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H。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 current circulating measles viruses, compare the genic charac- teristics with the strain of measles vaccine used and determine the cross neutralizing antibody （NTAb）for analyzing immuno-effect of the current measles vaccine. Methods The throat swab specimens were provided by Jiangsu CDC from acute measles patients in 2005. The viruses were isolated by the Vero/Slam cell. After extracted RNA from both the isolates and vaccine strain viruses, coding regions of hemagglutinin （H） and nucleoprotein （N） were amplified by RT-PCR and sequenced. The antibody titers for both the vaeeinees and convalescent-phase patients were measured using the antigen of the isolated viruses and vaccine strain by cross neutralization test. Resuits 4 epidemic wild strains were successfully isolated by once, one （JS/26-05）of them was sequenced and analyzed genotype that belonged to H1. Comparing with the genes of the S191 vaccine strain,the homology of nucleotide sequence and amino acid sequence in H gene were 94.8% and 95. 1%,and in N gene were 94.4% and 96.2% respectively,but the homology of the 150 amino acid sequence of COOH terminal in N gene was 90.0%. The titers of NTAb from vaccinated children were obviously lower than those from infected persons. Both the geometric mean titers （GMT）of the NTAb were 9.56 and 22.40 to the isolated wild strain,and 40. 05 and 65.41 to S191 vaccine strain,there were 2. 9～4.2 times difference between vaccinated and infected children in neutralization titers. The ability of neutralization of was 4. 2 times lower averagely than those against the wild type strain S191 vaccine strain. Conclusion The wild type measles viruses isolated in Jiangsu Province in 2005 were H1 genotype. There was apparent difference between current circulating measles viruses and vaccine strain viruses in gene levels. The immuno-effect of measles vaccine used currently tended to downwards and probably influenced the duration of immunity of measles vaccine.
Chinese Journal of Vaccines and Immunization
Shanghai 191 vaccine strain