塞内卡病毒（SVA）3C蛋白抑制I型干扰素产生的分子机制

Senecavirus A (SVA), is the single representative species of the genus Senecavirus, family Picornaviridae, has been associated with porcine idiopathic vesicular disease (PIVD) in pigs with lameness and vesicles on the snout and/or coronary bands, sometimes accompanied with lethargy and anorexia. Affected breeding herds had an increase of neonatal mortality (mainly piglets lessen than 7 days) ranging from 30 to 70%. Although SVA was already known as an oncolytic virus of potential use in human therapies, its association with swine disease is novel. As an emerging picornavirus, many aspects of SVA infection pathogenesis and antiviral innate immunity, remain unknown. Our previous studies have demonstrated that SVA infection and overexpression of 3C protein negatively regulate the production of type I interferon, while the molecular mechanism remain elusive. Based on the above findings, further studies will conducted to address the following questions: (1) Determine the signaling molecules targeted by SVA 3C protein in type I interferon pathway; (2) Illuminate the key cleavage sites and biological effects of special signaling molecules targeted by SVA 3C protein; (3) Elucidate the biological activity and biological significance of SVA 3C protein during the course of negatively regulation type I IFN production. Completion of this project will be useful to provide new insights into the pathogenesis and immune evasion mechanism of SVA, and help to provide a theoretical basis for the research and development ofbiological agents such as novel vaccine and oncolytic virus against SVA.

塞尼卡病毒（SVA）是近年刚发现与猪特发性水疱病（porcine idiopathic vesicular disease，PIVD)相关的新病原，感染猪表现为跛行，水疱并伴有精神沉郁、厌食，新生仔猪病死率高达30%--70%。作为猪新发的传染病病原，SVA感染的致病机制和抗病毒天然免疫仍然是未知的。我们前期研究发现SVA感染或表达3C蛋白均能抑制宿主的I型干扰素应答，但是它们是如何抑制I型干扰素产生的分子机制等尚不清楚。鉴于此，本项目拟开展以下研究：（1）确定SVA 3C蛋白抑制I型干扰素产生信号通路的关键靶点；（2）解析SVA 3C蛋白与靶标蛋白的相互作用及其效应机制；（3）阐明SVA 3C蛋白生物学活性及其生物学意义。本研究为进一步揭示SVA致病机理和免疫逃避的机制奠定基础，为SVA新型疫苗和溶瘤病毒等生物制剂的研发提供理论依据，具有重要意义。

塞尼卡病毒（Senecavirus A, SVA）或塞内卡谷病毒（Seneca Valley viru, SVV）是近年发现与猪特发性水疱病（porcine idiopathic vesicular disease，PIVD)相关的新病原，感染猪表现为跛行，水疱并伴有精神沉郁、厌食，新生仔猪病死率高达30%~70%。前期研究发现SVV感染或表达3C蛋白均能抑制宿主的I型干扰素应答，但是它们是如何抑制I型干扰素产生的分子机制等尚不清楚。本项目中，我们课题组投入大量的人力和物力，完成了：（1）SVV 3C抑制I型干扰素产生信号通路关键靶点的确定，解析了SVV 3C与靶标蛋白的相互作用及其效应机制，阐明了3C抑制I型干扰素产生的分子机制，证实SVV 3C通过特异性切割宿主抗病毒天然免疫相关重要接头分子MAVS、TRIF、TANK以及降解RIG进而负调控I型干扰素的产生，从而逃避宿主的抗病毒免疫。3C对TANK的切割也促进了TRAF6介导的NF-κB信号通路的激活，这与SVV感染激活宿主NF-κB信号通路，诱发炎性细胞因子的产生存在重要相关性；（2）系统评价了SVV 感染宿主细胞过程中3C的生物学功能：揭示了3C依赖于其蛋白酶活性诱导细胞凋亡、多位点切割p62进而抑制其介导选择性自噬的功能、诱导细胞焦亡并靶向切割猪源GSDMD、以及干扰eIF4GI-G3BP1相互作用抑制应激颗粒（SGs）形成；（3）评估了干扰素刺激因子胆固醇-25-羟化酶等对SVV增殖的影响：显示CH25H依赖于其酶活性有效抑制SVV复制，其催化产物25HC通过阻断SVV的吸附过程进而抑制SVV复制。本课题研究结果表明SVV通过 3C抑制I型干扰素产生进而负调控宿主抗病毒天然免疫，影响宿主细胞凋亡和细胞自噬、细胞焦亡和应激颗粒形成，干扰素刺激因子调控SVV复制等共同调控SVV与宿主间的相互作用，进而在其感染猪体致病中发挥重要作用。圆满完成了计划任务书的内容，在Virology、Autophagy、J Immunol、Front Microbiol、Virol Sin等杂志发表相关科技论文8篇；培养研究生5名，硕士和博士研究生分别为2名和3名。