# Patent

## Title
AAV vectors for gene delivery to the lung

## Abstract

Methods of making and using recombinant AAV vectors and virions for gene delivery to the lung are described. The recombinant AAV virions are derived from caprine AAV and bovine AAV, both of which display tropism for lung tissue.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit under 35 U.S.C. § 119(e) of provisional applications 60/576,506 filed Jun. 3, 2004 and 60/582,037 filed Jun. 21, 2004, which applications are hereby incorporated by reference in their entireties.


TECHNICAL FIELD
The present invention relates generally to compositions and methods for delivering genes to cells using recombinant adeno-associated virus (rAAV) virions. In particular, the present invention pertains to rAAV virions with tropism for lung tissue.
BACKGROUND
A number of lung disorders are genetically based. For example, cystic fibrosis (CF) is one of the most common, life-threatening, autosomal recessive diseases. Approximately 1 in 2,500 live births is affected by this genetic disorder. Patients with CF usually die at an early age due to lung infection. The disease is caused by a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
Similarly, alpha-1-antitrypsin deficiency is the second most common monogenic lung disease in humans, accounting for approximately 3% of all early deaths due to obstructive pulmonary disease such as pulmonary emphysema. The most common type of alpha-1-antitrypsin deficiency, termed protease inhibitor type Z (PiZ), is transmitted as an autosomal recessive trait and affects approximately 1 in 1700 live births in most Northern European and North American populations. The PiZ mutation is a single nucleotide substitution that results in a single amino acid substitution (glutamate 342 to lysine). The replacement of glutamate 342 with a lysine apparently prevents normal folding of the protein.
At present, treatment options for individuals with CF, as well as for patients with pathologies associated with alpha-1-antitrypsin deficiency, are limited. Accordingly, it would be desirable to develop gene therapy techniques to deliver genes to the lungs of subjects suffering from these and other lung disorders.
Gene transfer techniques have been developed in order to introduce DNA into a patient's cells in several ways. There are transfection methods, including chemical methods such as calcium phosphate precipitation and liposome-mediated transfection, and physical methods such as electroporation. In general, transfection methods are not suitable for in vivo gene delivery. There are also methods that use recombinant viruses. Current viral-mediated gene delivery vectors include those based on retrovirus, adenovirus, herpes virus, pox virus, and adeno-associated virus (AAV). Like the retroviruses, and unlike adenovirus, AAV has the ability to integrate its genome into a host cell chromosome.
AAV is a parvovirus belonging to the genus Dependovirus, and has several attractive features not found in other viruses. For example, AAV can infect a wide range of host cells, including non-dividing cells. AAV can also infect cells from different species. Importantly, AAV has not been associated with any human or animal disease, and does not appear to alter the physiological properties of the host cell upon integration. Furthermore, AAV is stable at a wide range of physical and chemical conditions, which lends itself to production, storage, and transportation requirements.
The AAV genome, a linear, single-stranded DNA molecule containing approximately 4700 nucleotides (the AAV-2 genome consists of 4681 nucleotides), generally comprises an internal non-repeating segment flanked on each end by inverted terminal repeats (ITRs). The ITRs are approximately 145 nucleotides in length (AAV-1 has ITRs of 143 nucleotides) and have multiple functions, including serving as origins of replication, and as packaging signals for the viral genome.
The internal non-repeated portion of the genome includes two large open reading frames (ORFs), known as the AAV replication (rep) and capsid (cap) regions. These ORFs encode replication and capsid gene products, respectively: replication and capsid gene products (i.e., proteins) allow for the replication, assembly, and packaging of a complete AAV virion. More specifically, a family of at least four viral proteins are expressed from the AAV rep region: Rep 78, Rep 68, Rep 52, and Rep 40, all of which are named for their apparent molecular weights. The AAV cap region encodes at least three proteins: VP1, VP2, and VP3.
In nature, AAV is a helper virus-dependent virus, i.e., it requires co-infection with a helper virus (e.g., adenovirus, herpesvirus, or vaccinia virus) in order to form functionally complete AAV virions. In the absence of co-infection with a helper virus, AAV establishes a latent state in which the viral genome inserts into a host cell chromosome or exists in an episomal form, but infectious virions are not produced. Subsequent infection by a helper virus “rescues” the integrated genome, allowing it to be replicated and packaged into viral capsids, thereby reconstituting the infectious virion. While AAV can infect cells from different species, the helper virus must be of the same species as the host cell. Thus, for example, human AAV will replicate in canine cells that have been co-infected with a canine adenovirus.
To construct infectious recombinant AAV (rAAV) containing a nucleic acid, a suitable host cell line is transfected with an AAV vector containing a nucleic acid. AAV helper functions and accessory functions are then expressed in the host cell. Once these factors come together, the HNA is replicated and packaged as though it were a wild-type (wt) AAV genome, forming a recombinant virion. When a patient's cells are infected with the resulting rAAV, the HNA enters and is expressed in the patient's cells. Because the patient's cells lack the rep and cap genes, as well as the adenovirus accessory function genes, the rAAV are replication defective; that is, they cannot further replicate and package their genomes. Similarly, without a source of rep and cap genes, wtAAV cannot be formed in the patient's cells.
There are several AAV serotypes that infect humans as well as other primates and mammals. Eight major serotypes have been identified, AAV-1 through AAV-8, including two serotypes recently isolated from rhesus monkeys. Gao et al. (2002) Proc. Natl. Acad. Sci. USA 99:11854-11859. Of those serotypes, AAV-2 is the best characterized, having been used to successfully deliver transgenes to several cell lines, tissue types, and organs in a variety of in vitro and in vivo assays. The various serotypes of AAV can be distinguished from one another using monoclonal antibodies or by employing nucleotide sequence analysis; e.g., AAV-1, AAV-2, AAV-3, and AAV-6 are 82% identical at the nucleotide level, while AAV-4 is 75 to 78% identical to the other serotypes (Russell et al. (1998) J. Virol. 72:309-319). Significant nucleotide sequence variation is noted for regions of the AAV genome that code for capsid proteins. Such variable regions may be responsible for differences in serological reactivity to the capsid proteins of the various AAV serotypes.
It would be desirable to develop AAV-based vectors with tropism to lung tissue in order to effectively treat lung disorders.
SUMMARY OF THE INVENTION
The present invention is based on the discovery of novel AAV variants with tropism to lung tissue. The AAV variants are derived from a caprine source and from a bovine source. The rAAV virions made using caprine and bovine AAV sequences are able to efficiently transduce lung cells and tissues and are especially useful for delivering heterologous nucleic acid molecules (HNAs) to subjects with lung disorders. Moreover, the caprine and bovine AAV sequences display significantly decreased immunoreactivity relative to rAAV virions typically used in gene therapy studies. Thus, subjects that have been previously exposed to AAV, either by natural infection or due to previous gene therapy or nucleic acid immunization treatments, and have therefore developed anti-AAV antibodies, can still benefit from the use of the caprine and bovine rAAV virions of the invention. Moreover, the caprine and bovine rAAV virions described herein are readily administered and display efficient transduction using a vascular route of administration. Thus delivery can be achieved by simple intravenous administration rather than via the airway, which is often highly damaged in serious lung disorders.
The rAAV virions described herein are therefore useful for treating or preventing a wide variety of lung disorders in vertebrate subjects in need of such treatment, whether or not the subject has been previously exposed to any of the various AAV serotypes.
In one aspect, the present invention provides methods and AAV vectors for the efficient delivery of HNAs, such as a gene of interest, to the lung cells or tissue of a vertebrate subject, such as a human, to provide a therapeutic effect. In certain preferred embodiments, rAAV virions are derived from caprine AAV In other rAAV virions are derived from bovine AAV. In some embodiments the rAAV virions comprise an HNA encoding antisense RNA, ribozymes, or one or more genes of interest that express proteins. The rAAV virions can be used to deliver these HNAs to the lung, wherein expression of said antisense RNA, ribozymes, or genes in lung cells or tissue provides for a biological effect in a mammalian subject.
Thus, in one aspect, the invention is directed to a method for delivering HNAs to the lung of a vertebrate subject using an rAAV virion. In one embodiment, the method comprises (a) providing a caprine rAAV virion, wherein the virion comprises a heterologous nucleic acid molecule encoding a therapeutic protein operably linked to control elements capable of directing the in vivo transcription and translation of said protein; and (b) delivering the recombinant AAV virion to the vertebrate subject, whereby the protein is expressed in the lung at a level that provides a therapeutic effect. In another embodiment, a bovine rAAV virion is used instead of the caprine rAAV in the method of the previous sentence.
In another embodiment, the rAAV virions containing an HNA are injected directly into a muscle (e.g., cardiac, smooth and/or skeletal muscle). In another embodiment the rAAV virions containing an HNA are administered into the vasculature via injection into veins, arteries, or other vascular conduits, or by using techniques such as isolated limb perfusion.
In an additional embodiment, the virions contain a gene encoding CFTR, the gene deficient or missing in cystic fibrosis patients, that when expressed at a sufficient concentration provides for a therapeutic effect, such as amelioration or reduction of symptoms caused by cystic fibrosis.
In another embodiment the virions contain a gene encoding alpha-1-antitrypsin that when expressed at a sufficient concentration provides for a therapeutic effect, such as amelioration or reduction of symptoms caused by alpha-1-antitrypsin deficiency (e.g. emphysema).
In another embodiment, the virions contain a gene encoding an enzyme capable of removing toxic metabolites that tend to accumulate in diseased lung tissue (e.g. such as superoxide dismutase (SOD) and catalase) that when expressed at a sufficient concentration, provides for a therapeutic effect, such as amelioration or reduction of the toxic metabolites.
In yet a further embodiment, the virions contain a gene encoding an anti-tumor agent or a tumor suppressor that when expressed at a sufficient concentration provides for a therapeutic effect, such as a reduction in tumor size and/or growth. Such agents include immunomodulators, such as any of the various cytokines including interleukin-1, interleukin-2, interleukin-3, interleukin-4, and gamma-interferon; p53; the retinoblastoma (rb) gene product; antisense oncogenes, e.g., anti-c-myc and anti-k-ras; and other growth control-related genes for cancer gene therapy.
In additional embodiments, the virions contain a gene encoding an agent useful for treating primary pulmonary hypertension, pulmonary vascular disease secondarily associated with chronic airways obstruction, and connective tissue diseases.
In further embodiments, the invention is directed to a recombinant AAV virion comprising any of the HNAs described above.
In yet further embodiments, the invention is directed to a method of delivering an HNA to a lung cell or tissue of a vertebrate subject using a recombinant caprine or bovine AAV virion. The method comprises:
(a) providing a recombinant caprine or bovine AAV virion as above, wherein the virion comprises an HNA encoding a protein;
(b) administering the recombinant AAV virion to the subject, whereby the protein is expressed at a level in lung cells or tissue that provides a therapeutic effect.
In certain embodiments, the recombinant AAV virion is delivered by intramuscular injection, or into the bloodstream (e.g. intravenously or intraarterially).
These and other embodiments of the subject invention will readily occur to those of skill in the art in view of the disclosure herein.



BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows the positions of capsid proteins VP1, VP2 and VP3, numbered relative to AAV-2. As shown in the figure, VP1, VP2 and VP3 share the same 533 C-terminal amino acids, which make up VP3.
FIGS. 2A-2B show a comparison of the nucleotide sequence encoding the AAV VP1 protein from a primate AAV-5 (SEQ ID NO: 1) and a caprine AAV (SEQ ID NO:3). Numbering is relative to the AAV-5 full-length sequence.
FIG. 3 shows a comparison of the amino acid sequence of VP 1 from a primate AAV-5 (SEQ ID NO:2) and a caprine AAV (SEQ ID NO:4). Amino acid differences are shaded. Conservative changes are shown in light grey; non-conservative changes are shown in dark grey.
FIG. 4 shows the biodistribution of human factor IX (hFIX) follow intravenous administration of a recombinant caprine AAV vector encoding the same.
FIG. 5 shows a comparison of the amino acid sequence of the capsid proteins (VP1) of bovine AAV disclosed herein (SEQ ID NO:5) and a previously reported bovine AAV (Schmidt at al. (2004) J. Virol. 78:6509-16) (SEQ ID NO:6), referred to herein as “Schmidt bovine AAV.” Amino acid differences are shown, and the dots in the alignment represent identical amino acids. Accessibility and Surface Feature designations are provided based on the AAV-2 crystal structure, in which B refers to amino acids buried between inside and outside surface; O refers to amino acids on outside surface; P refers to amino acids in a plateau; and S refers to amino acids in a spike
FIGS. 6A and 6B show the transduction of muscle in SCID mice by bovine AAV, AAV-8 and AAV-1. Male mice were injected intramuscularly with 2×1011 vector genomes of bovine rAAV hFIX9 (♦) in FIG. 6A, and AAV-1 (▴) and AAV-8 (▪) in FIG. 6B. Human factor IX concentration was measured by ELISA. Each data point corresponds to the mean of five animals. The human factor IX concentration in the control animals was considered as a blank, and was subtracted from human factor IX levels in the experimental animals.
FIG. 7 shows factor IX expression after systemic delivery of bovine AAV and AAV-8 derived factor IX vectors in SCID mice. Male SCID mice were injected via the tail vein with 5×1011 vector genomes of bovine rAAV hFIX9 (♦) or rAAV-8 hFIX9 (▪) (n=5). Retro-orbital blood was collected 1, 2, 4 (n=5) and 8 weeks (n=3) after vector injection. Human factor IX was measured by ELISA.
FIG. 8 shows the biodistribution of bovine rAAV hFIX9 after intravenous administration. Human factor IX DNA was quantitated in eight mouse tissues collected 12 weeks after intravenous administration of the recombinant bovine AAV vector. For each vector, tissues from two animals were analyzed and the results for each animal are presented. Bovine AAV hFIX9 (bars with black and white squares and bars with horizontal stripes) AAV-8 hFIX9 (bars in solid black and solid white).



DETAILED DESCRIPTION OF THE INVENTION
The practice of the present invention will employ, unless otherwise indicated, conventional methods of chemistry, biochemistry, recombinant DNA techniques and immunology, within the skill of the art. Such techniques are explained fully in the literature. See, e.g., Fundamental Virology, 2nd Edition, vol. I & II (B. N. Fields and D. M. Knipe, eds.); Handbook of Experimental Immunology, Vols. I-IV (D. M. Weir and C. C. Blackwell eds., Blackwell Scientific Publications); T. E. Creighton, Proteins: Structures and Molecular Properties (W. H. Freeman and Company, 1993); A. L. Lehninger, Biochemistry (Worth Publishers, Inc., current addition); Sambrook, et al., Molecular Cloning: A Laboratory Manual (2nd Edition, 1989); Methods In Enzymology (S. Colowick and N. Kaplan eds., Academic Press, Inc.).
All publications, patents and patent applications cited herein are hereby incorporated by reference in their entireties.
1. Definitions
In describing the present invention, the following terms will be employed, and are intended to be defined as indicated below.
It must be noted that, as used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a polypeptide” includes a mixture of two or more polypeptides, and the like.
The following amino acid abbreviations are used throughout the text:
















Alanine: Ala (A)
Arginine: Arg (R)



Asparagine: Asn (N)
Aspartic acid: Asp (D)



Cysteine: Cys (C)
Glutamine: Gin (Q)



Glutamic acid: Glu (E)
Glycine: Gly (G)



Histidine: His (H)
Isoleucine: Ile (I)



Leucine: Leu (L)
Lysine: Lys (K)



Methionine: Met (M)
Phenylalanine: Phe (F)



Proline: Pro (P)
Serine: Ser (S)



Threonine: Thr (T)
Tryptophan: Trp (W)



Tyrosine: Tyr (Y)
Valine: Val (V)










By “vector” is meant any genetic element, such as a plasmid, phage, transposon, cosmid, chromosome, virus, virion, etc., which is capable of replication when associated with the proper control elements and which can transfer gene sequences between cells. Thus, the term includes cloning and expression vehicles, as well as viral vectors.
By an “AAV vector” is meant a vector derived from any adeno-associated virus serotype isolated from any animal species, including without limitation, AAV-1, AAV-2, AAV-3, AAV-4, AAV-5, AAV-6, AAV-7, AAV-8 and caprine AAV (AAV-G1) as described herein. AAV vectors can have one or more of the AAV wild-type genes deleted in whole or part, preferably the rep and/or cap genes, but retain functional flanking ITR sequences. Functional ITR sequences are necessary for the rescue, replication and packaging of the AAV virion. Thus, an AAV vector is defined herein to include at least those sequences required in cis for replication and packaging (e.g., functional ITRs) of the virus. The ITRs need not be the wild-type nucleotide sequences, and may be altered, e.g., by the insertion, deletion or substitution of nucleotides, so long as the sequences provide for functional rescue, replication and packaging.
“AAV helper functions” refer to AAV-derived coding sequences which can be expressed to provide AAV gene products that, in turn, function in trans for productive AAV replication. Thus, AAV helper functions include both of the major AAV open reading frames (ORFs), rep and cap. The Rep expression products have been shown to possess many functions, including, among others: recognition, binding and nicking of the AAV origin of DNA replication; DNA helicase activity; and modulation of transcription from AAV (or other heterologous) promoters. The Cap expression products supply necessary packaging functions. AAV helper functions are used herein to complement AAV functions in trans that are missing from AAV vectors.
The term “AAV helper construct” refers generally to a nucleic acid molecule that includes nucleotide sequences providing AAV functions deleted from an AAV vector which is to be used to produce a transducing vector for delivery of a nucleotide sequence of interest. AAV helper constructs are commonly used to provide transient expression of AAV rep and/or cap genes to complement missing AAV functions that are necessary for lytic AAV replication; however, helper constructs lack AAV ITRs and can neither replicate nor package themselves. AAV helper constructs can be in the form of a plasmid, phage, transposon, cosmid, virus, or virion. A number of AAV helper constructs and vectors that encode Rep and/or Cap expression products have been described. See, e.g., U.S. Pat. Nos. 6,001,650, 5,139,941 and 6,376,237, all incorporated herein by reference in their entireties; Samulski et al. (1989) J. Virol. 63:3822-3828; and McCarty et al. (1991) J. Virol. 65:2936-2945. Particularly useful herein are AAV helper constructs including a caprine cap gene, such as a caprine VP1 protein, or a bovine cap gene, such as a bovine VP1 protein.
The term “accessory functions” refers to non-AAV derived viral and/or cellular functions upon which AAV is dependent for its replication. Thus, the term captures proteins and RNAs that are required in AAV replication, including those moieties involved in activation of AAV gene transcription, stage specific AAV MRNA splicing, AAV DNA replication, synthesis of Cap expression products and AAV capsid assembly. Viral-based accessory functions can be derived from any of the known helper viruses such as adenovirus, herpesvirus (other than herpes simplex virus type-1) and vaccinia virus.
The term “accessory function vector” refers generally to a nucleic acid molecule that includes nucleotide sequences providing accessory functions. An accessory function vector can be transfected into a suitable host cell, wherein the vector is then capable of supporting AAV virion production in the host cell. Expressly excluded from the term are infectious viral particles as they exist in nature, such as adenovirus, herpesvirus or vaccinia virus particles. Thus, accessory function vectors can be in the form of a plasmid, phage, transposon or cosmid.
It has been demonstrated that the full-complement of adenovirus genes are not required for accessory helper functions. In particular, adenovirus mutants incapable of DNA replication and late gene synthesis have been shown to be permissive for AAV replication. Ito et al., (1970) J. Gen. Virol. 9:243; Ishibashi et al, (1971) Virology 45:317. Similarly, mutants within the E2B and E3 regions have been shown to support AAV replication, indicating that the E2B and E3 regions are probably not involved in providing accessory functions. Carter et al., (1983) Virology 126:505. However, adenoviruses defective in the E1 region, or having a deleted E4 region, are unable to support AAV replication. Thus, E1A and E4 regions are likely required for AAV replication, either directly or indirectly. Laughlin et al., (1982) J. Virol. 41:868; Janik et al., (1981) Proc. Natl. Acad. Sci. USA 78:1925; Carter et al., (1983) Virology 126:505. Other characterized Ad mutants include: E1B (Laughlin et al. (1982), supra; Janik et al. (1981), supra; Ostrove et al., (1980) Virology 104:502); E2A (Handa et al., (1975) J. Gen. Virol. 29:239; Strauss et al., (1976) J. Virol. 17:140; Myers et al., (1980) J. Virol. 35:665; Jay et al., (1981) Proc. Natl. Acad. Sci. USA 78:2927; Myers et al., (1981) J. Biol. Chem. 256:567); E2B (Carter, Adeno-Associated Virus Helper Functions, in I CRC Handbook of Parvoviruses (P. Tijssen ed., 1990)); E3 (Carter et al. (1983), supra); and E4 (Carter et al.(1983), supra; Carter (1995)). Although studies of the accessory functions provided by adenoviruses having mutations in the E1B coding region have produced conflicting results, Sarnulski et al., (1988) J. Virol. 62:206-210, recently reported that E1B55k is required for AAV virion production, while E1B19k is not. In addition, International Publication WO 97/17458 and Matshushita et al., (1998) Gene Therapy 5:938-945, describe accessory function vectors encoding various Ad genes. Particularly preferred accessory function vectors comprise an adenovirus VA RNA coding region, an adenovirus E4 ORF6 coding region, an adenovirus E2A 72 kD coding region, an adenovirus E1A coding region, and an adenovirus E1B region lacking an intact E1B55k coding region. Such vectors are described in International Publication No. WO 01/83797.
By “recombinant virus” is meant a virus that has been genetically altered, e.g., by the addition or insertion of a heterologous nucleic acid construct into the particle.
By “AAV virion” is meant a complete virus particle, such as a wild-type (wt) AAV virus particle (comprising a linear, single-stranded AAV nucleic acid genome associated with an AAV capsid protein coat). In this regard, single-stranded AAV nucleic acid molecules of either complementary sense, e.g., “sense” or “antisense” strands, can be packaged into any one AAV virion and both strands are equally infectious.
A “recombinant AAV virion,” or “rAAV virion” is defined herein as an infectious, replication-defective virus including an AAV protein shell, encapsidating a heterologous nucleotide sequence of interest that is flanked on both sides by AAV ITRs. A rAAV virion is produced in a suitable host cell that has had an AAV vector, AAV helper functions and accessory functions introduced therein. In this manner, the host cell is rendered capable of encoding AAV polypeptides that are required for packaging the AAV vector (containing a recombinant nucleotide sequence of interest) into infectious recombinant virion particles for subsequent gene delivery.
A “caprine recombinant AAV virion” or “caprine rAAV virion” is a rAAV virion as described above that has been produced using AAV helper functions that include a gene encoding a caprine capsid protein, such as caprine VP1.
A “bovine recombinant AAV virion” or “bovine rAAV virion” is a rAAV virion as described above that has been produced using AAV helper functions that include a gene encoding a bovine capsid protein, such as bovine VP1.
The term “transfection” is used to refer to the uptake of foreign DNA by a cell, and a cell has been “transfected” when exogenous DNA has been introduced inside the cell membrane. A number of transfection techniques are generally known in the art. See, e.g., Graham et al. (1973) Virology, 52 :456, Sambrook et al. (1989) Molecular Cloning, a laboratory manual, Cold Spring Harbor Laboratories, New York, Davis et al. (1986) Basic Methods in Molecular Biology, Elsevier, and Chu et al. (1981) Gene 13:197. Such techniques can be used to introduce one or more exogenous DNA moieties, such as a nucleotide integration vector and other nucleic acid molecules, into suitable host cells.
The term “host cell” denotes, for example, microorganisms, yeast cells, insect cells, and mammalian cells, that can be, or have been, used as recipients of an AAV helper construct, an AAV vector plasmid, an accessory function vector, or other transfer DNA. The term includes the progeny of the original cell which has been transfected. Thus, a “host cell” as used herein generally refers to a cell which has been transfected with an exogenous DNA sequence. It is understood that the progeny of a single parental cell may not necessarily be completely identical in morphology or in genomic or total DNA complement as the original parent, due to natural, accidental, or deliberate mutation.
As used herein, the term “cell line” refers to a population of cells capable of continuous or prolonged growth and division in vitro. Often, cell lines are clonal populations derived from a single progenitor cell. It is further known in the art that spontaneous or induced changes can occur in karyotype during storage or transfer of such clonal populations. Therefore, cells derived from the cell line referred to may not be precisely identical to the ancestral cells or cultures, and the cell line referred to includes such variants.
“Homology” refers to the percent identity between two polynucleotide or two polypeptide moieties. Two DNA, or two polypeptide sequences are “substantially homologous” to each other when the sequences exhibit at least about 50%, preferably at least about 75%, more preferably at least about 80%-85%, preferably at least about 90%, and most preferably at least about 95%-98% sequence identity over a defined length of the molecules. As used herein, substantially homologous also refers to sequences showing complete identity to the specified DNA or polypeptide sequence.
In general, “identity” refers to an exact nucleotide-to-nucleotide or amino acid-to-amino acid correspondence of two polynucleotides or polypeptide sequences, respectively. Percent identity can be determined by a direct comparison of the sequence information between two molecules by aligning the sequences, counting the exact number of matches between the two aligned sequences, dividing by the length of the shorter sequence, and multiplying the result by 100. Readily available computer programs can be used to aid in the analysis, such as ALIGN, Dayhoff, M. O. in Atlas of Protein Sequence and Structure M. O. Dayhoff ed., 5 Suppl. 3:353-358, National Biomedical Research Foundation, Washington, D.C., which adapts the local homology algorithm of Smith and Waterman Advances in Appl. Math. 2:482-489, 1981 for peptide analysis. Programs for determining nucleotide sequence identity are available in the Wisconsin Sequence Analysis Package, Version 8 (available from Genetics Computer Group, Madison, Wis.) for example, the BESTFIT, FASTA and GAP programs, which also rely on the Smith and Waterman algorithm. These programs are readily utilized with the default parameters recommended by the manufacturer and described in the Wisconsin Sequence Analysis Package referred to above. For example, percent identity of a particular nucleotide sequence to a reference sequence can be determined using the homology algorithm of Smith and Waterman with a default scoring table and a gap penalty of six nucleotide positions.
Another method of establishing percent identity in the context of the present invention is to use the MPSRCH package of programs copyrighted by the University of Edinburgh, developed by John F. Collins and Shane S. Sturrok, and distributed by IntelliGenetics, Inc. (Mountain View, Calif.). From this suite of packages the Smith-Waterman algorithm can be employed where default parameters are used for the scoring table (for example, gap open penalty of 12, gap extension penalty of one, and a gap of six). From the data generated the “Match” value reflects “sequence identity.” Other suitable programs for calculating the percent identity or similarity between sequences are generally known in the art, for example, another alignment program is BLAST, used with default parameters. For example, BLASTN and BLASTP can be used using the following default parameters: genetic code=standard; filter=none; strand=both; cutoff=60; expect=10; Matrix=BLOSUM62; Descriptions=50 sequences; sort by=HIGH SCORE; Databases=non-redundant, GenBank+EMBL+DDBJ+PDB+GenBank CDS translations+Swiss protein+Spupdate+PIR. Details of these programs are well known in the art.
Alternatively, homology can be determined by hybridization of polynucleotides under conditions that form stable duplexes between homologous regions, followed by digestion with single-stranded-specific nuclease(s), and size determination of the digested fragments. DNA sequences that are substantially homologous can be identified in a Southern hybridization experiment under, for example, stringent conditions, as defined for that particular system. Defining appropriate hybridization conditions is within the skill of the art. See, e.g., Sambrook et al., supra; DNA Cloning, supra; Nucleic Acid Hybridization, supra.
By the term “degenerate variant” is intended a polynucleotide containing changes in the nucleic acid sequence thereof, that encodes a polypeptide having the same amino acid sequence as the polypeptide encoded by the polynucleotide from which the degenerate variant is derived.
A “coding sequence” or a sequence that “encodes” a selected polypeptide, is a nucleic acid molecule that is transcribed (in the case of DNA) and translated (in the case of mRNA) into a polypeptide in vivo when placed under the control of appropriate regulatory sequences. The boundaries of the coding sequence are determined by a start codon at the 5′ (amino) terminus and a translation stop codon at the 3′ (carboxy) terminus. A transcription termination sequence may be located 3′ to the coding sequence.
The term “heterologous” as it relates to nucleic acid sequences such as coding sequences and control sequences, denotes sequences that are not normally joined together, and/or are not normally associated with a particular cell. Thus, a “heterologous” region of a nucleic acid construct or a vector is a segment of nucleic acid within or attached to another nucleic acid molecule that is not found in association with the other molecule in nature. For example, a heterologous region of a nucleic acid construct could include a coding sequence flanked by sequences not found in association with the coding sequence in nature. Another example of a heterologous coding sequence is a construct where the coding sequence itself is not found in nature (e.g., synthetic sequences having codons different from the native gene). Similarly, a cell transformed with a construct that is not normally present in the cell would be considered heterologous for purposes of this invention. Allelic variation or naturally occurring mutational events do not give rise to heterologous DNA, as used herein.
A “nucleic acid” sequence refers to a DNA or RNA sequence. The term captures sequences that include any of the known base analogues of DNA and RNA such as, but not limited to 4-acetylcytosine, 8-hydroxy-N6-methyladenosine, aziridinylcytosine, pseudoisocytosine, 5-(carboxyhydroxyl-methyl) uracil, 5-fluorouracil, 5-bromouracil, 5-carboxymethylaminomethyl-2-thiouracil, 5-carboxymethyl-aminomethyluracil, dihydrouracil, inosine, N6-isopentenyladenine, 1-methyladenine, 1-methylpseudo-uracil, 1-methylguanine, 1-methylinosine, 2,2-dimethyl-guanine, 2-methyladenine, 2-methylguanine, 3-methyl-cytosine, 5-methylcytosine, N6-methyladenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxy-amino-methyl-2-thiouracil, beta-D-mannosylqueosine, 5′-methoxycarbonylmethyluracil, 5-methoxyuracil, 2-methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid, oxybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, -uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid, pseudouracil, queosine, 2-thiocytosine, and 2,6-diaminopurine.
The term DNA “control sequences” refers collectively to promoter sequences, polyadenylation signals, transcription termination sequences, upstream regulatory domains, origins of replication, internal ribosome entry sites (“IRES”), enhancers, and the like, which collectively provide for the replication, transcription and translation of a coding sequence in a recipient cell. Not all of these control sequences need always be present so long as the selected coding sequence is capable of being replicated, transcribed and translated in an appropriate host cell.
The term “promoter” is used herein in its ordinary sense to refer to a nucleotide region comprising a DNA regulatory sequence, wherein the regulatory sequence is derived from a gene that is capable of binding RNA polymerase and initiating transcription of a downstream (3′-direction) coding sequence. Transcription promoters can include “inducible promoters” (where expression of a polynucleotide sequence operably linked to the promoter is induced by an analyte, cofactor, regulatory protein, etc.), “repressible promoters” (where expression of a polynucleotide sequence operably linked to the promoter is induced by an analyte, cofactor, regulatory protein, etc.), and “constitutive promoters”.
“Operably linked” refers to an arrangement of elements wherein the components so described are configured so as to perform their usual function. Thus, control sequences operably linked to a coding sequence are capable of effecting the expression of the coding sequence. The control sequences need not be contiguous with the coding sequence, so long as they function to direct the expression thereof. Thus, for example, intervening untranslated yet transcribed sequences can be present between a promoter sequence and the coding sequence and the promoter sequence can still be considered “operably linked” to the coding sequence.
By “isolated” when referring to a nucleotide sequence, is meant that the indicated molecule is present in the substantial absence of other biological macromolecules of the same type. Thus, an “isolated nucleic acid molecule which encodes a particular polypeptide” refers to a nucleic acid molecule which is substantially free of other nucleic acid molecules that do not encode the subject polypeptide; however, the molecule may include some additional bases or moieties which do not deleteriously affect the basic characteristics of the composition.
For the purpose of describing the relative position of nucleotide sequences in a particular nucleic acid molecule throughout the instant application, such as when a particular nucleotide sequence is described as being situated “upstream,” “downstream,” “5 prime (5′)” or “3 prime (3′)” relative to another sequence, it is to be understood that it is the position of the sequences in the “sense” or “coding” strand of a DNA molecule that is being referred to as is conventional in the art.
A “functional homologue,” or a “functional equivalent” of a given AAV polypeptide includes molecules derived from the native polypeptide sequence, as well as recombinantly produced or chemically synthesized polypeptides which function in a manner similar to the reference AAV molecule to achieve a desired result. Thus, a functional homologue of AAV Rep68 or Rep78 encompasses derivatives and analogues of those polypeptides—including any single or multiple amino acid additions, substitutions and/or deletions occurring internally or at the amino or carboxy termini thereof—so long as integration activity remains.
By “capable of efficient transduction” is meant that the mutated constructs of the invention provide for rAAV vectors or virions that retain the ability to transfect cells in vitro and/or in vivo at a level that is within 1-10% of the transfection efficiency obtained using the corresponding wild-type sequence. Preferably, the mutant retains the ability to transfect cells or tissues at a level that is within 10-100% of the corresponding wild-type sequence. The mutated sequence may even provide for a construct with enhanced ability to transfect cells and tissues. Transduction efficiency is readily determined using techniques well known in the art, including the in vitro transduction assay described in the Examples.
The terms “subject”, “individual” or “patient” are used interchangeably herein and refer to a vertebrate, preferably a mammal. Mammals include, but are not limited to, murines, rodents, simians, humans, farm animals, sport animals and pets.
The terms “effective amount” or “therapeutically effective amount” of a composition or agent, as provided herein, refer to a nontoxic but sufficient amount of the composition or agent to provide the desired response. The exact amount required will vary from subject to subject, depending on the species, age, and general condition of the subject, the severity of the condition being treated, and the particular macromolecule of interest, mode of administration, and the like. An appropriate “effective” amount in any individual case may be determined by one of ordinary skill in the art using routine experimentation.
“Treating” or “treatment” of a disease includes: (1) preventing the disease, i.e. causing the clinical symptoms of the disease not to develop in a subject that may be exposed to or predisposed to the disease but does not yet experience or display symptoms of the disease, (2) inhibiting the disease, i.e., arresting the development of the disease or its clinical symptoms, or (3) relieving the disease, i.e., causing regression of the disease or its clinical symptoms.
2. Modes of Carrying out the Invention
Before describing the present invention in detail, it is to be understood that this invention is not limited to particular formulations or process parameters as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only, and is not intended to be limiting.
Although a number of methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
Central to the present invention is the discovery of novel caprine and bovine AAV sequences useful in the production of rAAV virions that display remarkable lung tropism. Thus, AAV vectors and virions derived from these caprine and bovine AAV sequences are useful for targeting gene delivery to lung cells and tissue. Delivery of genes to the pulmonary vascular endothelium is a rational approach for therapy of pulmonary vascular diseases including, but not limited to, primary pulmonary hypertension, pulmonary vascular disease secondarily associated with chronic airways obstruction, connective tissue diseases, HIV infection, and emphysema. Furthermore, in view of the exposure of this vascular bed to the entire cardiac output, delivery to the lungs is useful to achieve systhemic delivery of secreted factors. Aside from vascular disease per se, the pulmonary bed is frequently the site of metastatic spread of malignancy, and once this occurs conventional therapy options are most often inadequate.
Thus, the vectors and virions find use in the treatment of a wide variety of lung disorders, including without limitation, cystic fibrosis (CF), alpha-1-antitrypsin gene deficiencies, lung cancer, lung deterioration caused by degenerative lung diseases, and pulmonary vascular disease.
For example, it is known that CF is caused by a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Thus rAAV virions containing a gene encoding CFTR can be administered to patients suffering from CF to provide for a therapeutic effect, such as amelioration or reduction of symptoms caused by cystic fibrosis.
Similarly, a common type of alpha-1-antitrypsin deficiency, termed protease inhibitor type Z (PiZ), is caused by a single nucleotide substitution that results in a single amino acid substitution (glutamate 342 to lysine). The replacement of glutamate 342 with a lysine apparently prevents normal folding of the protein. Thus, rAAV virions containing a gene encoding the wild-type alpha-1-antitrypsin can be administered to patients suffering from alpha-1-antitrypsin to provide for a therapeutic effect, such as amelioration or reduction of symptoms caused by alpha-1-antitrypsin deficiency, such as emphysema.
Additionally, the rAAV vectors and virions of the present invention can also be used to deliver genes to patients with degenerative diseases of the lung, e.g., genes encoding enzymes capable of removing toxic metabolites which tend to accumulate in diseased lung tissue, such as superoxide dismutase (SOD) and catalase.
The caprine and bovine AAV vectors and virions of the present invention are also useful for treating cancers of the lung. For example, the caprine and bovine AAV vectors and virions can be used to deliver a gene encoding an anti-tumor agent or a tumor suppressor, that when expressed at a sufficient concentration, provides for a therapeutic effect, such as a reduction in tumor size and/or growth. Such agents include immunomodulators, such as any of the various cytokines including interleukin- 1, interleukin-2, interleukin-3, interleukin-4, and gamma-interferon; p53; the retinoblastoma (rb) gene; antisense oncogenes, e.g., anti-c-myc and anti-k-ras; and other growth control-related genes for cancer gene therapy.
Moreover, because the pulmonary vasculature bed is exposed to the entire cardiac output, delivery of a gene of interest to the lungs is useful to achieve systhemic delivery of a large number of secreted factors, including but not limited to, one or more peptides, polypeptides, or proteins that are useful for the treatment or prevention of disease states in a mammalian subject. Such DNA and associated disease states include, but are not limited to: DNA encoding glucose-6-phosphatase, associated with glycogen storage deficiency type 1A; DNA encoding phosphoenolpyruvate-carboxykinase, associated with Pepck deficiency; DNA encoding galactose-1 phosphate uridyl transferase, associated with galactosemia; DNA encoding phenylalanine hydroxylase, associated with phenylketonuria; DNA encoding branched chain alpha-ketoacid dehydrogenase, associated with Maple syrup urine disease; DNA encoding fumarylacetoacetate hydrolase, associated with tyrosinemia type 1; DNA encoding methylmalonyl-CoA mutase, associated with methylmalonic acidemia; DNA encoding medium chain acyl CoA dehydrogenase, associated with medium chain acetyl CoA deficiency; DNA encoding omithine transcarbamylase, associated with omithine transcarbamylase deficiency; DNA encoding argininosuccinic acid synthetase, associated with citrullinemia; DNA encoding low density lipoprotein receptor protein, associated with familial hypercholesterolemia; DNA encoding UDP-glucouronosyltransferase, associated with Crigler-Najjar disease; DNA encoding adenosine deaminase, associated with severe combined immunodeficiency disease; DNA encoding hypoxanthine guanine phosphoribosyl transferase, associated with Gout and Lesch-Nyan syndrome; DNA encoding biotinidase, associated with biotinidase deficiency; DNA encoding beta-glucocerebrosidase, associated with Gaucher disease; DNA encoding beta-glucuronidase, associated with Sly syndrome; DNA encoding peroxisome membrane protein 70 kDa, associated with Zellweger syndrome; DNA encoding porphobilinogen deaminase, associated with acute intermittent porphyria; DNA encoding erythropoietin for treatment of anemia due to thalassemia or to renal failure; DNA encoding vascular endothelial growth factor, DNA encoding angiopoietin-1, and DNA encoding fibroblast growth factor for the treatment of ischemic diseases; DNA encoding thrombomodulin and tissue factor pathway inhibitor for the treatment of occluded blood vessels as seen in, for example, atherosclerosis, thrombosis, or embolisms; DNA encoding aromatic amino acid decarboxylase (AADC), and DNA encoding tyrosine hydroxylase (TH) for the treatment of Parkinson's disease; DNA encoding the beta adrenergic receptor, DNA encoding anti-sense to, or DNA encoding a mutant form of, phospholamban, DNA encoding the sarco(endo)plasmic reticulum adenosine triphosphatase-2 (SERCA2), and DNA encoding the cardiac adenylyl cyclase for the treatment of congestive heart failure; DNA encoding a tumor suppressor gene such as p53 for the treatment of various cancers, including lung cancer; DNA encoding a cytokine such as one of the various interleukins for the treatment of inflammatory and immune disorders and cancers; DNA encoding dystrophin or minidystrophin and DNA encoding utrophin or miniutrophin for the treatment of muscular dystrophies; and, DNA encoding insulin for the treatment of diabetes.
The invention also provides caprine and bovine rAAV virions comprising a gene or genes coding for blood coagulation proteins, which proteins may be delivered, using the methods of the present invention, to the lung of a mammal having hemophilia for the treatment of hemophilia. Thus, the invention includes: delivery of the Factor IX gene to a mammal for treatment of hemophilia B, delivery of the Factor VIII gene to a mammal for treatment of hemophilia A, delivery of the Factor VII gene for treatment of Factor VII deficiency, delivery of the Factor X gene for treatment of Factor X deficiency, delivery of the Factor XI gene for treatment of Factor XI deficiency, delivery of the Factor XIII gene for treatment of Factor XIII deficiency, and, delivery of the Protein C gene for treatment of Protein C deficiency. Delivery of each of the above-recited genes to the cells of a mammal is accomplished by first generating a caprine and bovine rAAV virion comprising the gene and then administering the rAAV virion to the mammal. Thus, the invention includes rAAV virions comprising genes encoding any one of Factor IX, Factor VIII, Factor X, Factor VII, Factor XI, Factor XIII or Protein C.
Generally, caprine rAAV virions will include at least a caprine AAV capsid protein, and the bovine rAAV virions will include at least a bovine AAV capsid protein. Thus, by “caprine rAAV virion” is meant an rAAV virion that includes at least one caprine capsid protein, and by “bovine rAAV virion” is meant an rAAV virion that includes at least one bovine capsid protein. As explained above, the AAV cap region encodes at least three proteins: VP1, VP2, and VP3. FIG. 1 shows the overlapping structure of this region from AAV-2 which is similar to the caprine structure (see further below). Preferably, the rAAV virions include at least the caprine VP3 region, but can include the entire VP2 or VP1 region. The caprine AAV VP1 sequence is highly homologous to the VP1 sequence of AAV-5, but is approximately 100 times more resistant to neutralization by existing AAV antibodies than the native AAV-5 sequence.
More particularly, a 2805 bp PCR fragment of the caprine AAV described herein, encoding 603 bp of rep, the central intron, and all of cap, shows 94% homology to the corresponding AAV-5 sequence. The DNA and protein homologies for the partial rep are 98% and 99%, respectively. A comparison of the caprine VP1 coding sequence with a primate AAV-5 VP1 coding sequence is shown in FIGS. 2A-2B. The DNA for the cap region of the caprine AAV is 93% homologous to that of AAV-5. The amino acid sequences for the caprine VP1 versus a primate AAV-5 is shown in FIG. 3. The caprine sequence encodes a VP1 protein of 726 amino acids, while AAV-5 VP1 is 724 amino acids in length. Additionally, the sequences display 94% sequence identity and 96% sequence similarity. There are 43 amino acid differences between the caprine and the primate AAV-5 VP1 sequence. With respect to the linear amino acid sequence of VP1, the distribution of the amino acid differences between AAV-5 and caprine AAV is highly polar. All of the amino acid differences occur exclusively in the C-terminal hypervariable region of VP1 in a scattered fashion. This region relative to AAV-5 and caprine includes approximately 348 amino acids from amino acid 386 to the C-terminus, numbered relative to AAV-5 VP1.
Moreover, rAAV virions including such caprine sequences show substantial tropism to lung tissue. Thus, the present invention involves the production and use of caprine AAV sequences for incorporation into rAAV virions. Such rAAV virions can be used to deliver a “heterologous nucleic acid” (an “HNA”) to the lung tissue of a vertebrate subject, such as a mammal. As explained above, a “recombinant AAV virion” or “rAAV virion” is an infectious virus composed of an AAV protein shell (i.e., a capsid), derived from caprine AAV, encapsulating a “recombinant AAV (rAAV) vector,” the rAAV vector comprising the HNA and one or more AAV inverted terminal repeats (ITRs). AAV vectors can be constructed using recombinant techniques that are known in the art and include one or more HNAs flanked by functional ITRs. The ITRs of the rAAV vector need not be the wild-type nucleotide sequences, and may be altered, e.g., by the insertion, deletion, or substitution of nucleotides, so long as the sequences provide for proper function, i.e., rescue, replication, and packaging of the AAV genome.
Recombinant AAV virions may be produced using a variety of techniques known in the art, including the triple transfection method (described in detail in U.S. Pat. No. 6,001,650, the entirety of which is incorporated herein by reference). This system involves the use of three vectors for rAAV virion production, including an AAV helper function vector, an accessory function vector, and a rAAV vector that contains the HNA. One of skill in the art will appreciate, however, that the nucleic acid sequences encoded by these vectors can be provided on two or more vectors in various combinations. As used herein, the term “vector” includes any genetic element, such as a plasmid, phage, transposon, cosmid, chromosome, artificial chromosome, virus, virion, etc., that is capable of replication when associated with the proper control elements and that can transfer gene sequences between cells. Thus, the term includes cloning and expression vehicles, as well as viral vectors.
The AAV helper function vector encodes the “AAV helper function” sequences (i.e., rep and cap), which function in trans for productive AAV replication and encapsidation. Preferably, the AAV helper function vector supports efficient AAV vector production without generating any detectable wild-type AAV virions (i.e., AAV virions containing functional rep and cap genes). Examples of vectors suitable for use with the present invention include pHLP19, described in U.S. Pat. No. 6,001,650 and pRep6cap6 vector, described in U.S. Pat. No. 6,156,303, the disclosure of which is hereby incorporated by reference in its entirety.
The accessory function vector encodes nucleotide sequences for non-AAV derived viral and/or cellular functions upon which AAV is dependent for replication (i.e., “accessory functions”). The accessory functions include those functions required for AAV replication, including, without limitation, those moieties involved in activation of AAV gene transcription, stage specific AAV mRNA splicing, AAV DNA replication, synthesis of cap expression products, and AAV capsid assembly. Viral-based accessory functions can be derived from any of the known helper viruses such as adenovirus, herpesvirus (other than herpes simplex virus type-1), and vaccinia virus. In a preferred embodiment, the accessory function plasmid pladeno5 is used (details regarding pLadeno5 are described in U.S. Pat. No. 6,004,797, the disclosure of which is hereby incorporated by reference in its entirety). This plasmid provides a complete set of adenovirus accessory functions for AAV vector production, but lacks the components necessary to form replication-competent adenovirus.
The rAAV vector containing the heterologous nucleic acid (HNA) may be constructed using ITRs from any of the various AAV serotypes. The HNA comprises nucleic acid sequences joined together that are otherwise not found together in nature, this concept defining the term “heterologous.” To illustrate the point, an example of an HNA is a gene flanked by nucleotide sequences not found in association with that gene in nature. Another example of an HNA is a gene that itself is not found in nature (e.g., synthetic sequences having codons different from the native gene). Allelic variation or naturally occurring mutational events do not give rise to HNAs, as used herein. An HNA can comprise an anti-sense RNA molecule, a ribozyme, or a gene encoding a polypeptide.
The HNA is operably linked to a heterologous promoter (constitutive, cell-specific, or inducible) such that the HNA is capable of being expressed in the patient's target cells (here lung) under appropriate or desirable conditions. Numerous examples of constitutive, cell-specific, and inducible promoters are known in the art, and one of skill could readily select a promoter for a specific intended use, e.g., the selection of the constitutive CMV promoter for strong levels of continuous or near-continuous expression, or the selection of the inducible ecdysone promoter for induced expression. Induced expression allows the skilled artisan to control the amount of protein that is synthesized. In this manner, it is possible to vary the concentration of therapeutic product. Other examples of well known inducible promoters are: steroid promoters (e.g., estrogen and androgen promoters) and metallothionein promoters.
As explained above, in one embodiment, the invention relates to novel AAV virions including caprine and bovine capsids and comprising HNAs coding for one or more anti-sense RNA molecules, the rAAV virions preferably administered to one or more muscle cells or tissue of a mammal. Antisense RNA molecules suitable for use with the present invention in cancer anti-sense therapy or treatment of viral diseases have been described in the art. See, e.g., Han et al., (1991) Proc. Natl. Acad. Sci. USA 88:4313-4317; Uhlmann et al., (1990) Chem. Rev. 90:543-584; Helene et al., (1990) Biochim. Biophys. Acta. 1049:99-125; Agarawal et al., (1988) Proc. Natl. Acad. Sci. USA 85:7079-7083; and Heikkila et al., (1987) Nature 328:445-449. The invention also encompasses the delivery of ribozymes using the methods disclosed herein. For a discussion of suitable ribozymes, see, e.g., Cech et al., (1992) J. Biol. Chem. 267:17479-17482 and U.S. Pat. No. 5,225,347.
Preferably, the rAAV virions comprise HNAs coding for one or more polypeptides for treating a lung disorder. The rAAV virions are preferably administered to one or more cells or tissue of a mammal, and display tropism for lung. Thus, the invention embraces the delivery of HNAs encoding one or more peptides, polypeptides, or proteins, that are useful for the treatment or prevention of lung disease states in a mammalian subject. Such DNA and associated disease states are described above.
Delivery of the recombinant virions containing one or more HNAs to a mammalian subject may be by intramuscular injection or by administration into the bloodstream of the mammalian subject. Administration into the bloodstream may be by injection into a vein, an artery, or any other vascular conduit. The recombinant caprine and bovine virions of the invention may also be introduced into the bloodstream by way of isolated limb perfusion, a technique well known in the surgical arts, the method essentially enabling the artisan to isolate a limb from the systemic circulation prior to administration of the rAAV virions. A variant of the isolated limb perfusion technique, described in U.S. Pat. No. 6,177,403 and herein incorporated by reference, can also be employed by the skilled artisan to administer the virions into the vasculature of an isolated limb to potentially enhance transduction into lung cells or tissue.
The dose of rAAV virions required to achieve a particular “therapeutic effect,” e.g., the units of dose in vector genomes/per kilogram of body weight (vg/kg), will vary based on several factors including, but not limited to: the route of rAAV virion administration, the level of gene (or anti-sense RNA or ribozyme) expression required to achieve a therapeutic effect, the specific disease or disorder being treated, a host immune response to the rAAV virion, a host immune response to the gene (or anti-sense RNA or ribozyme) expression product, and the stability of the gene (or anti-sense RNA or ribozyme) product. One of skill in the art can readily determine a rAAV virion dose range to treat a patient having a particular disease or disorder based on the aforementioned factors, as well as other factors that are well known in the art.
Generally speaking, by “therapeutic effect” is meant a level of expression of one or more HNAs sufficient to alter a component of a lung disease (or disorder) toward a desired outcome or clinical endpoint, such that a patient's disease or disorder shows clinical improvement, often reflected by the amelioration of a clinical sign or symptom relating to the disease or disorder.
3. Experimental
Below are examples of specific embodiments for carrying out the present invention. The examples are offered for illustrative purposes only, and are not intended to limit the scope of the present invention in any way.
Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperatures, etc.), but some experimental error and deviation should, of course, be allowed for.
EXAMPLE 1
Isolation and Characterization of A Caprine AAV
A. Cell Culture and Virus Isolation
Ovine adenovirus preparations with evidence of parvovirus contamination were isolated from caprine ileum as follows. Tissue was homogenized in Eagle's MEM medium containing Earles salts (pH 7.2) and gentamicin. The homogenate was clarified by low speed centrifugation (1,500 ×g) for 20 minutes and filter-sterilized though a 0.45 μm device. Supernatant (500 μl) was inoculated onto a 25 cm2 flask containing primary cultures of fetal lamb kidney cells at passage 3 and incubated with fetal bovine serum (USA) and lactalbumin hydrolysate (USA) at 37° C. in humid, 5% CO2 incubator for one week. Cells were trypsinized, split, and incubated again as described above and finally assayed for typical adenoviral cytophatic effect (CPE). Flasks showing CPE were frozen at −70° C., thawed and layered onto other cell types. These flasks were later incubated and tested for CPE.
Other cell types used included non-immortalized (passage 8) ovine fetal turbinate cells derived from fetal ovine tissue and Maden Darby bovine kidney cells, maintained by long-term passage (used at passage 160). Porcine trypsin (USA) was used in all tissue culture processes and no human cell cultures or products were used.
B. Viral DNA Isolation and AAV Sequence Identification and Comparison
Four preparations from different cell cultures and passages were processed individually for DNA extraction. Virus-containing supernatant was treated with proteinase K (200 μg) in digestion buffer (10 mM Tris-HCl (pH 8.0), 10 mM EDTA (pH 8.0) and 0.5% SDS) and incubated at 37° C. for 1 hour. Following phenol chloroform extraction and ethanol precipitation the viral DNA was resuspended in TE. The DNA content of each preparation was determined by PicoGreen DNA quantitation (Molecular Probes, Eugene, Oreg.) and the preparations were diluted to 20 ng/μl to standardize DNA concentration for subsequent PCR assays.
Oligonucleotide Primers
Oligonucleotide primers were selected on the basis of sequence alignments from segments that were highly conserved among known AAVs. The forward primer 1 (GTGCCCTTCTACGGCTGCGTCAACTGGACCAATGAGAACTTTCC) (SEQ ID NO:7), was complementary to the helicase domain and the reverse primer 2 (GGAATCGCAATGCCAATTTCCTGAGGCATTAC) (SEQ ID NO:8), was complementary to the DNA binding domain. The expected size of PCR fragments was 1.5 kb.
PCR Amplifications
All reactions were performed in 50 μl in an automated Eppendorf Mastercycler® Gradient thermocycler (PerkinElmer, Boston, Mass.). Each reaction mixture contained 200 ng of template DNA, 1 μM each oligonucleotide primer, 1 mM Mn(OAc)2, 200 μM each deoxynucleoside triphosphate (dATP, dCTP, dGTP, and dTTP), and 1.0 unit of rTth polymerase, XL (Applied Biosystems, Foster City, Calif.) in 1 ×XL Buffer II. Ampliwax® PCR gem 100 was used to facilitate hot start (Applied Biosystems, Foster City, Calif.).
Cycling conditions were as follows: 2 min of denaturation at 94° C., followed by 35 cycles of 15 s of denaturation at 94° C., 30 s of annealing at 45° C., and 2 min of elongation at 72° C.
PCR products (10 μl) were electrophoretically separated in a 1% NuSieve® agarose gel (FMC BioProducts, Rockland, Minn.), stained with ethidium bromide, and visualized by UV light. DNA molecular markers were used on each gel to facilitate the determination of the sizes of the reaction products.
To control for specificity of the assay, PCR was also performed with 100 ng of DNA from a plasmid containing AAV2 sequences.
DNA Sequencing
PCR products were purified on 1% low-melting agarose gels (FMC Bioproducts, Rockland, Me.), and the sequences were determined using primers designed from AAV-5 sequences. Sequence data were analyzed with the NTI vector suite software package (InforMax, Frederick, Md.).
Virus preparations from different cell cultures and passages were processed individually for DNA extraction and PCR analysis. PCR amplification using primers forward 1 and reverse 2 revealed the presence of parvovirus-like sequences in all four preparations. Sequence analysis revealed the presence of AAV sequences. The VP1 ORF of caprine AAV, corresponding to nucleotides 2,207 to 4,381 of AAV-5 genome, has 93% nucleotide identity (2,104/2,266, Gaps 6/2,266) with primate AAV-5 (see FIGS. 2A-2B) isolated from humans (J. Virol 1999; 73:1309-1319). Protein comparison showed 94% identity (682/726) and 96% similarity (698/726) between the primate AAV-5 and caprine AAV VP1 proteins (see, FIG. 3). Most if not all mutations appeared to be on the surface.
EXAMPLE 2
Lung Tropism of Caprine AAV
In order to determine the biodistribution of vector genomes derived from caprine AAV following administration, the following experiment was conducted. Male SCID mice (15-25 g) were injected via the tail vein with 5×1011 vector genomes of caprine rAAV hF.IX (also referred to as rAAV-G1 hF.IX). In particular, the virions were generated using plasmid pAAV-hFIX16, containing the human factor IX gene under the control of a liver-specific promoter (described in Miao et al., Mol. Ther. (2000) 1:522-532). Plasmid pAAV-hFIX16 is an 11,277 bp plasmid encoding a human Factor IX minigene. In this construct, the FIX cDNA is interrupted between exons 1 and 2 with a deleted form of intron 1 that has been shown to increase expression of FIX. FIX expression is under the transcriptional control of the ApoE hepatic control region (HCR) and the human alpha 1 antitrypsin promoter (hAAT), as well as a bovine growth hormone polyadenylation signal (gGH PA). The backbone of plasmid pAAV-hFIX16 contains the β-lactamase gene, conferring ampicillin resistance, a bacterial origin of replication, a M13/F1 origin of replication, and a fragment of bacteriophage lambda DNA. The lambda DNA increases the size of the plasmid backbone to 6,966 bp, which prevents its packaging during AAV vector production.
The recombinant AAV virions were produced using the triple transfection method (described in detail in U.S. Pat. No. 6,001,650, incorporated herein by reference in its entirety), with the exception that the VP 1 coding sequence present in plasmid pHLP 19 (described in U.S. Pat. No. 6,001,650, incorporated herein by reference in its entirety) was substituted with the caprine VP1 coding sequence. Briefly, plasmid pHLP19 was digested with SwaI and AgeI (New England Biolabs, Beverly, Mass. 01915-5599), the fragment of interest was purified on a 1% low-melting agarose gel (FMC Bioproducts, Rockland, Me.), and used for ligation with the PCR fragment containing the caprine capsid. The caprine capsid PCR fragment was amplified using a forward primer: AAATCAGGTATGTCTTTTGTTGATCACCC (SEQ ID NO:9) and a reverse primer: ACACGAATTAACCGGTTTATTGAGGGTATGCGACATGAATGGG (SEQ ID NO: 10). The PCR fragment was digested with the enzyme Agel (New England Biolabs, Beverly, Mass. 01915-5599) and used for ligation with the digested plasmid.
For biodistribution analysis, mice were sacrificed and organs were collected 4 weeks after vector injection. Organs collected included brain, testis, muscle (quadriceps), kidney, spleen, lung, heart, and liver. To measure hF.IX, quantitative-PCR was done on DNA samples extracted from different tissues.
As shown in FIG. 4, the biodistribution of IV-administered caprine AAV hF.IX in male SCID mice showed that caprine AAV has lung tropism and is useful for delivering a gene of interest to the lungs of a mammal.
EXAMPLE 3
Isolation of a Bovine AAV
Materials and Methods
Bovine AAV was isolated as follows. Bovine adenovirus (BAV) type 8, strain Misk/67 (available from the ATCC, Manassas, Va., Accession No. VR-769) isolated from calf lungs, was processed for DNA extraction. Virus-containing supernatant was treated with proteinase K (200 μg/ml) in digestion buffer (10 mM Tris-HCl (pH 8.0), 10 mM EDTA (pH 8.0) and 0.5% SDS) and incubated at 37° C. for 1 hour. Following phenol/chloroform extraction and ethanol precipitation, the viral DNA was resuspended in TE.
Oligonucleotide primers for PCR screening were selected on the basis of sequence alignments from segments that are highly conserved among known AAVs.
The forward primer 5′-GTGCCCTTCTACGGCTGCGTCAACTGGACCAATGAGAAC TTTCC-3′ (SEQ ID NO: 11) is complementary to the helicase domain of rep and the reverse primer 5′-GGAATCGCAATGCCAATTTCCTGAGGCATTAC-3′ (SEQ ID NO: 12) is complementary to one of the several DNA binding domains in capsid. The expected size of PCR fragments was 1.5 kb.
PCR reaction was performed in 50 μl in an automated Eppendorf Mastercycler® Gradient thermocycler (PerkinElmer, Boston, Mass.). Each reaction mixture contained 200 ng of template DNA, 1 μM each oligonucleotide primer, 1 mM Mn(OAc)2, 200 μM each deoxyribonucleoside triphosphate (dATP, dCTP, dGTP, and dTTP), and 1.0 unit of rTth polymerase, XL (Applied Biosystems, Foster City, Calif.) in 1 ×XL Buffer II. Ampliwax PCR gem 100 (Applied Biosystems, Foster City, Calif.) was used to facilitate hot start.
Cycling conditions were as follows: 2 min of denaturation at 94° C., followed by 35 cycles of 15s of denaturation at 94° C., 30s of annealing at 45° C., and 2 min of elongation at 72° C. PCR products (10 μl) were electrophoretically separated in a 1% NuSieve® agarose gel (FMC BioProducts, Rockland, Minn.), stained with ethidium bromide, and visualized by ultraviolet light. To control for specificity, PCR was also performed with 100 ng of DNA from a plasmid containing AAV-2 rep and cap sequences. PCR products were purified on 1% low-melting agarose gels (FMC Bioproducts, Rockland, Me.) and sequenced using a model 3700HT DNA sequencer (Applied Biosystems, Foster City, Calif.). Sequence data was analyzed with the Vector NTI, version 9.0 package (Invitrogen, San Diego, Calif.).
The plasmid pHLP 19-cow was constructed as follows. The AAV-6 capsid gene and 3′ untranslated region (UTR) of pHLP19-6 (composed of the AAV-2 rep and the AAV-6 capsid and 3′UTR (Grimm et al. (2003) Blood 102:2412-9), were removed by digesting with SwaI and Agel (New England Biolabs). A bovine capsid coding region tailed with an AAV-6 3′ UTR sequence was created by PCR using the following set of primers: 5′-AAATCAGGTATGTCTTTTGTTGATCACCC-3′ (SEQ ID NO:13) and 5′-ACACGAATTAACCGGTTTATTGAGGGTATGCGACATGAATGGG-3′ (SEQ ID NO:14). The PCR fragment was digested with AgeI and ligated to the digested pHLP19-6 plasmid.
Recombinant bovine AAV vectors were produced and purified as follows, using a triple transfection procedure (Matsushita et al. (1998) Gene Ther 5:938-45). In each case the adenovirus helper gene plasmid pLadeno5 and the appropriate AAV helper plasmid (e.g., pHLP19-cow) were used. The transgene plasmids were pymLacZ (to express lacZ under CMV promoter control), pAAV hFIX9 (to express human factor IX under the CMV promoter control) (Miao et al. (2003) Hum Gene Ther 14:1297-305).
Human embryonic kidney cells type 293 (ATCC, catalog number CRL-1573) were transfected, and after six hours the DNA mixture was removed from the cells, which were then provided with fresh cell culture medium without fetal calf serum and the cells were incubated for a 66 hour production period. Then the cells were collected, disrupted, and vector was purified by polyethylene glycol precipitation followed by two rounds of CsCl density gradient centrifugation as described previously (Grinmm et al. (2003) Blood 102:2412-9). The purified vector was formulated in PBS, 0.01% Pluronic F-68 and sterile filtered (0.22 μM).
Vector genome titers were established by taking the average of three Q-PCR determinations (Heid et al. (1996) Genome Res 6:986-94) using primers and probe specific for HFIX as previously described (Sommer et al. (2003) Mol Ther 7:122-8).
Viral purity was assessed by SDS-PAGE (Invitrogen, Carlsbad, Calif.) and silver staining (Daiichi, Tokyo, Japan). Monodispersity was assessed by dynamic light scattering using a Protein Solutions, DynaPro® model according to the manufacturer's recommendations (Charlottesville, Va., USA). Analysis of 1×1012 to 1×1011 particles in a volume of 12 μl showed hydrodynamic radii of 12 nm for 100% of the vectors in each preparation used for the in vivo studies (bovine AAV hFIX9, AAV-8 hFIX9,), indicating that the particles were monomeric and not aggregated.
Analysis
Bovine AAV was partially amplified by PCR, and sequenced. FIG. 5 shows the amino acid sequence of VP1 from the bovine AAV isolated here (SEQ ID NO:5) and the previously described bovine AAV (Schmidt et al. (2004) J Virol 78:6509-16) (SEQ ID NO:6), referred to herein as “Schmidt et al. bovine AAV.” In particular, Schmidt et al. bovine AAV was partially amplified from bovine adenovirus type 2. Comparison of the nucleotide sequence of VP1 from bovine AAV and Schmidt et al. bovine AAV showed 12 nucleotide changes 5 amino acid differences. These differences occurred at positions 334 (Q substituted for H), 464 (K substituted for N), 465 (T substituted for K), 499 (R substituted for G) and 514 (G substituted for R). See FIG. 5.
VP1 from bovine AAV displayed 76% identity with AAV-4. Bovine AAV displayed 54% identity with AAV-5 VP1, with high homology in the Rep protein, the first 137 amino acids of AAV-5 VP1 and the non translated region after the stop of AAV-5 VP1 (not shown). Thus, bovine AAV appears to be a natural hybrid between AAV-5 and AAV-4. Bovine AAV also displayed approximately 58% sequence identity with VP1s from AAV-2 and AAV-8, approximately 59% sequence identity with VP1s from AAV-1 and AAV-6, and approximately 60% sequence identity with VP1 from AAV-3B.
The sequence differences between AAV-4 and bovine AAV were scattered throughout the capsid. The similarity with the AAV-4 sequence was from the VP2 start to the capsid stop. Bovine AAV appears to be one of the most divergent of the mammalian AAVs with approximately 58% sequence homology with AAV-2.
The full capsid of bovine AAV was cloned in a plasmid that was used for triple transfection procedure to pseudotyped AAV-2 vector genomes. A bovine AAV vector containing the lacZ gene (bovine AAV lacZ) was produced for further characterization, using the techniques described above. Bovine AAV lacZ vector was produced efficiently; high titers of vector (1.23×1012 vg/mL) were detected by Q-PCR. Bovine AAV lacZ vector showed efficient transduction of cells in vitro (cells expressing lacZ were present in numbers comparable to other AAVs).
EXAMPLE 4
Immunoreactivity of a Bovine AAV
In vitro neutralization assays were performed as follows. Human Intravenous Immune Globulin (IVIG; Panglobulin, ZLB Bioplasma Inc. Glendale, Calif.) was resuspended at a concentration of 100 mg/mL and then serially diluted in 2-fold increments using mouse serum (Nieffenegger Company, Woodland, Calif.) filter sterilized, heated at 56° C. for 30 min. Virus was diluted to 2.5×109 vg/μL using EMEM/0.1% Bovine Serum Albumin (BSA, Fraction V, Sigma). All neutralization reactions were performed in triplicate. Samples of EMEM/0.1%BSA and mouse serum alone were included as controls. Ten microliters of diluted AAV lacZ vector were mixed with 10 μl of serial dilutions of the IVIG and incubated at 37° C. for one hour. During the incubation, the HepG2 cells (ATCC catalog # HB-8065) were washed once with EMEM and then 0.5 mL of EMEM/0.1% BSA was added to each well. The amount of vector/IVIG mixture added to the cells for each vector was based on their transduction efficiency, dilutions of the mixture were prepared for the vectors with higher transduction efficiency in order to have equivalent number of blue cells when reading the plates transduced with different vectors. After one hour incubation at 37° C., FBS and etoposide was added to each well at a final concentration of 10% and 20 μM respectively. Cells were incubated for 24 hours, fixed as described above to detect β-galactosidase activity. After another 24 hours, the number of blue cells in each well were counted using light microscopy. The lowest concentration of IVIG tested showing 50% of neutralization was determined.
Bovine AAV relative was 27 times more resistant to neutralization by human IVIG than primate AAV-2 in vitro. The concentration of IVIG (mg/mL) showing 50% neutralization of AAV-2 was 0.7 mg/mL while AAV-8 was 9 mg/mL and bovine AAV was 19 mg/mL.
EXAMPLE 5
Lung Tropism of Bovine AAV
A. In Vivo Transduction of Muscle
Male SCID mice (15-25 g, 6 weeks old) were injected with bovine AAV hFIX9 (2×1011 vector genomes per mouse, 5 mice per group), into two sites of the quadriceps muscle (25 μl per site). Retro-orbital blood was collected at seven-day intervals after vector injection and circulating plasma concentrations of hFIX were measured by ELISA (FIX-EIA, Affinity Biologicals). All samples are assessed in duplicate. The lowest limit of detection is 0.02 ng/mL hFIX.
Results are presented at FIGS. 6A and 6B. Low levels of hFIX were observed in the plasma of the mice injected with the bovine AAV hFIX9 vector (“CO” in FIG. 6A), suggesting that the recombinant bovine AAV vector does not efficiently transduce muscle. FIG. 6A. High levels of expression were observed after administration of AAV-8 hFIX9 and AAV-1 hFIX9 vectors (FIG. 6B), consistent with the results observed previously by others (Gao et al. (2002) Proc Natl Acad Sci USA 99:11854-9; Grimm et al. (2003) Blood 102:2412-9).
B. In Vivo Transduction After Tail Vein Delivery
Male SCID mice (15-25 g) were injected via the tail vein with 5×1011 vector genomes of bovine AAV hFIX-9 or AAV-8 hFIX-9 vectors (5 mice per group). Retro-orbital blood was collected 1, 2, 4 (5 mice per group) and 8 weeks (2 mice per group) after injection and circulating plasma concentrations of human factor IX were measured by ELISA (Walter et al. (1996) Proc Natl Acad Sci USA 93:3056-61). All samples are assessed in duplicate.
Results are presented at FIG. 7. The bovine AAV hFIX9 vector (“CO IV” in FIG. 7) produced plasma HFIX levels that were approximately 10-fold lower than those produced by the AAV-8 hFIX9 vector. The HFIX expression construct was driven by the CMV promoter and consequently we can not determine what tissue is contributing to the HFIX expression.
C. Biodistribution of Bovine AAV Vector
For the biodistribution analysis, mice were sacrificed 12 weeks after IV injection of 5×1011 vg per mouse. Organs collected included brain, testis, muscle (quadriceps), kidney, brain, lung, muscle (quadriceps), and liver. To measure the copy number of the HFIX gene, quantitative-PCR was done on DNA samples extracted from these tissues. The biodistribution analysis of IV-administered bovine AAV hFIX9 vector in male SCID mice indicated that the bovine AAV had a pronounced lung tropism, as illustrated in FIG. 8.
D. Expression in Lung after Systemic Administration
Whole mount X-gal staining in mouse lung after systemic administration of different AAV serotypes carrying the β-galactosidase transgene was performed as follows. Male SCID mice (15-25 g) were injected via the tail vein with 5×1011 vector genomes of AAV-4 lacZ, AAV-5 lacZ, AAV-6 lacZ, caprine AAV lacZ, bovine AAV lacZ vectors (5 mice per group). The lung collection method was modified from the previously described (Hofland et al. (1997) Pharm Res 14:742-9). Animals received deep isoflurane anesthesia; the trachea was intubated and the lungs inflated with 5 mL of air. Cardiac perfusion with PBS was followed by perfusion with fixative. Lungs were postfixed by immersion in the same fixative for 30 min, in addition the lungs were flushed via the intubation tube. Washes with PBS containing 2 mM MgCl2; were repeated it 3 times for 5 min. The lungs were then incubated with the Xgal substrate solution at 37° C. overnight. The lungs were washed again as described above. The tissues were equilibrated in 30% sucrose solution and pictures of the whole lungs were taken followed by OCT embedding. 7-12 μm thick frozen sections were counter-stained with nuclear fast red.
The results demonstrate that bovine AAV is the most efficient vector transducing the lungs. The results also demonstrate that the staining is localized mainly to the epithelial cells of the bronchioles. A total of 31 bronchioles were counted on two slides and seven of these were positive. These cells are an important target for the treatment of cystic fibrosis since the presence of the CFTR was reported in the literature (Goncz et al. (2001) Gene Ther 8:961-5, Wilson (1995) J Clin Invest 96:2547-54). Previous reports compared the efficacy of AAV vectors for the transduction of the lung (Auricchio et al. (2002) J Clin Invest 110:499-504; Bals et al. (1999) J Virol 73:6085-8; Beck et al. (1999) J Virol 73:9446-55; Fischer et al. (2003) Mol Ther 8:918-26; Flotte et al. (2003) Hum Gene Ther 14:1079-88; Halbert et al. (2001) J Virol 75:6615-24; Halbert et al. (2000) J Virol 74:1524-32), but in previous studies the AAVs were delivered through the airway. Here we report the use of a bovine AAV which has lung tropism after systemic administration.
Thus, methods for making and using caprine and bovine rAAV virions with lung tropism are described. Although preferred embodiments of the subject invention have been described in some detail, it is understood that obvious variations can be made without departing from the spirit and the scope of the invention as defined herein.

## Claims

1. An infectious recombinant adeno-associated virus (AAV) virion comprising:
an AAV vector comprising a heterologous nucleic acid molecule encoding a protein, wherein the nucleic acid molecule is flanked on each end with an AAV inverted terminal repeat, wherein the AAV vector is encapsidated by a viral capsid comprising caprine VP1.

2. The virion of claim 1, wherein the caprine VP1 comprises the amino acid sequence of SEQ ID NO: 4.

3. The virion of claim 1, wherein the therapeutic protein is selected from the group consisting of CFTR, alpha-1-antitrypsin, superoxide dismutase (SOD), interleukin-1, interleukin-2, interleukin-3, interleukin-4, gamma-interferon, p53, and the retinoblastoma gene product.

4. The virion of claim 3, wherein the therapeutic protein is CFTR.