Use of Heterologous Vesiculovirus G Proteins Circumvents the Humoral Anti-envelope Immunity in Lentivector-Based In Vivo Gene Delivery.

Vesicular stomatitis virus Indiana strain glycoprotein (VSVind.G) mediates broad tissue tropism and efficient cellular uptake. Lentiviral vectors (LVs) are particularly promising, as they can efficiently transduce non-dividing cells and facilitate stable genomic transgene integration; therefore, LVs have an enormous untapped potential for gene therapy applications, but the development of humoral and cell-mediated anti-vector responses may restrict their efficacy. We hypothesized that G proteins from different members of the vesiculovirus genus might allow the generation of a panel of serotypically distinct LV pseudotypes with potential for repeated in vivo administration. We found that mice hyperimmunized with VSVind.G were not transduced to any significant degree following intravenous injection of LVs with VSVind.G envelopes, consistent with the thesis that multiple LV administrations would likely be blunted by an adaptive immune response. Excitingly, bioluminescence imaging studies demonstrated that the VSVind-neutralizing response could be evaded by LV pseudotyped with Piry and, to a lesser extent, Cocal virus glycoproteins. Heterologous dosing regimens using viral vectors and oncolytic viruses with Piry and Cocal envelopes could represent a novel strategy to achieve repeated vector-based interventions, unfettered by pre-existing anti-envelope antibodies.