A small amount of TSCM showed low expression of CCR5, which can be protected from HIV infection, but physiologically CD4+ TSCM expresses CCR5 (R5)- and CXCR4 (X4), which make them usual reservoirs for HIV, because silent or latent infection of these long-lived, self-renewing cells could provide an extremely stable niche for the virus which is modulated by SAMHD1 expression (132). This evidence concerns the gene CCR5 and disease arising from reactivation of latent virus.