麻疹减毒活疫苗S191生产用毒株的遗传稳定性

Genetic Stability of S191 Strain for Production of Live Attenuated Measles Vaccine

目的分析麻疹减毒活疫苗S191生产用毒株病毒结构基因的遗传稳定性。方法将北京天坛生物制品股份有限公司(天坛生物)用于麻疹疫苗生产的S191株25代病毒(S191-BJ25)传至29代(S191-BJ29),上海生物制品研究所保存的S191株24代病毒(S191-SH24)传至33代(S191-SH33)。从S191株传代病毒中提取RNA,对病毒结构基因片段N、M、F、H进行扩增及测序。将测序结果与GenBank中1994年收录的S191株麻疹病毒的相应序列进行比较分析。结果S191-BJ25传代病毒N、M、F、H4个基因的总突变率为0.02%,S191-SH24传代病毒为0.15%;与1994年的S191疫苗株相比,S191-BJ25传代病毒N、M、F、H4个基因的总突变率为0.3%,S191-SH24传代病毒为0.4%。结论目前天坛生物使用的麻疹疫苗S191株生产用三级种子库具有可靠的遗传稳定性,从主代种子到疫苗的传代过程中,N、M、F、H结构基因表现出稳定的分子遗传特征。目前使用的S191毒株的4个结构基因较1994年以前的疫苗株发生了变化,但目前没有证据表明这些变化对免疫原性产生不利影响。

Objective To analyze the genetic stability of structural gene of S191 strain for production of live attenuated measles vaccine. Methods The S191 strain for production of measles vaccine by Beijing Tiantan Biological Products Co. Ltd was subcuhured from passage 25 （S191-BJ25） to 29 （S191-BJ29）, and that by Shanghai Institute of Biological Products from passage 24 （S191-SH24） to 33 （S 191-SH33）. RNAs were extracted from the subcuhured strains for amplification and sequencing of structural gene fragments N, M, F and H. The sequencing results were compared with those of the corresponding sequences of S191 strain included in GenBank in 1994. Results The total mutation rate of N, M, F and H genes of subcuhured S19t-BJ25 was 0. 02%, while that of subcultured S191-SH24 was 0. 15%. Compared with those of S191 strain included in GenBank in 1994, the total mutation rate of the four genes of subcuhured S191-BJ25 and S191-SH24 were 0. 3% and 0. 4% respectively. Conclusion The virus seeds in three-tier virus seed bank of S191 strain for production of measles vaccine by Beijing Tiantan Biological Products Co. Ltd showed reliable genetic stability. During subculture from master seeds to vaccine, structural genes N, M, F and H showed stable molecular genetic character. Changes were observed in four structural genes of the current available S191 strain as compared with those used before 1994. However, there has no evidence indicating adverse effect of the changes on immunogenicity.