Fig. 3.

Blockade of dsRNA-induced IFN-β expression in HCV-infected cells. (A) HCV blocks dsRNA-induced IFN-β promoter activation. Huh-7 cells were infected with JFH-1 at moi = 0.2. On day 4 postinfection, cells were cotransfected with the IFN-β promoter luciferase reporter plasmid, an internal control plasmid pRL-TK, and a carrier plasmid pcDNA3.1. Thirty-six hours later, cells were transfected with or without poly(IC). Cells were subjected to dual luciferase assay 16 h after transfection. The results are expressed as fold induction of IFN-β promoter activity relative to the basal level. (B) HCV blocks dsRNA-induced ISRE promoter activation. The experiment was performed the same as in A, except that the ISRE promoter luciferase reporter plasmid was used. (C) HCV does not block IFN-induced JAK-STAT signaling. Similar to B, cells were transfected with the ISRE promoter reporter plasmid and then incubated with 100 units per ml of human IFN-β for 16 h before dual luciferase assay.