Furthermore, given the concurrent expression of type I, II, and likely III IFNs during chronic MHV68 infection, it is impossible to define the combined effect of global IFN responses without eliminating the infected host acutely, as evidenced by the uniform and acute mortality of Stat1−/− mice infected with a low (100 PFU) dose of MHV68 (41). The gene discussed is IFNA1; the disease is infection.