幽门螺杆菌上皮接触诱导基因iceA1的克隆及序列特征

目的:克隆和分析镇江地区来源于不同疾病的(胃癌、溃疡和胃炎)幽门螺杆菌(Helicobacter pylori,H.pylori)的表皮接触诱导基因iceA1.方法:从胃十二指肠疾病患者胃黏膜组织中分离培养获得H.pylori,PCR扩增检测iceA1基因,并克隆至pMD18-T载体上,进行测序和序列分析.结果:克隆和测序了镇江地区来源于不同疾病的(胃癌、溃疡和胃炎)共12株H.pylori的i c e A1基因片段,并与标准菌株60190比对,结果显示镇江地区的H.pylori的iceA1基因中存在着3处框内缺失突变热点(780del6、809del5、914del7),这些缺失突变在溃疡和胃炎中均存在,但是胃癌株只存在809del5.对缺失片段周围的序列进行分析,这些缺失序列的两端基本都与同向重复序列相连,这可能与复制过程中滑动错配的小片段缺失模型有关.结论:iceA1序列的变异性有可能作为分析H.pylori群体遗传学的有用工具.

Cloning and sequence analysis of the iceA1 gene of Helicobacter pylori strains isolated from patients with various gastric disorders

AIM: To clone and sequence the iceA1 gene of Helicobacter pylori(H.pylori) strains isolated from patients with various gastric disorders in Zhenjiang area.METHODS: H.pylori strains were isolated from the gastric mucosa of patients with chronic gastritis,peptic ulcer or gastric cancer,and cultured on solid agar medium.The iceA1 gene was amplified from H.pylori DNA by PCR,cloned intoT vector,sequenced and analyzed using bioinformatics methods.RESULTS: The iceA1 gene was cloned from 12 H.pylori strains derived from patients with chronic gastritis,peptic ulcer or gastric cancer and sequenced.Sequence analysis led to identification of three deletion hot spots(780del6,809del5,914del7) within the iceA1 open reading frame.All these deletion mutations were identified in strains from patients with peptic ulcer or chronic gastritis,but only 809del5 was detected in strains from cancer patients.Local DNA sequence analysis revealed that the endpoints of all there deletions coincided with direct repeats.We also found deletion hot spots that were associated with direct repeats in iceA1 and that favored a small-deletion model of slipped mispairing events during replication.