The Study On The Binding Characteristics And Structural Basis Of GⅡ.6 Genotype Norovirus And Glycans

Noroviruses(No Vs)are a foodborne virus that cause acute gastroenteritis.Typical clinical symptoms of No Vs include nausea,diarrhea,vomiting,and abdominal pain.The route transmission of No Vs is mainly through the fecal-mouth,and the population is generally susceptible.No Vs are currently divided into seven genomes(GI-GVⅡ),GI and GⅡ are the main groups that cause human infection.Histo-blood group antigens(HBGAs),as the main receptor for recognition and binding of Human noroviruses(Hu No Vs),play an important role in host susceptibility,host range and epidemic.Nearly two decades,genotypes GⅡ.4 have been the major outbreak strains in the world,but in recent years,rare genotypes GⅡ.17 and GⅡ.2have suddenly become the major outbreak strains.The study had been confirmed that the changes in the binding characteristics of the genotype P protein to glycans were crucial to the outbreak of the virus and the susceptibility of the host.However,the oligosaccharide binding characteristics of many other rare strains in the GⅡ group were not clear.Although GⅡ.6 is a rare genotype,its outbreak rate has been gradually increased in domestic and foreign reports,so further analysis of the oligosaccharide binding characteristics and molecular mechanisms of GⅡ.6 genotypes will provide scientific basis for predicting potential outbreak.Taking GⅡ.6 as the research object,this project constructs the expression vectors of GⅡ.6 P particles and P dimer for the functional and structural studies respectively.GⅡ6 P protein was expressed by Escherichia coli.P particles were successively obtained by GST purification system and 3C protease digestion,based on this method,gel chromatography was used for further purification obtained the P dimer.The combination experiment of P particles and 214 kinds of saliva showed that the GⅡ.6genotype mainly combined with the secreted saliva,including most B type and AB type,some A type and O type,but rarely with the nonsecreted saliva.The combination experiment of P particle and glycan showed that GⅡ.6 mainly bound to H oligosaccharide antigen in HBGAs.It suggests that people with secretory type and H disaccharide antigen may be susceptible to GⅡ.6 genotype.X-ray diffraction collected higher resolution data of GⅡ.6 P protein,and it was found that the GⅡ.6 P protein contained a α helix and 6 inverted parallel β layers.Homologous simulation results of GⅡ.6 and H disaccharide antigen showed similar binding sites and interacting amino acids with GⅡ.17 2014/15 epidemic strain.Its were elucidated the structural characteristics and molecular mechanism of interaction of GⅡ.6 P protein and its receptor complex.This laid the foundation for the comprehensive disclosure of the possible epidemic mechanism of GⅡ.6 Hu No Vs and the development of potential antiviral drugs.