Il17a−/− mice are more susceptible to WNV infection. Seven- to 9-week-old WT (C57BL/6J) and Il17a−/− mice were infected with WNV via the i.p. (1,000 PFU) or footpad (100 PFU) route and monitored for mortality twice daily for 21 days; survival percentages were compared using the Kaplan-Meier survival and log-rank tests. (A and B) Survival curves after i.p. inoculation (A) and footpad inoculation (B). (C to F) In i.p.-inoculated mice, qPCR was performed to measure WNV-E RNA in blood (C), liver (D), brain (E), and spleen (F), with viral burdens expressed as the ratio of WNV-E RNA copies to cellular β-actin transcripts. The ratios of viral loads between WT and Il17a−/− mice (means and SEM) were compared by two-tailed Student t tests; ns, no significant difference (P > 0.05).