Figure 2.

Innate immune response correlates of virus restriction to the periphery. F1 crosses of Collaborative Cross strains were grouped into peripheral restriction (PR) and neuroinvasion, no disease (NND) categories as defined in “Results” and Table 1. Cohorts of mice were infected with 100 plaque-forming units of West Nile virus (WNV) by subcutaneous injection in the rear footpad. At the indicated times after infection, age-matched male mice were euthanized, and spleens and brains were harvested and prepared for quantitative real-time polymerase chain reaction analysis to quantify the WNV load (A) and Ifit1 (B), Ifitm1 (C), Ifnb (D), and Il12 (E) expression. Statistical significance at each time point was determined by the unpaired t test. *P ≤ .05, **P ≤ .01, ***P ≤ .001, and ****P ≤ .0001.