中国幽门螺杆菌vacA基因型标签序列与VacA活性关系的分子系统发育分析

The molecular phylogenetic analysis based on the relationship between signature sequences of vacA gene types from Helicobacter pylori in China and VacA activities

目的探讨中国幽门螺杆菌vacA基因s、m和i区氨基酸序列分子系统发育关系及其对VacA活性的影响。方法从GenBank数据库中下载所有中国幽门螺杆菌VacA全长氨基酸序列,利用ClustalX 2.0和MEGA 5.05软件对vacA基因s、m和i区氨基酸序列及VacA全长氨基酸序列进行生物信息学分析,构建分子系统发育树。结果中国幽门螺杆菌无毒弱毒株vacA基因型全为s1/m2/i1型,而强毒株除Ch2菌株为m1-m2杂合型之外,全为s1/m1/i1型,s1型和i1型强相关。分子系统发育分析显示,中国幽门螺杆菌vacA基因s、m和i区氨基酸序列都呈现明显的地理特异性,其中m区分子系统发育树能够将VacA强毒株和无毒弱毒株分开,而s和i区分子系统发育树则不能将两者完全分开。结论 vacA基因m区氨基酸序列更适合作为中国幽门螺杆菌VacA的毒力标志。

Objective To analyze the molecular phylogenetic relationships among s,m and i regions amino acid sequences of vacA gene from China H.pylori stains,and its effect on VacA activities.Methods All VacA full-length amino acid sequences from China H.pylori stains were downloaded from GenBank database.The s,m and i regions amino acid sequences of vacA gene,and VacA full-length amino acid sequences were analyzed by ClustalX 2.0 and MEGA 5.05 software,and its molecular phylogeny trees were also constructed.Results All vacA gene types of no and low cytotoxin strain from China H.pylori were s1/m2/i1,while all high cytotoxin strain were s1/m1/i1,except for chimeric m1-m2 H.pylori strain,ch2.The s1 type was strongly related to i1 type.Molecular phylogenetic analysis showed the s,m and i regions amino acid sequences of vacA gene from China H.pylori stains indicated obviously geography specificity.The VacA high and no/low cytotoxin stains could be completely classified by the molecular phylogeny tree of m region,while s and i region not.Conclusion The m region amino acid of vacA might be better to as virulence marker of VacA for China H.pylori.