Improved adenovirus type 5 vector-mediated transduction of resistant cells by piggybacking on coxsackie B-adenovirus receptor-pseudotyped baculovirus

Taking advantage of the wide tropism of baculoviruses (BVs), we constructed a recombinant BV (BVCAR) pseudotyped with human coxsackie B-adenovirus receptor (CAR), the high-affinity attachment receptor for adenovirus type 5 (Ad5), and used the strategy of piggybacking Ad5-green fluorescent protein (Ad5GFP) vector on BVCAR to transduce various cells refractory to Ad5 infection. We found that transduction of all cells tested, including human primary cells and cancer cell lines, was significantly improved using the BVCAR-Ad5GFP biviral complex compared to that obtained with Ad5GFP or BVCARGFP alone. We determined the optimal conditions for the formation of the complex and found that a high level of BVCAR-Ad5GFP-mediated transduction occurred at relatively low adenovirus vector doses, compared with transduction by Ad5GFP alone. The increase in transduction was dependent on the direct coupling of BVCAR to Ad5GFP via CAR-fiber knob interaction, and the cell attachment of the BVCAR-Ad5GFP complex was mediated by the baculoviral envelope glycoprotein gp64. Analysis of the virus-cell binding reaction indicated that the presence of BVCAR in the complex provided kinetic benefits to Ad5GFP compared to the effects with Ad5GFP alone. The endocytic pathway of BVCAR-Ad5GFP did not require Ad5 penton base RGD-integrin interaction. Biodistribution of BVCAR-Ad5Luc complex in vivo was studied by intravenous administration to nude BALB/c mice and compared to Ad5Luc injected alone. No significant difference in viscerotropism was found between the two inocula, and the liver remained the preferred localization. In vitro, coagulation factor X drastically increased the Ad5GFP-mediated transduction of CAR-negative cells but had no effect on the efficiency of transduction by the BVCAR-Ad5GFP complex. Various situations in vitro or ex vivo in which our BVCAR-Ad5 duo could be advantageously used as gene transfer biviral vector are discussed.