Fig 3.

Kinase activity is required for US3-mediated inhibition of IFN-β production. (A) HEK 293T cells were cotransfected with PRL-TK plasmid and either IFN-β-Luc, (pRDIII-I)4-Luc, or ISRE-Luc reporter plasmid along with empty vector or plasmid encoding US3 WT, US3 K220M, or US3 D305A. Twenty-four hours posttransfection, cells were infected with 100 HAU/ml of SeV or mock-infected, and luciferase activity was analyzed as described in the legend to Fig. 1A. IB, immunoblot. (B and C) HEK 293T cells were transfected with empty vector or plasmid encoding US3 WT, US3 K220M, or US3 D305A. Twenty-four hours posttransfection, cells were infected with 100 HAU/ml of SeV or mock-infected for 16 h. (B) Quantitative PCR analysis was performed to detect the mRNA levels of IFN-β, ISG54, and ISG56. Data are means and standard deviations from three independent experiments. Statistical analysis was performed using the Student t test. *, P < 0.05. (C) Native PAGE assays were performed to detect IRF3 dimerization as described in the legend to Fig. 2F.