Objective To study the antigen variation of wild-type measled virus(MV)that circulated in Zhejiang province and immunoprotecive efficacy of measles vaccine.
Methods The anti-measles virus neutralization(NT)antibody titers in the immune serum of rats which were obtained in the earlier wild-type measles virus(Edmonston strain)and the vaccine strain and the two field strains(Zhe 98-5 and Zhe 00-4)isolated recently wae measured in cross neutralization test, meanwhile NT antibody titers in the serum of population which obtained from different sources were also measured respectively.
Results Antigenic ratios of Zhe 98-5 strain to Hu191 strain and Edm strain were 3.0 and 2.6 respectively, while those of Zhe 00-4 strain to the two standard strains described above were 7.30 and 5.65, suggesting an obvious mutual difference of antigenicity.The anti-wild type measles virus NT antibody geometric mean titer(GMT)in the serum of initial vaccines and naturally infected individuals were 15.03 and 5.04 respectively, which was obviously lower than anti-measles vaccine strain(GMT was 68.12 and 11.76 respectivety).But NT antibody titers to various strains in the serum of healthy population were with non-significant difference.
Conclusion Antigenic variation of wildtype measles virus that circulated in Zhejiang presented obviouly and immunoprotecive effcacy of measles vaccine was partly influenced.
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