We also found that compared to B6→ B6 and B6→ Ifnar1-/- mice, the viral loads in Ifnar1-/-→ B6 and Ifnar1-/-→ Ifnar1-/- mice were increased 10-fold at 5 days post-infection (dpi) in the spleen (Fig 1C) and 100-fold in the liver and the spleen at 7 dpi (Fig 1D). This evidence concerns the gene IFNAR1 and infection.