Effect of sfRNA on viral translation in cultured cells and in vitro. A. A diagram of the JEV minicon RNA is shown. B. JEV minicon RNAs were transcribed in vitro without or with capped analog and then transfected alone (-) or cotransfected with (+)sfRNA, (-)sfRNA, or control RNA (cRNA). The Renilla luciferase activity of cell lysates was determined at 8 h posttransfection. C. Renilla luciferase assays of JEV minicon RNA translated in rabbit reticulocyte lysate in the presence of (+)sfRNA, (-)sfRNA or control RNA. D. The effect of different amounts of (+)sfRNA or (-)sfRNA on in vitro translation of minicon RNA in rabbit reticulocyte lysate. The Renilla luciferase activity of cell lysate with five different treatments is shown. *** represents P < 0.005 in comparison with capped JEV minicon only.