MUTATION OF AMINO-ACIDS WITHIN THE GIBBON APE LEUKEMIA-VIRUS (GALV) RECEPTOR DIFFERENTIALLY AFFECTS FELINE LEUKEMIA-VIRUS SUBGROUP-B, SIMIAN SARCOMA-ASSOCIATED VIRUS, AND GALV INFECTIONS

The three type C retroviruses, gibbon ape leukemia virus (GALV), simian sarcoma-associated virus (SSAV), and feline leukemia virus subgroup B (FeLV-B), infect human cells by interacting with the same cell surface receptor, GLVR1. Using LacZ retroviral pseudotypes and murine cells transfected with mutant GLVR1 expression vectors, we show that the same 9-amino-acid region of human GLVR1 is critical for infection by the three viruses. Rat cells were not susceptible to infection by LacZ (FeLV-B) pseudotypes because of a block at the receptor level. We found multiple amino acid differences from human GLVR1 in the 9-amino-acid critical region of rat GLVR1. Expression of a human-rat chimeric GLVR1 in murine cells demonstrated that rat GLVR1 could function as a receptor for GALV and SSAV but not for FeLV-B. Substitution of human GLVR1 amino acids in the critical region of rat GLVR1 identified three amino acids as responsible for resistance to FeLV-B infection; two of these affect SSAV infection, but none affects GALV infection.