宿主限制因子IFITM3对人肠道病毒71型的抑制及其作用机制的研究

The interferon-inducible transmembrane proteins (IFITMs) belong to a family of broadly antiviral host restriction factors that can be induced by interferon (IFN). Among them, IFITM3 has been proved to inhibit cellular entry of a series of enveloped viruses, such as Influenza virus, dengue virus, and West Nile virus. Yet whether IFITM3 restricts infection of the non-enveloped virus such as EV71 remains unknown. Human enterovirus 71 (EV71) is responsible for the majority of severe cases of hand, foot and mouth diseases (HFMDs) and death. It has been reported that IFN inhibits EV71 infection both in vitro and on a mouse model and has also been used to treat severe HFMDs patients clinically, which indicate that IFN mediated EV71 restriction might depend on the induction of IFITM3. To determine whether IFITM3 inhibits EV71 and explore the underlying mechanism, we will carry out the following studies: 1) To confirm the contribution of IFITM3 to IFN mediated EV71 restriction and its own inhibition of EV71 infection; 2) To dissect the specific steps in EV71 lifecycle, which includes viral attachment, viral genome replication, protein translation, the assembly and release of viral particles, that might be inhibited by IFITM3; 3) To explore the detailed inhibiting mechanism of IFITM3 at specific steps in EV71 lifecycle. Our studies should advance our understandings on the interaction between enterovirus and host immune system, and shed new light on the discovery of new target for developing anti-EV71 drugs.

干扰素诱导跨膜蛋白（IFITMs）是受干扰素诱导的广谱性宿主限制因子。其成员IFITM3可以阻止多种囊膜病毒，如流感病毒、登革热病毒和西尼罗河病毒等入侵靶细胞，然而IFITM3是否抑制非囊膜病毒，如人肠道病毒71型（EV71）尚不可知。EV71感染是导致儿童手足口病重症及死亡的主要原因。据报道干扰素可在小鼠模型上抑制EV71感染，临床上也有用干扰素治疗重症手足口病的先例，表明干扰素可能通过诱导产生IFITM3来抑制EV71感染。为了明确IFITM3对EV71的抑制并阐明其作用机制，本项目拟开展如下研究：1）确定IFITM3在干扰素抑制EV71中的贡献以及IFITM3本身对EV71感染的抑制作用；2）明确IFITM3抑制EV71病毒生活周期的具体步骤；3）探索IFITM3发挥抑制作用的具体机制。本项目将加深我们对肠道病毒与宿主免疫系统之间相互作用的理解，为寻找新的抗EV71药物靶点提供思路。

肠道病毒感染（如EV71, CVA16 和 CVA10）是导致儿童手足口病重症及死亡的主要原因。目前尚无广谱性抗肠道病毒疫苗和药物。干扰素诱导跨膜蛋白（IFITMs）是受干扰素诱导的广谱性宿主限制因子。其成员IFITM3可以阻止多种囊膜病毒，如流感病毒、登革热病毒和西尼罗河病毒等入侵靶细胞，然而IFITM3是否抑制非囊膜病毒，如人肠道病毒71型（EV71）尚不可知。本项目确定了IFITM3 Knockdown对EV71和CVA16感染的影响；完成了对CVA16灭活病毒，CVA16病毒样颗粒，CVA10灭活病毒以及EV71 80S病毒样颗粒结构冷冻电镜结构的解析；依据CVA10高分辨率冷冻结构筛选到了广谱性抗病毒药物；评价了病毒样颗粒疫苗在小鼠模型上的保护效果。本项目加深了我们对肠道病毒与宿主免疫系统之间相互作用的理解，对开发抗手足口病药物以及疫苗有重要意义。