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. 2012 Nov 27;1(11):e56.
doi: 10.1038/mtna.2012.47.

Lentiviral vector gene transfer to porcine airways

Patrick L Sinn  1 , Ashley L Cooney, Mayumi Oakland, Douglas E Dylla, Tanner J Wallen, Alejandro A Pezzulo, Eugene H Chang, Paul B McCray Jr
Affiliations

Lentiviral vector gene transfer to porcine airways

Patrick L Sinn et al. Mol Ther Nucleic Acids. .

Abstract

In this study, we investigated lentiviral vector development and transduction efficiencies in well-differentiated primary cultures of pig airway epithelia (PAE) and wild-type pigs in vivo. We noted gene transfer efficiencies similar to that observed for human airway epithelia (HAE). Interestingly, feline immunodeficiency virus (FIV)-based vectors transduced immortalized pig cells as well as pig primary cells more efficiently than HIV-1-based vectors. PAE express TRIM5α, a well-characterized species-specific lentiviral restriction factor. We contrasted the restrictive properties of porcine TRIM5α against FIV- and HIV-based vectors using gain and loss of function approaches. We observed no effect on HIV-1 or FIV conferred transgene expression in response to porcine TRIM5α overexpression or knockdown. To evaluate the ability of GP64-FIV to transduce porcine airways in vivo, we delivered vector expressing mCherry to the tracheal lobe of the lung and the ethmoid sinus of 4-week-old pigs. One week later, epithelial cells expressing mCherry were readily detected. Our findings indicate that pseudotyped FIV vectors confer similar tropisms in porcine epithelia as observed in human HAE and provide further support for the selection of GP64 as an appropriate envelope pseudotype for future preclinical gene therapy studies in the porcine model of cystic fibrosis (CF).Molecular Therapy - Nucleic Acids (2012) 1, e56; doi:10.1038/mtna.2012.47; published online 27 November 2012.

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Figures

Figure 1
Figure 1
Transduction patterns of HIV- and FIV-based vectors. (a) Schematics of FIV and HIV transgene vectors expressing GFP are shown. ΨPackaging signal. (b) VSVG-pseudotyped HIV, FIV, N-MLV, and B-MLV expressing GFP were applied to human (HeLa), cow (MDBK), or pig (PK1) cell lines at an MOI = 0.5, 1, and 5 to examine transduction efficiency. Pig primary airway epithelia (PAE) were transduced with MOI = 5 and 20. GFP-positive cells were counted 4 days post-transduction by FACS. n = 4. (c) HIV-1 or FIV lentiviral vectors were applied at the same MOI to four airway-derived cell lines and the HeLa cervical adenocarcinoma cell line. Transduction efficiencies were measured by FACS analysis of GFP-positive cells and data normalized to HIV-1 efficiency. Data are presented as the mean ± SE, n = 6. B-MLV, B-tropic murine leukemia virus; CMV, cytomegalovirus; eGFP, enhanced green fluorescent protein; FACS, fluorescence-activated cell sorting; FIV, feline immunodeficiency virus; MOI, multiplicity of infection; N-MLV, N-tropic murine leukemia virus; VSVG, vesicular stomatitis virus G protein.
Figure 2
Figure 2
Species-specific restriction. (a) Total RNA was isolated from PK1 and PAE and mRNA levels of pig TRIM5α were determined using reverse transcription-PCR. The levels were normalized to pig GAPDH. (b) Protein expression of HA-tagged TRIM5α, or an HA-tagged VP35 positive control, was determined by western blot using an anti-HA antibody. (c) VSVG-pseudotyped HIV, FIV, N-MLV, or B-MLV expressing GFP (MOI = 5) were applied to HT1080 cells transiently transfected with empty plasmid or pig TRIM5α. Transduction efficiencies were measured as percentage of GFP-positive cell 48 hours after the transduction using flow cytometry. *P < 0.005, n = 3. (d) Silencing of porcine TRIM5 was confirmed by transfecting PK1 cells with 10 nmol/l of siRNA against porcine TRIM5 and compared with negative control siRNA (10 nmol/l). *P < 0.001. (e) Twenty-four hours after siRNA transfection, PK1 cells were transduced with VSVG-pseudotyped HIV, FIV, N-MLV, and B-MLV expressing GFP (MOI = 5); 48 hours after the transduction, transduction efficiencies were measured as percentage of GFP-positive cell using flow cytometry. *P < 0.01, n = 3. (f) MDTF cell lysates probed with an anti-HA antibody or α-tubulin demonstrate that all stably transduced cell lines express equivalent levels of TRIM5α. (g) The indicated stably transfected MDTF cells were transduced with B-MLV, N-MLV, or FIV at an MOI yielding 30–40% GFP-positive cells on parental MDTF cells. Percent transduction is normalized to parental control MDTF cells. Bars indicate means ± SE (n = 12). α-HA, α-hemaglutinin; B-MLV, B-tropic murine leukemia virus; FIV, feline immunodeficiency virus; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; GFP, green fluorescent protein; MDTF, Mus dunni tail fibroblast; MOI, multiplicity of infection; N-MLV, N-tropic murine leukemia virus; PAE, primary airway epithelium; siRNA, small-interfering RNA; VSVG, vesicular stomatitis virus G protein.
Figure 3
Figure 3
Envelope glycoprotein screen. FIV expressing secreted luciferase was pseudotyped with the indicated envelope glycoproteins and applied to the apical surface of HAE or PAE at an MOI of 30. Washings were collected at 1-, 3-, and 6-week timepoints and expression was quantified by luciferase assay. Each bar represents one culture each from four independent human or pig specimens. FIV, feline immunodeficiency virus; HAE, human airway epithelium; MOI, multiplicity of infection; PAE, primary airway epithelium; RLU, relative light units; VSVG, vesicular stomatitis virus G protein.
Figure 4
Figure 4
In vitro transduction of primary cultures. GP64-FIV expressing mCherry was applied to the apical surface of (a) porcine airway epithelia (PAE) at an MOI of 150. Bar = 100 µm. Cells were counterstained with β-tubulin (cilia marker, green) and To-Pro 3 (nuclei, blue). Bar = 20 µm. Using fluorescence microscopy expression was confirmed in both ciliated, white arrow, and nonciliated cells, yellow arrow ((b) en face view; (c) vertical section). (d) Primary cultures were transduced with GP64-FIV or VSVG vector applied to the apical (Ap) or basolateral (BL) surface. Four days after initial vector incubation, cells were harvested and the β-galactosidase activity was quantified and normalized to total protein. Each bar represents one culture each from four independent human or pig specimens. *P < 0.01; **P < 0.00001. PAE cells were transduced with GP64-FIV expressing firefly luciferase. (e) Persistence of expression was followed using bioluminescent imaging. Representative cultures are shown, inset. n = 4. (f) GP64-FIV or GP64-VSV expressing firefly luciferase were applied to the apical surface of PAE derived from the trachea or septa. n = 4. Well-differentiated PAE isolated from nasal (g,h) septa and (i,j) trachea of pigs were imaged using scanning electron microscopy. Representative ciliated (c) or nonciliated cells (nc) are indicated. Bars = 100 µm (in g,i) or 20 µm (in h,j). HAE, human airway epithelium; MOI, multiplicity of infection; RLU, relative light units; VSVG, vesicular stomatitis virus G protein.
Figure 5
Figure 5
In vivo gene transfer to the porcine lung. (a) Using a bronchoscope, GP64-FIV was delivered to the tracheal lobe of 4-week-old pigs. A bolus volume was delivered to the pig airways through a wedged catheter. Lungs were examined 1 week later by fluorescence microscopy ((c) low power; (d) high power). (b) Serial sections were H&E stained. (e) A separate cohort of pigs received a bolus volume of GP64-FIV delivered through a drug infusion balloon. As before, lungs were examined 1 week later by fluorescence microscopy ((g) low power; (h) high power) and (f) serial sections were H&E stained. Bars = 50 µm. H&E, hematoxylin and eosin.
Figure 6
Figure 6
Ethmoid sinus in vivo gene transfer. (a) GP64-FIV expressing mCherry was delivered to mice via nasal instillation (7 doses over 7 days, 1 dose/day). One week later, the septa were collected and the epithelia were cultured. mCherry was visualized by fluorescence microscopy. One dose of GP64-FIV expressing mCherry was delivered to the ethmoid sinus of pigs. One week later, (b) the transduced sinus and the (c) contralateral sinus were collected, cultured, and visualized by fluorescence microscopy. Bars = 100 µm. (d) GP64-FIV expressing mCherry (2 ml total volume in 1% methylcellulose) was delivered to the ethmoid sinus. n, nasal opening; s, septal bone; b, brain. (e) The ethmoid sinus was visualized with a rigid fiber optic endoscope. One week following vector delivery, the ethmoid sinus was removed, fixed, frozen, and sectioned. (f,g) mCherry expression (red) was visualized by fluorescence microscopy. Tissues were co-stained with DAPI nuclear stain (blue). Bars = 50 µm. DAPI, 4',6-diamidino-2-phenylindole.
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