Fig 2.

The VP4 protein is mainly responsible for IBDV-induced suppression of type I interferon expression in HEK293T cells. (A) Expression of GFP-VP1, -VP2, -VP3, -VP4, or -VP5 fusion proteins in HEK293T cells. HEK293T cells were transfected with 5 μg of pEGFP-N1, pEGFP-VP1, pEGFP-VP2, pEGFP-VP3, pEGFP-VP4, or pEGFP-VP5 plasmid. Twenty-four hours after transfection, cell lysates were prepared and examined by Western blotting (WB) using anti-GFP antibodies. (B to D) Effects of viral components on mRNA expressions of the type I IFN and NF-κB in host cells after SeV infection. HEK293T cells were left untransfected (NT) or were transfected with 5 μg of pEGFP-N1, pEGFP-VP1, pEGFP-VP2, pEGFP-VP3, pEGFP-VP4, or pEGFP-VP5 as described for panel A. Six hours after transfection, cells were mock infected or infected with SeV at an MOI of 10. Twenty-four hours after SeV infection, mRNA expression of IFN-α, IFN-β, and NF-κB was measured by quantitative RT-PCR using specific primers. The relative level of mRNA expression is calculated as follows: gene expression of plasmid-transfected cells or SeV-infected cells/gene expression of mock-infected nontransfected controls. Results are representative of three independent experiments. Data are represented as means ± SD; n = 3. **, P < 0.01; *, P < 0.05.