Hematopoietic-derived interferon is essential for the control of MHV and to limit hepatitis. WT mice, irf7^−/− mice, and BM chimeras (WT-BM > WT, WT-BM > irf7^−/−, irf7^−/−-BM > WT and irf7^−/−-BM > irf7^−/−) were infected with 50 plaque-forming units (PFU) MHV intraperitoneally. (A) After 2 days, viral titers were measured in the spleen, liver, lung, and blood (n = 4-5). (B) ALT levels were measured in the serum (n = 4-5).