IMMUNOGENIC DETERMINANTS OF A NEUROPATHOGENIC MURINE LEUKEMIA-VIRUS

Previous studies of Cas Br-M murine leukemia virus (MuLV) (Cas-MuLV) i nfection demonstrated that cytotoxic T cells (CTL) of the CD8(+) pheno type play a role in resistance to the neuropathogenic effects of the v irus in NFS/N mice, In the current study, we sought to identify the Ca s-MuLV epitopes that are immunogenic for the CTL response, Infection o f adult NPS/N mice with a well-characterized neuropathogenic variant o f Friend MuLV, PVC-211 MuLV (PVC-MuLV), was not immunogenic for MuLV-s pecific CTL. Therefore, we constructed chimeric viruses between Cas-Mu LV and PVC-MuLV. Infectious chimeras contained the Cas-MuLV env gene o n a PVC-MuLV background (PVC-Cas-(env)MuLV) and the PVC-MuLV env gene on a Cas-MuLV background (Cas-PVC(env)MuLV). Cas-MuLV-specific CTL wer e found following inoculation of both the chimeric viruses and the par ental Cas-MuLV but not the parental PVC-MuLV, despite evidence of anti body responses to both parental and chimeric MuLV, CTL generated in re sponse to infection with PVC-Cas(env)MuLV and Cas-PVC(env)MuLV were ex clusively of the CD8(+) phenotype. These results indicate that both th e env and gag-pol regions of Cas-MuLV express epitopes that are immuno genic for CTL.