Therefore, we speculate that in our experimental setting, chronic morphine administration may dampen the T cell activation, suppress their metabolic activity, and cause a reduction in seeding of SIV in CD4+ T cells during acute stage of infection before initiation of cART, which may result in a smaller size of persistent latent SIV reservoirs in CD4+ T cells of morphine-administered animals than in control macaques that received saline. Here, CD4 is linked to infection.