VP_4和VP_5蛋白在鸡传染性法氏囊病毒感染Vero细胞中的作用

The effect of VP_4 and VP_5 protein of IBDV on the infection of Vero cells

[目的]鸡传染性法氏囊病毒(IBDV)感染会引起鸡的免疫抑制,给养禽业带来巨大危害。本文旨在探讨鸡传染性法氏囊病毒(IBDV)蛋白VP4和VP5在病毒感染引起的免疫抑制中的作用。[方法]构建VP4和VP5蛋白的真核表达质粒并转染Vero细胞,再用IBDV CV03病毒株感染转染后的细胞,Western-blot方法检测细胞中模式识别受体及下游转录因子的表达;RT-q PCR检测细胞因子及抗病毒基因的表达。[结果]IBDV CV03病毒感染Vero细胞后,VP4蛋白在一定程度上能够提高TLR3、RIG-Ⅰ蛋白含量,但差异不显著;VP5对TLR3、RIG-Ⅰ等介导的天然免疫通路有一定的抑制作用;过表达VP5在IBDV CV03病毒感染后显著抑制了Vero细胞IRF3的表达及其磷酸化水平,也显著抑制了IRF7蛋白和NF-κB基因的表达,并在抑制NF-κB后抑制了TNF-α,而过表达VP4无此作用。[结论]VP5蛋白对Vero细胞相关信号通路有一定的抑制作用,这种抑制作用和核转录因子及TNF-α的抑制密切相关。

[ Objectives] The infection caused by chicken infectious bursal disease virus （IBDV）can lead to immune suppression, and then bring great damage to poultry industry. This study aims to investigate the role of VP4 and VP5 proteins of IBDV in the pathogenesis of IBDV infection. [ Methods]Vero cells were transfected with eukaryotic expression plasmid which contains VP, and VP5 genes,and then infected with IBDV CV03. Western-blot was performed to detect the expression of PRRs and downstream transcription factors. The expression of cytokines and antivirus genes was detected by quantitative PCR （RT-qPCR）. [ Results ] This study shows that the expression of VP4 protein improves the expression of TLR3 and RIG-I in a certain extent after infection of IBDV CV03. VPs has a certain inhibition in the innate immune pathway mediated by TLR3 and RIG-I. Overexpression of VP5 after the infection of IBDV CV03 significantly inhibits the expression of IRF3 and its phosphorylation, also significantly inhibits the expression of IRF7 protein and NF-κB gene, and inhibits TNF-α by the inhibition of NF-κB, but the effects were not observed after the overexpression of VP4. [ Conclusions ] It illustrates that VP5 protein has a certain inhibitory effect on the related signaling pathway,which is closely related to the inhibition of nuclear transcription factor and TNF-α.