STAT1 and infection: First, MNV infection in wild-type mice is largely asymptomatic, in contrast to Stat1-/- or types I and II IFN receptors-deficient (IFNαβγR-/-) mice, in which infection is accompanied by a considerable increase in viral RNA and causes severe symptoms, significant multi-organ pathology, and death in all infected mice within 2 weeks of infection [51, 86].