However, IFNγ may enhance HIV-1 infection [60], a finding that stands in conflict with preclinical vaccine trials in macaques, where the durable and sustained suppression of viral load and lack of disease progression were positively associated with increased SIV-specific IFNγ CD4+ [61] and CD8+ [61,62,63] T-cell responses. This evidence concerns the gene CD4 and HIV-1 infection.