples as described for the ELISA for anti-hGAA antibodies above, except that only 2 untreated controls were analyzed. Each sample was analyzed in duplicate at each dilution. The order of loading was the same as in FIG. 1 Panel B.
FIG. 4. The glycogen content for skeletal muscle and heart. (Panel A) Gastrocnemius and quadriceps at 6, 12, and 24 weeks following vector administration, and for hamstrings at 24 weeks, compared to the hGAA activity in gastrocnemius, quadriceps, and hamstrings for untreated, GAA-KO mice. The average and standard deviation are shown. The p value is indicated as follows: *<0.05, **<0.01, and ***<0.001. The number of mice (n) is shown for each time point. (Panel B) The glycogen content for heart and diaphragm, and for controls. Controls were untreated, GAA-KO mice (n=4). The average and standard deviation are shown for controls.
FIG. 5. Glycogen staining of skeletal muscle and heart. PAS staining showed glycogen accumulation in lysosomes, and pooling of glycogen outside lysosomes, that was corrected following Ad-AAV administration at the times indicated.
FIG. 6. hGAA synthesis (top panel) and glycogen content (lower panel) in muscle of GAA-KO/SCID mice administered an AAV2/6 (AAV6) vector expressing GAA intramuscularly.
FIG. 7. Secretion of hGAA from liver into plasma in GAA-KO/SCID mice administered an AAV2/2 (AAV2) or AAV2/6 (AAV6) vector. Western blot analysis of plasma from GAA-KO/SCID mice following AAV vector administration, and from untreated GAA-KO/SCID mice (controls).
FIG. 8A-8B. A full-length hGAA cDNA sequence; Genebank Accession No. NM_000152 (SEQ ID NO:1). The encoded protein is shown in SEQ ID NO:2. The ORF is nt 442 . . . 3300. The GAA 3′ UTR sequence is from nt 3301 to 3846, total 546 bp.
FIG. 9A-9B. A hGAA sequence with a deleted 3′ UTR (SEQ ID NO:3). The 411 bp from nt 3397 through to nt 3807 in the 3′ UTR of the sequence shown in FIG. 8A-8B (SEQ ID NO:1) were deleted (bold italic). Note that the polyA signal (bold, 3825 . . . 3830) and polyA site (3846) are not deleted. The 5′ UTR sequence of nt 1 through nt 409 was also deleted.
FIG. 10. GAA activity in liver and other tissues following portal vein injection of an AAV2/2 vector. GAA-KO/SCID mice received the vector packaged as AAV2 (AAV2/2) at 3 months of age (n=3), and were analyzed 12 weeks after injection. Controls were 3 month-old, untreated GAA-KO/SCID mice (n=3).
FIG. 11. Human GAA in liver and other tissues following portal vein injection of AAV vectors in GAA-KO/SCID mice. Western blot analysis of plasma from GAA-KO/SCID mice at the indicated times following AAV vector administration, and from untreated GAA-KO/SCID mice (controls). Recombinant hGAA (rhGAA) is shown as a standard.
FIG. 12. GAA activity in gastrocnemius muscles (injected and uninjected) and other tissues following intramuscular injection of an AAV2/6 vector. GAA-KO/SCID mice received the vector packaged as AAV 6 (AAV2/6) at 6 weeks of age (n=8), and were analyzed at 6, 12 and 24 weeks after injection. Controls were 3 month-old, untreated GAA-KO/SCID mice (n=3).
FIG. 13. Glycogen staining of skeletal muscle in GAA-KO/SCID mice. PAS staining showed glycogen accumulation in lysosomes, and pooling of glycogen outside lysosomes that was corrected following AAV2/6 administration.
FIG. 14. Localization (cellular vs. secreted) of GAA with various leader sequences expressed in transfected 293 cells.
FIG. 15. Western blot analysis of GAA with various leader sequences. GAA expressed in transfected 293 cells with the constructs containing hGAA linked to the indicated signal peptides. For transfected 293 cells, in lanes 3-14, the first (odd-numbered) of 2 lanes for each construct represents the cell lysate and the second lane (even-numbered) is the medium. The control represents untransfected 293 cells, showing endogenous, processed hGAA. Recombinant human GAA (rhGAA) is shown as a standard.
FIG. 16. Western blot analysis of plasma from GAA-KO/SCID mice at 2 weeks following vector administration, and from untreated GAA-KO/SCID mice (controls). Three-month-old GAA-KO/SCID mice received an AAV vector encoding the chimeric α-1-antitrypsin signal peptide linked to the hGAA cDNA (Alpha-1-antitrypsin, lanes 2-7), or an AAV vector encoding hGAA with its endogenous signal peptide (hGAA, lanes 8-13). Each lane represents an individual mouse. Lanes 5-7 and 11-13 were female mice. Recombinant human GAA (rhGAA) is shown as a standard.
FIG. 17. GAA activity in liver and other tissues at 2 weeks following intravenous injection of an AAV2/8 vector encoding hGAA linked to the alpha-1-antitrypsin leader sequence. Male 3 month-old GAA-KO/SCID mice (n=3) received an AAV vector encoding the chimeric alpha-1-antitrypsin signal peptide linked to the hGAA cDNA (minus the 27 amino acid GAA signal peptide). Controls were untreated GAA-KO/SCID mice (n=3).
FIG. 18. Human GAA in liver and other tissues following intravenous injection of an AAV vector containing a liver-specific promoter to drive GAA expression in immunocompetent GAA-KO mice. Western blot analysis of plasma from GAA-KO mice at 3 weeks following AAV vector administration, and from untreated GAA-KO mice (controls). Recombinant human rhGAA (rhGAA) is shown as a standard.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is based, in part, on the discovery of improved nucleic acid constructs for expressing lysosomal polypeptides such as GAA. One aspect of the invention provides an isolated nucleic acid encoding a chimeric polypeptide comprising a lysosomal polypeptide operably linked to a secretory signal sequence such that targeting of the lysosomal polypeptide to the secretory pathway (i.e., instead of to the lysosome) is enhanced. As another aspect, the invention encompasses isolated nucleic acids comprising a coding sequence for GAA and an “abbreviated” 3′ UTR.
The isolated nucleic acids of the invention are advantageous for delivery of lysosomal polypeptides (e.g., GAA) to target cells or for recombinant protein production in cultured cells or tissues or whole animal systems (e.g., for enzyme replacement therapy). In particular embodiments, the present invention can be practiced to deliver a coding sequence for a lysosomal polypeptide to a “depot” tissue or organ (e.g., liver, skeletal muscle, lung), where the polypeptide is expressed in the depot tissue or organ, secreted into the systemic circulation, and taken up by target tissues (e.g., skeletal muscle, cardiac muscle and/or diaphragm muscle in GAA deficient individuals). In representative embodiments, uptake of GAA polypeptide secreted from the liver by skeletal muscle and/or other tissues affected by GAA deficiency results in a reduction in glycogen stores or improvement in other clinical indicia of GAA deficiency. In other embodiments, the isolated nucleic acid is delivered to cells (e.g., neurons and/or glial cells) in the brain, the lysosomal polypeptide is produced and secreted by the transformed or transduced cells and taken up by other brain cells.
The present invention will now be described with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. This invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. In addition, numerous variations and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
Except as otherwise indicated, standard methods may be used for the production of viral and non-viral vectors, manipulation of nucleic acid sequences, production of transformed cells, recombinant protein production, and the like according to the present invention. Such techniques are known to those skilled in the art. See, e.g., SAMBROOK et al., MOLECULAR CLONING: A LABORATORY MANUAL 2nd Ed. (Cold Spring Harbor, N.Y., 1989); F. M. AUSUBEL et al. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (Green Publishing Associates, Inc. and John Wiley & Sons, Inc., New York).
Definitions
Unless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below:
As used in the description of the invention and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
As used herein, a “vector” or “delivery vector” may be a viral or non-viral vector that is used to deliver a nucleic acid to a cell, tissue or subject.
A “recombinant” vector or delivery vector refers to a viral or non-viral vector that comprises one or more heterologous nucleoli sequences (i.e., transgenes), e.g., two, three, four, five or more heterologous nucleotide sequences. The recombinant vectors of the invention comprise nucleotide sequences that encode GAA, but may also comprise one or more additional heterologous sequences.
As used herein, the term “viral vector” or “viral delivery vector” may refer to a virus particle that functions as a nucleic acid delivery vehicle, and which comprises the recombinant vector genome packaged within a virion. Alternatively, these terms may be used to refer to the vector genome when used as a nucleic acid delivery vehicle in the absence of the virion.
A viral “vector genome” refers to the viral genomic DNA or RNA, in either its naturally occurring or modified form. A “recombinant vector genome” is a viral genome (e.g., vDNA) that comprises one or more heterologous nucleotide sequence(s).
A “heterologous nucleotide sequence” will typically be a sequence that is not naturally-occurring in the vector. Alternatively, a heterologous nucleotide sequence may refer to a sequence that is placed into a non-naturally occurring environment (e.g., by association with a promoter with which it is not naturally associated).
By “infectious,” as used herein, it is meant that a virus can enter a cell by natural transduction mechanisms and express viral genes (including heterologous nucleotide sequence(s)). Alternatively, an “infectious” virus is one that can enter the cell by other mechanisms and express the genes encoded by the viral genome. As one illustrative example, the vector can enter a target cell by expressing a ligand or binding protein for a cell-surface receptor in the virion or by using an antibody(ies) directed against molecules on the cell-surface followed by internalization of the complex.
As used herein, “transduction” of a cell by AAV means that the AAV enters the cell to establish a latent infection. See, e.g., BERNARD N. FIELDS et al., VIROLOGY, volume 2, chapter 69 (3d ed., Lippincott-Raven Publishers).
The term “replication” as used herein in reference to viral vectors refers specifically to replication (i.e., making new copies of) of the vector genome (i.e., virion DNA or RNA).
The term “propagation” as used herein in reference to viral vectors refers to a productive viral infection wherein the viral genome is replicated and packaged to produce new virions, which typically can “spread” by infection of cells beyond the initially infected cell. A “propagation-defective” virus is impaired in its ability to produce a productive viral infection and spread beyond the initially infected cell.
As used herein, the term “polypeptide” encompasses both peptides and proteins, unless indicated otherwise.
A “chimeric polypeptide” is a polypeptide produced when two heterologous genes or fragments thereof coding for two (or more) different polypeptides or fragments thereof not found fused together in nature are fused together in the correct translational reading frame. Illustrative chimeric polypeptides include fusions of GAA or other lysosomal polypeptides to all or a portion of glutathione-S-transferase, maltose-binding protein, or a reporter protein (e.g., Green Fluorescent Protein, β-glucuronidase, and β-galactosidase, luciferase). In particular embodiments of the invention, the chimeric polypeptide comprises a secretory signal sequence operably linked to a lysosomal polypeptide (e.g., GAA).
As used herein, a “functional” polypeptide is one that retains at least one biological activity normally associated with that polypeptide. Preferably, a “functional” polypeptide retains all of the activities possessed by the unmodified polypeptide. By “retains” biological activity, it is meant that the polypeptide retains at least about 50%, 60%, 75%, 85%, 90%, 95%, 97%, 98%, 99%, or more, of the biological activity of the native polypeptide (and may even have a higher level of activity than the native polypeptide). A “non-functional” polypeptide is one that exhibits essentially no detectable biological activity normally associated with the polypeptide (e.g., at most, only an insignificant amount, e.g., less than about 10% or even 5%).
As used herein, an “isolated” nucleic acid (e.g., an “isolated DNA” or an “isolated vector genome”) means a nucleic acid separated or substantially free from at least some of the other components of the naturally occurring organism or virus, for example, the cell or viral structural components or other polypeptides or nucleic acids commonly found associated with the nucleic acid.
Likewise, an “isolated” polypeptide means a polypeptide that is separated or substantially free from at least some of the other components of the naturally occurring organism or virus, for example, the cell or viral structural components or other polypeptides or nucleic acids commonly found associated with the polypeptide.
A “therapeutically effective” amount as used herein is an amount that is sufficient to provide some improvement or benefit to the subject. Alternatively stated, a “therapeutically-effective” amount is an amount that will provide some alleviation, mitigation or decrease in at least one clinical symptom in the subject. To illustrate, in the case of GAA deficiency, an amount that provides some alleviation, mitigation or decrease in at least one clinical symptom of GAA deficiency (e.g., reduced glycogen stores in skeletal, diaphragm and/or cardiac muscle, improved muscle strength and function, improved pulmonary function, improved motor development or attainment of motor developmental milestones, reduction in need for or prevention of need for ventilator support, prevention of cardiac or cardiorespiratory failure, reduced premature mortality, and the like). Those skilled in the art will appreciate that the therapeutic effects need not be complete or curative, as long ad some benefit is provided to the subject.
By the terms “treating” or “treatment of,” it is intended that the severity of the patient's condition is reduced or at least partially improved and that some alleviation, mitigation, delay or decrease in at least one clinical symptom is achieved.
A “reduction in glycogen stores” in a tissue is intended to indicate about a 25%, 35%, 40%, 50%, 60%, 75%, 85%, 90% 95% or more reduction in total glycogen in a particular tissue, unless otherwise indicated (e.g., a reduction in lysosomal glycogen stores or in pooled tissues).
By the term “express” or “expression” of a nucleic acid coding sequence, in particular a GAA coding sequence, it is meant that the sequence is transcribed, and optionally, translated. Generally, however, according to the present invention, the term “express” or “expression” is intended to refer to transcription and translation of the coding sequence resulting in production of the encoded polypeptide.
By “enhanced” or “enhancement” (or grammatical variations thereof) with respect to nucleic acid expression or polypeptide production, it is meant an increase and/or prolongation of steady-state levels of the indicated nucleic acid or polypeptide, e.g., by at least about 20%, 25%, 40%, 50%, 60%, 75%, 2-fold, 2.5-fold, 3-fold, 5-fold, 10-fold, 15-fold, 20-fold, 30-fold, 50-fold, 100-fold or more.
Unless indicated otherwise, the terms “enhanced” or “enhancement” (or grammatical variations thereof) with respect to polypeptide secretion indicates an increase in the relative proportion of polypeptide that is secreted from the cell, e.g., by at least about 20%, 25%, 40%, 50%, 60%, 75%, 2-fold, 2.5-fold, 3-fold, 5-fold, 10-fold, 15-fold, 20-fold, 30-fold, 50-fold, 100-fold or more.
II. Improved Constructs for Producing Lysosomal Polypeptides.
As described in more detail below, the present invention provides improved constructs for producing lysosomal polypeptides, e.g., polypeptides that are targeted to the lysosomes. As known in the art, many lysosomal proteins are characterized by the presence of mannose-6-phosphate residues, and in embodiments of the invention the lysosomal polypeptide comprises mannose-6-phosphate glycosylation. In other representative embodiments, the lysosomal polypeptide is one that is associated with a lysosomal storage disease (e.g., because of a deficiency or defect in the lysosomal polypeptide). By “associated with a lysosomal storage disease”, it is meant that the lysosomal polypeptide is one that is deficient or defective in a lysosomal storage disorder, or is otherwise a causative agent in a lysosomal storage disorder.
As known in the art, there are a multitude of lysosomal storage diseases. Exemplary lysosomal storage disease include, but are not limited to, glycogen storage disease type II (GSD II or Pompe Disease), GM1 gangliosidosis, Tay-Sachs disease, GM2 gangliosidosis (AB variant), Sandhoff disease, Fabry disease, Gaucher disease, metachromatic leukodystrophy, Krabbe disease, Niemann-Pick disease (Types A-D), Farber disease, Wolman disease, Hurler Syndrome (MPS III), Scheie Syndrome (MPS IS), Hurler-Scheie Syndrome (MPS IH/S), Hunter Syndrome (MPS II), Sanfilippo A Syndrome (MPS IIIA), Sanfilippo B Syndrome (MPS IIIB), Sanfilippo C Syndrome (MPS IIIC), Sanfilippo D Syndrome (MPS IIID), Morquio A disease (MPS IVA), Morquio B disease (MPS IV B), Maroteaux-Lamy disease (MPS VI), Sly Syndrome (MPS VII), α-mannosidosis, β-mannosidosis, fucosidosis, aspartylglucosaminuria, sialidosis (mucolipidosis I), mucolipidosis II (I-Cell disease), mucolipidosis III (pseudo-Hurler polydystrophy), mucolipidosis IV, galactosialidosis (Goldberg Syndrome), Schindler disease, cystinosis, Salla disease, infantile sialic acid storage disease, Batten disease (juvenile neuronal ceroid lipofuscinosis), infantile neuronal ceroid lipofuscinosis, and prosaposin.
Lysosomal polypeptides that are associated with lysosomal storage diseases according to the present invention include, but are not limited to, lysosomal acid α-glucosidase (GAA; also known as acid maltase), α-galactosidase A, β-galactosidase, β-hexosaminidase A, β-hexosaminidase B, GM2 activator protein, glucocerebrosidase, arylsulfatase A, galactosylceramidase, acid sphingomyelinase, acid ceramidase, acid lipase, α-L-iduronidase, iduronate sulfatase, heparan N-sulfatase, α-N-acetylglucosaminidase, glucosaminide acetyltransferase, N-acetylglucosamine-6-sulfatase, arylsulfatase B, β-glucuronidase, α-mannosidase, β-mannosidase, α-L-fucosidase, N-aspartyl-β-glucosaminidase, N-acetylgalactosamine 4-sulfatase, α-neuraminidase, lysosomal protective protein, α-N-acetyl-galactosaminidase, N-acetylglucosamine-1-phosphotransferase, cystine transport protein, sialic acid transport protein, the CLN3 gene product, palmitoyl-protein thioesterase, saposin A, saposin B, saposin C, and saposin D.
Lysosomal acid α-glucosidase or “GAA” (E.C. 3.2.1.20) (1,4-α-D-glucan glucohydrolase), is an exo-1,4-α-D-glucosidase that hydrolyses both α-1,4 and α-1,6 linkages of oligosaccharides to liberate glucose. A deficiency in GAA results in glycogen storage disease type II (GSDII), also referred to as Pompe disease (although this term formally refers to the infantile onset form of the disease). It catalyzes the complete degradation of glycogen with slowing at branching points. The 28 kb human acid α-glucosidase gene on chromosome 17 encodes a 3.6 kb mRNA which produces a 951 amino acid polypeptide (Hoefsloot et al., (1988) EMBO J. 7:1697; Martiniuk et al., (1990) DNA and Cell Biology 9:85). The enzyme receives co-translational N-linked glycosylation in the endoplasmic reticulum. It is synthesized as a 110-kDa precursor form, which matures by extensive glycosylation modification, phosphorylation and by proteolytic processing through an approximately 90-kDa endosomal intermediate into the final lysosomal 76 and 67 kDa forms (Hoefsloot, (1988) EMBO J. 7:1697; Hoefsloot et al., (1990) Biochem. J. 272:485; Wisselaar et al., (1993) J. Biol. Chem. 268:2223; Hermans et al., (1993) Biochem. J. 289:681).
In patients with GSD II, a deficiency of acid α-glucosidase causes massive accumulation of glycogen in lysosomes, disrupting cellular function (Hirschhorn, R. and Reuser, A. J. (2001), in The Metabolic and Molecular Basis for Inherited Disease, (eds, Scriver, C. R. et al.) pages 3389-3419 (McGraw-Hill, New York). In the most common infantile form, patients exhibit progressive muscle degeneration and cardiomyopathy and die before two years of age. Severe debilitation is present in the juvenile and adult onset forms.
The term “GAA” or “GAA polypeptide,” as used herein, encompasses mature ( ̃76 or  ̃67 kDa) and precursor (e.g.,  ̃110 kDa) GAA as well as modified (e.g., truncated or mutated by insertion(s), deletion(s) and/or substitution(s)) GAA proteins or fragments thereof that retain biological function (i.e., have at least one biological activity of the native GAA protein, e.g., can hydrolyze glycogen, as defined above) and GAA variants (e.g., GAA II as described by Kunita et al., (1997) Biochemica et Biophysica Acta 1362:269; GAA polymorphisms and SNPs are described by Hirschhorn, R. and Reuser, A. J. (2001) in The Metabolic and Molecular Basis for Inherited Disease (Scriver, C. R., Beaudet. A. L., Sly, W. S. & Valle, D. Eds.), pp. 3389-3419, McGraw-Hill, New York, see pages 3403-3405; each incorporated herein by reference in its entirety). Any GAA coding sequence known in the art may be used, for example, see the coding sequences of FIGS. 8 and 9; GenBank Accession number NM_00152 and Hoefsloot et al., (1988) EMBO J. 7:1697 and Van Hove et al., (1996) Proc. Natl. Acad. Sci. USA 93:65 (human), GenBank Accession number NM_008064 (mouse), and Kunita et al., (1997) Biochemica et Biophysics Acta 1362:269 (quail); the disclosures of which are incorporated herein by reference for their teachings of GAA coding and noncoding sequences.
Likewise, the term “lysosomal polypeptide,” as used herein, encompasses mature and precursor lysosomal polypeptides as well as modified (e.g., truncated or mutated by insertion(s), deletion(s) and/or substitution(s)) lysosomal polypeptides or fragments thereof that retain biological function (i.e., have at least one biological activity of the native lysosomal polypeptide) and lysosomal polypeptide variants.
The coding sequence of the lysosomal polypeptide can be derived from any source, including avian and mammalian species. The term “avian” as used herein includes, but is not limited to, chickens, ducks, geese, quail, turkeys and pheasants. The term “mammal” as used herein includes, but is not limited to, humans, simians and other non-human primates, bovines, ovines, caprines, equines, felines, canines, lagomorphs, etc. In embodiments of the invention, the nucleic acids of the invention encode a human, mouse or quail lysosomal polypeptide.
A. Constructs for Targeting Lysosomal Polypeptides to the Secretory Pathway.
Lysosomal proteins generally have amino-terminal signal peptides that co-translationally transfer the nascent proteins to the lumen of the endoplasmic reticulum. It is believed that lysosomal polypeptides diverge from the secretory pathway and are directed to the lysosome by at least three distinct pathways (see, e.g., Wisselaar et al., (1993) J. Biol. Chem. 268:2223-31). The best studied of these involves the post-translational addition of mannose-6-phosphate residues that are recognized by the phosphomannosyl receptor, which directs the transport of the polypeptide to the lysosome.
The first 27 amino acids of the human GAA polypeptide are typical of signal peptides of lysosomal and secretory proteins. GAA may be targeted to lysosomes via the phosphomannosyl receptor and/or by sequences associated with the delayed cleavage of the signal peptide (Hirschhorn, R. and Reuser, A. J. (2001), in The Metabolic and Molecular Basis for Inherited Disease, (eds, Scriver, C. R. et al.) pages 3389-3419 (McGraw-Hill, New York). A membrane-bound precursor form of the enzyme (i.e., anchored by the uncleaved signal peptide) has been identified in the lumen of the endoplasmic reticulum (see, e.g., Wisselaar et al., (1993) J. Biol. Chem. 268:2223-31).
The present invention provides isolated nucleic acids encoding lysosomal polypeptides (e.g., GAA) that are fused to a signal peptide that enhances targeting of the polypeptide to the secretory pathway. Secretion of lysosomal polypeptides from the cell provides a number of advantages. For example, in recombinant protein production systems (both cultured cells/tissues or whole animals systems), it is generally preferable to purify a secreted polypeptide from the extracellular medium or fluids rather than harvesting the cells and isolating intracellular protein. With respect to therapeutic methods, it has been shown that administration of an Ad vector encoding hGAA that was targeted to liver in a GAA knock-out mouse model reversed glycogen accumulation in skeletal and cardiac muscle by secretion of hGAA from the liver and uptake by affected tissues (Amalfitano et al., Proc. Natl. Acad. Sci. USA 96:8861-8866). Presumably, secretion of significant amounts of GAA (i.e., rather than lysosomal targeting) was a result of over-expression of the GAA transgene delivered by the Ad vector and saturation of the “scavenger” system that normally redirects extracellular lysosomal proteins to the lysosome.
The present invention advantageously provides improved constructs that enhance secretion of lysosomal polypeptides from the transduced or transfected cell. These constructs facilitate the use of alternative delivery systems (e.g., AAV vectors for liver delivery), enhance the secretion of lysosomal polypeptides (e.g., for in vivo gene delivery or in vitro enzyme production), and can reduce or avoid cytotoxicity or organ toxicity (e.g., hepatotoxicity) that may result from over-accumulation of recombinant protein in the depot organ.
Accordingly, the invention encompasses isolated nucleic acids encoding a chimeric polypeptide comprising a secretory signal sequence operably linked to a lysosomal polypeptide (e.g., GAA) as well as the chimeric polypeptides. The secretory signal sequence is foreign to (e.g., exogenous to) the lysosomal polypeptide. While those skilled in the art will appreciate that secretory signal sequences are typically at the amino-terminus of the nascent polypeptide, the secretory signal sequence according to the present invention can be located at any position within the chimeric polypeptide (e.g., N-terminal, within the mature polypeptide, or C-terminal) as long as it functions as a secretory signal sequence (e.g., enhances secretion of the lysosomal polypeptide) and does not render the lysosomal polypeptide non-functional.
As used herein, the term “secretory signal sequence” or variations thereof are intended to refer to amino acid sequences that function to enhance (as defined above) secretion of an operably linked lysosomal polypeptide from the cell as compared with the level of secretion seen with the native lysosomal polypeptide. As defined above, by “enhanced” secretion, it is meant that the relative proportion of lysosomal polypeptide synthesized by the cell that is secreted from the cell is increased; it is not necessary that the absolute amount of secreted protein is also increased. In particular embodiments of the invention, essentially all (i.e., at least 95%, 97%, 98%, 99% or more) of the polypeptide is secreted. It is not necessary, however, that essentially all or even most of the lysosomal polypeptide is secreted, as long as the level of secretion is enhanced as compared with the native lysosomal polypeptide.
In particular embodiments, at least about 50%, 60%, 75%, 85%, 90%, 95%, 98% or more of the lysosomal polypeptide is secreted from the cell.
The relative proportion of newly-synthesized lysosomal polypeptide that is secreted from the cell can be routinely determined by methods known in the art and as described in the Examples. Secreted proteins can be detected by directly measuring the protein itself (e.g., by Western blot) or by protein activity assays (e.g., enzyme assays) in cell culture medium, serum, milk, etc.
Generally, secretory signal sequences are cleaved within the endoplasmic reticulum and, in particular embodiments of the invention, the secretory signal sequence is cleaved prior to secretion. It is not necessary, however, that the secretory signal sequence is cleaved as long as secretion of the lysosomal polypeptide from the cell is enhanced and the lysosomal polypeptide is functional. Thus, in embodiments of the invention, the secretory signal sequence is partially or entirely retained.
Thus, in particular embodiments of the invention, an isolated nucleic acid encoding a chimeric polypeptide comprising a lysosomal polypeptide operably linked to a secretory signal sequence is delivered to a cell, and the chimeric polypeptide is produced and the lysosomal polypeptide secreted from the cell. The lysosomal polypeptide can be secreted after cleavage of all or part of the secretory signal sequence. Alternatively, the lysosomal polypeptide can retain the secretory signal sequence (i.e., the secretory signal is not cleaved). Thus, in this context, the “lysosomal polypeptide” can be a chimeric polypeptide.
Those skilled in the art will further understand that the chimeric polypeptide can contain additional amino acids, e.g., as a result of manipulations of the nucleic acid construct such as the addition of a restriction site, as long as these additional amino acids do not render the secretory signal sequence or the lysosomal polypeptide non-functional. The additional amino acids can be cleaved or can be retained by the mature polypeptide as long as retention does not result in a nonfunctional polypeptide.
In representative embodiments, the secretory signal peptide replaces most, essentially all or all of the leader sequence found in the native lysosomal polypeptide. In particular embodiments, most or all of the native leader sequence is retained, as long as secretion of the lysosomal polypeptide is enhanced and the mature lysosomal polypeptide is functional.
The secretory signal sequence can be derived in whole or in part from the secretory signal of a secreted polypeptide (i.e., from the precursor) and/or can be in whole or in part synthetic. The secretory signal sequence can be from any species of origin, including animals (e.g., avians and mammals such as humans, simians and other non-human primates, bovines, ovines, caprines, equines, porcines, canines, felines, rats, mice, lagomorphs), plants, yeast, bacteria, protozoa or fungi. The length of the secretory signal sequence is not critical; generally, known secretory signal sequences are from about 10-15 to 50-60 amino acids in length. Further, known secretory signals from secreted polypeptides can be altered or modified (e.g., by substitution, deletion, truncation or insertion of amino acids) as long as the resulting secretory signal sequence functions to enhance secretion of an operably linked lysosomal polypeptide.
The secretory signal sequences of the invention can comprise, consist essentially of or consist of a naturally occurring secretory signal sequence or a modification thereof (as described above). Numerous secreted proteins and sequences that direct secretion from the cell are known in the art. Exemplary secreted proteins (and their secretory signals) include but are not limited to: erythropoietin, coagulation Factor IX, cystatin, lactotransferrin, plasma protease C1 inhibitor, apolipoproteins (e.g., APO A, C, E), MCP-1, α-2-HS-glycoprotein, α-1-microgolubilin, complement (e.g., C1Q, C3), vitronectin, lymphotoxin-α, azurocidin, VIP, metalloproteinase inhibitor 2, glypican-1, pancreatic hormone, clusterin, hepatocyte growth factor, insulin, α-1-antichymotrypsin, growth hormone, type IV collagenase, guanylin, properdin, proenkephalin A, inhibin β (e.g., A chain), prealbumin, angiocenin, lutropin (e.g., β chain), insulin-like growth factor binding protein 1 and 2, proactivator polypeptide, fibrinogen (e.g., β chain), gastric triacylglycerol lipase, midkine, neutrophil defensins 1, 2, and 3, α-1-antitrypsin, matrix gla-protein, α-tryptase, bile-salt-activated lipase, chymotrypsinogen B, elastin, IG lambda chain V region, platelet factor 4 variant, chromogranin A, WNT-1 proto-oncogene protein, oncostatin M, β-neoendorphin-dynorphin, von Willebrand factor, plasma serine protease inhibitor, serum amyloid A protein, nidogen, fibronectin, rennin, osteonectin, histatin 3, phospholipase A2, cartilage matrix Protein, GM-CSF, matrilysin, neuroendocrine protein 7B2, placental protein 11, gelsolin, IGF 1 and 2, M-CSF, transcobalamin I, lactase-phlorizin hydrolase, elastase 2B, pepsinogen A, MIP 1-β, prolactin, trypsinogen II, gastrin-releasing peptide II, atrial natriuretic factor, secreted alkaline phosphatase, pancreatic α-amylase, secretogranin I, β-casein, serotransferrin, tissue factor pathway inhibitor, follitropin β-chain, coagulation factor XII, growth hormone-releasing factor, prostate seminal plasma protein, interleukins (e.g., 2, 3, 4, 5, 9, 11), inhibin (e.g., alpha chain), angiotensinogen, thyroglobulin, IG heavy or light chains, plasminogen activator inhibitor-1, lysozyme C, plasminogen activator, antileukoproteinase 1, statherin, fibulin-1, isoform B, uromodulin, thyroxine-binding globulin, axonin-1, endometrial α-2 globulin, interferon (e.g., alpha, beta, gamma), β-2-microglobulin, procholecystokinin, progastricsin, prostatic acid phosphatase, bone sialoprotein II, colipase, Alzheimer's amyloid A4 protein, PDGF (e.g., A or B chain), coagulation factor V, triacylglycerol lipase, haptoglobuin-2, corticosteroid-binding globulin, triacylglycerol lipase, prorelaxin H2, follistatin 1 and 2, platelet glycoprotein IX, GCSF, VEGF, heparin cofactor II, antithrombin-III, leukemia inhibitory factor, interstitial collagenase, pleiotrophin, small inducible cytokine A1, melanin-concentrating hormone, angiotensin-converting enzyme, pancreatic trypsin inhibitor, coagulation factor VIII, α-fetoprotein, α-lactalbumin, senogelin II, kappa casein, glucagon, thyrotropin beta chain, transcobalamin II, thrombospondin 1, parathyroid hormone, vasopressin copeptin, tissue factor, motilin, MPIF-1, kininogen, neuroendocrine convertase 2, stem cell factor procollagen α1 chain, plasma kallikrein keratinocyte growth factor, as well as any other secreted hormone, growth factor, cytokine, enzyme, coagulation factor, milk protein, immunoglobulin chain, and the like.
In other particular embodiments, the secretory signal sequence is derived in part or in whole from a secreted polypeptide that is produced by liver cells.
The secretory signal sequence of the invention can further be in whole or in part synthetic or artificial. Synthetic or artificial secretory signal peptides are known in the art, see e.g., Barash et al., “Human secretory signal peptide description by hidden Markov model and generation of a strong artificial signal peptide for secreted protein expression,” Biochem. Biophys. Res. Comm. 294:835-42 (2002); the disclosure of which is incorporated herein in its entirety. In particular embodiments, the secretory signal sequence comprises, consists essentially of, or consists of the artificial secretory signal: MWWRLWWLLLLLLLLWPMVWA (SEQ ID NO: 5) or variations thereof having 1, 2, 3, 4, or 5 amino acid substitutions (optionally, conservative amino acid substitutions, conservative amino acid substitutions are known in the art).
The isolated nucleic acid encoding the chimeric polypeptide can further comprise an “abbreviated” 3′ UTR as described in more detail below.
B. “Abbreviated” GAA Constructs.
The present invention is based, in part, on the discovery that constructs expressing lysosomal acid α-glucosidase (GAA) that are deleted or altered (e.g., substituted) in the 3′ untranslated region (UTR), can have advantageous properties as compared with non-deleted or non-altered constructs. For example, the efficiency of packaging a 3′ UTR deleted or otherwise “abbreviated” 3′ UTR GAA construct (as discussed in more detail below) into viral vectors (e.g., AAV vectors) can be improved. Further, the level of expression of the GAA mRNA and/or polypeptide can be enhanced (e.g., as a result of a higher level of transcription and/or translation and/or longer half-life of the mRNA transcript and/or polypeptide) as compared with a full-length construct (e.g., SEQ ID NO:1, FIG. 8).
The present invention provides isolated nucleic acids encoding GAA, comprising a coding, sequence for GAA and an “abbreviated” 3′ untranslated region (UTR). The “abbreviated” 3′ UTR are altered as compared with the native GAA 3′ UTR sequence (e.g., the 3′ UTR of SEQ ID NO:1 is from nt 3301 through 3846; see also FIG. 8). In representative embodiments, the abbreviated 3′ UTR comprises, consists essentially of or consists of a deleted GAA 3′ UTR. In other embodiments, the abbreviated 3′ UTR is shortened as compared with the native GAA 3′ UTR and has been altered to contain a region from a heterologous 3′ UTR, which can be a partially or wholly synthetic 3′ UTR sequence. These embodiments of the invention are discussed in more detail below. The isolated nucleic acids encoding GAA and comprising an abbreviated 3′ UTR of the invention can provide for higher levels of GAA polypeptide expression. In particular embodiments, the abbreviated constructs can also be more efficiently packaged into viral vectors (e.g., rAAV vectors).
The abbreviated 3′ UTR of the invention encode functional 3′ UTR that, in the presence of all other necessary regulatory elements, permit the expression of a functional GAA polypeptide from a GAA coding sequence operably associated therewith. In illustrative embodiments, the isolated nucleic acid comprising a coding sequence for GAA and an abbreviated 3′ UTR further comprises a secretory signal sequence operably linked to the GAA coding sequence, as described hereinabove.
While not wishing to be held to any particular theory of the invention, the improved properties of “abbreviated” 3′ UTR nucleic acids encoding GAA may be a result of their shorter total size and/or removal of an inhibitory region, e.g., a region that reduces transcription, destabilizes the mRNA transcript and/or inhibits translation. Examples of small sequences that destabilize mRNA for cytokines (see, e.g., Shaw and Kamen, (1986) Cell 46:659-67; Reeves et al., (1987) Proc. Natl. Acad. Sci. USA 84:6531-35) and the HIV gag gene (see, e.g., Schwartz et al. (1992) J. Virology 66:150-59; Schwartz et al., (1992) J. Virol. 66:7175-82) have been described.
In particular embodiments, the isolated nucleic acid comprising the GAA coding sequence and abbreviated 3′ UTR is less than about 4.5, 4.4, 4.3, 4.2, 4.1, 4, 3.9 or 3.8 kb in length. To illustrate, according to representative embodiments, a GAA expression construct including 5′ and 3′ UTR sequences is less than about 4.5, 4.4, 4.3, 4.2, 4.1, 4, 3.9 or 3.8 kb in length.
The isolated nucleic acid encoding GAA can further comprise a 5′ UTR, which can further include all or a portion of the 5′ UTR of a GAA gene. Human GAA sequences with deletions in the 5′ UTR have been described, see, e.g., Van Hove et al. (1996) Proc. Natl. Acad. Sci. USA 93:65, in which nt 1-409 of the 5′ UTR of SEQ ID NO:1 (FIG. 8) have been deleted (see also SEQ ID NO:3; FIG. 9). Alternatively, the 5′ UTR can be derived in whole or in part from a heterologous gene (i.e., a gene other than a GAA gene) and/or can comprise in whole or in part synthetic sequences.
As one aspect, the present invention provides isolated nucleic acids that encode GAA, where the isolated nucleic acid comprises (i) a GAA coding sequence encoding a GAA and (ii) a GAA 3′ UTR region having a deletion therein.
A “coding region encoding a GAA polypeptide” comprises nucleotide sequences that can be transcribed and translated to yield a functional GAA polypeptide or functional fragment thereof (see above). Such coding sequences may include non-translated sequences (e.g., intron sequences).
A “GAA 3′ UTR region” refers to the non-translated nucleic acid sequences of a GAA gene that are located downstream of (i.e., 3′ to) the regions of the gene that encode the GAA protein.
By “deleted” GAA 3′ UTR, it is intended that there is an omission of at least one nucleotide from the 3′ UTR region of the GAA expression construct. Deletions can be greater than about 25, 50, 100, 150, 200, 300, 400 consecutive nucleotides, or more. In particular embodiments, essentially all of the 3′ UTR is deleted. By “essentially all” it is meant that only an insignificant fragment of the intact 3′ UTR remains (i.e., less than 10, 20 or 30 nucleotides). For example, essentially all, but not necessarily all, of the 3′ UTR can be conveniently removed using restriction enzymes (i.e., there may be some residual nucleotides left after restriction enzyme cleavage) or some untranslated nucleotides may remain 3′ of the coding sequence as an artifact of cloning procedures.
Alternatively stated, at least 25%, 50%, 60%, 70%, 80%, 90%, 95%, 99% or more of the GAA 3′ UTR can be deleted. As still a further alternative, in embodiments of the invention, the “deleted” GAA 3′ UTR is less than about 300, 250, 200, 175, 150, 125, 100, 75, 50, 30, 20 or 10 nucleotides in length or less.
In particular embodiments of the invention, the deleted 3′ UTR comprises, consists essentially of or consists of a deleted form of the 3′ UTR in the human GAA sequence provided in SEQ ID NO:1 (i.e., the 3′ UTR of SEQ ID NO:1 is from nt 3301 through 3846; see also FIG. 8). For example, the deleted 3′ UTR can comprise, consist essentially of or consist of the 3′ UTR shown in SEQ ID NO:3 (i.e., the 3′ UTR of SEQ ID NO:3 is from nt 2878 through 3012; see also, FIG. 9).
Referring to the 3′ UTR in the GAA sequence of SEQ ID NO:1 and FIG. 8 (nt 3301 through 3846), the deleted 3 UTR can comprise a deletion from nt 3301 through 3846 of SEQ ID NO:1. The deletion can also encompass from about nt 3400 through nt 3500, nt 3500 through nt 3600, nt 3600 through nt 3700, nt 3700 through nt 3800, nt 3800 through nt3846, nt 3301 through nt 3450, nt 3450 through nt 3600, nt 3600 through nt 3750, nt 3750 through nt 3846, nt 3301 through nt 3500, nt 3400 through nt 3600, nt 3500 through nt 3700, nt 3600 through nt 3800, nt 3700 through nt 3846, nt 3301 through nt 3600, nt 3400 through nt 3700, nt 3500 through nt 3800, nt 3600 through nt 3846, nt 3301 through nt 3700, nt 3400 through nt 3800, nt 3500 through nt 3845, nt 3300 through nt 3800, or nt 3400 through nt 3486.
Deletions can be intermittent, i.e., more than one region of the nucleotide sequence can be deleted to impart the functional improvements described herein. Alternatively, consecutive nucleotides can be deleted. Further, the deletion can be internal or start at either end of the 3′ UTR. For example, the 3′ UTR sequence can be truncated from the 5′ or 3′ end of the 3′ UTR by 50, 100, 200, 300 or 400 nt or more.
Those skilled in the art will readily appreciate that the deleted and intact (i.e., from which the deleted 3′ UTR are derived) GAA 3′ UTR regions within the scope of the present invention can deviate from those specifically disclosed herein and that any suitable GAA coding sequence or GAA 3′ UTR may be employed. The GAA coding sequences and 3′ UTR can contain other alterations such as substitutions or insertions therein. For example, It will be understood that the GAA 3′ UTR can contain some heterologous sequence(s) (e.g., the polyA signal may be from another gene, such as the human or bovine growth hormone gene).
In embodiments of the invention, the 3′ UTR deleted nucleic acid encoding GAA will hybridize to the 3′ UTR deleted nucleic acid sequences specifically disclosed herein (i.e., SEQ ID NO:3) under standard conditions as known by those skilled in the art and encode a functional GAA polypeptide (as defined above).
In other embodiments, the deleted GAA 3′ UTR of the invention will hybridize to the deleted GAA 3′ UTR sequences specifically disclosed herein (e.g., nt 2878 to 3012 of SEQ ID NO:3) under standard conditions as known by those skilled in the art and permit the expression of a functional GAA polypeptide from a GAA coding sequence operably associated therewith.
In still further embodiments, the coding sequence of the isolated nucleic acid encoding GAA will hybridize to the sequences encoding GAA specifically disclosed herein (e.g., nt 442 to nt 3300 of SEQ ID NO:1) under standard conditions as known by those skilled in the art and encode a functional GAA polypeptide.
For example, hybridization of such sequences can be carried out under conditions of reduced stringency, medium stringency or even stringent conditions (e.g., conditions represented by a wash stringency of 35-40% formamide with 5×Denhardt's solution, 0.5% SDS and 1×SSPE at 37° C.; conditions represented by a wash stringency of 40-45% formamide with 5×Denhardt's solution. 0.5% SDS, and 1×SSPE at 42° C. and conditions represented by a wash stringency of 50% formamide with 5×Denhardt's solution, 0.5% SDS and 1×SSPE at 42° C., respectively) to the sequences specifically disclosed herein. See, e.g., Sambrook et al., Molecular Cloning, A Laboratory Manual (2d Ed. 1989) (Cold Spring Harbor Laboratory).
Alternatively stated, in embodiments of the invention, 3′ UTR deleted nucleic acid encoding GAA of the invention have at least about 60%, 70%, 80%, 90%, 95%, 97%, 98% or higher nucleotide sequence homology with the isolated nucleic acid sequences specifically disclosed herein (or fragments thereof) and encode a functional GAA protein (mature or precursor forms).
Likewise, in embodiments of the invention, the deleted 3′ UTR according to the present invention have at least about 60%, 70%, 80%, 90%, 95%, 97%, 98%, or higher nucleotide sequence homology with the isolated nucleic acid sequences specifically disclosed herein (or fragments thereof) and permit the expression of a functional GAA polypeptide from a GAA coding sequence operably associated therewith.
Further, in embodiments of the invention, the coding region of the isolated nucleic acids encoding GAA of the invention have at least about 60%, 70%, 80%, 90%, 95%, 97%, 98% or higher nucleotide sequence homology with the isolated nucleic acid sequences specifically disclosed herein (or fragments thereof) and encode a functional GAA polypeptide.
It will be appreciated by those skilled in the art that there may be variability in the polynucleotides that encode the GAA proteins of the present invention due to the degeneracy of the genetic code. The degeneracy of the genetic code, which allows different nucleic acid sequences to code for the same polypeptide, is well known in the literature (see Table 1).










TABLE 1





Amino Acids


Codons


















Alanine
Ala
A
GCA GCC GCG GCT


 


Cysteine
Cys
C
TGC TGT


 


Aspartic acid
Asp
D
GAC GAT


 


Glutamic acid
Glu
E
GAA GAG


 


Phenylalanine
Phe
F
TTC TTT


 


Glycine
Gly
G
GGA GGC GGG GGT


 


Histidine
His
H
CAC CAT


 


Isoleucine
Ile
I
ATA ATC ATT


 


Lysine
Lys
K
AAA AAG


 


Leucine
Leu
L
TTA TTG CTA CTC CTG CTT


 


Methionine
Met
M
ATG


 


Asparagine
Asn
N
AAC AAT


 


Proline
Pro
P
CCA CCC CCG CCT


 


Glutamine
Gln
Q
CAA CAG


 


Arginine
Arg
R
AGA AGG CGA CGC CGG CGT


 


Serine
Ser
S
AGC ACT TCA TCC TCG TCT


 


Threonine
Thr
T
ACA ACC ACG ACT


 


Valine
Val
V
GTA GTC GTG GTT


 


Tryptophan
Trp
W
TGG


 


Tyrosine
Tyr
Y
TAC TAT









Further, in other embodiments, the isolated nucleic acids of the invention encompass those nucleic acids encoding GAA polypeptides that have at least about 60%, 70%, 80%, 90%, 95%, 97%, 98%, 99% or higher amino acid sequence homology with the polypeptide sequences specifically disclosed herein (or fragments thereof) and encode a functional GAA polypeptide.
As is known in the art, a number of different programs can be used to identify whether a nucleic acid or polypeptide has sequence identity or similarity to a known sequence. Sequence identity and/or similarity can be determined using standard techniques known in the art, including, but not limited to, the local sequence identity algorithm of Smith & Waterman, Adv. Appl. Math. 2, 482 (1981), by the sequence identity alignment algorithm of Needleman & Wunsch, J. Mol. Biol. 48, 443 (1970), by the search for similarity method of Pearson & Lipman, Proc. Natl. Acad. Sci. USA 85, 2444 (1988), by computerized implementations of these algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Genetics Computer Group, 575 Science Drive, Madison, Wis.), the Best Fit sequence program described by Devereux et al., Nucl. Acid Res. 12, 387-395 (1984), preferably using the default settings, or by inspection.
An example of a useful algorithm is PILEUP, which creates a multiple sequence alignment from a group of related sequences using progressive, pairwise alignments. It can also plot a tree showing the clustering relationships used to create the alignment. PILEUP uses a simplification of the progressive alignment method of Feng & Doolittle, J. Mol. Evol. 35, 351-360 (1987); the method is similar to that described by Higgins & Sharp, CABIOS 5, 151-153 (1989).
Another example of a useful algorithm is the BLAST algorithm, described in Altschul et al., J. Mol. Biol. 215, 403-410, (1990) and Karlin et al., Proc. Natl. Acad. Sci. USA 90, 5873-5787 (1993). A particularly useful BLAST program is the WU-BLAST-2 program which was obtained from Altschul et al., Methods in Enzymology, 266, 460-480 (1996); http://blast.wustl/edu/blast/README.html. WU-BLAST-2 uses several search parameters, which are preferably set to the default values. The parameters are dynamic values and are established by the program itself depending upon the composition of the particular sequence and composition of the particular database against which the sequence of interest is being searched; however, the values may be adjusted to increase sensitivity.
An additional useful algorithm is gapped BLAST as reported by Altschul et al. Nucleic Acids Res. 25, 3389-3402.
A percentage amino acid sequence identity value can be determined by the number of matching identical residues divided by the total number of residues of the “longer” sequence in the aligned region. The “longer” sequence is the one having the most actual residues in the aligned region (gaps introduced by WU-Blast-2 to maximize the alignment score are ignored).
The alignment can include the introduction of gaps in the sequences to be aligned. In addition, for sequences which contain either more or fewer amino acids than the polypeptides specifically disclosed herein, it is understood that in one embodiment, the percentage of sequence identity will be determined based on the number of identical amino acids in relation to the total number of amino acids. Thus, for example, sequence identity of sequences shorter than a sequence specifically disclosed herein, will be determined using the number of amino acids in the shorter sequence, in one embodiment. In percent identity calculations relative weight is not assigned to various manifestations of sequence variation, such as, insertions, deletions, substitutions, etc.
In one embodiment, only identities are scored positively (+1) and all forms of sequence variation including gaps are assigned a value of “0,” which obviates the need for a weighted scale or parameters as described below for sequence similarity calculations. Percent sequence identity can be calculated, for example, by dividing the number of matching identical residues by the total number of residues of the “shorter” sequence in the aligned region and multiplying by 100. The “longer” sequence is the one having the most actual residues in the aligned region.
In a further representative embodiment of the invention, the isolated nucleic acid encoding GAA comprises an abbreviated 3′ UTR that is shorter than the 3 UTR found in the native gene (e.g., nt 3301 to nt 3846 of SEQ ID NO:1), to illustrate, is less than about 75%, 50%, 40%, 30%, 20%, 10%, 5%, 4%, or less, of the size of the 3′ UTR found in the native GAA gene, and comprises a heterologous region that is substituted for all or a portion of the native 3′ UTR. According to this embodiment, all or at least a portion of the 3′ UTR is heterologous to the GAA coding region (i.e., is not derived from the 3′ UTR of a GAA gene). The heterologous segment can include all or a portion of a 3′ UTR of another gene and/or can be partially or completely synthetic. In particular embodiments, the heterologous region can be about 300, 250, 200, 175, 125, 100, 75, 50, 30, 20 or 10 nucleotides in length or less. To illustrate, the substituted 3′ UTR can include all or a portion of the bovine or human growth hormone 3′ UTR.
According to some embodiments of the invention, the total size of the abbreviated 3′ UTR is less than about 300, 250, 200, 175, 150, 125, 100, 75, 50, 30, 20 or 10 nucleotides.
By “substitute,” “substituted” or “substitution” in reference to the 3′ UTR is meant that a portion of the naturally-occurring nucleotide sequence of the GAA 3′ UTR has been replaced by a heterologous nucleotide sequence, resulting in a nucleic acid encoding GAA having the advantages described herein.
According to the present invention, an “abbreviated” 3′ UTR encompasses both deleted GAA 3′ UTR (described at length above) and the substituted/shortened 3′ UTR described in the preceding paragraphs. The abbreviated 3′ UTR of the invention may be DNA or RNA, or a chimera thereof.
It still other embodiments of the invention, the “abbreviated” 3′ UTR is less than about 300, 250, 200, 150 or 100 nucleotides in length and is derived in whole or in part from a native GAA 3′ UTR and/or in whole or in part from a heterologous 3′ UTR. Further, the heterologous 3′ UTR sequences can be derived from another gene or can be in whole or in part a synthetic sequence.
As described in more detail below, the abbreviated 3′ UTR nucleic acids of the invention can, upon introduction into a target cell (e.g., a liver cell), express GAA polypeptide at an enhanced (as defined above) level as compared with a cell expressing GAA polypeptide from a comparable construct that contains a full-length GAA 3′ UTR (e.g., SEQ ID NO:1).
III. Nucleic Acid Delivery Vectors.
The methods of the present invention provide a means for delivering and, optionally, expressing lysosomal polypeptides such as GAA in a broad range of host cells, including both dividing and non-dividing cells in vitro or in vivo. In embodiments of the invention, the nucleic acid may be stably introduced into the target cell, for example, by integration into the genome of the cell or by persistent expression from stably maintained episomes (e.g., derived from Epstein Barr Virus). Alternatively, the isolated nucleic acid can be transiently expressed in the cell.
The isolated nucleic acids, vectors, cells, methods and pharmaceutical formulations of the present invention are additionally useful in a method of administering lysosomal polypeptides such as GAA to a subject in need thereof. In this manner, the polypeptide can thus be produced in vivo in the subject. The subject may have a deficiency of the polypeptide, or the production of a foreign polypeptide in the subject may impart some therapeutic effect. Pharmaceutical formulations and methods of delivering lysosomal polypeptides such as GAA for therapeutic purposes are described in more detail in Section V below.
Alternatively, a polynucleotide encoding and expressing the lysosomal polypeptide (e.g., GAA) can be administered to a subject so that the polypeptide is expressed by the subject and purified therefrom, i.e., as a source of recombinant polypeptide. According to this embodiment, it is preferred that the polypeptide is secreted into the systemic circulation or into another body fluid (e.g., milk, lymph, spinal fluid, urine) that is easily collected and from which the polypeptide can be further purified. Alternatively, the polypeptide can be expressed in avian species and deposited in, and conveniently isolated from, egg proteins.
Likewise, the polypeptide can be expressed transiently or stably in a cell culture system. In particular embodiments, the polypeptide is secreted into the medium and can be purified therefrom using routine techniques known in the art. Additionally, or alternatively, the cells can be lysed and the recombinant polypeptide can be purified from the cell lysate. The cell may be a bacterial, protozoan, plant, yeast, fungus, or animal cell. The cell can be an animal cell (e.g., insect, avian or mammalian). Representative mammalian cells include but are not limited to fibroblasts, CHO cells, 293 cells, HT1080 cells, HeLa cells and C10 cells.
in the case of GAA, the recombinant GAA polypeptide can be isolated using standard techniques and administered to subjects with GAA deficiency using enzyme replacement protocols (see, e.g., Van der Ploeg et al., (1991) J. Clin. Invest. 87:513).
Transfer of a nucleic acid encoding a lysosomal polypeptide (e.g., GAA) to a cell in culture or to a subject also finds use as a model for understanding disease states such as GSD II and for investigating the biology of these polypeptides.
Still further, the instant invention finds use in screening methods, whereby the polypeptide is transiently or stably expressed in a cell culture system or animal model and used as a target for drug discovery.
Methods of producing lysosomal polypeptides such as GAA in cultured cells or organisms for the purposes described above are set forth in more detail in Section IV below.
It will be apparent to those skilled in the art that any suitable vector may be used to deliver the isolated nucleic acids of the invention to the target cell(s) or subject of interest. The choice of delivery vector may be made based on a number of factors known in the art, including age and species of the target host, in vitro vs. in vivo delivery, level and persistence of expression desired, intended purpose (e.g., for therapy or enzyme production), the target cell or organ, route of delivery, size of the isolated nucleic acid, safety concerns, and the like.
Any suitable vector known in the art can be used to deliver, and optionally, express the isolated nucleic acids of the invention, including, virus vectors (e.g., retrovirus, adenovirus, adeno-associated virus, or herpes simplex virus), lipid vectors, poly-lysine vectors, synthetic polyamino polymer vectors that are used with nucleic acid molecules, such as a plasmid, and the like.
Any viral vector that is known in the art may be used in the present invention. Examples of such viral vectors include, but are not limited to vectors derived from: Adenoviridae; Birnaviridae; Bunyaviridae; Caliciviridae, Capillovirus group; Carlavirus group; Carmovirus virus group; Group Caulimovirus; Closterovirus Group; Commelina yellow mottle virus group; Comovirus virus group; Coronaviridae; PM2 phage group; Corcicoviridae; Group Cryptic virus; group Cryptovirus; Cucumovirus virus group family ([PHgr]6 phage group; Cysioviridae; Group Carnation ringspot; Dianthovirus virus group; Group Broad bean wilt; Fabavirus virus group; Filoviridae; Flaviviridae; Furovirus group; Group Germinivirus; Group Giardiavirus; Hepadnaviridae; Herpesviridae; Hordeivirus virus group; Illarvirus virus group; Inoviridae; Iridoviridae; Leviviridae; Lipothrixviridae; Luteovirus group; Marafivirus virus group; Maize chlorotic dwarf virus group; icroviridae; Myoviridae; Necrovirus group; Nepovirus virus group; Nodaviridae; Orthomyxoviridae; Papovaviridae; Paramyxoviridae; Parsnip yellow fleck virus group; Partitiviridae; Parvoviridae; Pea enation mosaic virus group; Phycodnaviridae; Picornaviridae; Plasmaviridae; Prodoviridae; Polydnaviridae; Potexvirus group; Potyvirus; Poxyiridae; Reoviridae; Retroviridae; Rhabdoviridae; Group Rhizidiovirus; Siphoviridae; Sobemovirus group; SSV 1-Type Phages; Tectiviridae; Tenuivirus; Tetraviridae; Group Tobamovirus; Group Tobravirus; Togaviridae; Group Tombusvirus; Group Torovirus; Totiviridae; Group Tymovirus; and plant virus satellites.
Protocols for producing recombinant viral vectors and for using viral vectors for nucleic acid delivery can be found in Current Protocols in Molecular Biology; Ausubel, F. M. et al. (eds.) Greene Publishing Associates; (1989) and other standard laboratory manuals (e.g., Vectors for Gene Therapy, In: Current Protocols in Human Genetics, John Wiley and Sons, Inc.; 1997).
Particularly preferred viral vectors are those previously employed for the delivery of transgenes including, for example, retrovirus, adenovirus, AAV, herpes virus, hybrid adenovirus-AAV, and poxvirus vectors. In particular embodiments, the vector is an adenovirus vector, AAV vector or hybrid Ad-AAV vector.
In certain preferred embodiments of the present invention, the delivery vector is an adenovirus vector. The term “adenovirus” as used herein is intended to encompass all adenoviruses, including the Mastadenovirus and Aviadenovirus genera. To date, at least forty-seven human serotypes of adenoviruses have been identified (see, e.g., FIELDS et al., VIROLOGY, volume 2, chapter 67 (3d ed., Lippincott-Raven Publishers)). Preferably, the adenovirus is a serogroup C adenovirus, still more preferably the adenovirus is serotype 2 (Ad2) or serotype 5 (Ad5).
The various regions of the adenovirus genome have been mapped and are understood by those skilled in the art (see, e.g., FIELDS et al., VIROLOGY, volume 2, chapters 67 and 68 (3d ed., Lippincott-Raven Publishers)). The genomic sequences of the various Ad serotypes, as well as the nucleotide sequence of the particular coding regions of the Ad genome, are known in the art and may be accessed, e.g., from GenBank and NCBI (see, e.g., GenBank Accession Nos. J0917, M73260, X73487, AF108105, L19443, NC 003266 and NCBI Accession Nos. NC 001405, NC 001460, NC 002067, NC 00454).
Those skilled in the art will appreciate that the inventive adenovirus vectors may be modified or “targeted” as described in Douglas et al., (1996) Nature Biotechnology 14:1574; U.S. Pat. No. 5,922,315 to Roy et al.; U.S. Pat. No. 5,770,442 to Wickham et al.; and/or U.S. Pat. No. 5,712,136 to Wickham et al.
An adenovirus vector genome or rAd vector genome will typically comprise the Ad terminal repeat sequences and packaging signal. An “adenovirus particle” or “recombinant adenovirus particle” comprises an adenovirus vector genome or recombinant adenovirus vector genome, respectively, packaged within an adenovirus capsid. Generally, the adenovirus vector genome is most stable at sizes of about 28 kb to 38 kb (approximately 75% to 105% of the native genome size). In the case of an adenovirus vector containing large deletions and a relatively small transgene, “stutter DNA” can be used to maintain the total size of the vector within the desired range by methods known in the art.
Normally adenoviruses bind to a cell surface receptor (CAR) of susceptible cells via the knob domain of the fiber protein on the virus surface. The fiber knob receptor is a 45 kDa cell surface protein which has potential sites for both glycosylation and phosphorylation. (Bergelson, et al., (1997) Science 275:1320-1323. A secondary method of entry for adenovirus is through integrins present on the cell surface. Arginine-Glycine-Aspartic Acid (RGD) sequences of the adenoviral penton base protein bind integrins on the cell surface.
The genome of an adenovirus can be manipulated such that it encodes and expresses a gene product of interest but is inactivated in terms of its ability to replicate in a normal lytic viral life cycle. See, for example. Berkner et al. (1988) BioTechniques 6:616; Rosenfeld et al. (1991) Science 252:431-434; and Rosenfeld et al. (1992) Cell 68:143-155. Suitable adenoviral vectors derived from the adenovirus strain Ad type 5 d 1324 or other strains of adenovirus (e.g., Ad2, Ad3, Ad7, etc.) are known to those skilled in the art. Recombinant adenoviruses can be advantageous in certain circumstances in that they are not capable of infecting nondividing cells and can be used to infect a wide variety of cell types, including epithelial cells. Furthermore, the virus particle is relatively stable and amenable to purification and concentration, and as above, can be modified so as to affect the spectrum of infectivity. Additionally, introduced adenoviral DNA (and foreign DNA contained therein) is not integrated into the genome of a host cell but remains episomal, thereby avoiding potential problems that can occur as a result of insertional mutagenesis in situations where introduced DNA becomes integrated into the host genome (e.g., retroviral DNA). Moreover, the carrying capacity of the adenoviral genome for foreign DNA is large relative to other nucleic acid delivery vectors (Haj-Ahmand and Graham (1986) J. Virol. 57:267).
In particular embodiments, the adenovirus genome contains a deletion therein, so that at least one of the adenovirus gene regions does not encode a functional protein. For example, first-generation adenovirus vectors are typically deleted for the E1 genes and packaged using a cell that expresses the E1 proteins (e.g., 293 cells). The E3 region is also frequently deleted as well, as there is no need for complementation of this deletion. In addition, deletions in the E4, E2a, protein IX, and fiber protein regions have been described, e.g., by Armentano et al, (1997) J. Virology 71:2408, Gao et al., (1996) J. Virology 70:8934, Dedieu et al., (1997) J. Virology 71; 4526, Wang et al., (1997) Gene Therapy 4:393, and U.S. Pat. No. 5,882,877 to Gregory et al. (the disclosures of which are incorporated herein in their entirety). Preferably, the deletions are selected to avoid toxicity to the packaging cell. Wang et al., (1997) Gene Therapy 4:393, has described toxicity from constitutive co-expression of the E4 and E1 genes by a packaging cell line. Toxicity may be avoided by regulating expression of the E1 and/or E4 gene products by an inducible, rather than a constitutive, promoter. Combinations of deletions that avoid toxicity or other deleterious effects on the host cell can be routinely selected by those skilled in the art.
As further examples, in particular embodiments, the adenovirus is deleted in the polymerase (pol), preterminal protein (pTP), IVa2 and/or 100K regions (see, e.g., U.S. Pat. No. 6,328,958; PCT publication WO 00/12740; and PCT publication WO 02/098466; Ding et al., (2002) Mol. Ther. 5:436; Hodges et al., J. Virol. 75:5913; Ding et al., (2001) Hum Gene Ther 12:955; the disclosures of which are incorporated herein by reference in their entireties for the teachings of how to make and use deleted adenovirus vectors for nucleic acid delivery). In representative embodiments, the vector is a [E1−, E3−, pol−]Ad, [E1−, E3−, pTP−]Ad, [E1−, E3−, pol1, pTP−]Ad, [E1+, 100K−]Ad or [E1a+, E1b−, 100K]Ad.
The term “deleted” adenovirus as used herein refers to the omission of at least one nucleotide from the indicated region of the adenovirus genome. Deletions can be greater than about 1, 2, 3, 5, 10, 20, 50, 100, 200, or even 500 nucleotides. Deletions in the various regions of the adenovirus genome may be about at least 1%, 5%, 10%, 25%, 50%, 75%, 90%, 95%, 99%, or more of the indicated region. Alternately, the entire region of the adenovirus genome is deleted. Preferably, the deletion will prevent or essentially prevent the expression of a functional protein from that region. For example, it is preferred that the deletion in the 100K region results in the loss of expression of a functional 100K protein from that region. In other words, even if there is transcription across the deleted 100K region and translation of the resulting RNA transcripts, the resulting protein will be essentially non-functional, more preferably, completely non-functional. Alternatively, an insignificant amount of a functional protein is expressed. In general, larger deletions are preferred as these have the additional advantage that they will increase the carrying capacity of the deleted adenovirus for a heterologous nucleotide sequence of interest. The various regions of the adenovirus genome have been mapped and are understood by those skilled in the art (see, e.g., FIELDS et al., VIROLOGY, volume 2, chapters 67 and 68 (3d ed., Lippincott-Raven Publishers)).
Those skilled in the art will appreciate that typically, with the exception of the E3 genes, any deletions will need to be complemented in order to propagate (replicate and package) additional virus, e.g., by transcomplementation with a packaging cell.
In particular embodiments, the present invention excludes “gutted adenovirus” vectors (as that term is understood in the art, see e.g., Lieber, et al., (1996) J. Virol. 70:8944-60) in which essentially all of the adenovirus genomic sequences are deleted. In alternate embodiments, such gutted adenovirus vectors may be an aspect of the invention.
Adeno-associated viruses (AAV) have also been employed as nucleic acid delivery vectors. For a review, see Muzyczka et al. Curr. Topics in Micro. and Immunol. (1992) 158:97-129). AAV are parvoviruses and have small icoshedral virions, 18-26 nanometers in diameter and contain a single stranded DNA molecule 4-5 kilobases in size. The viruses contain either the sense or antisense strand of the DNA molecule and either strand is incorporated into the virion. Two open reading frames encode a series of Rep and Cap polypeptides. Rep polypeptides (Rep50, Rep52, Rep68 and Rep78) are involved in replication, rescue and integration of the AAV genome, although significant activity may be observed in the absence of all four Rep polypeptides. The Cap proteins (VP1, VP2, VP3) form the virion capsid. Flanking the rep and cap open reading frames at the 5′ and 3′ ends of the genome are 145 basepair inverted terminal repeats (ITRs), the first 125 basepairs of which are capable of forming Y- or T-shaped duplex structures. It has been shown that the ITRs represent the minimal cis sequences required for replication, rescue, packaging and integration of the AAV genome. Typically, in recombinant AAV vectors (rAAV), the entire rep and cap coding regions are excised and replaced with a transgene of interest.
AAV are among the few viruses that may integrate their DNA into non-dividing cells, and exhibit a high frequency of stable integration into human chromosome 19 (see, for example, Flotte et al. (1992) Am. J. Respir. Cell. Mol. Biol. 7:349-356; Samulski et al., (1989) J Virol. 63:3822-3828; and McLaughlin et al., (1989) J. Virol, 62:1963-1973). A variety of nucleic acids have been introduced into different cell types using AAV vectors (see, for example, Hermonat et al., (1984) Proc. Natl. Acad. Sci. USA 81:6466-6470; Tratschin et al., (1985) Mol. Cell. Biol. 4:2072-2081; Wondisford et al., (1988) Mol. Endocrinol. 2:32-39; Tratschin et al., (1984) J. Virol. 51:611-619; and Flotte et al., (1993) J. Biol. Chem. 268:3781-3790).
A rAAV vector genome will typically comprise the AAV terminal repeat sequences and packaging signal. An “AAV particle” or “rAAV particle” comprises an AAV vector genome or rAAV vector genome, respectively, packaged within an AAV capsid. The rAAV vector itself need not contain AAV genes encoding the capsid and Rep proteins. In particular embodiments of the invention, the rep and/or cap genes are deleted from the AAV genome. In a representative embodiment, the rAAV vector retains only the terminal AAV sequences (ITRs) necessary for integration, excision, replication.
Sources for the AAV capsid genes may include serotypes AAV-1, AAV-2, AAV-3 (including 3a and 3b), AAV-4, AAV-5, AAV-6, AAV-7, AAV-8, as well as bovine AAV and avian AAV, and any other virus classified by the International Committee on Taxonomy of Viruses (ICTV) as an AAV (see, e.g., BERNARD N. FIELDS et al., VIROLOGY, volume 2, chapter 69 (4th ed., Lippincott-Raven Publishers)).
In particular embodiments, the AAV capsid genes are derived from AAV serotypes 1, 2, 5, 6 or 8.
Because of packaging limitations, the total size of the rAAV genome will preferably be less than about 5.2, 5, 4.8, 4.6 or 4.5 kb in size.
Any suitable method known in the art may be used to produce AAV vectors (see, e.g., U.S. Pat. Nos. 5,139,941; 5,858,775; 6,146,874 for illustrative methods). In one particular method, AAV stocks may be produced by co-transfection of a rep/cap vector encoding AAV packaging functions and the template encoding the AAV vDNA into human cells infected with the helper adenovirus (Samulski et al., (1989) J. Virology 63:3822).
In other particular embodiments, the adenovirus helper virus is a hybrid helper virus that encodes AAV Rep and/or capsid proteins. Hybrid helper Ad/AAV vectors expressing AAV rep and/or cap genes and methods of producing AAV stocks using these reagents are known in the art (see, e.g., U.S. Pat. Nos. 5,589,377; and 5,871,982, 6,251,677; and 6,387,368). Preferably, the hybrid Ad of the invention expresses the AAV capsid proteins (i.e., VP1, VP2, and VP3). Alternatively, or additionally, the hybrid adenovirus may express one or more of AAV Rep proteins (i.e., Rep40, Rep52, Rep68 and/or Rep78). The AAV sequences may be operatively associated with a tissue-specific or inducible promoter.
The AAV rep and/or cap genes may alternatively be provided by a packaging cell that stably expresses the genes (see, e.g., Gao et al., (1998) Human Gene Therapy 9:2353; Inoue et al., (1998) J. Virol. 72:7024; U.S. Pat. No. 5,837,484; WO 98/27207; U.S. Pat. No. 5,658,785: WO 96/17947).
In a representative embodiment, the present invention provides a method of producing a rAAV particle comprising an isolated nucleic acid according to the invention, comprising providing to a cell: (a) a nucleic acid encoding a rAAV genome comprising (i) 5′ and/or 3′ AAV ITR sequences, (ii) an isolated nucleic acid as described above (e.g., a nucleic acid encoding GAA and comprising an abbreviated 3′ UTR or a nucleic acid encoding a chimeric lysosomal polypeptide comprising a secretory signal sequence), and (iii) an AAV packaging signal; (b) AAV rep coding sequences sufficient for replication of the recombinant AAV genome; (c) AAV cap coding sequences sufficient to produce a functional AAV capsid; wherein (a) to (c) are provided to the cell under conditions sufficient for replication and packaging of the rAAV genome into the AAV capsid, whereby AAV particles comprising the AAV capsid packaging the rAAV genome are produced in the cell. Typically, the adenovirus or HSV helper functions for AAV replication and packaging are also provided. The method may further include the step of collecting the rAAV particles.
In still further embodiments, the delivery vector is a hybrid Ad-AAV delivery vector, for example, as described in the working Examples and in U.S. Provisional Application 60/376,397 (incorporated by reference herein in its entirety for its teaching of how to make and use hybrid Ad-AAV delivery vectors). Briefly, the hybrid Ad-AAV vector comprises an adenovirus vector genome comprising adenovirus (i) 5′ and 3′ cis-elements for viral replication and encapsidation and, further, (ii) a recombinant AAV vector genome comprising the AAV 5′ and 3′ inverted terminal repeats (ITRs), an AAV packaging sequence, and a heterologous sequence(s) flanked by the AAV ITRs, where the recombinant AAV vector genome is flanked by the adenovirus 5′ and 3′ cis-elements. The adenovirus vector genome may further be deleted, as described above.
Another vector for use in the present invention comprises Herpes Simplex Virus (HSV). Herpes simplex virions have an overall diameter of 150 to 200 nm and a genome consisting of one double-stranded DNA molecule that is 120 to 200 kilobases in length. Glycoprotein D (gD) is a structural component of the HSV envelope that mediates virus entry into host cells. The initial interaction of HSV with cell surface heparin sulfate proteoglycans is mediated by another glycoprotein, glycoprotein C (gC) and/or glycoprotein B (gB). This is followed by interaction with one or more of the viral glycoproteins with cellular receptors. Recently it has been shown that glycoprotein D of HSV binds directly to Herpes virus entry mediator (HVEM) of host cells. HVEM is a member of the tumor necrosis factor receptor superfamily (Whitbeck, J. C. et al., 1997, J. Virol.; 71:6083-6093). Finally, gD, gB and the complex of gH and gL act individually or in combination to trigger pH-independent fusion of the viral envelope with the host cell plasma membrane. The virus itself is transmitted by direct contact and replicates in the skin or mucosal membranes before infecting cells of the nervous system for which HSV has particular tropism. It exhibits both a lytic and a latent function. The lytic cycle results in viral replication and cell death. The latent function allows for the virus to be maintained in the host for an extremely long period of time.
HSV can be modified for the delivery of transgenes to cells by producing a vector that exhibits only the latent function for long-term gene maintenance. HSV vectors are useful for nucleic acid delivery because they allow for a large DNA insert of up to or greater than 20 kilobases; they can be produced with extremely high titers; and they have been shown to express transgenes for a long period of time in the central nervous system as long as the lytic cycle does not occur.
In other preferred embodiments of the present invention, the delivery vector of interest is a retrovirus. Retroviruses normally bind to a species specific cell surface receptor, e.g., CD4 (for HIV); CAT (for MLV-E; ecotropic Murine leukemic virus E); RAM1/GLVR2 (for murine leukemic virus-A; MLV-A); GLVR1 (for Gibbon Ape leukemia virus (GALV) and Feline leukemia virus B (FeLV-B)). The development of specialized cell lines (termed “packaging cells”) which produce only replication-defective retroviruses has increased the utility of retroviruses for gene therapy, and defective retroviruses are characterized for use in gene transfer for gene therapy purposes (for a review, see Miller, (1990) Blood 76:271). A replication-defective retrovirus can be packaged into virions which can be used to infect a target cell through the use of a helper virus by standard techniques.
Yet another suitable vector is a poxvirus vector. These viruses are very complex, containing more than 100 proteins, although the detailed structure of the virus is presently unknown. Extracellular forms of the virus have two membranes while intracellular particles only have an inner membrane. The outer surface of the virus is made up of lipids and proteins that surround the biconcave core. Poxviruses are very complex antigenically, inducing both specific and cross-reacting antibodies after infection. Poxvirus receptors are not presently known, but it is likely that there exists more than one given the ability of poxvirus to infect a wide range of cells. Poxvirus gene expression is well studied due to the interest in using vaccinia virus as a vector for expression of transgenes.
In addition to viral transfer methods, such as those illustrated above, non-viral methods can also be employed. Many non-viral methods of gene transfer rely on normal mechanisms used by mammalian cells for the uptake and intracellular transport of macromolecules. In particular embodiments, non-viral delivery systems rely on endocytic pathways for the uptake of the nucleic acid molecule by the targeted cell. Exemplary nucleic acid delivery systems of this type include liposomal derived systems, poly-lysine conjugates, and artificial viral envelopes.
In particular embodiments, plasmid vectors are used in the practice of the present invention. Naked plasmids can be introduced into muscle cells by injection into the tissue. Expression can extend over many months, although the number of positive cells is typically low (Wolff et al., (1989) Science 247:247). Cationic lipids have been demonstrated to aid in introduction of DNA into some cells in culture (Feigner and Ringold, (1989) Nature 337:387). Injection of cationic lipid plasmid DNA complexes into the circulation of mice has been shown to result in expression of the DNA in lung (Brigham et al., (1989) Am. J. Med. Sci. 298:278). One advantage of plasmid DNA is that it may be introduced into non-replicating cells.
In a representative embodiment, a nucleic acid molecule (e.g., a plasmid) may be entrapped in a lipid particle bearing positive changes on its surface and, optionally, tagged with antibodies against cell surface antigens of the target tissue (Mizuno et al., (1992) No Shinkei Geka 20:547; PCT publication WO 91/06309; Japanese patent application 1047381; and European patent publication EP-A-43075).
Liposomes that consist of amphiphilic cationic molecules are useful non-viral vectors for nucleic acid delivery in vitro and in vivo (reviewed in Crystal, Science 270: 404-410 (1995); Blaese et al., Cancer Gene Ther. 2: 291-297 (1995); Behr et al., Bioconjugate Chem. 5: 382-389 (1994); Remy et al., Bioconjugate Chem. 5: 647-654 (1994); and Gao et al., Gene Therapy 2: 710-722 (1995)). The positively charged liposomes are believed to complex with negatively charged nucleic acids via electrostatic interactions to form lipid:nucleic acid complexes. The lipid:nucleic acid complexes have several advantages as gene transfer vectors. Unlike viral vectors, the lipid:nucleic acid complexes can be used to transfer expression cassettes of essentially unlimited size. Since the complexes lack proteins, they may evoke fewer immunogenic and inflammatory responses. Moreover, they cannot replicate or recombine to form an infectious agent and have low integration frequency. A number of publications have demonstrated that amphiphilic cationic lipids can mediate nucleic acid delivery in vivo and in vitro (Feigner et al., Proc. Natl. Acad. Sci. USA 84: 7413-17 (1987); Loeffler et al., Methods in Enzymology 217: 599-618 (1993); Feigner et al., J. Biol. Chem. 269: 2550-2561 (1994)).
Several groups have reported the use of amphiphilic cationic lipid:nucleic acid complexes for in vivo transfection both in animals and in humans (reviewed in Gao et al., Gene Therapy 2: 710-722 (1995); Zhu et al., Science 261: 209-211 (1993); and Thierry et al., Proc. Natl. Acad. Sci. USA 92: 9742-9746 (1995)). U.S. Pat. No. 6,410,049 describes a method of preparing cationic lipid:nucleic acid complexes that have prolonged shelf life.
IV. Production of Recombinant Lysosomal Polypeptides.
As indicated above, recombinant lysosomal polypeptides such as GAA can be produced in, and optionally purified from, cultured cells or organisms for a variety of purposes. Methods of delivering a recombinant nucleic acid encoding a lysosomal polypeptide for therapeutic methods are described in more detail below. The isolated nucleic acid may be carried by a delivery vector as described in the preceding section.
Those skilled in the art will appreciate that the isolated nucleic acid encoding the lysosomal polypeptide can be operably associated with appropriate expression control sequences, e.g., transcription/translation control signals, which can be included in the isolated nucleic acid or by a vector backbone. For example, specific initiation signals are generally required for efficient translation of inserted protein coding sequences. These exogenous translational control sequences, which may include the ATG initiation codon and adjacent sequences, can be of a variety of origins, both natural and synthetic.
The isolated nucleic acid can further, comprise a polyadenylation signal. (e.g., a signal for polyA polymerase to add the polyA tail to the 3′ end of the transcribed mRNA). It is common, however, that the polyadenylation signal is provided by a vector backbone into which the coding sequence is inserted (e.g., a plasmid or a recombinant viral genome) and, therefore, in particular embodiments a polyadenylation signal may not be present in the isolated nucleic acid molecule.
A variety of promoter/enhancer elements may be used depending on the level and tissue-specific expression desired. The promoter can be constitutive or inducible (e.g., the metallothionein promoter or a hormone inducible promoter), depending on the pattern of expression desired. The promoter may be native or foreign and can be a natural or a synthetic sequence. By foreign, it is intended that the transcriptional initiation region is not found in the wild-type host into which the transcriptional initiation region is introduced. The promoter is chosen so that it will function in the target cell(s) of interest. Promoters that function in liver (for example, liver parenchyma, e.g., alpha-1 antitrypsin promoter), skeletal muscle, cardiac muscle, smooth muscle, diaphragm muscle, endothelial cells, intestinal cells, pulmonary cells (e.g., smooth muscle or epithelium), peritoneal epithelial cells and fibroblasts are preferred. The promoter may further be “specific” for these cells and tissues, in that it may only show significant activity in the specific cell or tissue type.
The isolated nucleic acid can be operatively associated with a cytomegalovirus (CMV) major immediate-early promoter, an albumin promoter, an Elongation Factor 1-α (EF1-α) promoter, a PγK promoter, a MFG promoter, or a Rous sarcoma virus promoter. A hybrid promoter containing the CMV major immediate-early enhancer and chicken beta-actin (CB) promoter is also suitable. It has been speculated that driving heterologous nucleotide transcription with the CMV promoter results in down-regulation of expression in immunocompetent animals (see, e.g., Guo et al., (1996) Gene Therapy 3:802). Accordingly, it may be advantageous to operably associate the isolated nucleic acid with a modified CMV promoter that does not result in this down-regulation of transgene expression.
The isolated nucleic acids of the invention can comprise two or more coding sequences. In embodiments wherein there is more than one coding sequence, the coding sequences may be operatively associated with separate promoters or, alternatively, with a single upstream promoter and one or more downstream internal ribosome entry site (IRES) sequences (e.g., the picornavirus EMC IRES sequence).
In particular embodiments of the invention, the total size of the isolated nucleic acid is less than about 5, 4.8, 4.7, 4.6, 4.5, 4.3, 4.2, 4, 3.8, 3.7, 3.6, 3.5, 3.2, 3 or 2.8 kb or less in length. Relatively small expression cassettes can be particularly advantageous for delivery by AAV vectors.
An isolated nucleic acid of the invention can be introduced into a host cell, e.g., a cell of a primary or immortalized cell line. The recombinant cells can be used to produce the encoded polypeptide. Generally, the isolated nucleic acid is incorporated into an expression vector (viral or nonviral as described above).
Expression vectors can be designed for expression of polypeptides in prokaryotic or eukaryotic cells. For example, polypeptides can be expressed in bacterial cells such as E. coli, insect cells (e.g., in the baculovirus expression system), yeast cells or mammalian cells. Some suitable host cells are discussed further in Goeddel, Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990). Examples of vectors for expression in yeast S. cerevisiae include pYepSecl (Baldari et al., (1987) EMBO J. 6:229-234), pMFa (Kurjan and Herskowitz, (1982) Cell 30:933-943), pJRY88 (Schultz et al., (1987) Gene 54; 113-123), and pYES2 (Invitrogen Corporation, San Diego, Calif.). Baculovirus vectors available for expression of proteins in cultured insect cells (e.g., Sf 9 cells) include the pAc series (Smith et al., (1983) Mol. Cell. Biol. 3:2156-2165) and the pVL series (Lucklow, V. A., and Summers, M.d. (1989) Virology 170:31-39).
Examples of mammalian expression vectors include pCDM8 (Seed, (1987) Nature 329:840) and pMT2PC (Kaufman et al. (1987), EMBO J. 6:187-195). When used in mammalian cells, the expression vector's control functions are often provided by viral regulatory elements. For example, commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40.
In addition to the regulatory control sequences discussed above, the recombinant expression vector can contain additional nucleotide sequences. For example, the recombinant expression vector may encode a selectable marker gene to identify host cells that have incorporated the vector.
Vector DNA can be introduced into prokaryotic or eukaryotic cells via conventional technique including but not limited to calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, electroporation, microinjection and viral-mediated transfection and transduction. Suitable methods for transforming or transfecting host cells can be found in Sambrook et al. (Molecular Cloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor Laboratory press (1989)), and other laboratory manuals.
Often only a small fraction of cells (in particular, mammalian cells) integrate the foreign DNA into their genome. In order to identify and select these integrants, a nucleic acid sequence that encodes a selectable marker (e.g., resistance to antibiotics) can be introduced into the host cells along with the gene encoding the protein of interest. Preferred selectable markers include those that confer resistance to drugs, such as G418, hygromycin and methotrexate. Nucleic acids encoding a selectable marker can be introduced into a host cell on the same vector as that encoding the protein of interest or can be introduced on a separate vector. Cells stably transfected with the introduced nucleic acid can be identified by drug selection (e.g., cells that have incorporated the selectable marker gene will survive, while the other cells die).
A. Transgenic Animals.
The lysosomal polypeptide may be produced in a non-human transgenic animal (i.e., containing a nucleic acid introduced by human intervention using recombinant nucleic acid techniques). Methods for generating non-human transgenic animals are known in the art. DNA constructs can be introduced into the germ line of an avian or mammal to make a transgenic animal. For example, one or several copies of the construct can be incorporated into the genome of an embryo by standard transgenic techniques.
It is often desirable to express the transgenic polypeptide in the milk of a transgenic mammal. Mammals that produce large volumes of milk and have long lactating periods are preferred. Preferred mammals are ruminants, e.g., cows, sheep, camels or goats (including goats of Swiss origin, such as the Alpine, Saanen and Toggenburg breed goats). Other preferred mammals include oxen, rabbits and pigs.
In an exemplary embodiment, a transgenic non-human animal is produced by introducing a transgene into the germ line of the non-human animal. Transgenes can be introduced into embryonal target cells at various developmental stages. Different methods are used depending on the stage of development of the embryonal target cell. The specific line(s) of any animal used should, if possible, be selected for general good health, good embryo yields, good pronuclear visibility in the embryo, and good reproductive fitness.
Introduction of the transgene into the embryo can be accomplished by any of a variety of means known in the art such as microinjection, electroporation, lipofection or a viral vector. For example, the transgene can be introduced into a mammal by microinjection of the construct into the pronuclei of the fertilized mammalian egg(s) to cause one or more copies of the construct to be retained in the cells of the developing mammal(s). Following introduction of the transgene construct into the fertilized egg, the egg can be incubated in vitro for varying amounts of time or reimplanted into the surrogate host, or both. One common method is to incubate the embryos in vitro for about 1-7 days, depending on the species, and then reimplant them into the surrogate host.
The progeny of the transgenically manipulated embryos can be tested for the presence of the construct, e.g., by Southern blot analysis of a segment of tissue. An embryo having one or more copies of the exogenous cloned construct stably integrated into the genome can be used to establish a permanent transgenic animal line carrying the transgenic construct.
Litters of transgenically altered mammals can be assayed after birth for the incorporation of the construct into the genome of the offspring. This can be done by hybridizing a probe corresponding to the transgenic sequence to chromosomal material from the progeny. Those mammalian progeny found to contain at least one copy of the construct in their genome are grown to maturity. The female species of these progeny will produce the desired polypeptide in or along with their milk. The transgenic mammals can be bred to produce other transgenic progeny useful in producing the desired polypeptides in their milk.
Transgenic females may be tested for polypeptide secretion into milk, using any art-known assay technique, e.g., a Western blot or enzymatic assay.
Useful transcriptional promoters for expressing the polypeptide in the milk of a transgenic animal are those promoters that are preferentially activated in mammary epithelial cells, including promoters that control the genes encoding milk polypeptides such as caseins, beta-lactoglobulin (Clark et al., (1989) Bio/Technology 7:487-492), whey acid protein (Gorton et al., (1987) Bio/Technology 5: 1183-1187), and lactalbumin (Soulier et al., (1992) FEBS Lets. 297:13). The alpha-, beta-, gamma- or kappa-casein gene promoters of any mammalian species can be used to provide mammary expression; a preferred promoter is the goat beta-casein gene promoter (DiTullio, (1992) Bio/Technology 10:74-77). Other milk-specific polypeptide promoter or promoters that are specifically activated in mammary tissue can be isolated from cDNA or genomic sequences.
DNA sequence information is available for mammary gland specific genes listed above, in at least one, and often in several organisms. See, e.g., Richards et al., J Biol. Chem. 256, 526-532 (1981) (rat alpha-lactalbumin); Campbell et al., Nucleic Acids Res. 12, 8685-8697 (1984) (rat WAP); Jones et al., J. Biol. Chem. 260: 7042-7050 (1985) (rat beta-casein); Yu-Lee & Rosen, J. Biol. Chem. 258, 10794-10804 (1983) (rat gamma-casein); Hall, Biochem. J. 242, 735-742 (1987) (human alpha-lactalbumin); Stewart, Nucleic Acids Res. 12, 389 (1984) (bovine alpha S1 and kappa casein cDNAs); Gorodetsky et al., Gene 66, 87-96 (1988) (bovine beta-casein); Alexander et al., Eur. J. Biochem. 178, 395-401 (1988) (bovine kappa-casein); Brignon et al., FEBS Lett. 188, 48-55 (1977) (bovine alpha S2 casein); Jamieson et al., Gene 61, 85-90 (1987), Ivanov et al., Biol. Chem. Hoppe-Seyler 369, 425-429 (1988), Alexander et al., Nucleic Acids Res. 17, 6739 (1989) (bovine beta lactoglobulin); Vilotte et al., Biochimie 69, 609-620 (1987) (bovine alpha-lactalbumin). The structure and function of the various milk protein genes are reviewed by Mercier & Vilotte, J. Dairy Sci. 76, 3079-3098 (1993). If additional flanking sequence are useful in optimizing expression, such sequences can be cloned using the existing sequences, as probes. Mammary-gland specific regulatory sequences from different organisms can be obtained by screening libraries from such organisms using known cognate nucleotide sequences, or antibodies to cognate polypeptides, as probes.
According to this embodiment, the isolated nucleic acid may be operatively associated with a milk-specific signal sequence, e.g., from a gene which encodes a product secreted into milk. For example, signal sequences from genes coding for caseins (e.g., alpha-, beta-, gamma- or kappa-caseins). beta-lactoglobulin, whey acid protein, and lactalbumin are useful in the present invention.
The polypeptide can be expressed from an illustrative expression construct that includes a promoter specific for mammary epithelial cells, e.g., a casein promoter (for example, a goat beta-casein promoter), a milk-specific signal sequence, e.g., a casein signal sequence (for example, beta-casein signal sequence), and a sequence encoding the polypeptide.
The transgenic polypeptide can be produced in milk at relatively high concentrations and in large volumes, providing continuous high level output of normally processed polypeptide that is easily harvested from a renewable resource. There are several different methods known in the art for isolation of polypeptides from milk.
Milk polypeptides usually are isolated by a combination of processes. Raw milk first is fractionated to remove fats, for example, by skimming, centrifugation, sedimentation (H. E. Swaisgood, Developments in Dairy Chemistry, I: Chemistry of Milk Protein, Applied Science Publishers, NY, 1982), acid precipitation (U.S. Pat. No. 4,644,056) or enzymatic coagulation with rennin or chymotrypsin (Swaisgood, ibid.). Next, the major milk proteins may be fractionated into either a clear solution or a bulk precipitate from which the specific protein of interest may be readily purified.
U.S. Ser. No. 08/648,235 discloses a method for isolating a soluble milk component, such as a protein, in its biologically active form from whole milk or a milk fraction by tangential flow filtration. Unlike previous isolation methods, this eliminates the need for a first fractionation of whole milk to remove fat and casein micelles, thereby simplifying the process and avoiding losses of recovery and bioactivity. This method may be used in combination with additional purification steps to further remove contaminants and purify the component of interest.
B. Production of Transgenic Polypeptides in the Eggs of a Transgenic Avian.
Recombinant polypeptide can also be produced in the eggs of a transgenic avian, e.g., a transgenic chicken, turkey, duck, goose, ostrich, guinea fowl, peacock, partridge, pheasant, pigeon, quail using methods known in the art (Sang et al., Trends Biotechnology, 12:415-20, 1994). Genes encoding polypeptides specifically expressed in the egg, such as yolk-protein genes and albumin-protein genes, can be modified to direct expression of the lysosomal polypeptides of the invention.
Useful promoters for producing polypeptides in avian eggs are those promoters that are preferentially activated in the egg, including promoters that control the genes encoding egg polypeptides, e.g., ovalbumin, lysozyme and avidin. Promoters from the chicken ovalbumin, lysozyme or avidin genes are preferred. Egg-specific promoters or the promoters that are specifically activated in egg tissue can be from cDNA or genomic sequences.
DNA sequences of egg specific genes are known in the art (see, e.g., Burley et al., “The Avian Egg”, John Wiley and Sons, p. 472, 1989, the contents of which are incorporated herein by reference). Egg specific regulatory sequences from different organisms can be obtained by screening libraries from such organisms using known cognate nucleotide sequences, or antibodies to cognate polypeptides, as probes.
C. Transgenic Plants.
Recombinant polypeptides can be expressed in a transgenic plant in which the transgene is inserted into the nuclear or plastidic genome. Plant transformation is known as the art. See, in general, Methods in Enzymology Vol. 153 (“Recombinant DNA Part D”) 1987, Wu and Grossman Eds., Academic Press and European Patent Application EP 693 554.
Foreign nucleic acids can be introduced into plant cells or protoplasts by several methods. For example, nucleic acid can be mechanically transferred by microinjection directly into plant cells by use of micropipettes. Foreign nucleic acid can also be transferred into a plant cell by using polyethylene glycol which forms a precipitation complex with the genetic material that is taken up by the cell (Paszkowski et al. (1954) EMBO J. 3:2712-22). Foreign nucleic acid can also be introduced into a plant cell by electroporation (Fromm et al. (1985) Proc. Natl. Acad. Sci. USA 62:5824). In this technique, plant protoplasts are electroporated in the presence of plasmids or nucleic acids containing the relevant genetic construct. Electrical impulses of high field strength reversibly permeabilize biomembranes allowing the introduction of the plasmids. Electroporated plant protoplasts reform the cell wall, divide, and form a plant callus. Selection of the transformed plant cells with the transformed gene can be accomplished using phenotypic markers.
Cauliflower mosaic virus (CaMV) can be used as a vector for introducing foreign nucleic acids into plant cells (Hohn et al. (1982) “Molecular Biology of Plant Tumors,” Academic Press, New York, pp. 549-560; Howell, U.S. Pat. No. 4,407,956). CaMV viral DNA genome is inserted into a parent bacterial plasmid creating a recombinant DNA molecule which can be propagated in bacteria. The recombinant plasmid can be further modified by introduction of the desired DNA sequence. The modified viral portion of the recombinant plasmid is then excised from the parent bacterial plasmid, and used to inoculate the plant cells or plants.
High velocity ballistic penetration by small particles can be used to introduce foreign nucleic acid into plant cells. Nucleic acid is disposed within the matrix of small beads or particles, or on the surface (Klein et al. (1987) Nature 327:70-73). Although typically only a single introduction of a new nucleic acid segment is required, this method also provides for multiple introductions.
A nucleic acid can be introduced into a plant cell by infection of a plant cell, an explant, a meristem or a seed with Agrobacterium tumefaciens or Agrobacterium rhizogenes transformed with the nucleic acid. Under appropriate conditions, the transformed plant cells are grown to form shoots, roots, and develop further into plants. The nucleic acids can be introduced into plant cells, for example, by means of the Ti plasmid of Agrobacteria. The Ti plasmid is transmitted to plant cells upon infection by Agrobacteria, and is stably integrated into the plant genome (Horsch et al. (1984) “Inheritance of Functional Foreign Genes in Plants,” Science 233:496498; Fraley et al. (1983) Proc. Natl. Aced. Sci. USA 80:4803).
Plants from which protoplasts can be isolated and cultured to give whole regenerated plants can be transformed so that whole plants are recovered which contain the transferred foreign gene. Some suitable plants include, for example, species from the genera Fragaria, Lotus, Medicago, Onobrychis, Trifolium, Trigonella, Vigna, Citrus, Linum, Geranium, Manihot, Daucus, Arabidopsis, Brassica, Raphanus, Sinapis, Atropa, Capsicum, Hyoscyamus, Lycopersicon, Nicotiana, Solanum, Petunia, Digitalis, Majorana, Ciohorium, Helianthus, Lactuca, Bromus, Asparagus, Antirrhinum, Hererocallis, Nemesia, Pelargonium, Panicum, Pennisetum, Ranunculus, Senecio, Salpiglossis, Cucumis, Browaalia, Glycine, Lolium, Zea, Triticum, Sorghum, and Datura. 
Plant regeneration from cultured protoplasts is described in Evans et al. “Protoplasts Isolation and Culture,” Handbook of Plant Cell Cultures 1:124-176 (MacMillan Publishing Co. New York 1983); M. R. Davey, “Recent Developments in the Culture and Regeneration of Plant Protoplasts,” Protoplasts (1983)—Lecture Proceedings, pp. 12-29, (Birkhauser, Basal 1983); P. J. Dale, “Protoplast Culture and Plant Regeneration of Cereals and Other Recalcitrant Crops.” Protoplasts (1983)—Lecture Proceedings, pp. 31-41, (Birkhauser, Basel 1983); and H. Binding, “Regeneration of Plants,” Plant Protoplasts, pp. 21-73, (CRC Press, Boca Raton 1985).
Regeneration from protoplasts varies from species to species of plants, but generally a suspension of transformed protoplasts containing copies of the exogenous sequence is first generated. In certain species, embryo formation can then be induced from the protoplast suspension, to the stage of ripening and germination as natural embryos. The culture media can contain various amino acids and hormones, such as auxin and cytokinins. It can also be advantageous to add glutamic acid and praline to the medium especially for such species as corn and alfalfa. Shoots and roots normally develop simultaneously. Efficient regeneration will depend on the medium, on the genotype, and on the history of the culture. If these three variables are controlled, then regeneration is fully reproducible and repeatable.
In vegetatively propagated crops, the mature transgenic plants can be propagated by the taking of cuttings or by tissue culture techniques to produce multiple identical plants for trailing, such as testing for production characteristics. Selection of a desirable transgenic plant is made and new varieties are obtained thereby, and propagated vegetatively for commercial sale. In seed propagated crops, the mature transgenic plants can be self crossed to produce a homozygous inbred plant. The inbred plant produces seed containing the transgene. These seed can be grown to produce plants that have the selected phenotype. The inbreds according to this invention can be used to develop new hybrids. In this method a selected inbred line is crossed with another inbred line to produce the hybrid.
Parts obtained from a transgenic plant, such as flowers, seeds, leaves, branches, fruit, and the like are covered by the invention, provided that these pats include cells which have been so transformed. Progeny and variants, and mutants of the regenerated plants are also included within the scope of this invention, provided that these parts comprise the introduced nucleic acid sequences. Progeny and variants, and mutants of the regenerated plants are also included within the scope of this invention.
Selection of transgenic plants or plant cells can be based upon a visual assay, such as observing color changes (e.g., a white flower, variable pigment production, and uniform color pattern on flowers or irregular patterns), but can also involve biochemical assays of either enzyme activity or product quantitation. Transgenic plants or plant cells are grown into plants bearing the plant part of interest and the gene activities are monitored, such as by biochemical assays (Northern blots); Western blots, and enzyme assays. Appropriate plants are selected and further evaluated. Methods for generation of genetically engineered plants are further described in U.S. Pat. Nos. 5,283,184, 5,482,852, and European Patent Application EP 693 554, all of which are incorporated herein by reference.
V. Subjects, Pharmaceutical Formulations, Vaccine and Modes of Administration.
The present invention finds use in veterinary and medical applications. Suitable subjects include both avians and mammals, with mammals being preferred. The term “avian” as used herein includes, but is not limited to, chickens, ducks, geese, quail, turkeys and pheasants. The term “mammal” as used herein includes, but is not limited to, non-human primates, bovines, ovines, caprines, equines, felines, canines, lagomorphs, rats, mice etc. Human subjects are preferred. Human subjects include neonates, infants, juveniles, and adults. In representative embodiments, the subject is a human subject that has or is believed to have a lysosomal polypeptide (e.g., GAA) deficiency.
In particular embodiments, the present invention provides a pharmaceutical composition comprising an isolated nucleic acid or vector of the invention in a pharmaceutically-acceptable carrier and, optionally, other medicinal agents, pharmaceutical agents, carriers, adjuvants, dispersing agents, diluents, and the like. For injection, the carrier will typically be a liquid, such as sterile pyrogen-free water, pyrogen-free phosphate-buffered saline solution, bacteriostatic water, or Cremophor EL[R] (BASF, Parsippany, N.J.). For other methods of administration, the carrier may be either solid or liquid.
By “pharmaceutically acceptable” it is meant a material that is not biologically or otherwise undesirable, i.e., the material may be administered to a subject along with the isolated nucleic acid or vector without causing any undesirable biological effects such as toxicity. Thus, such a pharmaceutical composition can be used, for example, in transfection of a cell ex vivo or in administering an isolated nucleic acid or vector directly to a subject.
In the case of a viral vector, virus particles may be contacted with the cells at the appropriate multiplicity of infection according to standard transduction methods appropriate for the particular target cells. Titers of virus to administer can vary, depending upon the target cell type and the particular virus vector, and can be determined by those of skill in the an without undue experimentation. Typically, at least about 103 virus particles, at least about 105 particles, at least about 107 particles, at least about 109 particles, at least about 1011 particles, or at least about 1012 particles are administered to the cell. In exemplary embodiments, about 107 to about 1015 particles, about 107 to about 1013 particles, about 108 to about 1012 particles, about 1010 to about 1015 particles, about 1011 to about 1015 particles, about 1012 to about 1014 particles, or about 1012 to about 1013 particles are administered.
The cell to be administered the vectors of the invention can be of any type, including but not limited to neuronal cells (including cells of the peripheral and central nervous systems), retinal cells, epithelial cells (including dermal, gut, respiratory, bladder, pulmonary, peritoneal and breast tissue epithelium), muscle (including cardiac, smooth muscle, including pulmonary smooth muscle cells, skeletal muscle, and diaphragm muscle), pancreatic cells (including islet cells), hepatic cells (including parenchyma), cells of the intestine, fibroblasts (e.g., skin fibroblasts such as human skin fibroblasts), fibroblast-derived cells, endothelial cells, intestinal cells, germ cells, lung cells (including bronchial cells and alveolar cells), prostate cells, stem cells, progenitor cells, dendritic cells, and the like. Alternatively, the cell is a cancer cell (including tumor cells). Moreover, the cells can be from any species of origin, as indicated above.
Mammalian cells include but are not limited to CHO cells, 293 cells, HT1080 cells, HeLa cells or C10 cells.
In particular embodiments of the invention, the cell has been removed from a subject, the vector is introduced therein, and the cell is then replaced back into the subject. Methods of removing cells from subjects for treatment ex vivo, followed by introduction back into the subject are known in the art (see, e.g., U.S. Pat. No. 5,399,346 for the teaching of ex vivo virus vector administration). As a further alternative, the cells that are manipulated and then introduced into the subject are provided from another subject or cell line as a cell-based form of therapy.
A further aspect of the invention is a method of treating subjects in vivo with the inventive nucleic acids or delivery vectors. Administration of the nucleic acid or delivery vectors of the present invention to a human subject or an animal can be by any means known in the art. The subject can be a mammalian subject, more particularly a human subject. In other embodiments, the subject is in need of treatment, for example, has been diagnosed with or is suspected of having a lysosomal polypeptide (e.g., GAA) deficiency.
Dosages will depend upon the mode of administration, the severity of the disease or condition to be treated, the individual subject's condition, the particular vector, and the gene to be delivered, and can be determined in a routine manner (see, e.g., Remington, The Science And Practice of Pharmacy (9th Ed. 1995)). In particular embodiments, the isolated nucleic acid or vector is administered to the subject in a therapeutically effective amount, as that term is defined above.
Typically, with respect to viral vectors, at least about 103, at least about 105, at least about 107, at least about 109, at least about 1011 virus particles, or at least about 1012 virus particles are administered to the subject per treatment. Exemplary doses are virus titers of about 107 to about 1015 particles, about 107 to about 1014 particles, about 108 to about 1013 particles, about 1010 to about 1015 particles, about 1011 to about 1015 particles, about 1012 to about 1014 particles, or about 1012 to about 1013 particles.
In particular embodiments of the invention, more than one administration (e.g., two, three, four, or more administrations) may be employed to achieve therapeutic levels of nucleic acid expression.
Exemplary modes of administration include oral, rectal, transmucosal, topical, transdermal, inhalation, parenteral, e.g., intravenous, subcutaneous, intradermal, intramuscular (i.e., administration to cardiac, skeletal, diaphragm and/or smooth muscle), and intraarticular administration, and the like, as well as direct tissue (e.g., muscle) or organ injection (e.g., into the liver, into the brain for delivery to the central nervous system), alternatively, intrathecal, direct intramuscular (e.g., into cardiac, skeletal, or diaphragm muscle), intraventricular, intravenous, intraperitoneal, intranasal, or intraocular injections. Administration to the liver (discussed below) is another representative mode of administration.
Injectables can be prepared in conventional forms, either as liquid solutions or suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions. An injection medium will typically be an aqueous liquid that contains the additives usual for injection solutions, such as stabilizing agents, salts or saline, and/or buffers.
For oral administration, the isolated nucleic acid or vector can be administered in solid dosage forms, such as capsules, tablets, and powders, or in liquid dosage forms, such as elixirs, syrups, and suspensions. Active component(s) can be encapsulated in gelatin capsules together with inactive ingredients and powdered carriers, such as glucose, lactose, sucrose, mannitol, starch, cellulose or cellulose derivatives, magnesium stearate, stearic acid, sodium saccharin, talcum, magnesium carbonate and the like. Examples of additional inactive ingredients that may be added to provide desirable color, taste, stability, buffering capacity, dispersion or other known desirable features are red iron oxide, silica gel, sodium lauryl sulfate, titanium dioxide, edible white ink and the like. Similar diluents can be used to make compressed tablets. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of medication over a period of hours. Compressed tablets can be sugar coated or film coated to mask any unpleasant taste and protect the tablet from the atmosphere, or enteric-coated for selective disintegration in the gastrointestinal tract. Liquid dosage forms for oral administration can contain coloring and flavoring to increase patient acceptance.
Oral administration of AAV vectors has been described by U.S. Pat. No. 6,110,456 (incorporated by reference herein in its entirety).
The isolated nucleic acid or vector may alternatively be formulated for nasal administration or otherwise administered to the lungs of a subject by any suitable means, but is preferably administered by an aerosol suspension of respirable particles comprising the vector, which the subject inhales. The respirable particles may be liquid or solid. The term “aerosol” includes any gas-borne suspended phase, which is capable of being inhaled into the bronchioles or nasal passages. Specifically, aerosol includes a gas-borne suspension of droplets, as may be produced in a metered dose inhaler or nebulizer, or in a mist sprayer. Aerosol also includes a dry powder composition suspended in air or other carrier gas, which may be delivered by insufflation from an inhaler device, for example. See Ganderton & Jones, Drug Delivery to the Respiratory Tract, Ellis Horwood (1987); Gonda (1990) Critical Reviews in Therapeutic Drug Carrier Systems 6:273-313; and Raeburn et al. (1992) J. Pharmacol. Toxicol. Methods 27:143-159. Aerosols of liquid particles comprising the isolated nucleic acid or vector may be produced by any suitable means, such as with a pressure-driven aerosol nebulizer or an ultrasonic nebulizer, as is known to those of skill in the art. See, e.g., U.S. Pat. No. 4,501,729. Aerosols of solid particles comprising the isolated nucleic acid or vector may likewise be produced with any solid particulate medicament aerosol generator, by techniques known in the pharmaceutical art.
Alternatively, one may administer the isolated nucleic acid or vector in a local rather than systemic manner, for example, in a depot or sustained-release formulation.
In particular embodiments of the invention, the isolated nucleic acid or vector is delivered to the liver of the subject. Administration to the liver can be achieved by any method known in the art, including, but not limited to intravenous administration, intraportal administration, intrabiliary administration, intra-arterial administration, injection into the liver parenchyma, and intrasplenic injection.
Intramuscular delivery and intracardiac delivery to skeletal muscle or cardiac muscle, respectively, or direct injection into diaphragm muscle is also preferred. In other particular embodiments, intraperitoneal administration is used to deliver the isolated nucleic acid or vector to diaphragm muscle.
In particular embodiments, the isolated nucleic acid (e.g., carried by an Ad, AAV or hybrid Ad/AAV vector) encoding a lysosomal polypeptide is introduced into a depot organ or tissue (e.g., liver, skeletal muscle, lung) and the polypeptide is expressed therein and secreted into the circulatory system, where it is optionally delivered to target tissues, preferably, in a therapeutically effective amount. Intramuscular delivery to skeletal muscle or delivery to the liver are illustrative for the practice of this embodiment of the invention. Alternatively, the isolated nucleic acid or vector can be administered to the brain (e.g., to treat MPS disorders such as Sly disease), where the polypeptide can be expressed and secreted by transformed or transduced cells (e.g., neurons, glial cells) and taken up by other brain cells.
Having now described the invention, the same will be illustrated with reference to certain examples, which are included herein for illustration purposes only, and which are not intended to be limiting of the invention.
EXAMPLE 1
Materials and Methods
Cell Culture. 293 cells and C-7 cells (Amalfitano and Chamberlain. (1997) Gene Ther. 4:258-263) were maintained in Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum, 100 U penicillin per milliliter, and 100 μg streptomycin per milliliter at 37° C. in a 5% CO2-air atmosphere. C-7 cells were grown in the presence of hygromycin, 50 μg/ml. HeLa cells were maintained in minimum essential medium Eagle supplemented with 10% fetal bovine serum, 1 mM minimum essential medium sodium pyruvate, 0.1 mM minimum essential medium nonessential amino acids, 100 U penicillin per milliliter, and 100 μg streptomycin per milliliter at 37° C. in a 5% CO2-air atmosphere.
Construction of an AAV Vector Plasmid Encoding hGAA. The hGAA cDNA was subcloned with the CMV promoter from pcDNA3-hGAA (Van Hove et al., (1996), Proc. Natl. Acad. Sci. USA 93:65-70) into an AAV vector plasmid, as an NruI-EcoRV fragment, upstream of the human growth hormone intron 4 and polyadenylation sequence (Brinster et al. (1988), Proc. Natl. Acad. Sci. USA 85: 836-840). The resulting transcriptional unit was flanked by the AAV2 terminal repeat (TR) sequences in pAAV-ChGAAGH. A 530 bp deletion spanning the human growth hormone intron 4 was generated by EcoRV and partial PvuII digestion followed by blunting of ends with T4 DNA polymerase and ligation with T4 DNA ligase to generate pAAV-ChGAAG(−). The hybrid CMV enhancer/chicken β-actin (CB) promoter was amplified by polymerase chain reaction from pTriEx1 (Novagen, Madison, Wis.) with primers that introduced unique upstream XbaI and downstream KpnI restriction sites, and the CB promoter was subcloned as a KpnI-XbaI fragment to replace the CMV promoter in pAAV-ChGAAG(−), to generate pAAV-CBhGAAG(−). Next, in order to reduce the packaging size further, the plasmid pAAV-CBhGAAG(−) was linearized at a unique AflII site in the 3′ untranslated sequence of the hGAA cDNA and partially digested with NspI to introduce a 411 bp deletion in the 3′ untranslated sequence of the hGAA cDNA, followed by blunting of ends with T4 DNA polymerase and ligation with T4 DNA ligase to generate pAAV-CBGAApA. Finally, the vector sequences from pAAV-CBGAApA were isolated as a 4.4 kbp fragment from a partial BglII digest, and ligated with the calf intestinal alkaline phosphatase-dephosphorylated BglII site of pShuttle (He et al. (1998). Proc. Natl. Acad. Sci. USA 95:2509-2514).
Construction of a hybrid [E1-, polymerase-, preterminal protein-] Ad-AAV vector encoding hGAA. Kanamycin-resistant shuttle plasmids were constructed to contain within the Ad E1 region the CB promoter+hGAA cDNA+polyA transgene cassette flanked by the AAV2 TR sequences. The shuttle plasmid was digested with PmeI, and electroporated into the BJ5183 recombinogenic strain of E. Coli with the pAd[E1-, polymerase-, preterminal protein-] plasmid (Hodges et al. (2000), J. Gene Med. 2:250-259). Recombinant kanamycin-resistant clones were screened by restriction enzyme digestion (BstXI) to confirm successful generation of the full-length recombinant Ad vector genomes. These clones were digested with PacI and transfected as previously described into the E1, and E2b expressing cell line, C-7 (Hodges et al., (2000), J. Gene Med. 2:250-259). The vectors were amplified and confirmed to have the correct construction by restriction enzyme mapping of vector genomes, and subsequent functional assays in vitro and in vivo. Once isolated, the respective Ad vectors are serially propagated in increasing numbers of C-7 cells (Amalfitano et al. (1998) J. Virol. 72:926-933). Forty-eight hours after infection, infected cell pellets were harvested by low speed centrifugation, resuspended in 10 mM Tris-HCl pH 8.0, vector released from the cells by repeated freeze-thawing (×3) of the lysate, released by ultrasonification, and the vector containing supernatant subjected to two rounds of equilibrium density CsCl centrifugation (Amalfitano et al., (1998) J. Virol. 72:926-933). Two virus bands were visible. The virus bands were then removed, dialyzed extensively against 10 mM Tris-HCl pH 8.0 (or PBS), sucrose added to 1%, and aliquots stored at −80° C. The number of vector particles was quantified based on the OD250 of vector contained in dialysis buffer with sodium dodecyl sulfate (SDS) disruption, and by DNase I digestion, DNA extraction, and Southern blot analysis.
Hybrid Ad-AAV vector DNA analysis consisted of vector DNA isolation and restriction enzyme digestion followed by Southern blotting to verify the presence of intact AAV vector sequences within the lower band in the cesium chloride gradient, including restriction enzymes that demonstrated the presence of AAV terminal repeat sequences flanking the transgene (AhdI and BssHII).
All viral vector stocks were handled according to Biohazard Safety Level 2 guidelines published by the NIH.
In vivo administration of hybrid Ad-AAV or AAV vector stocks. The vector was administered intramuscularly into both gastrocnemius muscles of 3-day-old GAA-KO mice (Raben et al. (1998) J. Biol. Chem., 273:19086-19092). A total of 4×1010 DNase I-resistant Ad-AAV vector particles were administered, divided between 2 equal injections per animal. Alternatively, a total of 1011 DNase I-resistant AAV vector particles was administered intramuscularly in the right gastrocnemius muscle of 6 week-old GAA-KO/SCID mice. For liver-targeted administration, a total of 1011 DNase I-resistant AAV vector particles was administered intravenously via the retroorbital sinus or via the portal vein to 3 month-old GAA-KO/SCID or GAA-KO mice as indicated. At the respective time points post-injection, plasma or tissue samples were obtained and processed as described below. All animal procedures were done in accordance with Duke University Institutional Animal Care and Use Committee-approved guidelines.
Determination of hGAA activity and glycogen content. Tissue hGAA activity was measured following removal of the tissue from control or treated mice, flash-freezing on dry ice, homogenization and sonication in distilled water, and pelleting of insoluble membranes/proteins by centrifugation. The protein concentrations of the clarified suspensions were quantified via the Bradford assay. hGAA activity in the muscle was determined as described (Amalfitano et al. (1999) Proc. Natl. Acad. Sci. USA 96:8861-8866). Glycogen content of tissues was measured using the Aspergillus niger assay system, as described (Kikuchi et al. (1998) J. Clin. Invest. 101:827-833). A two-tailed homscedastic Student's t-test was used to determine significant differences in hGAA levels and glycogen content between GAA-KO mice with or without administration of the vector encoding hGAA.
Western blotting analysis of hGAA. For direct detection of hGAA in tissues, samples (100 μg of protein) were electrophoresed overnight in a 6% polyacrylamide gel to separate proteins, and transferred to a nylon membrane. The blots were blocked with 5% nonfat milk solution, incubated with primary and secondary antibodies and visualized via the enhanced chemiluminescence (ECL) detection system (Amersham Pharmacia, Piscataway, N.J.).
ELISA detection of plasma anti-hGAA and anti-Ad antibodies. Recombinant hGAA (5 μg) in carbonate buffer was coated onto each well of a 96-well plate at 4° C. overnight. Alternatively, the wells were coated with 5×108 Ad vector particles per well at 4° C. overnight for detection of anti-Ad antibody. After washing with phosphate buffered saline (PBS) containing 0.05% Tween 20, serial dilutions of the plasma were added to the wells, and incubated for 1 hour at room temperature. The wells were washed with 0.05% Tween 20+PBS, incubated with a 1:2,500 dilution of alkaline phosphatase-conjugated sheep anti-mouse IgG (H+L) at room temperature for 1 hour, washed, and alkaline phosphatase substrate (p-nitrophenyl phosphate) added. The absorbance values of the plates were read at 405 nm with a Bio-Rad microplate reader ELISA (all samples yielded absorbance values that were within the linear range of the assay at this dilution) (Ding et al. (2002) Mol. Ther. 5:436-446). The titer of antibody was determined as the highest dilution where the value for absorbance exceeded 0.1.
EXAMPLE 2
Neonatal Muscle-Targeted Ad-AAV Administration and hGAA Production in GAA-KO Mice
Muscle-targeted expression of hGAA with an Ad-AAV hybrid vector was evaluated in neonatal GAA-KO mice. While the Ad-AAV vector delivered muscle-targeted hGAA in these experiments, the hybrid Ad-AAV vector in question was developed to provide improved AAV vector packaging efficiency. Administration of the Ad-AAV vector in 3 day-aid mice reversed the effects of GSD II within the injected gastrocnemius muscle, and sustained hGAA expression provided long-term therapeutic results evidenced by generally reduced glycogen storage in the muscles of the hind limb.
The Ad-AAV vector encoding hGAA was targeted to both gastrocnemius muscles by intramuscular injection on day of life 3 in GAA-KO mice, and hGAA levels were analyzed at 6, 12, and 24 weeks of age. Western blot analysis of hGAA in the gastrocnemius, hamstrings and quadriceps muscle groups at 24 weeks of age showed hGAA of the  ̃110 kD, 76 kD and 67 kD isoforms following Ad-AAV vector administration, and hGAA was absent for the skeletal muscle of untreated GAA-KO mice (FIG. 1 Panel A). Apparently due to transduction of muscle adjacent to the gastrocnemius, the highest amount of hGAA was seen in the hamstrings, with slightly lower hGAA in the gastrocnemius and the lowest hGAA in the quadriceps. A similar pattern of introduced hGAA, was detected by Western Blot analysis of gastrocnemius and quadriceps muscle groups following Ad-AAV vector administration at 6 and 12 weeks of ace (not shown).
Western blot analysis of hGAA in heart, diaphragm, and liver at 6, 12, and 24 weeks of age following neonatal Ad-AAV vector administration demonstrated low, detectable levels of hGAA for the  ̃76 kD isoform of hGAA in 2 of 4 GAA-KO mice at 6 weeks (FIG. 1 Panel B; m1 and m4). Lower hGAA was present in the heart for 1 of 4 GAA-KO mice at 24 weeks (FIG. 1 Panel B) m12), and was not detected in the heart for 5 GAA-KO mice at 12 weeks of age (FIG. 1 Panel B) Finally, hGAA was not detected in plasma by Western blot at 3 weeks following vector administration (not shown).
The function of hGAA introduced by the Ad-AAV vector was analyzed by GAA enzyme assay, and GAA activity correlated with the relative amounts of hGAA protein detected by Western blot analysis (FIG. 2 Panel A). At 24 weeks, the highest GAA activity was present in hamstrings (1180+/−620 nmol/mg/hr), followed by gastrocnemius (717+/−275 nmol/mg/hr), and lowest in quadriceps (44+/−28 nmol/mg/hr). GAA activity was elevated in all muscle groups at 6, 12, and 24 weeks, compared to the same muscle groups in untreated, GAA-KO mice (FIG. 2 Panel B). The hGAA activity for hamstrings was approximately 50-fold elevated compared to the GAA activity in wild-type mouse skeletal muscle (Ding, E., et al. (2002) Mol. Ther. 5:436-446).
GAA activity was elevated in heart, diaphragm and liver at 6 weeks of age following Ad-AAV vector administration in 2 of 4 GAA-KO mice (FIG. 2 Panel B; m1 and m4). However, GAA activity in these tissues was much lower than for skeletal muscles in the hindleg closer to the site of Ad-AAV vector injection (FIG. 2 Panel B).
EXAMPLE 3
Anti-hGAA Antibodies Following Neonatal Ad-AAV Administration
Ant-hGAA antibody formation occurred during hGAA enzyme replacement in GSD II during a clinical trial (Amalfitano et al. (2001) Genet. In Med. 3:132-138) and in preclinical use of adenoviral vectors in GAA-KO mice (Ding et al. (2002) Mol. Ther. 5:436-446). Anti-hGAA antibodies were detected in GAA-KO mice at 6, 12, and 24 weeks after neonatal Ad-AAV vector administration (FIG. 3 Panel A, Neonatal intramuscular Ad-AAV), with 3 exceptions, while anti-hGAA antibodies were absent in untreated GAA-KO mice (FIG. 3 Panel A, Control). Adult GAA-KO mice that received the Ad-AAV vector intravenously were used as positive controls (FIG. 3 Panel A, Ad-AAV). These mice developed high-titer antihGAA antibodies as reported previously (Ding, E., et al. (2002) Mol. Ther. 5:436-446). The presence of hGAA antibodies at a titer of >1:4,000 was demonstrated for 10 of 13 mice following neonatal Ad-AAV vector administration (FIG. 3 Panel B, Neonatal intramuscular Ad-AAV), and for 3 of 3 adult GAA-KO mice following intravenous Ad-AAV vector administration (FIG. 3 Panel B, Ad-AAV). Only the 3 GAA-KO mice that failed to generate anti-hGAA antibodies following neonatal vector administration (m1, m4, and m12 in FIG. 3 Panel B) also featured significant hGAA by Western blot analysis in heart at 6 and 24 weeks of age (FIG. 1 Panel B). The formation of anti-hGAA antibodies appeared to be related to the persistent expression of the foreign transgene (hGAA), because GAA-KO mice failed to generate anti-Ad antibodies following neonatal, one-time exposure to the Ad-AAV vector (FIG. 3 Panel C).
EXAMPLE 4
Reduced Glycogen Content in Skeletal Muscles of the Hind Limb Following Injection of the Gastrocnemius in Neonatal GAA-KO Mice
The benefit of introduced hGAA in GSD II was shown by glycogen quantitation in skeletal muscle. Glycogen storage was reduced significantly for skeletal muscle groups at all time points except for the quadriceps at 24 weeks (FIG. 4 Panel A), when hGAA in the quadriceps was not as high as for other timepoints (FIG. 2 Panel A). Glycogen content was significantly reduced for the hamstrings, gastrocnemius, and quadriceps compared to untreated, GAA-KO mice (FIG. 4 Panel A). Glycogen content was reduced to 0.77+/−0.42 mmol glucose/gm protein in the heart of GAA-KO mice (n=4) 6 weeks after neonatal Ad-AAV vector administration, compared to 2.1+/1.3 mmol glucose/gm protein in untreated GAA-KO mice (n=3). Only 2 of 4 GAA-KO mice had detectable heart and diaphragm hGAA at 6 weeks by Western blot analysis (FIG. 1 Panel B; m1 and m4), and both the heart and diaphragm glycogen content was somewhat reduced in 1 of those mice (FIG. 4 Panel B; m4).
The correction of glycogen storage by introduced hGAA was evident by glycogen staining of gastrocnemius and heart. Periodic-acid Schiff (PAS) staining of gastrocnemius showed much less lysosomal accumulation of glycogen at 24 weeks following Ad-AAV vector administration compared to an untreated GAA-KO mouse (FIG. 5). In a GAA-KO mouse that had significant hGAA in heart at 6 weeks (FIG. 1 Panel B; m4), the glycogen accumulation in heart was less than for an untreated, GAA-KO mouse (FIG. 5). In aggregate, these data provide evidence for the continued benefit of hGAA introduced with a vector in muscle.
EXAMPLE 5
Construction of an AAV Vector Plasmid Encoding hGAA
The hGAA cDNA was subcloned with the CMV promoter from pcDNA3-hGAA (Van Hove et al. (1996). Proc. Natl. Acad. Sci. USA 93:65-70) into an AAV vector plasmid, as an NruI-EcoRV fragment, upstream of the human growth hormone intron 4 and polyadenylation sequence (Brinster et al. (1988). Proc. Natl. Acad. Sci. USA 85: 836-340). The resulting transcriptional unit was flanked by the AAV2 TR sequences in pAAV-ChGAAGH. A 530 bp deletion spanning the human growth hormone intron 4 was generated by EcoRV and partial PvuII digestion followed by blunting of ends with T4DNA polymerase and ligation with T4 DNA ligase to generate pAAV-ChGAAG(−). The hybrid CMV enhancer/chicken β-actin (CB) promoter was amplified by polymerase chain reaction from pTriEx1 (Novagen, Madison, Wis.) with primers that introduced unique upstream XbaI and downstream KpnI restriction sites, and the CB promoter was subcloned as a KpnI-XbaI fragment to replace the CMV promoter in pAAV-ChGAAG(−), to generate pAAV-CBhGAAG(−), in order to reduce the packaging size further, the plasmid pAAV-CBhGAAG(−) was linearized at a unique AflII site in the 3′ untranslated sequence of the hGAA cDNA and partially digested with NspI to introduce a 411 bp deletion in the 3′ untranslated sequence of the hGAA cDNA, followed by blunting of ends with T4 DNA polymerase and ligation with T4 DNA ligase to generate pAAV-CBGAApA. Finally, the vector sequences from pAAV-CBGAApA were isolated as a 4.4 kbp fragment from a partial BglII digest, and ligated with the calf intestinal alkaline phosphatase-dephosphorylated BglII site of pShuttle (He, T.-C., et al. (1998). Proc. Natl. Acad. Sci. USA 95:2509-2514).
EXAMPLE 6
Construction of a Hybrid [E1-, Polymerase-, Preterminal Protein-] Ad-AAV Vector Encoding hGAA
Kanamycin-resistant shuttle plasmids were constructed to contain within the Ad E1 region the CB promoter+hGAA cDNA+polyA transgene cassette flanked by the AAV2 TR sequences. The shuttle plasmid was digested with PmeI, and electroporated into the BJ5183 recombinogenic strain of E. Coli with the pAd[E1-, polymerase-, preterminal protein-] plasmid (Hodges et al., (2000). J. Gene Med. 2:250-259). Recombinant kanamycin-resistant clones were screened by restriction enzyme digestion (BstXI) to confirm successful generation of the full-length recombinant Ad vector genomes. These clones were digested with PacI and transfected as previously described into the E1, and E2b expressing cell line, C-7 (Amalfitano et al. (1998), J. Virol. 72:926-933).
The vectors were amplified and confirmed to have the correct construction by restriction enzyme mapping of vector genomes, and subsequent functional assays in vitro and in vivo. Once isolated, the respective Ad vectors are serially propagated in increasing numbers of C-7 cells (Amalfitano et al. (1993), J. Virol. 72:925-933). Forty-eight hours after infection, infected cell pellets were harvested by low speed centrifugation, resuspended in 10 mM Tris-HCl pH 8.0, vector released from the cells by repeated freeze-thawing (×3) of the lysate, released by ultrasonification, and the supernatant containing vector was subjected to two rounds of equilibrium density CsCl centrifugation (Amalfitano et al. (1998). J. Virol. 72:926-933). Two virus bands were visible. The virus bands were then removed, dialyzed extensively against 10 mm Tris-HCl pH 8.0 (or PBS), sucrose added to 1%, and aliquots stored at −80° C. The number of vector particles was quantified based on the OD260 of vector contained in dialysis buffer with sodium dodecyl sulfate [SDS] disruption, and by DNase I digestion, DNA extraction, and Southern blot analysis.
Hybrid Ad-AAV vector DNA analysis consisted of vector DNA isolation and restriction enzyme digestion followed by Southern blotting to verify the presence of intact AAV vector sequences within the lower band in the cesium chloride gradient, including restriction enzymes that demonstrated the presence of AAV terminal repeat sequences flanking the transgene (AhdI and BssHII) (Sun et al., (2003) Mol Ther 7:193-201).
EXAMPLE 7
Preparation of AAV Vectors
AAV vector stocks were prepared as described herein with modifications as described (Sun B D, Chen Y-T, Bird A, Xu F, Hou Y-X, Amalfitano A, and Koeberl D D. Packaging of an AAV vector encoding human acid α-glucosidase for gene therapy in glycogen storage disease type II with a modified hybrid adenovirus-adeno-associated virus vector. Mol Ther 7:467-477, 2003; Halbert C L, Alien J M, Miller A D. Adeno-associated virus type 6 (AAV) vectors mediate efficient transduction of airway epithelial cells in mouse lungs compared to that of AAV2 vectors. (Halbert et al., (2001) J Virol 75:6615-6624). Briefly, 293 cells were infected with the hybrid Ad-AAV vector (2000 DNase I-resistant vector particles/cell as quantitated by Southern blot analysis) containing the AAV vector sequences 15-30 minutes before transfection with an AAV packaging plasmid containing the AAV2 Rep and AAV2 or AAV6 (for AAV6 vector [Halbert et al. (2001) J. Virol. 75:6615-3624]). Cap genes were driven by heterologous promoters, which typically generate no detectable replication-competent AAV (rcAAV) (Allen et al. (2000) Mol. Ther. 1:88-95, Allen et al. (1997) J. Virol. 71:6816-6822). Cell lysate was harvested 48 hours following infection and freeze-thawed 3 times, isolated by iodixanol step gradient centrifugation before heparin affinity column purification (Zolotukhin et al. (1999) Gene Ther. 6:973-995; Halbert C L, Allen J M, Miller A D. Adeno-associated virus type 6 (AAV) vectors mediate efficient transduction of airway epithelial cells in mouse lungs compared to that of AAV2 vectors. J Virol 2001; 75:6615-6624.), and aliquots were stored at −80° C. The number of vector DNA containing-particles was determined by DNase I digestion, DNA extraction, and Southern blot analysis. Contaminating wt AAV particles were detected in recombinant AAV vector preparations by Southern blot analysis of extracted vector DNA, and by a sensitive PCR assay utilizing primers spanning the junction between the rep and cap genes. The level of rcAAV was less than 1 particle in 105 AAV vector particles. All viral vector stocks were handled according to Biohazard Safety Level 2 guidelines published by the NIH.
EXAMPLE 8
In vivo Administration of AAV Vector Stocks
AAV vector was administered intramuscularly into the gastrocnemius muscle of 6 week-old GAA-KO mice (Raben et al. (1998) J. Biol. Chem. 273:19086-19092)/SCID mice. One hundred μl containing 1×1011 DNase I-resistant AAV vector particles were injected per gastrocnemius. For portal vein injection, an AAV vector was administered via portal vein injection. At the respective time points post-injection, plasma or tissue samples were obtained and processed as described below. For intravenous administration, an AAV vector was administered via the retroorbital sinus. All animal procedures were done in accordance with Duke University Institutional Animal Care and Use Committee-approved guidelines.
EXAMPLE 9
Determination of hGAA Activity and Glycogen Content
Tissue hGAA activity was measured following removal of the tissue from control or treated mice, flash-freezing on dry ice, homogenization and sonication in distilled water, and pelleting of insoluble membranes/proteins by centrifugation. Untreated, affected controls were GAA-KO mice, 12 weeks old at the time of analysis except where noted otherwise. The protein concentrations of the clarified suspensions were quantified via the Bradford assay. hGAA activity in the muscle was determined as described (Kikuchi, T., et al. (1998) J. Clin. Invest. 101:827-833). Glycogen content of tissues was measured using the Aspergillus niger assay system, as described (Amalfitano et al. (1999) Proc. Natl. Acad. Sci. USA 968861-8866). A two-tailed homoscedastic Student's t-test was used to determine significant differences in hGAA levels and glycogen content between GAA-KO mice with or without administration of the vector encoding hGAA.
EXAMPLE 10
Western Blotting Analysis of hGAA
For direct detection of hGAA in tissues, samples (100 μg of protein) were electrophoresed overnight in a 6% polyacrylamide gel to separate proteins, and transferred to a nylon membrane. The blots were blocked with 5% nonfat milk solution, incubated with primary and secondary antibodies and visualized via the enhanced chemiluminescence (ECL) detection system (Amersham Pharmacia, Piscataway, N.J.).
EXAMPLE 11
Results with Abbreviated hGAA cDNA
High-level production of hGAA in muscle was shown with an AAV2/6 (AAV6) vector containing the shortened hGAA cDNA (FIG. 6). The hGAA level in skeletal muscle with the AAV6 vector is approximately 10-fold higher than the GAA level in normal mice. The hGAA and glycogen content was analyzed in GAA-knockout (GAA-KO)/SCID mice that were treated at 6 weeks of age, so these levels reflect the delivery of hGAA in adult animals. The analysis was done 6 weeks following intramuscular AAV6 injection, and demonstrated a trend toward long-term expression. In addition, glycogen content was significantly reduced (p<0.002), indicating a therapeutically-relevant effect from this level of hGAA, production in muscle at that time point. Furthermore, prolonged hGAA expression and complete reduction of glycogen content to normal was observed in the injected gastrocnemius muscle at 12 weeks after AAV6 vector administration (not shown).
These data indicate that intramuscular injection of AAV vector is efficacious in glycogen storage disease II.
We have further shown secretion from liver with the AAV2/6 (AAV6) and AAV2/2 (AAV2) versions of the vector containing the shortened hGAA cDNA in GAA-KO/SCID mice following portal vein injection (FIG. 7). The abbreviated GAA vector was packaged within either an AAV2 or AAV6 capsid to generate two different vector stocks. Each stock was administered to a different mouse by portal vein injection. hGAA was detected in plasma from both mice by Western blot analysis. The data further demonstrate uptake of hGAA by skeletal muscle and heart with these vectors.
These results indicate that the liver can be used as a depot organ for hGAA production, with delivery to skeletal muscle and heart that results in a reduction in glycogen stores in these tissues due to uptake of secreted GAA.
EXAMPLE 12
Intramuscular versus Intraportal Delivery of AAV Vectors in GAA-KO Mice
An AAV2 vector packaged as AAV1 (AAV2/1) corrected glycogen storage when injected intramuscularly; however, the effect was observed only in the injected muscle (Fraites et al. (2002) Mol. Ther. 5:571-578). On the other hand, when we administered an AAV vector by portal vein injection in immunodeficient GAA-KO mice (GAA-KO/SCID mice), GAA was delivered to liver and other tissues (Sun et al. (2003) Mol. Ther. 2003; 7:467-477). Therefore, we investigated the difference in benefit between intramuscular and intraportal injection of the AAV vector, since the latter approach delivered GAA to multiple target tissues including skeletal muscles, the diaphragm and the heart.
We chose to evaluate the benefit of an AAV vector encoding the shortened GAA targeted to skeletal muscle or to liver in the GAA-KO/SCID mouse model. We administered an AAV vector encoding the shortened GAA by intramuscular or portal vein injection in GAA-KO/SCID mice, and analyzed GAA activity and glycogen content in tissues. The AAV2-derived vector was packaged as AAV2 (AAV2/2) or AAV6 (AAV2/6) for portal vein injections. Based on homology between the capsid proteins of AAV6 and AAV1, it was deemed likely that AAV2/6 would transduce myofibers more efficiently than AAV2/2 (Chao et al. (2000) Mol. Ther. 2:619-623; Rabinowitz et al. (2002) J. Virol. 76:791-801; Rutledge et al. (1998) J. Virol. 72:309-319). The AAV2/6 vector was injected intramuscularly. Glycogen content and GAA activity were analyzed in tissues at 6, 12, and 24 weeks after vector injection.
Results.
Following portal vein injection of an AAV2/2 vector, secreted GAA was detectable by Western blot analysis of plasma starting at 2 weeks and persisted for 12 weeks (Data not shown). GAA activity was highly elevated in multiple tissues compared to baseline levels in untreated GAA-KO/SCID mice, and approximately 10-fold higher than wild-type levels in the liver at 12 weeks following vector administration (FIG. 10). Human GAA was detected by Western blot analysis of multiple tissues, including the target tissues of heart and diaphragm (FIG. 11). Enzyme analysis revealed that GAA activity was concordantly elevated in these tissues (FIG. 10). These results demonstrated the secretion and uptake of GAA following portal vein injection of the AAV vector, consistent with the model of the liver as a depot organ for GAA production in GAA-deficient states as established with an Ad vector.
Following intramuscular injection with the AAV2/6 vector, GAA activity in the gastrocnemius muscle exceeded normal levels by approximately 20-fold at 6, 12 and 24 weeks following vector administration (FIG. 12). In these mice the glycogen content in the injected muscle diminished to near-normal levels for up to 24 weeks following vector administration, and decreased glycogen accumulation as evidenced by decreased staining for glycogen (FIG. 13). Despite the achievement of high-level GAA production in skeletal muscle, the GAA activity in other tissues was not markedly increased (FIG. 12).
EXAMPLE 13
hGAA AAV Vectors with Altered Leader Signal Peptides
The peptide leader sequence (SEQ ID NO: 4, corresponding to amino acids 1-27, SEQ ID NO: 2) of hGAA was replaced with the synthetic peptide leader sequence SP38 (Barash et al., (2002) Biochem. Biophys. Res. Comm. 294:835-42), as well as peptide leader sequences from erythropoietin, albumin, alpha-1-antitrypsin and factor IX. The amino acid sequences of these leader peptides are shown in Table 2.







TABLE 2







Amino acid sequences for leader peptides








Leader sequence
Peptide sequence





hGAA
MGVRHPPCSHRLLAVCALVSLATAALL



(SEQ ID NO: 4)


 


SP38
MWWRLWWLLLLLLLLWPMVWA



(SEQ ID NO: 5)


 


Human
MGVHECPAWLWLLLSLLSLPLGLPVLG


erythropoietin
(SEQ ID NO: 6)


 


Human albumin
MKWVTFISLLFLFSSAYS



(SEQ ID NO: 7)


 


Human alpha-1-
MPSSVSWGILLLAGLCCLVPVSLA


antityrpsin
(SEQ ID NO: 8)


 


Human coagulation
MQRVNMIMAESPGLITCLLGYLLSAECT


factor IX
VFLDHENANKILNRPKR



(SEQ ID NO: 9)









Plasmid vectors that express hGAA in which the wild-type hGAA peptide leader sequence (SEQ ID NO: 4) is replaced with the different leader peptides listed in Table 2 were constructed using the plasmid AVCBhGAAG-delta as described briefly below. The resulting constructs encode a GAA peptide in which one of the peptides of SEQ ID NOS: 5-9 replaces the first 27 amino acids of SEQ ID NO: 1.
AVCBSP38GAAG-delta preparation strategy. A 0.37 kb PCR product from AVCBhGAAG-delta was amplified using the primers 5′-GCT GCA AAGCTT ggg cac atc cta ctc cat-3′ (SEQ ID NO: 10) and 5′-cct gca gcc cct gct ttg cag gga tgt agc-3 (SEQ ID NO: 11). The resulting PCR product comprises nucleotide sequences that code for the region of the hGAA protein immediately downstream from the native hGAA, signal peptide (nucleotides 523-796, SEQ ID NO: 1) and adds a HindIII restriction site at the signal peptide cleavage site. This PCP product was digested with HindIII and SacII and gel-purified to produce DNA fragment 1.
A second DNA fragment coding for the SP38 leader sequence, KpnI-SP38-HindIII, 5′-AGC TGC TGA GGTACC TCA GCC ACC atg tgg tgg cgc ctg tgg tgg ctg ctg ctg ctg ctg ctg ctg ctg tgg ccc atg gtg tgg gcc AAGCTT CGA TGC TAC GTC-3′, SEQ ID NO: 12, was hybridized with a reverse primer, 5′-GAC GTA GCA TCG AAG CTT-3′, SEQ ID NO: 13. The resulting hybrid was extended Klenow DNA polymerase in the presence of dNTPs to form a double-stranded DNA fragment. The resulting DNA fragment contains a KpnI site near the 5′ end followed by an optimal Kozak sequence (GCCACC) and the SP38 leader peptide coding sequence, followed with a HindIII site at the 3′ end of the SP38 sequence. This DNA was digested with KpnI and HindIII and gel-purified to produce DNA fragment II.
DNA fragments I and II described above were then ligated into AVCBhGAAG-delta plasmid DNA digested with KpnI and SacII. The resulting ligation mixture was used to transform STBL2 cells (Gibco-BRL), and transformants containing AVCBSP38GAAG-delta were selected in the presence of antibiotics and structure confirmed by gel electrophoresis. The resulting construct codes for a GAA peptide in which the hGAA leader sequence (SEQ ID NO: 4) has been replaced with the SP38 leader sequence (SEQ ID NO: 5).
AVCBSP-hEpoGAAG-delta preparation strategy. The plasmid AVCBSP-hEpoGAAG-delta was prepared in the same manner as AVCBSP38GAAG-delta, wherein fragment II was replaced with the KpnI-HindIII digestion product of the double-stranded DNA fragment with sequence 5′-AGC TGC TGA GGTACC TCA GCC ACC atgggggtg cacgaatgtc ctgcctggct gtggcttctc ctgtccctgc tgtcgctccc tctgggcctc ccagtcctgg gc AAGCTT CGA TGC TAC GTC-3 (SEQ ID NO: 14). The resulting construct codes for a GAA peptide in which the hGAA leader sequence (SEQ ID NO: 4) has been replaced with the hEPO leader sequence (SEQ ID NO: 6).
AVCBSPantitrypsinGAAG-delta preparation strategy. The plasmid AVCBSPantitrypsinGAAG-delta was prepared in the same manner as AVCBSP38GAAG-delta, using the KpnI-HindIII digestion product of the double-stranded DNA fragment with sequence 5′-C TGA GGTACC T GCC ACC-at gccgtcttct gtctcgtggg gcatcctcct gctggcaggc ctgtgctgcc tggtccctgt ctccctggct-AAGCTT CGA T-3′ (SEQ ID NO: 15) in lieu of fragment II. The resulting construct codes for a GAA peptide in which the hGAA leader sequence (SEQ ID NO: 4) has been replaced with the human alpha-1-antityrpsin leader sequence (SEQ ID NO: 7).
AVCBSPALBGAAG-delta preparation strategy. AVCBSPALBGAAG-delta was prepared in the same manner as AVCBSP38GAAG-delta, using the KpnI-HindIII digestion product of the double-stranded DNA fragment with sequence 5′-C TGA GGTACC T GCC ACC-a tgaagtgggt aacctttatt tcccttcttt ttctctttag ctcgacttat tcc-AAGCTT CGA T-3′ (SEQ ID NO: 16) in lieu of fragment II. The resulting construct codes for a GAA peptide in which the hGAA leader sequence (SEQ ID NO: 4) has been replaced with the human albumin leader sequence (SEQ ID NO: 8).
AVCBSPFIXGAAG-delta preparation strategy. Lastly, AVCBSPFIXGAAG-delta was prepared in the same manner as AVCBSP38GAAG-delta, using the KpnI-HindIII digestion product of the double-stranded DNA fragment with sequence 5′-C TGA GGTACC T GCC ACC atgcagcgcg tgaacatgat catggca-3′ (SEQ ID NO: 17) in lieu of fragment II. The resulting construct codes for a GAA peptide in which the hGAA leader sequence (SEQ ID NO: 4) has been replaced with the human factor IX leader sequence (SEQ ID NO: 9).
The resulting plasmids were used to examine the effect of different leader sequences on the localization of hGAA in cells transfected with these plasmids.
EXAMPLE 14
Relative Secretion of hGAA with Altered Leader Sequences in 293 Cells
293 cells were transfected with AAV vector plasmids described in Example 13 and were collected 40 hours post-transfection. Total hGAA activity was assayed both in the cells and in the medium. These results are depicted in FIG. 14 and the relative hGAA secretion is summarized in Table 3.







TABLE 3







hGAA secretion with different leader sequences











Proportion hGAA




Leader
secreted (hGAA
% Total hGAA
Increased hGAA


sequence
medium/hGAA cells)
secreted
secretion (fold)













HGAA
0.53
34
N/A


SP38.1
9.7
91
18


Epo
1.1
53
2.1


α-1-
8.5
90
16


antitrypsin


Factor IX
14
93
26









Western blot analysis of cellular and secreted hGAA in 293 cells transfected with the AAV vector plasmids described in Example 13 demonstrated normal migration, consistent with unaltered glycosylation and processing of chimeric hGAA linked to alternative signal peptides (FIG. 15). This data supported the normal glycosylation of hGAA, despite the increased secretion and presumably shortened residence in the Golgi (Wisselaar et al., (1993) J. Biol. Chem. 268 (3): 2223-31). For further evidence of the normal glycosylation of hGAA produced with these constructs, we injected mice with the AAV2/8 vector encoding the chimeric α-1-antitrypsin signal peptide linked to the hGAA cDNA (minus the 27 amino acid GAA signal peptide), and hGAA was detected corresponding to the  ̃110 kD hGAA precursor (FIG. 16). The hGAA level was lower for female mice (lanes 5-7 and 11-13), as expected given lower transduction with AAV2/8 vectors in female mice. Significantly, hGAA secretion was higher for the vector containing the chimeric α-1-antitrypsin signal peptide (lanes 2-7), than for the vector containing the hGAA signal peptide (lanes 8-13).
Tissue GAA activity was increased in tissues for the 3 male GAA-KO/SCID mice that received the AAV vector encoding the alpha-1-antitrypsin signal peptide linked to hGAA (corresponding to lanes 2-5 in FIG. 16). Significantly, liver GAA activity remained at near normal levels, despite increased GAA activity in tissues compared to controls (FIG. 17). These results were obtained at only 2 weeks following vector administration, as opposed to the later 6-week time point used in the other experiments, and indicated early uptake of secreted GAA in the target tissues of heart, diaphragm, and at lower levels, skeletal muscle. GAA uptake in target tissues is expected to increase after the 2-week time point, based on previous results. Finally, a Western blot of the target tissues showed appropriate processing of hGAA to  ̃76 kD and  ̃67 kD (data not shown). These data support the hypothesis that chimeric hGAA linked to alternative signal peptides will be appropriately secreted, processed and targeted to lysosomes in target tissues, despite the maintenance of normal GAA levels in liver. This novel development will reduce any potential toxicity for overexpression of hGAA in the depot organ, the liver, in contrast to all previous approaches to liver-targeted gene therapy in Pompe disease that produced extreme supra-physiological levels of GAA in the liver
EXAMPLE 15
Expression of hGAA with a Liver-specific Promoter in Immunocompetent GAA-KO Mice
An AAV2/8 vector encoding hGAA driven by a liver-specific promoter (Wang L et al., (1999) Proc Nat Acad Sci USA 96:3906-10) was administered intravenously in GAA-KO mice. Contrary to previous experiments, where hGAA, was eliminated in plasma by anti-GAA antibodies in immunocompetent GAA-KO mice, hGAA persisted in plasma as detected by Western blot analysis (FIG. 18). Therefore, the limitation of GAA expression to the liver eliminated the antibody response and allowed persistent GAA secretion with implications for gene therapy in Pompe disease.
The foregoing is illustrative of the present invention, and is not to be construed as limiting thereof. The invention is defined by the following claims, with equivalents of the claims to be included therein.

## Claims

1. An adeno-associated virus (AAV) vector comprising a nucleic acid encoding a chimeric polypeptide comprising a secretory signal sequence of α1-antitrypsin having the sequence of SEQ ID NO:8 operably linked to a lysosomal acid α-glucosidase (GAA) polypeptide, wherein said secretory signal sequence replaces the first 27 amino acids of SEQ ID NO:2 of the native lysosomal GAA polypeptide.

2. The vector of claim 1 wherein said nucleic acid is operatively linked to a transcriptional control element operable in liver cells.

3. A pharmaceutical formulation comprising the vector of claim 1 in a pharmaceutically acceptable carrier.

4. An isolated cell comprising the vector of claim 1.

5. An in-vitro method of delivering a nucleic acid encoding a lysosomal GAA polypeptide to a cell, comprising contacting a cell in-vitro with the vector according to claim 1 under conditions sufficient for the vector to be introduced into the cell and for the nucleic acid to be expressed to produce the chimeric polypeptide comprising the secretory signal sequence of α1-antitrypsin having the sequence of SEQ ID NO:8 operably linked to the lysosomal GAA polypeptide wherein said secretory signal sequence replaces the first 27 amino acids of SEQ ID NO:2 of the native lysosomal GAA polypeptide.

6. A method of producing a lysosomal a-glucosidase (GAA) polypeptide in a cultured cell, comprising:
contacting a cultured cell with the vector according to claim 1 under conditions sufficient for the vector to be introduced into the cultured cell and for the nucleic acid to be expressed to produce the chimeric polypeptide comprising the secretory signal sequence of α1-antitrypsin having the sequence of SEQ ID NO:8 operably linked to the GAA polypeptide wherein said secretory signal sequence replaces the first 27 amino acids of SEQ ID NO:2 of the native lysosomal GAA polypeptide and the GAA polypeptide is secreted from the cultured, and collecting the GAA polypeptide secreted onto the cell culture medium.

7. A pharmaceutical formulation comprising the vector of claim 2 in a pharmaceutically acceptable carrier.

8. An isolated cell comprising the vector of claim 2.

9. An in-vitro method of delivering a nucleic acid encoding a lysosomal GAA polypeptide to a cell, comprising contacting a cell in-vitro with the vector according to claim 2 under conditions sufficient for the vector to be introduced into the cell and for the nucleic acid to be expressed to produce the chimeric polypeptide comprising the secretory signal sequence of α1-antitrypsin having the sequence of SEQ ID NO:8 operably linked to the lysosomal GAA polypeptide wherein said secretory signal sequence replaces the first 27 amino acids of SEQ ID NO:2 of the native lysosomal GAA polypeptide.

10. A method of producing a lysosomal α-glucosidase (GAA) polypeptide in a cultured cell, comprising: contacting a cultured cell with the vector according to claim 2 under conditions sufficient for the vector to be introduced into the cultured cell and for the nucleic acid to be expressed to produce the chimeric polypeptide comprising the secretory signal sequence of α1-antitrypsin having the sequence of SEQ ID NO:8 operably linked to the GAA polypeptide wherein said secretory signal sequence replaces the first 27 amino acids of SEQ ID NO:2 of the native lysosomal GAA polypeptide and the GAA polypeptide is secreted from the cultured, and collecting the GAA polypeptide secreted onto the cell culture medium.

11. The vector of claim 1 wherein GAA secretion is increased relative to the native lysosomal GAA polypeptide of SEQ ID NO:2.