The feline immunodeficiency virus vif gene is required for productive infection of feline peripheral blood mononuclear cells and monocyte-derived macrophages

The role of the feline immunodeficiency virus (FIV) vif gene in establishin g productive infection in feline peripheral blood mononuclear cells (PBMCs) and monocyte-derived macrophages (MDMs) was examined in cell culture syste ms. A 375-bp deletion was introduced into the vif gene of the wild-type FIV -pPPR infectious molecular clone to produce Vif deletion mutant FIV-pPPR De lta vif. This mutant FIV proviral construct expressed FIV proteins p24gag a nd gp100env in transfected Crandell feline kidney cells as measured by immu noprecipitation and Western blot analysis as well as immunocytochemical ana lysis; these cultures produced very low levels of virus by cocultivation of transfected cells with PBMCs and K-258 cells, as measured by production of p24gag. Replication kinetics of wild-type and vif-deleted virus were compa red in PBMCs and monocyte-derived macrophages (MDMs) by infection with cell -free virus preparations. Similar to findings with other lentiviruses, the vif gene was found to be essential for establishment of productive FIV infe ction in both PBMCs and MDMs. This study indicates that vif is essential fo r productive FIV infection of host target cells in vitro and that FIV-pPPR Delta vif may be an excellent candidate viral mutant for attenuated virus v accine studies. (C) 1999 Academic Press.