Chen Meng, Zhang Tie-gang, Chen Li-juan, Wu Jiang, Yang Jie, Zhang Wei
Beijing Center for Disease Control and Prevention, Beijing 100013, China.
Zhonghua Liu Xing Bing Xue Za Zhi. 2009 Nov;30(11):1184-8.
To compare the genetic characteristics of mumps virus strain circulating in Beijing with vaccine strain and to preliminarily analysis the reasons of vaccine ineffectiveness.
The following methods were used: Isolation and identification of the mumps virus which had been circulating in Beijing, immunization history analysis, SH gene sequence analysis and comparison genotype homology with reference strains and analysis of the key amino acid sites of HN variation.
In 38 mumps cases that virus had been isolated from, another seven cases were IgM negative. In 2007 and 2008, the positive rates on virus isolation, RT-PCR and IgM-decreased significantly, while the cases with immunization history had an increase. Cases without histories of vaccination had both higher positive rates on virus isolation and IgM. Thirty-eight strains belonged to F genotype virus, but vaccine strain was A genotype. The circulating viruses showed 5.6% sequence divergence on SH gene nucleotide and 16.0% - 18.1% from vaccine strain. Conservative hydrophobic amino acids on SH protein of some Beijing strains had changed. For example, there were 6 strains, from No.8: L-->F. The circulating viruses showed 2.3% sequence divergence on HN protein amino acid sequences and 4.2% - 5.3% from vaccine strain. Amino acids sites, which deciding the ability of cross-neutralization of the Beijing strains and vaccine strains were different. At the 354 and 356 sites, all the Beijing strains were different from the vaccine strains. The N-glycosylation sites on HN of Beijing strains were also different from those on vaccine strains. Locations 464 - 466 appeared to be NCS on Beijing strain, but locations 464 - 466 were NCR on the vaccine strains. Another 18 unknown function amino acids sites of all Beijing strains were different from those on vaccine strains.
In recent years, genotype F became the main genotype of circulating strains in Beijing without genotype variation, but larger difference was found between them. There was a big difference between SH and HN protein of Beijing strains and vaccine strain, which might explain the ineffectiveness of the vaccine.
比较北京地区流行的腮腺炎病毒株与疫苗株的基因特征，初步分析疫苗接种后免疫失败的原因。
采用北京地区腮腺炎病毒的分离鉴定、免疫史分析、SH基因序列分析、与参考毒株比较基因型同源性以及HN变异关键氨基酸位点分析等方法。
在38例分离到病毒的腮腺炎病例中，另有7例IgM阴性。2007年和2008年，病毒分离、RT-PCR及IgM阳性率显著下降，有免疫史的病例有所增加。未接种疫苗的病例病毒分离及IgM阳性率均较高。38株病毒属于F基因型病毒，而疫苗株为A基因型。流行毒株SH基因核苷酸序列与疫苗株有5.6%的差异，氨基酸序列差异为16.0% - 18.1%。部分北京毒株SH蛋白保守疏水性氨基酸发生改变，如8号毒株有6株L→F。流行毒株HN蛋白氨基酸序列与疫苗株有2.3%的差异，氨基酸位点差异为4.2% - 5.3%。决定北京毒株与疫苗株交叉中和能力的氨基酸位点不同，北京毒株354和356位点与疫苗株均不同。北京毒株HN蛋白N-糖基化位点与疫苗株也不同，北京毒株464 - 466位点为NCS，疫苗株该位点为NCR。北京毒株另外18个未知功能氨基酸位点与疫苗株也不同。
近年来，F基因型成为北京地区流行毒株的主要基因型，无基因型变异，但两者差异较大。北京毒株与疫苗株SH和HN蛋白存在较大差异，可能是疫苗免疫失败的原因。
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