While the inflammatory milieu in the gut during SIV infection has been proposed to directly drive RORγt repression and apoptosis in ILC3 [25,26], a recent study has suggested that CD4+ T cell deficiency, compounded with dextran sodium sulfate (DSS)-induced gastrointestinal damage, is associated with the loss of ILC3 in the mesenteric lymph nodes of uninfected macaques [27]. Here, CD4 is linked to congenital T-cell immunodeficiency.