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Divergent CD4+ T Memory Stem Cell Dynamics in Pathogenic and Nonpathogenic Simian Immunodeficiency Virus Infections

Recent studies have identified a subset of memory T cells with stem cell-like properties (TSCM) that include increased longevity and proliferative potential. In this study, we examined the dynamics of CD4+ TSCM during pathogenic SIV infection of rhesus macaques (RM) and nonpathogenic SIV infection of sooty mangabeys (SM). Whereas SIV-infected RM show selective numeric preservation of CD4+ TSCM, SIV infection induced a complex perturbation of these cells defined by depletion of CD4+CCR5+ TSCM, increased rates of CD4+ TSCM proliferation, and high levels of direct virus infection. The increased rates of CD4+ TSCM proliferation in SIV-infected RM correlated inversely with the levels of central memory CD4+ T cells. In contrast, nonpathogenic SIV infection of SM evidenced preservation of both CD4+ TSCM and CD4+ central memory T cells, with normal levels of CD4+ TSCM proliferation, and lack of selective depletion of CD4+CCR5+ TSCM. Importantly, SIV DNA was below the detectable limit in CD4+ TSCM from 8 of 10 SIV-infected SM. We propose that increased proliferation and infection of CD4+ TSCM may contribute to the pathogenesis of SIV infection in RM.