We therefore analyzed the expression and function of CD160 and PD-1 on CMV and HIV-specific CD8 T cells during different stages of infection and identified 4 functionally distinct subsets of CD8 T cells (CD160−PD-1−, CD160−PD-1+, CD160+PD-1−, CD160+PD-1+). The gene discussed is CD8A; the disease is infection.