Single residue mutation in integrase catalytic core domain affects feline foamy viral DNA integration.

DD(35)E motif in catalytic core domain (CCD) of integrase (IN) is extremely involved in retroviral integration step. Here, nine single residue mutants of feline foamy virus (FFV) IN were generated to study their effects on IN activities and on viral replication. As expected, mutations in the highly conserved D107, D164, and E200 residues abolished all IN catalytic activities (3'-end processing, strand transfer, and disintegration) as well as viral infectivity by blocking viral DNA integration into cellular DNA. However, Q165, Y191, and S195 mutants, which are located closely to DDE motif were observed to have diverse levels of enzymatic activities, compared to those of the wild type IN. Their mutant viruses produced by one-cycle transfection showed different infectivity on their natural host cells. Therefore, it is likely that effects of single residue mutation at DDE motif is critical on viral replication depending on the position of the residues.