FIG 1.

HSV-1 VP22 inhibits IFN-β activation induced by cGAS/STING. (A) HEK293T cells were cotransfected with IFN-β promoter plasmid (IFN-β-Luc, 200 ng), Renilla luciferase (pRL-TK, 50 ng) reporter plasmid, cGAS-Flag (15 ng), and STING-HA (2.5 ng), along with empty vector (200 ng) or VP22-Flag plasmid (200 ng). Luciferase activity was measured 24 h posttransfection in the cell lysates. (B) HEK293T cells were cotransfected with cGAS-Flag and STING-HA, along with empty vector or VP22-Flag plasmid. At 24 h posttransfection, cells were harvested and subjected to qRT-PCR analysis. (C) Effects of VP22 deficiency on transcription of downstream antiviral genes. HFF cells were infected with WT (MOI = 1) or ΔVP22 (MOI = 1) virus for the indicated times before qRT-PCR analysis. (D and E) HFF cells were infected with WT or ΔVP22 virus at an MOI of 5 for 2 h, cell medium was then replaced by DMEM containing 10% FBS, and ISD (2 μg/ml) was transfected using Lipofectamine LTX according to the manufacturer's recommendations. Cells were harvested and subjected to qRT-PCR analysis at 7 h posttransfection (D) or ELISA analysis at 18 h posttransfection (E). (F and G) HFF cells were infected and transfected as described for panel D, and then cells were harvested at 7 h posttransfection and subjected to WB analysis to detect IRF3 phosphorylation (F) or native PAGE to detect IRF3 dimerization (G). The data represent results from one of triplicate experiments. Error bars represent the standard deviation of results of three independent experiments. Statistical analysis was performed using Student's t test with the GraphPad Prism 5.0 software. (*, 0.01 < P < 0.05; **, 0.001 < P < 0.01; ***, P < 0.001).