CD4 and infection: It is worth noting that a panel of interferon-stimulated genes (ISGs) were up-regulated by the V3 epitope, namely IFI6, IRF7, SP100 and IFRD1. The integral role of these ISGs in HIV pathogenesis is underpinned by studies that corroborate the observed transcriptional up-regulation in activated CD4+ T cells of untreated HIV-positive individuals (IFI6, IRF7) [39], in an HIV-infected CD4+ T cell population derived from human tonsils (IFI6, IRF7, SP100) [44] and in lymphatic tissue of HIV-1 positive individuals throughout all stages of infection (IFI6) [45].