华东部分农村地区结核分枝杆菌的VNTR-MIRU分子特征

 目的  评价VNTR-MIRU分型方法在结核病流行病学中的应用,并描述华东部分农村地区结核分枝杆菌的基因型分布及成簇特征。方法  对浙江省宁波市鄞州区及江苏省盐城市阜宁县从2009年6月1日至2010年11月31日登记的结核病患者的结核分离菌株采用VNTR-MIRU方法进行分型,通过Hunter-Gaston指数(HGI)及遗传差异值(h)对MIRU位点进行分辨力及遗传差异性评价,同时进行问卷调查以收集患者的社会人口学及临床治疗信息。结果  在297株结核杆菌分离株中发现了281种基因型,近期传播比例为5.4%,MIRU位点组合的分辨力(HGI)为0.9995,7个位点的分辨力大小依次为:VNTR3820>Qub18>Qub11a>MIRU26>Qub11b>Mtub21> Qub26,位点的h大小排序与分辨力的大小排序相同,遗传差异性最大的位点为VNTR3820 (h=0.8794),最小的为Qub26 (h=0.6613)。比较两个研究地区的结核枝杆菌成簇特征,阜宁县菌株成簇率为19%,而鄞州区无菌株成簇,均呈现“唯一”基因型,这种差异的产生很可能与当地的人口迁徙有关。结论  7位点VNTR-MIRU分型法对结核枝杆菌进行分型简便快速,而且具有较高的分辨力,适合于结核的大规模快速检测。我国华东农村地区结核的流行以既往感染复燃为主,并存在一定比例的近期传播。

Molecular characteristics of Mycobacterium tuberculosis in rural eastern China using VNTR-MIRU method

Objective  To determine the value and effectiveness of 7 variable number loci tandem repeat-mycobacterial interspersed repetitive unit (VNTR-MIRU) method,and to describe the genotypes and cluster characteristics of Mycobacterium tuberculosis (M.tuberculosis) in rural eastern China.Methods  M.tuberculosis isolates were collected from the tuberculosis patients registered in Yinzhou district of Ningbo city,Zhejiang Province,and Funing county of Yancheng city,Jiangsu Province,between Jun.1,2009 to Nov.31,2010.The isolates were genotyped by VNTR-MIRU and evaluated with Hunter-Gaston index (HGI) and the allelic diversity (h).A structured questionnaire was used to collect the social,demographic and clinical information of each patient.Results  VNTR-MIRU identified 281 genotypes from a total of 297 isolates,with an estimated proportion of recent transmission to be 5.4%.The cumulative discriminatory power (HGI) of the 7 VNTR MIRU loci was 0.9995,while the individual discriminatory power of the 7 loci was sorted as:VNTR3820>Qub18>Qub11a>MIRU26>Qub11b>Mtub21>Qub26,which was in accordance with the polymorphism of the 7 loci.In Funing,the proportion of the isolates in clusters was 19%,while no cluster was identified in Yinzhou.This difference was likely relevant to population migration.Conclusions  Seven loci VNTR-MIRU may be potentially used in rapid detection of tuberculosis because of its convenience and high discriminatory power.Reactivation was the main source of tuberculosis in rural eastern China.