中文摘要：

目的：比较戊型肝炎病毒（HEV）第4基因型ORF2编码蛋白片段pN472-C617（aa472～617）和pN477-C613（aa477～613）的免疫原性，找到能诱生HEV中和抗体的ORF2编码蛋白的更短片段。方法：表达和纯化pN472-C617和pN477-C613，分别免疫BALB/c小鼠，以间接ELISA检测免疫血清的抗体效价，并以基于PCR的体外中和试验检测免疫血清的中和活性。结果：pN472-C617和pN477-C613可在大肠杆菌高效可溶性表达，纯化后的重组蛋白能在小鼠体内诱导出高效价的抗体。基于PCR的体外中和试验显示pN472-C617免疫血清可有效中和HEV，阻断其在敏感细胞表面的吸附和细胞内复制；而两端仅比pN472-C617各短5个氨基酸的pN477-C613的免疫血清不具有中和HEV的活性。结论：重组蛋白pN472-C617具有良好的抗原性和诱生中和抗体的能力，是目前文献报道中含有HEV中和抗原表位的最短ORF2编码蛋白片段，可作为重组亚单位候选疫苗用于HEV疫苗的开发。

英文摘要：

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-enceded 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.