BALB/c mice were intranasally infected with X31 virus and reinfected with NY-ESO-1 S-FLU (X31) or NY-ESO-1 S-FLU (PR8) on day 24 post infection, and NY-ESO-1- and NP-specific CD8+ T cell responses in lungs were analysed on day 7 post secondary infection by ex vivo stimulation with NY-ESO-1 CTL peptide 81-88(RGPESRLL) and NP tetramer staining, respectively. The gene discussed is CD8A; the disease is infection.