Envelope proteins of spleen necrosis virus form infectious human immunodeficiency virus type 1 pseudotype vector particles, but fail to incorporate upon substitution of the cytoplasmic domain with that of Gibbon ape leukemia virus

The wild-type (wt) envelope (Env) proteins of spleen necrosis virus (SNV), together with the transmembrane (TM) protein fused to antibody domains (scFv), have been used for the generation of stable packaging cell lines releasing pseudotyped cell targeting vectors derived from SNV and Murine leukemia virus (MLV). As a first step towards assessing whether HIV-1 (SNV/TM-scFv) packaging cells could be established for the production of lentiviral cell targeting vectors, it is reported here that infectious HIV-1-derived particles pseudotyped with wt SNV Env proteins could be generated. Using novel chimeric SNV-derived Env proteins encompassing wt and engineered cytoplasmic domains (C-tail) of the Gibbon ape leukemia virus (GaLV) TM protein, it was further shown that the wt C-tail not only excludes the GaLV TM protein from incorporation into HIV-1 particles, but confers this phenotype to other retroviral envelopes upon C-terminal fusion.