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目的鉴别在接种甲肝减毒活疫苗（Ｈ２株）后２３天发生的一例甲型肝炎，其病原体是疫苗株还是野毒株。方法用细胞培养、ＩＥＭ等确认病原体，接种普通狨猴检定病毒毒力，测定核苷酸序列分析病毒基因型。结果甲型肝炎的确诊依据有：抗ＩｇＭ（＋），双份血清ＨＡＶ总抗体效价１６倍增长以及粪便排出ＨＡＶ（郑株）。该粪便悬液攻击普通狨猴后，肝脏呈现持续性组织病理改变，证明郑株是强毒ＨＡＶ。郑株的３个片段共１３７７个核苷酸序列分析表明，与１９８８年上海甲肝流行株合－５２的同源性高达（９８．３０～９９．４０）％，判定为ＩＡ基因亚型，与Ｈ２株疫苗病毒的基因亚型不同。结论该例甲型肝炎是接种甲肝减毒活疫苗中交叉感染野毒株引发的偶合病例，与疫苗接种无关
Objective To identify a case of hepatitis A that occurred 23 days after inoculation of a live attenuated hepatitis A vaccine (H2 strain), whether the vaccine is a vaccine strain or a wild-type strain. Methods The pathogen was identified by cell culture, IEM and other tests, and the virulence of common marmosets was tested and the nucleotide sequence was analyzed for the virus genotype. Results Hepatitis A was diagnosed on the basis of anti-IgM (+), a 16-fold increase in total titers of double serum HAV antibody, and excretion of HAV from feces (Zheng strain). The fecal suspension attack common marmosets, the liver showed persistent histopathological changes, Zheng strain is proved to be highly virulent HAV. A total of 1377 nucleotide sequences of the 3 fragments of Zheng strain showed that the homology with Hepatitis A of Shanghai 1988 was 98.30-99.40% H2 vaccine strains have different gene subtypes. Conclusion This case of hepatitis A is a coupled case caused by cross-infection of wild-type virus in live attenuated hepatitis A vaccine, and has nothing to do with vaccination