上海地区幽门螺杆菌cagA基因3’区和vacA基因的多态性分析及其临床意义

Prevalence and Genetic Diversity of cagA 3' Region and vacA in Helicobacter pylori Strains Isolated from Shanghai Population and their Relations to Gastroduodenal Diseases

探讨上海地区人群中幽门螺杆菌（H．pylori）cagA基因3’区和vacA基因的多态性及其临床意义。方法：99株H．pylori菌株分离自17例慢性浅表性胃炎（CSG）、21例慢性萎缩性胃炎（CAG）、19例胃溃疡（GU）、23例十二指肠溃疡（DU）和19例胃癌（GC）患者。用聚合酶链反应（PCR）技术对H．pylori菌株的cagA基因3’区和vacA基因信号序列及中间区等位基因进行扩增和检测。结果：99株H．pylori菌株中84株（84．8％）cagA基因阳性，其3’区产物大小均约650bp，属A型。vacA基因信号序列仅检出sla型，见于从94．1％（16／17）的CSG、952％（20／21）的CAG、89．5％（17／19）的GU、87．00（20／23）的DU和89．5％（17／19）的GC患者中分离的菌株（P＝0．87）；中间区等位基因仅检出m2型，见于从70．6％（12／17）的CSG、71．4％（15／21）的CAG、63．20（12／19）的GU、73．9％（17／23）的DU和57．9％（11／19）的GC患者中分局的菌株（P＝0．72）。结论：上海地区人群中H．pylori菌株的cagA基因3’区相对保守；绝大多数vacA基因属sla／m2型。本研究结果不支持这些基因的多态性与H．pylori感染临床结局相关的观点。

Background/Aims: To investigate the prevalence and genetic diversity of cagA 3' region and vacA in Helicobacter pylori (H. pylori) strains isolated from Shanghai population and their relations to gastroduodenal diseases. Methods: 99 H. pylori strains isolated from 17 patients with chronic superficial gastritis (CSG), 21 with chronic atrophic gastritis (CAG), 19 with gastric ulcer (GU), 23 with duodenal ulcer (DU) and 19 with gastric cancer (GC) were investigated. The prevalence and genetic diversity in cagA 3' region, vacA signal sequence and middle-region alleles were studied by the technique of polymerase chain reaction (PCR). Results: The prevalence of cagA was 84.8% (84/99) and all the 84 strains were type A of the cagA 3' region. The only type of vacA signal sequence was sla, seen in 94.1% (16/17) CSG, 95.2% (20/21) CAG, 89.5% (17/19) GU, 87.0% (20/23) DU and 89.5% (17/19) GC patients, respectively (P= 0.87). The only type of vacA middle-region alleles was m2, seen in 70.6% (12/17) CSG, 71.4% (15/21) CAG, 63.2% (12/19) GU, 73.9% (17/23) DU and 57.9% (11/19) GC patients,respectively (P= 0.72). The relation between the diversity of these genes and gastroduodenal diseases was not established. Conclusions: The structure of cagA 3' region in H. pylori strains isolated from Shanghai population is relatively conservative. The only form of cagA 3' region was type A. Most of the 99 strains were vacA sla/m2 type, regardless of their clinical outcomes. The result of this study does not support the view that the diversity of these genes is correlated with the clinical outcome of H. pylori infection.