Unlike its reported role in promoting virus-specific cytotoxic responses in HIV-1 disease7, 8, 9, 10, 11, 12, the activity of IL-21 in suppressing initial HIV-1 infection in CD4 T cells was independent of cytotoxic CD8, NK and NK T cells but dependent on cell-intrinsic miR-29 species, which suppress HIV-1 production and infectivity17, 18. This evidence concerns the gene CD4 and HIV-1 infection.