Figure 1
From: Foot-and-mouth disease virus non-structural protein 3A inhibits the interferon-β signaling pathway
FMDV 3A protein inhibits the SeV-induced IFN-β signaling pathway.
(a,b) Effects of overexpression of FMDV nonstructural proteins on SeV-triggered IFN-β promoter or IRSE activation. HEK293T cells (5 × 104) were transfected with the IFN-β or ISRE reporter (0.1 μg), 10 ng of pRL-TK (as an internal control) and the indicated expression plasmids (0.1 μg) for 24 h. Cells were infected or uninfected with SeV for 12 h before luciferase assays were performed. (c) Effects of overexpression of FMDV proteins on IFNγ-triggered IRF1 activation. The experiments were similarly performed as in a. (d–f) FMDV 3A inhibits SeV- or IFNγ-induced activation of IFN-β, ISRE and IRF1 promoter in a dose-dependent manner. The experiments were similarly performed as in a. (g) FMDV 3A inhibits SeV-induced transcription of endogenous Ifnb, Cxcl-10, Isg56 and Rantes genes. HEK293T cells were transfected with 4 μg FMDV 3A or empty vector (EV) for 24 h followed by SeV infection for 12 h before a relative quantitative RT-PCR experiments were performed. (h) 3A inhibited the transcriptional level of the endogenous IFN-β mRNA in PK-15 cells. PK-15 (2 × 105) cells were transfected with 4 μg pMSCV-3A plasmid using lipofectamine 2000 for 12 h, subsequently treated with puromycin (1 mg/ml) for 24 h. Cells were then infected with the type O FMDV (moi: 0.1) for 6 h. IFN-β mRNA abundance in PK-15 cells was assessed using a relative quantitative RT-PCR. (i) Increased FMDV genome copies in 3A-transfected PK-15 cells. The experiments were similarly performed as in i. FMDV genome copies were assessed using a quantitative RT-PCR assay. (j,k) FMDV 3A inhibits phosphorylation and dimerization of IRF3 and the expression of RIG-I and MDA5 after SeV stimulation. HEK293T (2 × 105) cells were transfected with 4 μg the FMDV 3A plasmid or EV for 24 h. Cells were infected with SeV at various time points and then harvested for analysis by western blotting. Values are presented as mean ± SD of three independent experiments. Rel. Luc. Act., relative luciferase activity.
