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

LI Shuangjie;LU Yu;ZHANG Jinqiu;MIAO Jinfeng;HOU Jibo;College of Veterinary Medicine,Nanjing Agricultural University;National Research Center of Veterinary Biologicals Engineering and Technology,Jiangsu Academy of Agricultural Sciences;

VP protein;;infectious bursal disease virus(IBDV);;cell transfection;;immune suppression

[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 VP_4 and VP_5 proteins of IBDV in the pathogenesis of IBDV infection. [Methods]Vero cells were transfected with eukaryotic expression plasmid which contains VP_4 and VP_5 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-q PCR). [Results]This study shows that the expression of VP_4 protein improves the expression of TLR3 and RIG-Ⅰin a certain extent after infection of IBDV CV03. VP_5 has a certain inhibition in the innate immune pathway mediated by TLR3 and RIG-Ⅰ. Overexpression of VP_5 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 VP_4.[Conclusions]It illustrates that VP_5 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.