Transfection and dual-luciferase reporter (DLR) assays.

HFF cells and L929 cells were transfected with Lipofectamine LTX (Invitrogen, CA, USA) according to the manufacturer’s recommendations. HEK293T cells were transfected with reporter plasmids, such as IFN-β-Luc and internal control plasmid pRL-TK, with or without expression plasmids, as indicated, by Lipofectamine 2000 (Invitrogen, CA, USA). At 24 h posttransfection, luciferase assays were performed with a dual-specific luciferase assay kit (Promega, Madison, WI) as described in our previous studies (24, 41).