Having identified a key correlation between IL-18Rα on activated CD44hiCD62Llo CD8 T cells in the lung (Fig. 4d) and morbidity at day 6 after infection in mice, and in patients hospitalized with respiratory viral diseases (Fig. 2), we further delved into the mechanisms underlying high levels of IL-18Rα on effector CD8 T cells following high dose influenza infection. This evidence concerns the gene CD8A and infection.