As observed in human HIV infection, rhTIGIT expression was more prominently expressed in SIV infection on effector memory (EM, CD28-CD95+), and central memory (CM, CD28+CD95+) CD8+ T cells when compared to naïve (N, CD28+CD95-) CD8+ T cells from PBMCs, LN and from the spleen (S6C Fig). Here, CD28 is linked to HIV infectious disease.