Taken together, even though strong infectivity recoveries were evident in single round infections of cells completely lacking A3G or A3F or cells lacking A3F plus knocked-down A3D or A3G, the remaining endogenous A3s were still sufficient to restrict the spread of Vif-deficient virus (i.e., those A3s that were not manipulated by knockout or knockdown). Here, APOBEC3G is linked to infection.