IRF-3−/− mice also averaged significantly higher viral titers than wild-type mice in the brain on days 6, 8, and 10 after infection (20-fold, p < 0.0001; ∼200-fold, p < 0.0001; and 10-fold, p < 0.005, respectively), which corresponded with increased morbidity and mortality (Figure 1F). This evidence concerns the gene IRF3 and infection.