CD4 and HIV infectious disease: Additionally, we found a positive correlation between PB gut homing CD4+ T and CD8+ T cell activation and pVL in the ART naive group (r = 0.51, p = 0.02; Fig 4D and r = 0.65, p = 0.003; Fig 4E respectively), indicating that active viral replication is responsible to gut homing T cell activation in HIV infection.