Although protection of CD4+ T cells from HIV-infection in vitro has been shown by the exogenous addition of MIP-1α, MIP-1β and RANTES to CD4+ T cells in culture [20]–[22], by the production of MIP-1α, MIP-1β and RANTES by CD8+ T cells cultured with CD4+ T cells [21],[23],[24], and by the production of MIP-1α, MIP-1β and RANTES by CD4+ T cells themselves [25],[26], little direct evidence exists showing that production of these chemokines actually protect CD4+ T cells from infection in vivo. The gene discussed is CD4; the disease is infection.