S protein-derived epitopes of SARS-CoV elicited recall CD8+ T cell secretion of IFN-γ as well as intracellular production of IFN-γ, TNF-α, perforin, and granzyme A from recovered patients over 1-year post infection, indicating that SARS-CoV infection can induce strong and long-lasting cytotoxic T lymphocyte (CTL)-mediated immunity in patients (75, 76). This evidence concerns the gene TNF and infection.