Herremans M, Bakker J, Duizer E, Vennema H, Koopmans M P G
National Institute for Public Health and the Environment, RIVM, Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
Clin Vaccine Immunol. 2007 May;14(5):562-8. doi: 10.1128/CVI.00231-06. Epub 2007 Mar 14.
Because of the occurrence of genotype 3 hepatitis E virus (HEV) in regions of low endemicity, it is important to validate the currently used serological assays for diagnosing infections with viruses belonging to this lineage, since these assays only use antigens derived from genotype 1 and 2 viruses. We evaluated the Genelabs enzyme-linked immunosorbent assay (ELISA) and the RecomBlot from Mikrogen for the detection of HEV-specific immunoglobulin M (IgM) and IgG under conditions of low endemicity. We compared test results of 16 patients with locally acquired genotype 3 HEV, 8 genotype 1 patients, 167 healthy controls from the general population, and 101 cases with hepatitis due to other viral causes. The measured specificities of the ELISA (98%) and the RecomBlot (97%) were comparable to those given by the manufacturer for IgM but were significantly lower for IgG (93% by ELISA and 66% by immunoblotting, versus reported values of 98% for ELISA and 95% for blotting). Antibody levels detected following infections with genotype 3 were lower than those following genotype 1 infections except for those measured in the IgM ELISA. Reactivity to the four antigens used in the immunoblot assay were analyzed and showed differences in the IgM immunoblot reactions between genotype 1 patients and genotype 3 patients. The ORF3 antigen was the most specific antigen. The specificity could be improved by a combined testing regimen with confirmation by immunoblotting of all positive ELISA results and by raising the cutoff of the IgG immunoblot assay without loss of sensitivity. We conclude that a combination of ELISA and immunoblotting is needed for acceptable specificity and sensitivity of HEV assays under conditions of low endemicity.
由于在低流行地区出现了3型戊型肝炎病毒（HEV），因此有必要对目前用于诊断该病毒谱系感染的血清学检测方法进行验证，因为这些检测方法仅使用源自1型和2型病毒的抗原。我们评估了Genelabs酶联免疫吸附测定（ELISA）和Mikrogen公司的RecomBlot在低流行条件下检测HEV特异性免疫球蛋白M（IgM）和IgG的情况。我们比较了16例本地获得的3型HEV患者、8例1型患者、167名普通人群健康对照以及101例其他病毒引起的肝炎病例的检测结果。ELISA（98%）和RecomBlot（97%）测得的IgM特异性与制造商给出的结果相当，但IgG的特异性显著较低（ELISA为93%，免疫印迹法为66%，而ELISA报告值为98%，印迹法为95%）。除了IgM ELISA检测到的抗体水平外，3型感染后检测到的抗体水平低于1型感染后的水平。分析了免疫印迹试验中使用的四种抗原的反应性，结果显示1型患者和3型患者的IgM免疫印迹反应存在差异。ORF3抗原是最具特异性的抗原。通过对所有ELISA阳性结果进行免疫印迹确认的联合检测方案以及提高IgG免疫印迹试验的临界值而不损失敏感性，可以提高特异性。我们得出结论，在低流行条件下，为了使HEV检测具有可接受的特异性和敏感性，需要将ELISA和免疫印迹法结合使用。
