ABSTRACT
Objective:To find a short, neutralizing antibody-inducible, ORF2-encoded protein by means of comparing the immunogenicity of pN472-C617 and pN477-C613 which represent amino acids 472-617 and 477-613 of HEV ORF2-encoded protein of hepatitis E virus(HEV) genotype 4, respectively.Methods:The two recombinant proteins were expressed, purified, and then used to immunize BALB/c mice. Anti-HEV titers in the immune sera were detected by ELISA. Anti-HEV neutralizing activity was tested by a PCR-based in vitro neutralization assay.Results:Both of the two recombinant proteins were efficiently expressed in E.coli in soluble forms. The purified proteins induced mice to develop high levels of anti-HEV specific antibodies. However, only the immune sera obtained from the mice immunized with pN472-C617 showed the neutralizing activity to the homologous HEV strain by preventing the virus from absorption on PLC/PRF/5 cells surfaces and replication in the cells. The immune sera against pN477-C613, which was truncated five amino acids from both N- and C-terminal of pN472-C617, had no HEV neutralizing activity.Conclusion:The pN472-C617 is the shortest neutralizing antibody-inducible ORF2-encoded protein of HEV reported in literatures so far. It may be considered as a potential candidate for a novel HEV subunit vaccine in our future study.