柯萨奇病毒 A16 实心/空心颗粒抗原性差异的结构基础

CA16 virus is one of the two major pathogens that cause hand, foot and mouth disease, which currently no cure and effective preventive vaccine. Our previous studies have found, CA16 culture viruses exists in two forms of particles of virus virions, mature/solid paticles and empty particles, and exiting antigenic differences between the two particles, which may affect the development of vaccines and antiviral drugs. Basing on preliminary studies, in this study, we will analysis high-resolution Cryo-EM structure of the two virus particles using three-dimensional reconstruction of cryo-electron microscopy (Cryo-EM), compare structural differences between two particles, then pick the dominant specific neutralizing mAb against mature particles，reconstruct Cryo-EM structure of virus-Fab complex，analyze the specific neutralizing epitope, compare antigenic difference of two different particles. The study will clarify the structural difference of the two CA16 particles and their impact on viral antigenicity, which can provide structural basis and theoretical guidance for the mechanism and the expected immune response of CA16 vaccine.

CA16病毒是引起手足口病的两种主要病原体之一，由肠道病毒引起的手足口病目前暂无特效药及有效的预防性疫苗。我们的前期研究发现，CA16培养病毒中存在实心颗粒及空心颗粒两种形式的病毒粒子，且两种颗粒存在抗原性及免疫原性差异，对疫苗及抗病毒药物的研究至关重要。本课题将在前期研究基础上，利用低温电镜三维重构技术，解析两种病毒颗粒的高分辨率Cryo-EM结构，比较两种颗粒的结构差异，并挑选针对实心颗粒病毒的特异性优势中和表位单抗，解析病毒颗粒与代表性单抗复合物的Cryo-EM结构，分析实心颗粒的特异性优势中和表位，比较两种颗粒的抗原性差异，阐明CA16不同颗粒形式的结构差异及其对病毒抗原性的影响，为CA16疫苗的作用机制及免疫应答效果提供结构基础及理论依据。

CA16病毒是引起手足口病的两种主要病原体之一，由肠道病毒引起的手足口病目前暂无特效药及有效的预防性疫苗。本研究通过高纯度CA16实心及空心病毒颗粒的冷冻电镜（Cryo-EM)三维结构解析，获得CA16病毒实心颗粒及空心颗粒高分辨率三维结构，同时筛选获得了CA16优势中和单抗18A7，其能结合不同形式的CA16颗粒，并具有较高的亲和、中和活性及体内保护效力。进一步解析获得18A7与CA16实心颗粒，A颗粒及空心颗粒等三种颗粒免疫复合物的近原子分辨率Cryo-EM三维结构，精确定位这一保守表位。本研究在生化及结构水平上证实CA16病毒不同颗粒形式的抗原性差异，并首次发现了不同颗粒间存在保守的免疫优势中和表位位点，证实不同颗粒形式均具有良好的疫苗潜能，并在结构水平上提供了这一论据的理论基础，本研究对CA16诊断试剂、疫苗及抗病毒药物的研发均具有重要的指导意义。

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