幽门螺杆菌中国分离株vacA基因多态性分析

Polymorphism of Helicobacter pylori vacA, isolated in China

目的分析幽门螺杆菌（HP）中国菌株vacA基因多态性。方法对分离自中国7个不同地区、不同胃十二指肠相关疾病患者的119株HP，采用特异引物聚合酶链反应（PCR）方法，对其vacA基因进行PCR扩增。根据核酸电泳中产物片段大小确定vacA等位基因类型并统计分析各型分布。对vacA基因核心片段进行PCR扩增和DNA测序，利用软件MEGA4．0对DNA测序结果进行聚类分析。结果119株HP的vacA基因以sla、m2和il型为主，分别为97．5％（116／119）、68．9％（82／119）和91．6％（109／119）。26．1％（31／119）为mlb；slb，mla未检出。vacA组合基因型以sla／m2／il为主（62．2％，74／119），sla／mlb／il次之（25．2％，30／119）。不同地区、不同疾病来源菌株sla分布的差异无统计学意义（P〉0．05）。而m区基因多态性在疾病类型及分离地区间差异有统计学意义（P〈0．01）。不同疾病来源菌株间i区基因分型分布的差异无统计学意义，但不同分离地区菌株间差异有统计学意义（P〈0．01）。119株的vacA基因序列聚类为三个不同组群。结论HP中国分离株vacA基因型以sla／m2／il组合型为主，sla分型结果与菌株分离地区及疾病类型无关。不同地区、不同疾病来源菌株m区基因分型不同。不同地区菌株vacA基因i区分型不同，但i区基因分型与菌株的疾病来源无显著相关性。

Objective To understand the polymorphism of Helicobacter pylori （H. pylori） vacA alleles in China. Methods A total of 119 H. pylori strains were isolated from different gastroduodenal diseases in 7 different geographic regions in China. vacA and its alleles were identified according to the length of PCR products with DNA electrophoresis. The distributions of vacA alleles were statistically analyzed. The core fragment of vacA was sequentially analyzed by software MEGA4.0. Results The alleles in vacA dominantly belonged to sla, m2 and il in the tested strains. The distribution appeared to be 97.5 % （ 116/119 ）, 68.9 % （ 82/119 ） and 91.6% （ 109/119 ）, respectively. The mlb allele appeared to be 26.1% （31/119）. slb and mla were not found. The major vacA recombination was between sla/m2/il and 62.2% , followed by sla/mlb/il （25.2% , 30/119）. No association was found between the distribution of sla allele and the clinical outcome, as well as the geographical regions （P〉0.05）. However, the distribution of m alleles showed significant difference both among the types of disease and the geographic regions （P〈 0.01 ）. The present of i alleles did not show significant differences among disease patterns, but had significant differences between different geographic groups （P〈0.01）. Three clusters were identified among these 119 isolates according to the DNA sequence of vacA. Conclusion sla/m2/il appeared to be the main allele in H. pylori vacA isolates from China in this study. The distribution of m alleles in vacA was correlated both to the regions and the disease patterns. The presence of i allele was associated to the regions but not the disease patterns.