四川省结核分枝杆菌VNTR分型研究

Genotyping of Mycobacterium tuberculosis strain isolated from Sichuan province by variable number tandem repeat analysis method

目的评价不同串联重复序列(VNTR)位点在四川省结核分枝杆菌中的基因多态性,以及不同VNTR位点组合在四川省结核分枝杆菌基因分型中的应用。方法采用多位点数目可变串联重复序列分析技术(ML-VA)对102株四川省结核分枝杆菌菌株的15个VNTR位点进行分析,基因多态性分析采用Hunter-Gaston指数,聚类分析采用BioNumerics软件。结果 15个VNTR位点的基因多态性存在较大的差异,位点Mtub21(HGI 0.772)和MIRU26(HGI 0.764)的多态性较高,ETR-C(HGI 0.168)和MIRU23(HGI 0.077)的多态性较差。ETR-B和ETR-C两个位点在对四川省北京基因型结核分枝杆菌进行分型时则不具有多态性。对不同的VNTR位点组合进行比较,随着VNTR位点的增加,VNTR分型方法的分辨能力也有所提高。10个VNTR位点组合的分辨指数与15位点组合的分辨指数相差不大。同一VNTR位点在不同地区北京基因型菌株中的分辨力也存在较大的差异。结论不同VNTR位点在四川省结核分枝杆菌中具有不同的分辨力,并且同一VNTR位点在不同地区的北京家族菌株中的分辨力也不同。10个VNTR位点组合的基因分型方案可用于四川省结核分枝杆菌基因分型的一线方法。本研究的数据结果对挑选适合中国结核分枝杆菌基因分型的VNTR位点组合法具有重要的作用。

Objective To investigate the polymorphism of different tandem repeats in Mycobacterium tuberculosis isolated from Sichuan province.MethodsFifteen tandem repeat loci were used to genotype 102 Mycobacterium tuberculosis collected from Sichuan province.The polymorphisms of different loci were analyzed by Hunter-Gaston Index and Bionumerics 5.0 software.ResultsIn this study,15 loci showed different polymorphism.Mtub21（HGI 0.772）and MIRU26（HGI 0.764）loci were highly polymorphic,whereas ETR-C（HGI 0.168） and MIRU23（HGI 0.077） were less polymorphic.Diversities were not observed for ETR-B and ETR-C loci among Beijing genotype strains.The capability of the VNTR analysis method to differentiate the Mycobacterium tuberculosis strains was improved with increasing VNTR locus.The HGI of 10-locus set was similar to that of 15-locus set.In addition,VNTR showed variation in the ability to differentiate Beijing genotype strains from other geographical areas.ConclusionsThe discriminatory power of different locus was different,and the same VNTR locus variation in the ability to differentiate Beijing gentry strains from different geographical areas.The 10-locus set was shown to be ideal for use in first-time molecular typing in Sichuan province.The analysis of VNTR data in this study might be useful to select appropriate VNTR loci for the gene-typing of M.tuberculosis in China.