学术
摘 要:
目的探讨幽门螺杆菌（H．pylon）eagA基因3’端多态性及其与临床疾病的相关性。方法收集NCBI网络数据库H．pylorieagA基因全序列95条，eagA基因3’端可变区碱基、氨基酸序列387条，用Vector NTI advance 10软件对已知疾病背景的256条网络数据库eagA氨基酸序列进行多序列比较，分析eagA基因3’端序列特征及其与临床疾病的相关性。结果（1）91条eagA基因全长氨基酸序列之间相同氨基酸百分比为27％，相似性较低；其3’端序列之间差异明显，存在大量氨基酸的插入、缺失、替换外和重复，而5’端序列相对保守。（2）eagA基因3’端氨基酸序列含有六种重复序列，分别命名为C1，C2，C3，C4，C5，C6；其中C3，C4，C6可分为两种类型，东亚型（Cn东）和西方型（Cn西）。大部分（81．86％）eagA基因3’端氨基酸序列基本结构为C1—C2-C1-C3东／C3西-C4东／C西-C5-C1-C6东／C6西。少数菌株eagA基因3’端氨基酸序列长度较长，具有不同的重复序列数目及组合方式，根据其重复序列数目及组合方式不同，可将这少数菌株eagA基因3’端氨基酸序列分为10型，其中1、7、9、10型仅存在于西方来源菌株，2、3、5、8型仅存在于东方来源菌株，4、6型为东西方菌株共有类型。（3）〉4个EPIYA模体的菌株检出率在萎缩性胃炎组（11．90％）与消化性溃疡（PU）组（1．27％）比较差异有统计学意义（P〈’0．05），且含有4个以上EPIYA模体的菌株87．5％是在萎缩性胃炎及胃癌（GU）中检出。含多个EPIYA—C／D位点的菌株在胃癌患者中的检出率（16．67％）显著高于消化性溃疡（5．06％）患者（P〈0．05）。c4数目=3时，GC组（14．81％）与Pu组（2．53％）比较差异有统计学意义（P〈0．05），其余重复序列数目在不同胃十二指肠疾病中无统计学意义（P〉0．05）。第6型菌株在胃癌患者中的检出率（14．81％）显著高于消化性溃疡（2．53％）患者（P〈0．05）。结论（1）且pylori菌株casA基因3’可变区多态性明显，其差异主要由重复序列的种类、数目和组合方式造成。（2）感染〉4个EPIYA模体的CagA＋H.pylori可能与萎缩性胃炎及胃癌有关。（3）含多个EPIYA—C／D位点的CagA＋H.pylori及第6型CagA＋H．pylori可能与胃癌有关。[著者文摘]
文章出处:
《中华现代内科学杂志》-2007年4卷7期 -577-583页
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A
文章编号:
1681-6676（2007）07-0577-07
相关文章:
Polymorphism of 3＇ region of cagA in helicobacter pylori strains and its clinical significance
HU Lin ,XU Can-xia, LUO Xiao-ling （Department of Gastroenterology, The Third Xiangya Hospital of Central South University, Changsha 410013, China）
Abstract:
Objective To explore the polymorphism of 3＇ region of cagA in helicobacter pylori strains and its relevances with clinical diseases. Methods We searched out 95 items of cagA gene complete sequence and 387 items of nucleotide and corresponding amino acid sequence of 3＇ region of cagA gene of helicobacter pylori （H. pylori） from NCBI database on network. Vector NTI advance 10 software was used to multiple-sequence alignment and similarity analysis of the 256 items of 3＇ region of cagA having the distinct disease background. Then analysed the Polymorphism of 3＇ region of cagA and its relevances with clinical disease. Results （ 1 ） The comparison of complete amino acid sequence of cagA showed that the 5＇ region of cagA gene was relatively conservative,and the differences among the 3＇ regions were obvious;the identity position of amino acid among complete amino acid sequences of ca- gA was 27% , the similarity is relatively low,besides lots of insertion,deletion, substitution, there were many repeated sequences in 3＇ region. （2）There were 6 kinds of repeated sequences in amino acid sequences of 3＇ region, named as C1, C2, C3, C4, C5, C6 ; the sequences C3, C4, C6 could be classified into two types ： East Asian type （Cneast） and western type（Cn ）. The basic structure of amino acid sequences of 3＇ region was C1 - C2 - C1 - C3east/C3west -C4east/Cwest-C5 -C1 -C6eas/C6west. A few amino acid sequences of 3＇ region of cagA were longer, they had different number of repeated sequences and different combination types, based on this, these few amino acid sequences of 3＇ region of cagA were divided into 10 types,the types of 1,7,9,10 only could be found in East Asian strains,on the contrary, the types of 2,3,5,8 only could be found in west strains, types of 4,6 could be found both in East Asian and west strains. （3）The detection rate of strains with more than 4 EPIYA motif in atrophic gastritis group was 11.90% ,and in peptic ulcer group was 1.27% ,the difference between them had statistical significance（P 〈 0.05 ） ,87.5% strains with more than 4 EPIYA motif were detected in atrophic gastritis and gastic cancer group. The detection rate of strainswith multiple EPIYA - C/D site in gastic cancer group （ 16.67% ） was obviously higher than in peptic ulcer group （5.06% , P 〈 0.05 ）. In the sequences of which C4 repeated 3 times, the comparision between GC （ 14.81% ） and PU （2.53%） showed statistical significance （P 〈 0.05 ）. The number of other repeated sequences in different gastroduodenal diseases had no statistical significance（P 〉0.05）. The detection rate Of the sixth type strain in gastic cancer group（ 14.81% ） was obviously higher than that in peptic ulcer group（2.53% ,P 〈 0.05）. Conclusion （ 1 ） Polymorphism of variable region of 3＇ region of cagA gene in H. pylori strains is significant, the differences were mainly caused by the type, number and combination type of repeated sequences. （2） CagA ＋ H. pylori with more than 4 EPIYA motif maybe is correlated with atrophic gastritis and gastic cancer. （3） CagA ＋ H. pylori with multiple EPIYA - C/D site and the sixth type maybe is correlated with gastic cancer.[著者文摘]
Key words:
Helicobactor pylori; cytotoxin-associated gene A ; sequence analysis ; polymorphism ; disease type
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