猪流行性腹泻病毒（PEDV）是危害当前养猪业的重要肠道冠状病毒。PEDV感染后可通过抑制干扰素(IFN)产生促进自身增殖并致病。我们的前期研究发现，PEDV编码的非结构蛋白nsp7既能拮抗RIG-I介导的IFN-β产生，又能抑制IFN-β诱导的干扰素刺激基因(ISGs)的表达，提示nsp7可同时靶向IFN-β产生和信号转导这两个紧密联系的过程，但其作用机制尚不清楚。本项目拟进一步探讨nsp7与RIG-I信号通路中各种信号分子的相互作用，分析nsp7对JAK-STAT信号通路中信号分子的磷酸化、核转运以及STAT1/STAT2/IRF9复合物形成的影响，确定nsp7的作用靶点；同时，挖掘nsp7拮抗IFN-β产生及其信号转导的功能域或关键氨基酸位点，并借助感染性克隆与反向遗传操作系统从病毒水平进一步分析这些氨基酸位点在PEDV拮抗IFN-β中的作用，更深入地揭示nsp7的免疫抑制功能。

Porcine epidemic diarrhea virus (PEDV) is an important porcine enteropathogenic coronavirus which causes lethal watery diarrhea in piglets and results in high economic losses. Previous studies have demonstrated that PEDV infection inhibits interferon (IFN) production to promote its proliferation. In our preliminary experiments, we found that the nsp7, a nonstructural protein encoded by PEDV, inhibits RIG-I-mediated IFN-β production and IFN-β-induced expression of IFN-stimulated gene (ISGs), indicating that PEDV nsp7 can antagonize both IFN-β production pathway and IFN-β signaling transduction pathway. However, the mechanism(s) utilized by nsp7 to do so remain elusive. Based on these preliminary findings, here we plan to identify the targets of nsp7, by investigating interaction between the components of RIG-I signal pathway and nsp7, and by analyzing the role of nsp7 to the phosphorylation and nuclear translocation of molecules of JAK-STAT signal pathway and the assembly of STAT1/STAT2/IRF9 complex. Furthermore, we will identify the possible function domain(s) or key amino acid site(s) of nsp7 responsible for its IFN inhibitory property. By using the infectious clone and reverse-genetic system of PEDV, recombinant PEDV with mutants in the possible function domain(s) or key amino acid site(s) of nsp7 will be constructed to analyze the immune regulation function of nsp7 under virus infection condition.