In murine models of viral infection, NK cells have been shown to lyse DCs as well as CD4+ and CD8+ T cells in a perforin-dependent manner (Andrews et al., 2010, Waggoner et al., 2012, Lang et al., 2012), whilst in vitro, NK cells induce neutrophil apoptosis by death receptor ligation, which requires recognition of an as of yet unidentified ligand on the neutrophil surface by the NCR NKp46 (Thoren et al., 2012). This evidence concerns the gene CD4 and viral infectious disease.