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目的基因多态性已逐渐成为幽门螺杆菌(Helicobacter pylori,Hp)新的研究热点。文中旨在研究临床Hp菌株中cagA、cagM、cagZ、cagⅠ-Ⅱ接点、IS605等cag致病岛(cag pathogenicity island,cagPAI)相关的遗传学位点的多样性分布及其与胃十二指肠疾病的关系。方法参照标准菌株NCTC11638序列设计引物,特异性PCR方法检测253株Hp菌株中,cagA、cagM、cagZ基因、cagⅠ-Ⅱ接点以及IS605等不同遗传学位点的分布情况。结果 253株临床分离的Hp菌株中,cagA基因的检出率为92.5%(234/253);cagM的检出率为86.2%(218/253);cagZ的检出率为66%(167/253);在慢性非萎缩性胃炎、消化性溃疡、胃癌中的检出率差异均无统计学意义(P>0.05)。仅5.1%(13/253)的Hp菌株中可检测到具有西方菌株特征的cagⅠ-Ⅱ接点的存在,提示中国大部分菌株中的cagⅠ-Ⅱ接点存在明显不同于西方菌株的结构形式;含西方菌株连续状态特征的cagPAI在消化性溃疡中13.3%(10/75)的检出率明显高于慢性非萎缩性胃炎中1.4%(2/146)的检出率(P<0.01)。IS605在慢性非萎缩性胃炎中51.4%(75/146)的检出率明显高于消化性溃疡中28%(21/75)的检出率(P<0.01)。结论cagPAI集群的序列结构具有丰富的基因多样性;cagA、cagM、cagZ等遗传学位点单独无一可作为临床Hp菌株的毒力标志;IS605的存在可能影响菌株的毒力发挥;cagⅠ-Ⅱ接点区域可能存在中国或东亚菌株的特征性结构。
The target gene polymorphism has gradually become a new research hotspot of Helicobacter pylori (Hp). The aim of this study was to investigate the genetic diversity of cagA, cagM, cagZ, cagⅠ-Ⅱ contacts and cag pathogenicity island (cagPAI) in clinical Hp isolates and their association with gastroduodenal diseases Relationship. Methods According to the standard strain NCTC11638, primers were designed to detect the distribution of cagA, cagM, cagZ, cagⅠ-Ⅱ and IS605 among 253 Hp strains by using specific PCR method. Results The positive rate of cagA gene was 92.5% (234/253) in 253 strains of Hp isolates clinically. The detection rate of cagM was 86.2% (218/253) and that of cagZ was 66% (167 / 253). There was no significant difference in the detection rate of chronic non-atrophic gastritis, peptic ulcer and gastric cancer (P> 0.05). Only 5.1% (13/253) of Hp isolates could detect the presence of cagⅠ-Ⅱ contacts with western strains, suggesting that the cagⅠ-Ⅱ contacts in most strains of China were significantly different from those of western strains. The detection rate of 13.3% (10/75) of cagPAI characterized by continuous strain in peptic ulcer was significantly higher than that of 1.4% (2/146) in chronic non-atrophic gastritis (P <0.01). The detection rate of 51.4% (75/146) of IS605 in chronic non-atrophic gastritis was significantly higher than that of 28% (21/75) in peptic ulcer (P <0.01). CONCLUSION: The sequence structure of cagPAI cluster is rich in genetic diversity. None of the genetic loci such as cagA, cagM and cagZ can be used as virulence markers of clinical H. pylori strains. The presence of IS605 may affect the virulence of strains. The cagⅠ-Ⅱ junction The region may have characteristic structures of Chinese or East Asian strains.