CASP3 and infection: Whereas E11 infection of immunocompetent and IFNAR-/- animals exhibited no cleaved caspase-3 staining as assessed by immunohistochemistry, E11-infected hFcRnTg32-IFNAR-/- adults (Black arrows, Fig 5B) and suckling mice (S2E Fig) exhibited pronounced positive cleaved caspase-3 staining.