This was apparent as early as 3 days post-infection, when swelling at the infection site was greater in IFNαR-/- mice (Fig 1C), and progressed to produce a larger VACV lesion (Fig 1D), greater tissue loss (Fig 1E) and overall tissue damage (lesion size + tissue loss) (Fig 1F) in IFNαR-/- mice. This evidence concerns the gene IFNAR1 and infection.