The mechanism of this effect may involve that the viral genome is delivered into the cell in a ribonucleoprotein complex composed largely of Gag after infection, so that Gag epitopes can be processed, presented on the cell surface and finally recognized by Gag-specific CD8+ T cells within a few hours of infection before Nef-mediated down-regulation takes place [18–20]. This evidence concerns the gene CD8A and infection.