TurboFect transfection reagent (Fermentas) was used for transient transfection following the manufacturer's protocol. Cells cultured in 12-well plate were transfected with NF-kB-or IFN-b-Luc reporter plasmids [12, 25] . pRL-TK (Promega), encoding Renilla luciferase under an HSV thymidine kinase promoter, was used as an internal control. After transfection for 24 h, cells were infected with DENV-2; in some experiments, cells were further stimulated with LPS or polyI:C (both 1 mg/ml). Cell lysates were collected at the indicated times for dual-luciferase assays (Promega). Relative firefly luciferase activity was normalized to Renilla luciferase activity.