西北农林科技大学王晶钰教授组在小反刍兽疫病毒致病机理方面取得新进展

小反刍兽疫（Peste des petits ruminants，PPR）是由小反刍兽疫病毒（Peste des petits ruminants virus，PPRV）引起的山羊、绵羊等小反刍动物的一种急性烈性高度接触性传染病，致死率高。该病被世界动物卫生组织（OIE）列为A类疫病，也是我国规定的Ⅰ类动物疫病。2007年在我国西藏首次发生PPR，2014年先后在青海、宁夏、甘肃、陕西等24个省市自治区暴发，造成了巨大的经济损失。PPRV病毒感染动物后能引起宿主免疫抑制，但其潜在的致病机制仍不清楚。

西北农林科技大学动物医学院王晶钰教授课题组 研究发现，PPRV能够诱导山羊子宫内膜上皮细胞（EECs）发生完全自噬，该病毒能利用细胞自噬增强自身的复制水平。在PPRV感染EECs的过程中，抑制细胞自噬的形成能够促进Caspase依赖的细胞凋亡，而抑制自噬溶酶体融合过程并不影响细胞的凋亡率。进一步研究发现，PPRV的C、N、H蛋白通过与胞内LC3蛋白共定位可以不同程度诱导宿主细胞自噬的发生。其中C蛋白与IRGM以及N蛋白与HSP70的相互作用是PPRV通过IRGM-HSP70依赖性途径诱导宿主细胞第二波自噬的关键因素。这一原创性成果近日发表在生物学领域权威期刊《 Autophagy 》（IF=11.059，2018，中科院一区，TOP期刊），题目为“ Autophagy induction by the pathogen receptor NECTIN4 and sustained autophagy contribute to peste des petits ruminants virus infectivity ”， 西北农林科技大学动物医学院博士生杨勃，中国兽医药品监察所薛青红研究员为共同第一作者，王晶钰教授和齐雪峰教授为共同通讯作者。

王晶钰教授课题组近年来在揭示PPRV的致病机制方面取得了一系列进展，系统研究了小反刍兽疫病毒进入宿主细胞的途径，受感染细胞内两波细胞自噬的发生规律和MicroRNA表达谱变化及对病毒复制的调节机制。 2018年至今另有4篇相关研究成果 先后以 “Binding and entry of peste des petits ruminants virus into caprine endometrial epithelial cells profoundly affect early cellular gene expression ”，“MicroRNA expression profiling of goat peripheral blood mononuclear cells in response to peste des petits ruminants virus infection”，“Peste des Petits Ruminants Virus Enters Caprine Endometrial Epithelial Cells via the Caveolae-Mediated Endocytosis Pathway ”，“Autophagy enhances the replication of Peste des petits ruminants virus and inhibits caspase-dependent apoptosis in vitro.”为题发表在国际权威期刊《Veterinary Research》（IF=3.117，兽医领域TOP期刊）、《Frontiers in Microbiology》（IF=4.259）、《Virulence》（IF=4.775）。研究成果为揭示小反刍兽疫病毒致病机制和新型疫苗的研发提供了科学依据。

该研究得到了西北农林科技大学双一流学科群动物生物技术张彦明教授PI团队的支持。该研究得到了国家自然科学基金（31602035）、“十三五”国家重点研发计划项目（2017YFD0500902）的资助。

Abstract

Macroautophagy/autophagy is an essential cellular response in the fight against intracellular pathogens. Although some viruses can escape from or utilize autophagy to ensure their own replication, the responses of autophagy pathways to viral invasion remain poorly documented. Here, we show that peste des petits ruminants virus (PPRV) infection induces successive autophagic signalling in host cells via distinct and uncoupled molecular pathways. Immediately upon invasion, PPRV induced a first transient wave of autophagy via a mechanism involving the cellular pathogen receptor NECTIN4 and an AKT-MTOR-dependent pathway. Autophagic detection showed that early PPRV infection not only increased the amounts of autophagosomes and LC3-II but also downregulated the phosphorylation of AKT-MTOR. Subsequently, we found that the binding of viral protein H to NECTIN4 ultimately induced a wave of autophagy and inactivated the AKT-MTOR pathway, which is a critical step for the control of infection. Soon after infection, new autophagic signalling was initiated that required viral replication and protein expression. Interestingly, expression of IRGM and HSPA1A was significantly upregulated following PPRV replication. Strikingly, knockdown of IRGM and HSPA1A expression using small interfering RNAs impaired the PPRV-induced second autophagic wave and viral particle production. Moreover, IRGM-interacting PPRV-C and HSPA1A-interacting PPRV-N expression was sufficient to induce autophagy through an IRGM-HSPA1A-dependent pathway. Importantly, syncytia formation could facilitate sustained autophagy and the replication of PPRV. Overall, our work reveals distinct molecular pathways underlying the induction of self-beneficial sustained autophagy by attenuated PPRV, which will contribute to improving the use of vaccines for therapy.