诺如病毒是全球非细菌性急性胃肠炎的主要病原之一， 而贝类是病毒感染的重要来源。借助自身的高变异率，近二十年来突变株不断产生并造成多次全球规模的大流行。诺如病毒GⅡ.4型为目前主要流行基因型，通过对历年来出现的变异株序列分析显示，结合宿主受体及逃避人类免疫的能力是病毒长期流行的关键因素。本课题拟针对以上条件建立诺如病毒GⅡ.4的体外进化模型，分析影响病毒功能与抗原性的关键氨基酸位点，达到预测变异趋势的目的。.在获得污染GⅡ.4型病毒的贝类样本基础上，克隆并制备活性衣壳蛋白；建立高通量蛋白表达和功能/抗原性筛选平台，借助体外进化技术，加速模拟自然条件下的病毒衣壳蛋白变异过程，筛选受体结合功能和/或抗原性的突变株；通过突变株的变异位点分析，确定维持感染力的关键氨基酸位点，同时与历史上出现的变异代表株进行比对，探讨病毒进化的分子机理，为监测高危突变株的出现及对其暴发传播进行风险预警提供理论基础。

Norovirus is the main cause of non-bacterial acute gastroenteritis in the world, and shellfish is a well-known source for viral infections. By its high mutation rate, there were several global pandemics caused by norovirus virants in recent 20 years. GII.4 is the major epidemic genotype, by sequence analysis of GII.4 variants appeared over the years, it found that host immunity and histo-blood group antigens (HBGAs) were the key factors for NV persistence in human populations. In our research we will build models of norovirus GII.4 evolution in vitro and find the important animo acid sits for receptor binding and antigenicity, so as to forecast the variation trends..Firse will clone and express capsid protein of norovirus GII.4 detected in shellfish preserved. And then on the basis of the establishment of high-throughput protein expression and function /antigen screening platform, we will accelerate the simulation of viral capsid protein evolution under natural conditions in vitro by directed evolution methods, and screen positive mutants with new function and/or antigenicity. Compared with sequences of initial strains, mutants screend out and variants which were epidemic in history , we will find critical amino acid sites for virus infection, and explore virus evolution mechanisms, which will provide a theoretical basis for monitoring high-risk mutations and risk warning for its spread and outbreak.