In some chronic infections where high pathogen loads persist, such as HIV and LCMV, chronic stimulation leads to functional impairment or exhaustion of CD8+ T cells, and production of IL-10, which slows clearance of the pathogen [20], while in other infections, such as HCV, virus-specific CD8+ memory T cells actually accumulate [9], [21]. The gene discussed is CD8A; the disease is infection.