Quantification and statistical analysis

Figures were generated using GraphPad Prism 7. Data are shown as mean values ± SEM as indicated in the figure legends. Data were log-transformed and assessed for normality, and then a one-way analysis of variance (ANOVA) with Sidek’s or Tukey’s multiple comparison test or Student’s t test was performed. To compare survival after challenge, groups were compared using Fisher’s exact test. The statistical tests performed on the data are indicated in the figure legends and results, along with sample size indicating the number of animals used. *P < 0.05, **P < 0.01, ***P < 0.001, or ****P < 0.0001 was considered statistically significant.