It has generally been thought that viral and immune-cell mediated killing of CD4+ T cells and AICD accompanying chronic immune activation are respectively the major direct and indirect mechanisms of CD4+ depletion in HIV-1 infection, and that the slow and incomplete restoration of naïve CD4+ T cells is a consequence of the restricted capacity of the adult thymus to re-supply naive T cells [1]. Here, CD4 is linked to HIV-1 infection.