流行性腮腺炎疫苗株S79全基因序列测定与分析

目的 腮腺炎疫苗株S79工作种子噬斑纯化及全基因组测序,针对国内已经分离出的毒株,从分子生物学角度探讨疫苗保护力相关问题.方法 噬斑纯化S79疫苗株,利用RT-PCR分段扩增S79株两种亚株的全基因并测序,比较S79株与其来源株Jeryl Lynn(JL)核酸序列差异;从GenBank中获得WHO各基因型参考株和中国腮腺炎流行株疏水蛋白(SH)序列,分析病毒株和疫苗株遗传距离,并构建基因亲缘性关系树.结果 S79疫苗株由两种亚株构成,比例为2∶5(major∶minor),获得全基因序列并递交GenBank;与相应的JL株相比,核苷酸序列同源性分别为99.7%和100%.亚株序列中存在散在区段异源重组.S79疫苗株为A基因型,中国的流行株为F基因型,遗传距离为11.2%～20.0%.结论 S79疫苗株由两种亚株构成,两亚株的全基因序列与JL株基本一致,但亚株的比例与国际上应用的其他JL疫苗株存在较大差异.疫苗株与中国流行株不属于同一基因型,遗传距离较远.S79疫苗免疫保护效果的差异可能主要与疫苗株和流行株不属于同一基因型有关.

Sequencing and analysis of mumps virus vaccine strain S79 Genome

Objective To analyze the genome sequencing of mumps virus strain 79 purified from working seeds plague and examine its phylogenetic relationship with wild type virus strain isolated in China,and to explore the efficacy of vaccine at molecular level.Methods Whole genome sequences of two substrains of S79(major and minor),were obtained with fragment amplification by RT-PCR.Genetic distances between S79 and strains identified in China were analyzed based on the phylogenic analysis of small hydrophobic protein(SH) sequences.Results The nucleotide homologies of two S79 substrains(major and minor),with a ratio of 2:5 during culture,with Jeryl Lynn(JL) strain were 99.7% and 100%,respectively.There were scattered non-homologous recombination between two substrains.The genetic distances between strain S79,which was genotype A,and wild type virus strain identified in China,which were genotype F,was 11.2% -20.0%.S79 live vaccine was composed of two substrains,major and minor component,which were highly similar to JL strain in their genome sequences,but different from JL in their ratios during culture.Conclusion Different from wild type virus strain identified in China,the genotype of S79 was A,and phylogenetically distant from other strains,which may account for the low efficacy of S79 live vaccine.The ratios of two substrains might also be of interest for further study of the vaccine protection and efficacy.