Wang Y, Zhang H, Li Z, Gu W, Lan H, Hao W, Ling R, Li H, Harrison T J
Centre for Hepatology, Royal Free and University College Medical School, Royal Free Campus, London NW3 2PF, United Kingdom.
J Clin Microbiol. 2001 Dec;39(12):4370-9. doi: 10.1128/JCM.39.12.4370-4379.2001.
We reported previously on the complete sequence of hepatitis E virus (HEV) genotype 4, isolated from patients with sporadic cases of acute HEV infection in China. At least eight HEV genotypes have now been described worldwide, and further isolates await classification. Current immunoassays for the detection of anti-HEV antibodies are based on polypeptides from genotypes 1 and 2 only and may be inadequate for the reliable detection of other genotypes. Because genotypes 1 and 4 predominate in China, we wished to investigate the antigenic reactivities of HEV genotype 4 proteins. Four overlapping regions of open reading frame 2 (ORF2) (FB5, amino acids [aa] 1 to 130; E4, aa 67 to 308; F2-2, aa 288 to 461; E5, aa 414 to 672) and the entire ORF3 product were expressed in Escherichia coli as fusion proteins. Enzyme immunoassays based on each of the five purified polypeptides were evaluated with sera from patients with sporadic cases of acute HEV infection. Individual immunoassays derived from HEV genotype 4 detected more cases of acute hepatitis E than a commercial assay. Some serum samples, which were positive for anti-HEV immunoglobulin G only by assays based on HEV genotype 4, were positive for HEV RNA by reverse transcription-PCR. Polypeptide FB5, from the N terminus of ORF2, had the greatest immunoreactivity with sera from patients with acute hepatitis E. These data indicate that the N terminus of ORF2 may provide epitopes which are highly reactive with acute-phase sera and that assays based on genotypes 1 and 2 alone may be inadequate for the detection of HEV infection in China, where sporadic cases of HEV infection are caused predominantly by HEV genotypes 4 and 1.
我们之前报道过从中国急性戊型肝炎散发病例患者中分离出的戊型肝炎病毒（HEV）基因型4的完整序列。目前全球已描述了至少8种HEV基因型，还有更多分离株有待分类。当前用于检测抗HEV抗体的免疫测定仅基于基因型1和2的多肽，可能不足以可靠地检测其他基因型。由于基因型1和4在中国占主导地位，我们希望研究HEV基因型4蛋白的抗原反应性。开放阅读框2（ORF2）的四个重叠区域（FB5，氨基酸[aa]1至130；E4，aa 67至308；F2 - 2，aa 288至461；E5，aa 414至672）和整个ORF3产物在大肠杆菌中作为融合蛋白表达。基于这五种纯化多肽中的每一种的酶免疫测定，用急性HEV感染散发病例患者的血清进行评估。源自HEV基因型4的单个免疫测定比商业测定检测到更多的急性戊型肝炎病例。一些血清样本，仅通过基于HEV基因型4的测定显示抗HEV免疫球蛋白G呈阳性，但通过逆转录 - PCR检测HEV RNA呈阳性。来自ORF2 N端的多肽FB5与急性戊型肝炎患者的血清具有最强的免疫反应性。这些数据表明，ORF2的N端可能提供与急性期血清高度反应的表位，并且仅基于基因型1和2的测定可能不足以在中国检测HEV感染，在中国，HEV感染散发病例主要由HEV基因型4和1引起。
