Susceptibility of WT and DKO mice to influenza virus A infection. WT (n = 25), Het (n = 34), and DKO (n = 29) mice were infected intranasally with 2,000 EID50 of PR8. Mice were monitored daily for weight loss (A) and survival (B). *, P < 0.04, log-rank Mantel-Cox test. Data are from three independent experiments (mean and SEM).