Of note, the levels of CD4+ and CD8+ T cells were decreased in PR8-HK6 infected Daf-/- mice when compared to their WT counterparts (57.5±26.2% vs. 100±35.9% CD4+ T cells and 49.3±36.7% vs. 100±50.5% CD8+ T cells) (Fig 7E and 7F), contrarily to what was seen in PR8-HK4,6 infection (Fig 4G and 4H) and showing that HA-DAF interaction may be implicated in modulating the adaptive immune response. This evidence concerns the gene CD4 and infection.