FIG 9.

Effects of mutations introduced into CE(NiP)ΔP2-5 on the activities of P1 as an IFN antagonist and a cofactor of viral RNA polymerase in muscle cells. (A) IFN-β promoter-reporter assay to compare the activities of P1s of CE(NiP) and CE(NiP)ΔP2-5 to suppress IFN induction. G-8 cells were transfected with an empty plasmid, pCAGGS-P1, or pCAGGS-P1ΔP2-5, together with the reporter plasmid IFNB-pGL3. The cells were transfected with poly(I·C) at 24 h posttransfection and incubated for 6 h. Cell lysates then were prepared and used to measure luciferase activities. (Bottom) P1s and tubulin in the cell lysates were detected by Western blotting. (B) Minigenome assay to compare polymerase cofactor activities of P1s of CE(NiP) and CE(NiP)ΔP2-5 in muscle cells. G-8 cells were transfected with an empty plasmid, pCAGGS-P1, or pCAGGS-P1ΔP2-5, together with plasmids expressing luciferase-based minigenome RNA and viral N and L proteins. At 48 h posttransfection, luciferase activities in cell lysates were measured. All assays were carried out in triplicate, and the values in the graph are shown as means ± standard errors of the means. *, Significant difference at a P value of <0.01; ns, not significant (P ≧ 0.05).