Systemic replication of LCMV is inhibited by IFN-I produced by hematopoietic cells. (A) WT mice, irf7^−/− mice, and BM chimeras (WT-BM > WT, WT-BM > irf7^−/−, irf7^−/−-BM > WT and irf7^−/−-BM > irf7^−/−) were infected with 200 PFU LCMV. After 4 days, viral titers were analyzed (n = 4-5). (B) WT mice, WT mice depleted of CD8⁺ T cells and NK cells, and Rag^−/− mice depleted of NK cells were infected with 200 PFU LCMV-WE intravenously. Virus titers were analyzed in spleen liver, lung, and kidney 3 days after infection. (C) MC57 cells were treated with different concentrations of IFN-α and then infected with VSV or LCMV (MOI 0.001). After 6, 12, and 24 hours, infectious virus was analyzed in the supernatant.