猪繁殖与呼吸综合征病毒（PRRSV）非结构蛋白1β（NSP1β）通过调控干扰素调节因子3（IRF3）的磷酸化而抑制I型干扰素产生，但具体机制尚不清楚。本研究前期以PRRSV NSP1β为"诱饵"，通过酵母双杂交筛选猪肺泡巨噬细胞文库，发现并证实NSP1β与热休克蛋白40（HSP40）相互作用。已有研究报道HSP40在其它病毒蛋白抑制IRF3磷酸化过程中发挥作用，因此，本研究将通过免疫共沉淀、共定位、上调表达和下调表达等方法研究HSP40在NSP1β抑制I型干扰素产生中的功能；通过研究HSP40作用通路中重要分子的表达及磷酸化水平的变化，以及对I型干扰素产生和病毒复制水平的影响，揭示NSP1β与HSP40相互作用抑制宿主I型干扰素产生的分子机制，研究结果将为阐明PRRSV抑制I型干扰素产生的分子机制提供科学依据。

Porcine reproductive and respiratory syndrome virus (PRRSV) NSP1β inhibits type I interferon production by antagonizing IRF3 phosphorylation and nuclear translocation. However, the molecular mechanism of IRF3 phosphorylation in PRRSV-mediated innate immune response is less understood. In previous studies, NSP1β was used as a "bait" to search for its novel interacting factors by using yeast two-hybrid system to screen porcine alveolar macrophages cDNA library. We found that NSP1β interacts with heat shock protein (HSP40) and the interaction was confirmed in mammalian cells by co-immunoprecipitation and co-localization. Considering the known function of HSP40 in regulation of IRF3 phosphorylation during other virus infection, we proposed a hypothesized that PRRSV NSP1β exploits HSP40 to inhibit IRF3 phosphorylation and type I interferon production. In the project, we will test the hypothesis and elucidate the molecular mechanism of IRF3 phosphorylation. 1) We will confirm the interaction of NSP1β and HSP40 in PAM post PRRSV infection by co-immunoprecipitation and co-localization. 2) We will confirm the release P58IPK from HSP40-P58IPK complex by NSP1β competitive binding to HSP40. 3) We will investigate whether NSP1β regulates type I IFN through HSP40 by overexpression and knock-down. 4) We will identify the possible signaling pathway of HSP40 in regulation of IRF3 phosphorylation. 5) We will analyse the expression and phosphorylation difference of each node in the pathway by overexpression and knock-down. 6) At last we will investigate type I interferon production and virus replication. This project is expected to uncover the molecular mechanism of inhibiting type I interferon production by the interaction of NSP1β and HSP40, providing useful data for understanding the mechanism of inhibition type I interferon production in PRRSV-infected cells.