Molecular Mechanism Of Broad-spectrum Protection Of Hepatitis E Vaccine

Hepatitis E virus(HEY),prevalent in many countries,can lead to viral hepatitis-Hepatitis E(HE).The capsid protein of HEV containing 660 amino acids.E2(a.a.394-606)is a domain necessary for the host to recognize the virus and contains an immunodominant epitope.The virus-like particle p239(a.a.368-606)was obtained by the modified of E2,and the p239 protein which can be assembled into particles in vitro was expressed by the E.coli expression system.Hepatitis E vaccine made by the genotype-1 p239 protein,has been clinically proven to provide good and long-lasting protection against genotypes-1 or 4 viral infectionsThis study mainly studied the molecular mechanism of broad-spectrum protection of hepatitis E vaccine.By applying a high-efficiency antigen-specific human monoclonal antibody screening platform,the corresponding antibodies were screened from the peripheral blood of vaccine immunized patients and identified.Using this platform,the memory B cells of anti-HEV capsid in peripheral blood were acquired by sorting flow cytometry,and the antibodies sequence were obtained by single cell RT-PCR Finally,34 human antibodies of anti-HEV capsid protein were obtained by expressing and screening.To gain insight into specific antibody properties of obtained HEV vaccine recipients,we examined some indexes and found that more than 80%of the antibodies have stronger binding activity to p239 protein of different genotypes.Besides,88.24%of antibodies have considerable binding activity to p239 protein of genotypes-1 or 4.94.12%of the antibodies have neutralizing activity.We also studied epitopes recognized by antibodies and found that a great majority of antibodies recognize C2 epitope,suggesting that the C2 epitope is an immunodominant epitope of human antibodies.The sensitive amino acids of the C2 epitope are conserved among different genotype viruses.In summary,this study successfully screened antigen-specific human antibodies by antigen-specific human monoclonal antibody screening platform,laying the foundation for the study of multiple pathogen-associated antibodies;by detecting and analyzing the properties of human antibodies,the high protection rate and broad-spectrum protection of HEV vaccine were found.This can further analyze the evolution process of antibodies by next-generation sequencing,and provide theoretical support for the design of other high-protection vaccines.