Activated CD8+ T cells employ a number of cellular functions to control viral infections like cytolysis of the infected cells via the granule exocytosis pathway, the initiation of programmed cell death via Fas/FasL interaction and the expression of pro-inflammatory cytokines, such as IFN-γ, TNF-α, IL-2 and certain chemokines. The gene discussed is IFNG; the disease is viral infectious disease.