Tryptophan 95, an amino acid residue of the caprine arthritis encephalitisvirus Vif protein which is essential for virus replication

The Caprine arthritis encephalitis virus (CAEV) vif gene was demonstrated t o be essential for efficient virus replication. CAEV Vif deletion mutants d emonstrated an attenuated replication phenotype in primary goat cell cultur es and resulted in abortive infection when inoculated into goats. In this s tudy, we determined the in vitro replication phenotype of five CAEV Vif poi nt mutant infectious molecular clones and the ability of the corresponding in vitro translated Vif proteins to interact with the CAEV Pr55(gag) in the glutathione S-transferase (GST) binding assay. Here we show that (i) three of the mutants (S170E, S170G, S197G) behaved as the wild-type CAEV accordi ng to virus replication and Vif-Gag interactions; (ii) one mutant (Vif smut ) was replication incompetent and bound weakly to GST-Gag fusion proteins; and (iii) one mutant (Vif RG) was impaired for replication while retaining its interaction properties. This mutant points out the critical importance of the CAEV Vif tryptophan residue at position 95 for efficient virus repli cation, defining for this lentivirus a functional domain unrelated to the G ag binding region, (C) 2001 Academic Press.