By day 10 after infection/vaccination, equivalent sized populations of NP-tetramer+ CD8+ T cells were observed in both the mLN and spleen of both cohorts; however, the number of NP-tetramer+ cells in the lung of influenza virus–infected animals now exceeded the numbers present in the respiratory tissue of the vaccinated cohort (Fig. 1, B, D, and E). The gene discussed is CD8A; the disease is infection.