中文摘要：

目的分离鉴定临床分离株幽门螺杆菌（Helicobacter pylori，Hp），分析其CagA蛋白的磷酸化基序EPIYA，探讨东亚株HpCagA序列的结构特点。方法选取胃相关疾病患者的胃黏膜组织，剪碎后接种于哥伦比亚血琼脂平板，微需氧培养，菌落生长后通过尿素酶试验、革兰染色及显微镜检查对Hp进行初步鉴定。提取菌落基因组，PCR扩增HP16SrRNA基因并进行测序鉴定；扩增cagA基因全长序列，连接入pMD18-T载体。将重组质粒转入感受态E．coliDH5a，测序鉴定重组质粒，利用DNAStar和MEGA6软件对cagA序列进行比对及聚类分析。结果成功分离Hp共26株。构建pMD18-T／cagA克隆载体后对26株Hp的cagA基因全长测序，序列比对分析显示有6株为西方型，20株为东亚型。东亚型CagA第815～834位点存在13个氨基酸的缺失、部分缺失或变异，西方型中有3株丢失磷酸化位点EPIYA-C；聚类分析显示Hp分离株分别聚类为东亚群、西方型东亚群以及西方群3群。结论Hp分离株以东亚株为主，但也存在西方株感染；东、西方型CagA在EPIYA基序及侧翼序列显著差异，菌株之间存在聚类关系。

英文摘要：

Objective To investigate the structural characteristics of cagA sequences from East Asian strains by isola- ting and identifying clinical strains of Helicobacter pylori and analyzing phosphorylation motifs such as EPIYA in CagA protein. Method Specimens of gastric mucosa from patients with gastric diseases were obtained and cut into pieces. These pieces were then placed onto Columbia blood agar plates with selective medium and bacteria in those pieces were cultured under microaerobic conditions. Bacterial colonies were preliminarily identified using a urease test, Gram staining, and a microscopic examination. DNA was extracted from the bacteria and a polymerase chain reaction （PCR） was used to amplify the 16S rRNA gene of H. pylori for sequencing. The cagA gene of H. pylori was amplified and ligated into a pMD-18T vector. The recombinant vector was transformed into competent E. coli DH5 to select positive clones. Plasmid DNA was extracted from these positive clones and sequenced for identification. The software DNAStar was used to ana- lyze CagA sequences and MEGA 6 was used to construct a molecular phylogenetic tree for CagA. Results In total, 26 clinical strains of H. pylori were successfully isolated and a recombinant pMD18-T/cagA vector was successfully constructed and sequenced. All sequences were submitted to GenBank with the accession numbers KR154731-KR154758. Sequence alignment using blast software and clustering analysis revealed that 6 of 26 H. pylori strains were Western and the remaining 20 strains were East Asian. The deletion, partial deletion, or variation of 13 amino acids at sites 834-815 was detected in CagA from East Asian strains and the deletion of the EPIYA-C motif was noted in CagA from Western strains. Clustering analysis indicated that the clinical isolates of H. pylori were clustered in an East Asian group, a Western/East Asian group, and a Western group. Further, only 4.87% of the East Asian strains had CagA protein con- taining cysteine while the most of the Western CagA （82.86%