Virus-specific effector CD8+ cytotoxic T cells also produce high levels of immune effector cytokines, such as IFN-γ, TNF-α, and IL-2; chemokines, such as chemokine (C-X-C motif) ligand-9 and -10 (CXCL-9 and -10); and cytotoxic granules, mainly perforin and granzyme B, after the virus peptide is recognized on target cells at the site of infection (51–54). The gene discussed is CD8A; the disease is infection.