Figure 5. BL 5′-UAG-3′ element is important for EV71 RNA translation and replication. (A) Diagram of the bicistronic construct used in the dual luciferase assay. (B) Effect of CCC substitution on EV71 IRES activity. Cells were transfected with CMV-RLuc-EV71-5′UTR-FLuc or CMV-RLuc-EV71-5′UTR-CCC-FLuc RNA transcript as described in Materials and Methods. Relative luciferase activity was measured 2 d after transfection. Mean values and standard errors from triplicate samples are shown in the bar graph. (C) Replication of CCC mutant EV71 in RD cells. RD cells were infected with wild tpe or CCC mutant EV71 at an m.o.i. of 0.01 pfu/cell and incubated at 37°C. Medium was harvested at various times and assayed for infectious virus by plaque formation on RD cells. Mean values and standard errors from triplicate samples are shown.