Replication levels of HSV-1 and VSV are markedly reduced in Ksrp−/− MEFs. (A and B) Ksrp+/+ and Ksrp−/− MEFs were infected with HSV-1 (MOI, 3). The levels of Ifna4 (A) and Ifnb (B) were analyzed by qRT-PCR. Values represent means ± standard errors of the means (n = 3; Ifna4, P < 0.05 at 3 h and P < 0.001 at 6 h; Ifnb, P < 0.005 at 3 h and P < 0.001 at 6 h). (C) IFNB levels in culture supernatants of Ksrp+/+ and Ksrp−/− MEFs were analyzed by ELISA 24 h after HSV-1 infection. Data are means ± standard errors of the means (n = 3; P < 0.03). (D) Reduced HSV-1 replication in Ksrp−/− MEFs. Ksrp+/+ and Ksrp−/− MEFs were infected with HSV-1 using different MOIs (1, 0.1, or 0.01). At 72 h after infection, viral production was analyzed by plaque assay. Data are means ± standard errors of the means of three independent experiments (MOI, 1 [P < 0.0001]; MOI, 0.1 [P < 0.0002]; MOI, 0.01 [P < 0.001]). (E) Reduced VSV replication in Ksrp−/− MEFs. Ksrp+/+ and Ksrp−/− MEFs were infected with VSV at an MOI of 0.2. At 24 h after infection, viral production was analyzed by plaque assay. Data are means ± standard errors of the means of three experiments (P < 0.004).