目的　表达庚型肝炎病毒 (HGV)基因组NS5区部分基因重组抗原 ,分析其抗原性。方法　分别亚克隆了HGVNS5a、NS5b以及NS5b与C区嵌和的基因至pThioC表达载体上 ,构建成 3个重组表达质粒 ,分别转化大肠埃希菌JM1 0 9(DE3) ,用IPTG诱导表达重组蛋白。表达产物经纯化后采用Westernblot和间接ELISA方法分析 3个重组蛋白的抗原性。结果　经酶切和序列分析鉴定正确 ,3种表达蛋白均高效表达且相对分子质量与预期大小相符。Westernblot分析和间接ELISA试验表明 ,3种表达蛋白均能与抗 HGV阳性血清发生特异性反应。将应用重组蛋白检测的抗 HGV抗体与混合重组抗原 (包括C区合成肽、NS5a合成肽、NS3区基因重组抗原 )的检测结果进行了比较 ,在混合重组抗原阳性的 2 2份血清中 ,P5a检出率为 68% (1 5 2 2 ) ,P5b检出率为 91 % (2 0 2 2 ) ,Pc 5b检出率为 73 % (1 6 2 2 )。在 70份阴性标本中 ,3种抗原的检出率分别为P5a:7% (5 70 ) ;P5b :1 % (1 70 ) ;Pc 5b :6 % (4 70 )。3个重组抗原单独检出阳性的标本 ,其中有一部分经RT PCR检测亦为阳性。结论　原核表达的NS5区蛋白所检测的抗 HGV抗体不能完全被其他区段的抗原所覆盖 ,是免疫诊断HGV感染所必需的抗原表位之一。 Objective To express recombinant antigen of partial gene of NS5 in the genome of hepatitis G virus (HGV) and analyze its antigenicity. Methods The gene encoding HGVNS5a, NS5b, NS5b and C was cloned into pThioC expression vector. Three recombinant plasmids were constructed and transformed into Escherichia coli JM1 0 9 (DE3) respectively. The recombinant protein was induced by IPTG . The expressed products were purified and the antigenicity of the three recombinant proteins was analyzed by Western blot and indirect ELISA. The results of enzyme digestion and sequence analysis identified the correct expression of three kinds of proteins were highly expressed and the relative molecular mass consistent with the expected size. Western blot analysis and indirect ELISA showed that all the three expressed proteins reacted specifically with anti-HGV-positive sera. The anti-HGV antibody detected by using recombinant protein was compared with that of mixed recombinant antigen (including C-domain synthetic peptide, NS5a synthetic peptide and NS3 gene recombinant antigen). Of the 22 serums mixed with recombinant antigen, P5a The detection rate was 68% (15 2 2), the detection rate of P5b was 91% (202 2), and the detection rate of Pc 5b was 73% (1 6 2 2). Among the 70 negative samples, the detection rates of the three antigens were P5a: 7% (570); P5b: 1% (170); Pc5b: 6% (470), respectively. Three recombinant antigens alone positive samples were detected, some of which were also positive by RT PCR. Conclusion The anti-HGV antibodies detected by prokaryotic expression of NS5 protein can not be completely covered by antigens of other regions, which is one of the epitopes necessary for immunodiagnosis of HGV infection.