It was found that even at the earliest stages of primary HIV-1 infection, Gag-specific CD4 T cells were dominated by expression of CLTA-4 (18), and it was found that in vitro blockade of CTLA-4 significantly increased CD4 T cell proliferation and improved cytokine secretion from HIV-specific CD4 T cells responding to cognate antigen (207). The gene discussed is CD4; the disease is HIV-1 infection.