RETROVIRAL PSEUDO-VIRUS CARRYING THE ENVELOPE PROTEINS OF NEUROTROPICFRIEND MURINE LEUKEMIA-VIRUS EFFECTIVELY TRANSFERRED RETROVIRAL VECTOR INTO GLIAL-CELLS

We isolated the neurotropic Friend murine leukemia virus, FrC6 and its molecular clone A8, which proliferated in rat glial cell lines in vit ro and in the rat brain in vivo. To investigate the contribution of vi ral envelope proteins to the neurotropism of A8 virus, the retroviral pseudo-virus carrying the envelope proteins of A8 virus and Moloney mu rine leukemia virus (MoMLV) was produced by transfecting the env gene of A8 virus (A8env) in the MoMLV based packaging cell, psi CRE. The ph enotypically mixed pseudo-virus infected the rat glial cell lines as w ell as NIH 3T3 cells, whereas the psi CRE-produced pure pseudo-virus w ithout A8env expression infected the glial cells at lower efficiency. Furthermore, the psi CRE cells with A8env expression produced pseudo-v irus at a higher titer than normal psi CRE cells. The infectivity of t he phenotypically mixed pseudo-virus to the glial cells was abolished by a neutralizing antibody against A8 virus, which did not reduce the ability of the psi CRE-produced pure pseudo-virus to infect NIH 3T3 ce lls. These results indicated that the envelope protein of A8 virus is assembled into the pseudo-viral particles and that it contributes to g lial cell infection by the AS virus.