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目的分离麻疹流行病毒,与现用麻疹减毒活疫苗(Measles Vaccine,Live;MV)株病毒进行基因比较和交叉中和试验,以分析现行MV的免疫保护性。方法由江苏省疾病预防控制中心提供2005年麻疹局部流行时急性期病人的咽拭子标本,用Vero/Slam细胞分离病毒,同时提取分离病毒和疫苗病毒核糖核酸,用逆转录-聚合酶链反应扩增血凝素蛋白(H)和核蛋白(N)基因,并进行核苷酸测序分析;另用MV免疫者的血清和麻疹病人的恢复期血清与分离野毒株和疫苗株进行交叉中和试验。结果一次成功分离到4株麻疹野病毒,对其中1株(JS/26-05)作基因测序,N基因进化树分析为H1基因型;与疫苗株病毒基因比较,H基因核苷酸同源性为94.8%,氨基酸同源性为95.1%;N基因核苷酸同源性为94.4%,氨基酸同源性为96.2%,但碳末端150个氨基酸的同源性为90.0%。疫苗免疫者产生的中和抗体水平低于自然感染者,两者的抗体几何平均滴度分别为:针对野毒株1∶9.56和1∶22.40,针对疫苗株1∶40.05和1∶65.41,相差2.9~4.2倍;疫苗免疫产生的抗体中和野毒株的能力平均低于疫苗株4.2倍。结论2005年江苏省局部地区麻疹流行时分离的病毒为H1基因型,麻疹分离株与现用疫苗株在基因水平上的差异明显,现用MV的免疫保护作用有所减弱,可能已影响到MV的免疫持久性。
OBJECTIVE: To isolate the measles virus and compare it with Measles Vaccine (Live; MV) strain to detect the immunoprotective activity of MV. Methods Jiangsu Provincial Center for Disease Control and Prevention provided throat swab samples for acute cases of local epidemic of measles in 2005, separated the virus from Vero / Slam cells, extracted and isolated virus and vaccine virus RNA, and used reverse transcription - polymerase chain reaction The hemagglutinin (H) and nucleoprotein (N) genes were amplified and sequenced. Nucleotide sequence analysis was also performed in the sera of patients with MV immunization and convalescent sera from measles patients. And test. Results Four wild measles virus strains were successfully isolated and one of them (JS / 26-05) was sequenced. The N gene was analyzed by phylogenetic tree for H1 genotype. Compared with the vaccine strain, the nucleotide homology The homology was 94.8% for amino acids and 95.1% for amino acids. The homology of N gene was 94.4% and that of amino acid was 96.2%, but the homology of 150 amino acids was 90.0%. The level of neutralizing antibody produced by vaccine immunization was lower than that of naturally infected patients. The geometric mean titers of the two antibodies were respectively 1:9.56 and 1:22.40 for the wild strains and 1:40.05 and 1:65.41 for the vaccine strains 2.9 to 4.2 times; the ability of the antibody produced by the vaccine to neutralize the wild-type strain was lower than that of the vaccine strain by 4.2-fold on average. Conclusions The virus isolated from measles epidemic in some areas of Jiangsu Province in 2005 was H1 genotype. The difference between the measles isolates and the current vaccine strains was significant at the gene level, and the immunoprotection of current MVs was weakened, which may have affected the MV Immune persistence.