During HIV-1 infection, PD1 is highly expressed by exhausted dysfunctional HIV-1-specific T cells [159], and blockade of PD1-PDL1 interaction enhances HIV-1-specific T cell immunity and immune-mediated control of viraemia in humanized mice and simian models of HIV-1 infection [160–164]. The gene discussed is CD274; the disease is HIV-1 infection.