HK1014549B - Adeno-associated virus with inverted terminal repeat sequences as promoter for the in vivo transfer of a functional cftr gene - Google Patents

Description

BACKGROUND OF THE INVENTION

Adeno-associated virus (AAV) usually is defective for replication and depends on co-existent adenovirus or herpesvirus infection for efficient replication and a productive life cycle. In the absence of helper virus, AAV can undergo stable integration of its genome into the host cell but the integrated AAV genome has no pathogenic effect. These properties formed the basis for the development of AAV vectors for gene expression in mammalian cells. AAV vectors have been used to express both selective markers (Hermonat and Muzyczka, 1984, Proc. Natl. Acad. Sci. USA 81:6466-6470; Tratschin et al., 1985, Mol. Cell. Biol. 5:3251-3260) such as neomycin phosphotransferase (neo) and unselected genes including chloramphenicol acetyltransferase (cat) (Tratschin et al., 1984, Mol. Cell. Biol. 4:2072-2081) and thyroid stimulating hormone in eukaryotic cells (Mendelson et al., 1988, Virology 166:154-165; Wondisford et al., 1988, Molec. Endocrinol. 2:32-39).

For use as a viral transducing vector AAV may present some advantages including a high frequency of stable DNA integration and the lack of pathogenicity of wild type AAV. One limitation of AAV is that of size, since the packaging limit for foreign DNA in AAV particles is approximately 4.5 kilobases. This limitation is an important consideration for the design of AAV vectors for expression of genes or cDNA constructs in which the gene coding sequence approaches that of the AAV packaging limit, i.e., approximately 4.5 kilobases.

One such gene, for example, is the cystic fibrosis gene (CFTR). The airway epithelium is a critical site of cellular dysfunction in cystic fibrosis (CF), the most common lethal genetic disease in North America, and is characterized by a defect in regulation of Cl^- conductance (Hwang et al., 1989, Science 244:1351-1353; Li, et al., 1988, Nature (London) 331:358-360, Li et al., 1989,Science 244:1353-1356; Schoumacher et al., 1987, Nature (London) 330:752-754). The cDNA for the CFTR gene (Riordan et al., 1989, Science 245:1066-1073; Rommens et al., 1989, Science 245:1059-1065) has been expressed in eukaryotic cells. Expression of the CFTR protein in non-epithelial cell lines resulted in generation of a Cl^- conductance (Andersen et al., 1991, Science 251:679-682; Kartner et al., 1991, Cell 64:681-691). The CF defect has been complemented by expression of CFTR in a CF pancreatic adenocarcinoma cell line by stable transduction with a retrovirus vector (Drumm et al., 1990, Cell 62: 1227-1233), and in a CF airway cell line by infection with a vaccinia virus (Rich et al., Nature (London) 347:358-363) or an adenovirus vector (Rosenfeld et al., 1992, Cell 68:143-155).

Gene therapy has been proposed as a way to reverse the cellular defect and prevent progression of disease in affected patients. Previous approaches to gene therapy have involved in vitro transduction of cells (such as lymphocytes) which can be easily reintroduced into patients. This may be difficult in an intact respiratory epithelium. An alternative approach is to use a virus vector to deliver the CFTR gene directly to the airway surface. One candidate is adeno-associated virus (AAV), a human parvovirus. The coding sequence (Riordan et al., 1989, Science 245:1066-1073) of CFTF, however, is 4.4 kilobases, which approaches the packaging limit of AAV particles. Thus, AAV has a potential drawback for its use as a vector for CFTR in that it barely accommodates the coding sequence of CFTR (Collins, 1992, Science 256:774-779).

AAV transducing vectors are described in the patent of Carter et al., (U.S. Patent No. 4,797,368, issued January 10, 1989). This patent describes AAV vectors using AAV transcription promoters p₄₀, p₁₉ and p₅.

AAV vectors must have one copy of the AAV inverted terminal repeat sequences (ITRs) at each end of the genome in order to be replicated, packaged into AAV particles and integrated efficiently into cell chromosomes. The ITR consists of nucleotides 1 to 145 at the left end of the AAV DNA genome and the corresponding nucleotides 4681 to 4536 (i.e., the same sequence) at the right hand end of the AAV DNA genome. Thus, AAV vectors must have a total of at least 300 nucleotides of the terminal sequence.

For packaging large coding regions, such as the CFTR gene into AAV vector particles, it is important to develop the smallest possible regulatory sequences, such as transcription promoters and polyA addition signal. Also in this latter study and another study (Beaton et al., 1981, J. Virol. 63:4450-4454) it was shown that the AAV ITR sequence can act as an enhancer for the SV40 virus early gene transcription promoter. However, it was not shown that the AAV ITR region had any intrinsic transcription promoter activity. Indeed, it is taught in the literature that the AAV ITR regions have no transcriptional function (Walsh et al., 1992, PNAS [in press]). Therefore, in the previous AAV vectors a small transcription promoter was utilized, namely the AAV p₅ promoter, which consists of nucleotides 145 to 268 of the AAV genome positioned immediately adjacent to an ITR.

SUMMARY OF THE INVENTION

According to the present invention, a novel functional cystic fibrosis transmembrane conductance regulator (CFTR) protein has a deletion of any or all of the amino terminal 118 amino-acids. Further, a novel polynucleotide comprises the inverted terminal repeat (ITR) sequences of adeno-associated virus and a heterologous nucleic acid encoding the CFTR protein, wherein the ITR sequences promote transcription of the nucleic acid. A vector comprising the polynucleotide may be used in treating cystic fibrosis, especially in humans.

AAV vectors containing the full-length CFTR cDNA are larger than wild-type AAV and are difficult to package into AAV-transducing particles. However, a CFTR cDNA expressed from an AAV ITR promoter according to the invention can complement the CF defect and is regulated appropriately, as indicated by functional assays. It has been demonstrated that this truncated CFTR cDNA can be packaged into an AAV vector and infected into IB3 cells such that the bulk culture could be complemented for the CF defect. It is thus possible to obtain efficient complementation of the CF defect with AAV-transducing vectors.

DESCRIPTION OF THE INVENTION

Preferably, the vector used in the invention is an adeno-associated virus vector. By "adeno-associated virus vector" is meant any vector which has the ITR sequences necessary to package the viral genome, integrate into a host chromosome and promote transcription of additional sequences. Thus, any changes in the ITR which retain these essential functions are considered within the meaning.

The polynucleotide may also comprise a poly A site that is capable of being translationally read in the reverse direction. The polyA site has SEQ ID NO. 6.

The viral vector can be contained in a suitable host. Any cell can be a suitable host so long as the vector is capable of infecting the cell type. One example of a suitable host is an epithelial cell containing a non-functional CFTR sequence.

The vector can contain additional sequences, such as from adenovirus, which aid in effecting a desired function of the vector. For example, the addition of adenovirus DNA sequences enclosing the AAV vector could provide an approach to packaging AAV vectors in adenovirus particles.

The vector can also be contained in any pharmaceutically acceptable carrier for administration. Examples of suitable carriers are saline and phosphate-buffered saline.

As used herein, AAV means all serotypes of AAV. Thus, it is routine in this art to use the ITR sequences from other serotypes of AAV since the ITRs of all AAV serotypes are expected to have similar structures and functions with regard to replication, integration, excision and transcriptional mechanisms.

EXPERIMENTAL PROCEDURES AND RESULTS

Cells. The CFBE IB3-1 cell line (IB3 cells) is a human bronchial epithelial cell line derived from a CF patient and immortalized with an adeno/SV40 hybrid virus (Luo et al, 1989, Pflugers Arch. 415:198-203; Zeitlin et al., 1991, Am. J. Respir. Cell Mol. Biol. 4:313-319). These cells retain characteristics of epithelial cells and are deficient in protein kinase A activation of chloride conductance. IB3 cells were grown at 37°C in 5% CO₂ in LHC-8 medium (Biofluids, Inc. Md) plus 10% fetal calf serum with added endothelial cell growth supplement (15 ug/ml) in culture flasks or dishes coated with collagen (150 ug/ml), fibronectin (10 ug/ml) and bovine serum albumin (10 ug/ml). The 293-31 cell line (293 cells), originally derived from human embryonic kidney cells transformed with the adenovirus type 5 E1A and E1B genes, was grown at 37°C in 5% CO₂ in Eagle's Minimal Essential Medium with 10% fetal calf serum and was used for packaging AAV vectors into virus particles (Tratschin et al., 1984, Mol. Cell. Biol. 4:2072-2081).

Plasmids. Plasmids were constructed and grown using standard methods (Sambrook et al., 1989, Molecular Cloning, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York). The parental plasmid, pAV2, contains the entire 4681 nucleotide sequence of AAV2 inserted in a pBR322 derived plasmid via a polylinker and BglII linkers (Laughlin et al., 1983, Gene 23:681-691). From this a plasmid pYT45 was obtained which contained a prokaryotic cat gene immediately downstream of AAV nucleotides 1 to 263 (which placed the cat gene under control the AAV p₅ promoter) followed by AAV nucleotides 1882-1910 and 4162-4681 (containing the polyA signal and right hand ITR) downstream of the cat gene.

pAAVp₅ neo is analogous to pYT45 except that it has a neo coding sequence in place of the cat gene and the downstream AAV nucleotides 1882-1910 and 4162-4492 (the KpnI/SnaB fragment) were replaced 60 bp SPA.

pSA313 is analogous to pAAVp₅ neo except that the neo sequence was replaced with the CFTR coding sequence contained in a 4502 bp AvaI-SstI fragment excised from a plasmid pBA-CFTRBQ (Drumm et al., 1990, Cell 62:1227-1233). This CFTR cDNA sequence contains the three silent point mutations in exon 6a which eliminate the prokaryotic promoter sequence. In pSA313, the CFTR gene is under control of the AAV p₅ promoter. The plasmid pSA315 is analogous to pSA313, except that the CFTR cDNA is inserted in the opposite direction. The plasmid pSA306 is analogous to pSA315 except that it has a deletion of the CFTR nucleotides 131 to 486. In both pSA315 and pSA306 the CFTR gene is expressed from the AAV ITR as discussed below. The junction sequences between the CFTR insert and the AAV termini and SPA regions of pSA313, pSA315, and pSA306 were verified by DNA sequencing. pSA464 was derived from pSA306 by cleaving with AflII at nucleotide of the CFTR sequence and filling in and blunt-end ligation with T4 DNA polymerase and T4 DNA ligase. This generated a frameshift in the CFTR sequence. The presence of this mutation was verified by DNA sequencing.

Transfection. DNA transfection in IB3 was performed in 6- or 24-well dishes using lipofection. Thirty ug of lipofection reagent (BRL, Gaithersburg, MD) was used for each 5 to 6 ug of DNA transfected. Lipofectin and DNA were mixed in 1.0 ml of LHC-8 serum-free medium and added to cells (5x10⁵ to 5x10⁶ in 35 mm wells) already covered with 0.5 ml of medium. Cells were exposed to DNA for 4 hours, rinsed with PBS and then grown in 2 ml of fresh medium. DNA transfection in 293 cells was performed by the standard DNA- calcium phosphate precipitation procedure.

Geneticin selection. IB3 cells used for stable neo expression were split 1:3 into 10 cm dishes at 24 to 48 hours after transfection and geneticin sulfate was added 72 to 96 hours after transfection at a concentration of 120 ug/ml. The amount of geneticin used was based on a minimal lethal dose titration. Geneticin resistant (gen^r) colonies were counted at 14 to 16 days after beginning selection.

CFTR complementation. IB3 cells were plated at approximately 5 x 10⁵ cells 35 mm dish. Twenty-four hours after plating, cells were transfected using either 6 ug of pAAVp₅ neo or 1 ug of pAAVp₅ neo together with 5 µg of pSA313, pSA315, pSA306, or pSA464 by lipofection, and geneticin selection was performed as described above. Gen^r colonies were isolated at 14 days after beginning selection from each of the other two sets of plates. Each isolated colony was trypsinized using a cloning cylinder and expanded from 10 mm wells. After expanding each clone, cells were prepared for ³⁶Cl^- efflux assays and Western blot analysis.

Chloride efflux assays. Chloride efflux assays were performed as described (Trapnell et al., 1991, J. Biol. Chem. 266:10319-10323) on individual clones at passage 4 to 8. Briefly, cells were grown in 35 mm dishes and loaded with 3 uCi of ³⁶Cl^- in bicarbonate-free Ringer's balanced salt solution for 2 to 9 hours. Initial experiments involving repeated assays on the same clone of cells did not reveal significant differences in efflux following different loading times and a 2 hr loading period was then used for subsequent experiments. After loading the cells were washed 2 to 3 times in ice cold 0.15 M NaCl, 5mM Hepes, pH 7.4. One ml of Ringer's solution was added and removed immediately (time zero) and replaced with 1 ml of Ringer's. This process was repeated at various time points over a 15 min period. The amount of radioactivity in each 1 ml sample of medium was determined by liquid scintillation counting. After the last sample was removed at 15 min, residual radioactivity remaining in the cells was determined by lysing the cells in 0.2 N NaOH and scintillation counting. The total radioactivity from all time points and the final cell lysate was then summed and the efflux was expressed as a percent of total radioactivity remaining in the cells at each time point. Effluxes were then repeated for each clone tested, using 10 uM forskolin dissolved in the Ringer's efflux solution, starting at time zero. The relative stimulation by forskolin was then expressed by calculating the rate (k_a) of efflux in the presence of forskolin and expressing this as a ration relative to the rate of efflux in the absence of forskolin. For IB3 cells which exhibit the CF defect this ratio is 1.0 or less. For cells complemented by CFTR vectors this ration is greater than 1.0.

Packaqinq of AAV2-CFTR vectors. Packaging of AAV2 vectors was accomplished by first infecting 293-31 cells (grown to semiconfluence in 100mm dishes) with adenovirus type 5 (Ad5) (at a multiplicity of 5 to 10 infectious units/cell) and then co-transfecting the vector plasmid, pSA306 or pSA464 (1 µg) and the packaging pAAV/Ad (5 µg) using the CaPO₄ transfection procedure (Tratschin et al., 1984, Mol. Cell. Biol. 4:2072-2081). Medium was replaced 2 hr prior to transfection and Ad5 was inoculated into the medium 1 hr prior to transfection. The medium was changed 4 hr after transfection. Cells were grown for 3 to 4 days then harvested by gently scraping into the medium. For direct analysis of packaging, the lysates were frozen and thawed three times, debris was removed by low speed centrifugation, then heated at 60°C for 15 min to inactivate adenovirus. For use of vectors in transduction of IB3 cells the scraped cells were concentrated by low-speed (4000 rpm) centrifugation and resuspension in 10 mM Tris-HCl buffer, pH 8.0. Cells were lysed by freezing and thawing three times and the virus was concentrated and purified using CsCl density gradient ultracentrifugation (Carter et al., 1979, Virology 92:449-462). Fractions taken for transduction assays were then dialyzed against 1 X SSC three times for 1 h at room temperature and heat-treated at 60°C for 15 minutes to inactivate any possible residual adenovirus. The titer of the vector preparation was determined by DNA slot-blot hybridization (Samulski et al., 1989, J. Virol. 63:3822-3828)

AAV2-particle mediated transduction. Virus particle-mediated neo transduction of IB3-1 CF bronchial epithelial cells was accomplished by infecting 10³ to 4 x 10⁴ cells in individual wells of a 24 well dish with a known number of AAV-CFTR vector particles per cell. The cells were grown for several weeks and assayed for complementation of the CF defect.

In the course of constructing vectors that were designed to express CFTR from the AAV p₅ promoter, we inadvertently made one such plasmid construct in which the gene was inserted in the opposite direction. This vector plasmid would not have been expected to function because it did not have a known promoter in the correct orientation. However, due to a serendipitous mistake in a laboratory experiment, we tested this plasmid construct and discovered that it functioned to express the gene. This caused us to examine the construct carefully and we concluded that the ITR may be functioning as a transcription promoter. As a result, we performed specific experiments detailed in this specification which demonstrate that the ITR can act as a transcription promoter.

Thus, AAV vectors need have only the ITR sequences and a polyA site in order to express a foreign gene. This is a new and novel finding and indeed is against the expectation based on previously taught work, in which there was a commonly accepted agreement that the ITRs of AAV are not transcriptionally active (Walsh et al., 1992, PNAS [in press]). We show here that the AAV ITR is transcriptionally active in stable integration assays to express a functional CFTR cDNA.

Construction of AAV-CFTR vectors. Figure 1 shows the structure of several AAV-CFTR vectors designed to express CFTR either from the AAV p₅ promoter as in pSA313 or from the AAV ITR as in pSA313 or pSA306. In pSA313, the CFTR cDNA (cross-hatched region and arrow head) of 4500 nucleotides is inserted downstream of the AAV P₅ promoter i.e, AAV nucleotides 1 to 263, at the left. It contains the synthetic polyA site. In pSA315 the CFTR cDNA was inserted in the opposite orientation such that it is downstream of the right-hand AAV ITR sequence and the synthetic polyA site. In this configuration the CFTR is expressed from the right-hand ITR and the polyA site can be read through translationally in the reverse direction as noted above. In pSA306, the construct is exactly analogous to pSA313 except that 350 nucleotides of the amino terminal region of CFTR cDNA, nucleotides 131-486, have been deleted. This results in expression from the right-hand ITR of a fusion protein consisting of a N-terminally deleted CFTR protein having a fusion region at its N-terminus derived from reading through the synthetic polyA site in the reverse direction i.e., from right to left in the orientation of Figure 1.

The plasmid pSA464 is a control derived from pSA306 by introducing a frameshift mutation at an AFlII site at nucleotide 993, such that it can not produce a functional CFTR protein. This is indicated by the vertical solid bar.

Expression of CFTR and complementation of the CF defect in stable transfectants of CF airway cells. To examine the efficiency of the AAV-CFTR vectors for expression of the CFTR gene, the plasmids shown in Figure 1 were each transfected using cationic liposomes (Lipofectin Reagent, BRL, Gaithersburg, Md) into IB3 cells, together with pAAVp₅ neo. Control cells were transfected with pAAVp₅ neo alone. Gen^r colonies were picked from the original plates and expanded into stable cultures and characterized for functional expression of the CFTR protein. All of these clones were stable for neo expression during repeated passage over several months in culture.

Expression of CFTR can be detected in functional assays in IB3 cells which have the cystic defect. A functional CFTR protein should restore to these cells a Cl^- conductance which is regulated by cAMP and thus is stimulated by forskolin (Drumm et al., 1990, Cell 62:1227-1233, Hwang et al., Science 244:1351-1353; Li et al., 1988, Nature (London) 331:358-360; Li et al., 1989, Science 244:1353-1356; Rich et al., 1990, Nature 347:358-363). Examples of Cl^- efflux are shown in Figure 2 and a summary of the rate constants calculated from this data are shown in Figure 3. Both the parental IB3 cells and the control N6 clone (transfected with pAAVp₅ neo alone) exhibited a relatively slow Cl^- efflux rate that was not responsive to forskolin (Figure 2). In contrast, a number of the clones of AAV-CFTR transfectants, as shown in Figure 2 for clones C35 and C38 (both derived from transfection of pSA306), exhibited significantly increased basal rates of efflux but more significantly showed the characteristic additional increase in efflux in response to forskolin. Efflux was measured in the absence (○) or presence (●) of 20 µm forskolin.

Figure 3 shows Cl^- efflux assays in IB3-1 cells complemented with the CFTR gene by stable transfection of AAV-CFTR vectors. IB-3 cells were transfected with pAAVp₅ neo and either pSA313, pSA315, pSA306, or pSA464. Geneticin-resistant clones were selected and analyzed for responsible to forskolin stimulation in a Cl^- efflux assay. The ratio of the rate of efflux in the presence of forskolin to the rate in the absence of forskolin (k_a forskolin/k_a Ringer's) is plotted. For each vector, n indicates the number of individual clones which did (hatched bars) or did not (open bars) show a forskolin response. For each group of clones the average ratio was calculated. For the parental IB3-1 cells or the cell clone transfected with the pAAVp₅ neo alone, n indicates the number of measurements on the same clone.

(Figure 3 shows that 28% (4/14) of the pSA313 transfectants, and 50% (6/12) of the transfectants with either pSA315 or pSA306 were complemented for the defect. This shows that all three vector constructs were functional. The increased number of functional clones with pSA313 or pSA306 may indicate that the ITR promoter in the vectors was more efficient than the p₅ promoter in pSA313. None of the clones transfected with the control vector pSA464 were complemented. These results show two novel findings. First, the AAV ITR sequence functions efficiently also as a promoter when stably integrated into cells as shown by the function of both pSA313 and pSA306. Second, the truncated CFTR protein expressed from pSA306 is also functional for complementation of the CFTR defect. In the pSA306 vector the largest open reading frame expresses a fusion protein by reading through most of the synthetic polyA sequence in the reverse direction.

The observations with pSA306 are especially pertinent because it was taught previously that the region of CFTR that is deleted in pSA306 was in fact essential for CFTR function when CFTR is expressed from various others vectors such as vaccinia (Andersen et al., 1991, Science 251:679-682). Also, the overall size of the AAV-CFTR vector in pSA306 is equivalent to the size of wild type AAV DNA and thus this vector should be packageable into AAV particles to use as a transducing vector. We examined packaging of the pSA306 vector into AAV particles. To examine packaging of AAV-CFTR vector pSA306 into AAV particles adenovirus-infected 293 cells were transfected with the AAV-CFTR vector (pSA306) in the presence (+) or absence (-) of the AAV packaging plasmid (pAAV/Ad). Lysates of the cultures were prepared 72 hr after transfection and used to infect fresh cultures of adenovirus-infected 293 cells in the absence (minus wt) or presence (plus wt) of added wild type AAV particles (m.o.i 3). 40 hr after infection, Hirt lysates of the cells were prepared and viral DNA was electrophoresed in an agarose gel, blotted to nitrocellulose, and hybridized with a CFTR ³²P-DNA probe specific for the SA306 vector (306) or with AAV ³²P-DNA probe specific for wild-type AAV (AAV). Replication of the SA306 vector was only detected in lysates that had been packaged in the presence of pAAV/Ad and were subsequently infected in the presence of added wild-type AAV particles. This showed that the AAV-CFTR vector could be packaged into AAV transducing particles.

To demonstrate the functionality of the SA306 AAV-CFTR transducing vector IB3 cell cultures were infected with vector preparations containing packaged SA306 or a control SA464 vector at a multiplicity of approximately 300 to 400 vector particles per cell. The cultures were grown several weeks in culture and assayed for functional expression of the CFTR. As shown in Figure 4, the culture infected with the SA306 vector (A0 cells) was functionally complemented for the CF defect as shown by the response to forskolin. In contrast the control culture infected with the control SA464 vector (2F2 cells) was not complemented as shown by the lack of response to forskolin.

The results shown in Figures 2, 3, and 4 have been confirmed by other functional assays including immunofluorescent detection of the CFTR protein and electrophysiological assays using patch-clamp techniques.

The results described above demonstrate complementation and stable correction of the CF defect in airway epithelial cells after cationic liposome mediated transfection with AAV-CFTR vector or after infection of the cells with AAV-CFTR transducing vector particles. These results demonstrate the utility of the AAV vectors and the invention as practised with AAV vectors using an ITR as the promoter and incorporating a synthetic polyA site having special features.

Our studies with the AAV-CFTR vectors were performed as an initial step in evaluating the feasibility of using an AAV vector for gene therapy. In this respect it is important that we have demonstrated stable complementation of the CF defect in cells derived from bronchial epithelium since this the site of the major clinical manifestation of the disease and is the most likely site for targeting of gene therapy vectors. The complementation experiments reported with a retroviral vector (Drumm et al., 1990, Cell 62A:1227-1233) were performed in CFPAC cells which are pancreatic cells rather than airway cells.

Expression of CFTR in vivo

AAV vectors, especially those expressing a gene from the ITR, can be used to treat human patients in the following general way. If the vector is to be delivered as transducing particles, it can first be packaged into AAV particles, in the general way described here for the AAV-CFTR vector SA306, or using any other suitable packaging system. The AAV transducing vector can be purified to remove and/or inactivate any adventitious agents or toxic compounds by banding in CsCl or any other appropriate procedure. For AAV vectors expressing a functional CFTR gene, or any other gene for treating a pulmonary disease, the vector can be delivered directly in vivo to the lung either by intubation and bronchoscopy or by a nebulizer or by a nasal spray or by inhalation as an appropriate formulation of nose drops. For this or other diseases, the AAV vector particles can be delivered in vivo by intravenous or enteric administration or perhaps subcutaneously.

The vector can also be used in ex vivo gene therapy procedures by removal of cells from a patient that is then infected with the AAV vector particles and the cells are returned to the patient after a period of maintenance and/or growth ex vivo.

The AAV vectors can also be administered in either in vivo or ex vivo gene therapy procedures in various other formulations in which the vector plasmid is administered as free DNA either by direct injection or after incorporation into other delivery systems such as liposomes or systems designed to target by receptor-mediated or other endocytosis procedures. The AAV vector can also be incorporated into an adenovirus, retrovirus or other virus which can be used as the delivery vehicle.

Other vectors utilizing the promoter region sequences from ITR.

An additional use of the present discovery is to utilize the sequences of ITR which are responsible for promotion in other vectors. The ITR region of AAV does not have a normal TATA motif common to many eukaryotic promoters and was not previously recognized to function within the context of an AAV genome as a transcription promoter. It is likely that in the context of the AAV genome this ITR does not function as a promoter perhaps because of effects of the other known AAV promoters downstream of this. However, not all eukaryotic transcription promoters require or possess the TATA motif. After we demonstrated that the AAV ITR functions as a promoter we examined the ITR sequence for elements that are likely to explain this function.

Inspection of the ITR sequence shows two motifs that are likely to be important in its function as a promoter. First, in the region between AAV nucleotide 125 and 145 (commonly known as the AAV d sequence) there is the sequence 5'-AACTCCATCACT-3' [SEQ ID NO1]. This is only one base different from similar sequences at the 5' start site of the promoters for human terminal deoxynucleotidyl transferase gene and for the adenovirus major late gene promoter and matches closely the consensus sequence for an element described as an Inr (Initiator) element (Smale, S.T. and Baltimore, D., 1989, Cell 57:103-113; Smale et al., 1990, Proc. Natl. Acad. Sci. U.S.A. 87:4509-4513). A second series of GC-rich elements is present in the ITR region between nucleotides 1 and 125 including the elements, GGCCGCCCGGGC [SEQ ID NO2] from nucleotides 41 to 50, AAAGCCCGGGCGTCGGGCGACC [SEQ ID NO3] from nucleotides 51 to 73, GGTCGCCCGGCCTCA [SEQ ID NO4] from nucleotides 76 to 90, and GAGCGGCGAGAG [SEQ ID NO5] from nucleotides 101 to 112 which have strong homology with the series of consensus sites shown to be sites for the common transcription factor Sp1 (Pitluck and Ward, 1991, J. Virol. 65:6661-6670). Finally, it is now known that an Inr sequence in the presence of sites for other factors such as Sp1 can function as a transcription promoter (Smale and Baltimore, 1989; Smale et al., 1990).

It is likely that these or other regions of the ITR may be important in allowing it to function as a transcription promoter. It is now straightforward and obvious to others experienced in the field to perform standard mutagenesis techniques to alter the ITR sequence to determine precisely the controlling elements and to modulate the transcriptional activity of the ITR either up or down.

SEQUENCE LISTING

• (1) GENERAL INFORMATION: (i) APPLICANT: (A) NAME: UNITED STATES OF AMERICA, as represented by the Secretary, Department of He(B) STREET: c/o National Institutes of Health(C) CITY: Bethesda(D) STATE: Maryland(E) COUNTRY: USA(F) POSTAL CODE (ZIP): 20892(ii) TITLE OF INVENTION: MODIFIED ADENO-ASSOCIATED VIRUS VECTOR CAPABLE OF EXPRESSION FROM A NOVEL PROMOTER(iii) NUMBER OF SEQUENCES: 6(iv) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk(B) COMPUTER: IBM PC compatible(C) OPERATING SYSTEM: PC-DOS/MS-DOS(D) SOFTWARE: PatentIn Release #1.0, Version #1.30 (EPO)(v) CURRENT APPLICATION DATA:    APPLICATION NUMBER: EP 93916425.7
• (2) INFORMATION FOR SEQ ID NO: 1: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 12 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1:
• (2) INFORMATION FOR SEQ ID NO: 2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 12 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2:
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• (2) INFORMATION FOR SEQ ID NO: 4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 15 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4:
• (2) INFORMATION FOR SEQ ID NO: 5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 12 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 5:
• (2) INFORMATION FOR SEQ ID NO: 6: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 58 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: double(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(xi) SEQUENCE DESCRIPTION: SEQ ID NO: 6:

Claims (10)

1. A functional cystic fibrosis transmembrane conductance regulator protein having a deletion of any or all of the amino terminal 118 amino-acids.
2. The protein of claim 1, wherein the deletion is of amino-acids 1 to 118.
3. A polynucleotide comprising the inverted terminal repeat (ITR) sequences of adeno-associated virus and a heterologous nucleic acid encoding the protein of claim 1 or claim 2, wherein the ITR sequences promote transcription of the nucleic acid.
4. The polynucleotide of claim 3, also comprising a polyA site having the nucleotide sequence
5. A vector comprising the polynucleotide of claim 3 or claim 4.
6. The vector of claim 5, which is an adeno-associated virus vector.
7. A host cell containing the vector of claim 5 or claim 6.
8. The host cell of claim 7, which is an epithelial cell.
9. A composition comprising the vector of claim 5 or claim 6 and a pharmaceutically-acceptable carrier.
10. Use of the vector of claim 5 or claim 6 for the manufacture of a medicament for use in treating cystic fibrosis in a subject.