幽门螺杆菌cagA基因及蛋白序列多态性分析  

Sequence diversity analysis of CagA gene and corresponding protein in Helicobacter pylori

作　　者：周军 曾浔 尹焱 郭欣 张建中 

机构地区：[1]中国疾病预防与控制中心传染病预防与控制所传染病诊断室,北京市102206 [2]中国疾病预防与控制中心传染病预防与控制所中国现场流行病学培训项目,北京市100050

出　　处：《世界华人消化杂志》2004年第6期1307-1312,共6页World Chinese Journal of Digestology

基　　金：国家自然科学基金资助项目;No.30370078~~

摘　　要：目的:结合本实验室研究结果,充分利用NCBI的核酸和蛋白数据库中检索到的CagA基因碱基和蛋白质氨基酸序列,分析其序列特征以及与地域和疾病的相关性. 方法:利用Vector NTI Suite 9.0,ClastalX(version 1.8), Phylip(version 3.5)和Treeview(version 1.61)软件对检索到的幽门螺杆菌CagA基因碱基和蛋白质氨基酸序列进行多序列比较和系统发育分析. 结果:检索到可以利用的全序列44条,部分序列560条. 通过44条全序列比对,相似性分析和构建系统进化树, 发现CagA基因碱基和蛋白质氨基酸序列可分为具有明显地域特征的东西方两类.通过44条CagA全序列和266条C端部分序列分析,发现C端相对多变区的重复序列可分为两类:第一类为菌株共有的不连续重复序列,第二类为个别菌株特有的连续重复序列,此类重复序列包含EPIYA模体的重复.序列特征与疾病的关系分析表明,非胃癌株中包含第二类重复序列的菌株占13%(9/71),胃癌株中包含第二类重复序列的菌株占31%(12/39),),X2检验P=0.021<0.05, 故可以认为胃癌株中包含第二类重复序列出现率高于非胃癌株,可以认为包含第二类重复序列的菌株与胃癌有关. 结论:幽门螺杆菌CagA基因及蛋白序列多态性明显,具有东西方两个地域聚类特征,重复序列可分为两类.第二类重复序列中包含EPIYA模体的重复可能导致菌株致病性增强.AIM: To find the structural characteristics and correlation with region and the clinical outcomes by analyzing nucleotide and amino acid sequences of CagA, our research results and data of CagA sequences deposited in NCBI database. METHODS: The characteristics of CagA sequences were analyzed, and a phylogenetic tree was constructed by using Vector NTI Suite 9.0, ClastalX (version 1.8), Phylip (version 3.5) and Treeview (version 1.61). RESULTS: Through searching NCBI nucleotide and protein database, we obtained 44 complete and 560 partial CagA sequences. Aligning these sequences, analyzing similarity and constructing phylogenetic tree, we found CagA seqenceses could be classified into two types: western type and eastern type. Analyzing the CagA C terminal of 44 complete and 266 partial sequences, we classified the repeat sequence of CagA C terminal into two types: type I was discontinuous repeat sequence, common among all the strains, and type II was continuous repeat sequence, found in some individual strains. The type II repeat sequence was found in 31% (12/39) of strains from gastric cancer patients, compared with 13% (9/71) of strains from non-cancer patients (P=0.021 < 0.05). Strains with the type Ⅱ repeat sequence were associated with gastric cancer. CONCLUSION: There is a high diversity of CagA nucle otide and amino acid sequences among H pylori strains, showing a distinct geographic character as western and eastern region collection. The repeat sequence of CagA C terminal can be classified into two types, and strains with the type II repeat sequence containing EPIYA motif exhibits a stronger pathogenecity.

关 键 词：幽门螺杆菌 CAGA基因 蛋白序列 基因多态性 重复序列 

分 类 号：R378[医药卫生—病原生物学]