肠道病毒68型基因变异与致病力增强及其逃逸天然免疫的机制研究

Human enterovirus D68 (EV-D68) is a member of species enterovirus D (EV-D), which belongs to the genus Enterovirus and the family of Picornaviridae. As a rare virus which associated with respiratory tract infections (RTIs), EV-D68 infections upsurged in recent years in different parts of the world. Phylogenetic analysis showed that multiple divergences had occurred in the circulating strains. Mutated 3’UTR could inhibit interferon-β induced by Sendai virus. These results indicated that EV-D68 could attenuate antiviral innate immune responses through gene mutation. This may be one of the reasons for EV-D68 epidemic in recent years. To test this, this study will use reverse genetics technology to mutated these sites one by one and screen the mutated strains which replicate fast in cells and can cause severe symptoms in mice. Using technology of functional proteomics to study the mechanism of interaction between host factors related about innate immunity and mutated sites. The objective of this study is to investigate the pathogenesis of key mutations of EV-D68 attenuating antiviral innate immune responses and novel therapeutic target for EV-D68 infection.

肠道病毒68型（EV-D68）近年突然在全球范围内流行呈上升趋势的原因不清楚。前期研究显示，近年流行的EV-D68基因序列存在变异，变异的3’UTR抑制仙台病毒刺激的I型干扰素的表达。这些结果提示EV-D68通过基因变异逃逸天然免疫应答可能是近年流行增加的机制之一。为证实该假说，本研究拟利用反向遗传学技术，构建EV-D68全部代表性变异位点的突变株，在细胞水平和动物水平筛选导致病毒复制特性和致病力改变的突变株，验证生物信息学找到的这些突变位点。进一步利用功能蛋白质组学技术研究这些突变位点逃逸天然免疫的作用机制，以期从拮抗天然免疫的角度初步阐明EV-D68的基因变异与致病能力增强的分子机制，为抗EV-D68药物的开发提供新靶点。

EV-D68的流行毒株在进化上存在3个分支，目前世界范围内流行的为B3分支，B3分支的VP2在207和220位是T和E。通过将B3分支的不同位点的突变发现，无论在细胞水平的复制特性还是小鼠体内的致病能力方面，T207和A220的组合是复制和致病能力最强的，VP2的突变导致小鼠体内致病能力的改变。因此，EV-D68的VP2在病毒复制中起非常重要的作用。通过干扰素诱导基因LGALS9表达蛋白Galectin-9抑制病毒复制的机制研究，发现VP2是Galectin-9抑制病毒复制的靶点。