肠道病毒71型影响线粒体介导的天然免疫信号转导机制的研究

Hand-foot-and mouth disease（HFMD）, the major causative pathogen of which is Enterovirus 71(EV71),has been posed a heavy threat to human health and social stability. Currently, there is no effective vaccine or specific antiviral medicine for its prevention and treatment. The uncertain pathogenesis and immune protection mechanisms have been largely restricted the development of vaccine and antiviral medicine. Evasion of innate immunity by EV71 has been regarded as the key factor of viral pathogenicity. Previously, we had reported EV71 3C protease could inhibit the interaction between the pathogen recognition receptor RIG-I and the mitochondria signaling protein MAVS and was able to cleave TRIF, a key adaptor molecule of Toll-like receptor 3 mediated signaling pathway, to inhibit the production of typeⅠinterferon. Recently, our preliminary data have shown that EV71 infection could also cause the cleavage of MAVS and result in abnormal mitochondrial morphology, the VP1 protein of EV71 was found to be localized on mitochondria as well, suggesting EV71 might target to multiple host factors and probably take advantage of mitochondria as a platform to regulate or evade host innate immunity. Based on the above findings, this project is going to focus on the distinctive molecular mechanism by which EV71 cleaves MAVS and how the functional changes of mitochondria affect the production of type I interferon and inflammasome activation. Addressing these scientific questions would be helpful to find potential antiviral drug targets and provide new insights and theoretical evidence to develop effective anti-EV71 medicine.

手足口病严重威胁人类健康和社会安定，疫苗和特异性抗病毒药物缺乏严重影响了该病的防治,发病和免疫保护机制不清是制约特异性抗病毒药物和疫苗研发的重要因素。肠道病毒71型（EV71）是引起手足口病的重要病原体，逃逸宿主天然免疫防御被认为是其重要的致病机理之一。本课题组前期报道了EV71 3C蛋白酶抑制RIG-I和MAVS相互作用及裂解TRIF来抑制Ⅰ型干扰素产生。近期，我们又发现EV71可以裂解线粒体重要信号转导分子MAVS，导致细胞线粒体形态异常，并在线粒体上可检测到EV71 VP1蛋白,提示EV71极可能通过多作用靶点和以线粒体为作用平台通过多种方式进行天然免疫逃逸。本课题将围绕EV71裂解MAVS的具体分子机制和线粒体功能改变对Ⅰ型干扰素产生和炎症小体活化的调控机制进行深入研究，以期进一步了解EV71的免疫逃逸机制，发现潜在的抗病毒药物靶标，为抗病毒药物的设计和疫苗的研发提供理论依据。

手足口病严重危害婴幼儿的健康，肠道病毒71型（EV71）是引起手足口病的主要病原体，但其感染致病机制尚未阐明，病毒逃逸天然免疫防御被认为是其重要的致病机理之一。本研究进一步阐明了EV71逃逸天然免疫的机制，主要研究内容包括：1）EV71感染引起MAVS裂解的机制；2）EV71感染对于线粒体功能的影响；3）EV71介导NLRP3炎性小体活化的机制及其相互调控作用。预期结果是明确EV71裂解MAVS的具体分子机制，初步阐明以线粒体为靶标拮抗天然免疫反应的新机制。经过4年的努力，本课题较好的完成了课题的计划任务，基本达到预期目标。.主要的研究结果包括：1）阐明了EV71感染致MAVS裂解的分子机制。EV71感染可以导致MAVS裂解，其中EV71编码的2A蛋白酶在MAVS裂解中起重要作用，2A可以引起MAVS的切割，产生与感染类似的切割条带。2）发现EV71感染THP-1细胞能够激活NLRP3炎症小体，诱导细胞因子IL-1β的分泌。在NLRP3炎症小体相关基因缺失的细胞内，EV71复制增强，说明NLRP3炎症小体的激活有利于细胞对于EV71病毒的拮抗。EV71进一步研究发现EV71编码的2A和3C蛋白酶能够切割NLRP3，抵抗NLRP3炎症小体的抗病毒作用。