Further supporting their roles in disease progression, IL-17 and IL-22 producing CD4+ T-cells have been shown to be relatively preserved in the gastrointestinal tracts of chronically SIV-infected sooty mangabeys (SMs) and African green monkeys [29,34,38,39], natural hosts of SIV infection that avoid microbial translocation, chronic immune activation and progression to AIDS, as well as in HIV controllers and long-term nonprogressors [40–42]. The gene discussed is CD4; the disease is AIDS.