Lentiviral vectors pseudotyped with a modified RD114 envelope glycoprotein show increased stability in sera and augmented transduction of primary lymphocytes and CD34+ cells derived from human and nonhuman primates

Generating lentiviral vectors pseudotyped with different viral glycoproteins (GPs) may modulate the physicochemical properties of the vectors, their interaction with the host immune system, and their host range. We have investigated the capacity of a panel of GPs of both retroviral (amphotropic murine leukemia virus [MLV-A]; gibbon ape leukemia virus [GALV]; RD114, feline endogenous virus) and nonretroviral (fowl plague virus [FPV]; Ebola virus [EboV]; vesicular stomatitis virus [VSV]; lymphocytic choriomeningitis virus [LCMV]) origins to pseudotype lentiviral vectors derived from simian immunodeficiency virus (SIVmac251). SIV vectors were efficiently pseudotyped with the FPV hemagglutinin, VSV-G, LCMV, and MLV-A GPs. In contrast, the GALV and RD114 GPs conferred much lower infectivity to the vectors. Capitalizing on the conservation of some structural features in the transmembrane domains and cytoplasmic tails of the incorporation-competent MLV-A GP and in RD114 and GALV GPs, we generated chimeric GPs encoding the extracellular and transmembrane domains of GALV or RD114 GPs fused to the cytoplasmic tail (designated TR) of MLV-A GP. Importantly, SIV-derived vectors pseudotyped with these GALV/TR and RD114/TR GP chimeras had significantly higher titers than vectors coated with the parental GPs. Additionally, RD114/TR-pseudotyped vectors were efficiently concentrated and were resistant to inactivation induced by the complement of both human and macaque sera, indicating that modified RD114 GP-pseudotyped lentiviral vectors may be of particular interest for in vivo gene transfer applications. Furthermore, as compared to vectors pseudotyped with other retroviral GPs or with VSV-G, RD114/TR-pseudotyped vectors showed augmented transduction of human and macaque primary blood lymphocytes and CD34+ cells.