Allelic variation in the cagA gene of Helicobacter pylori obtained from Korea compared to the United States.
Allelic variation in the cagA gene of Helicobacter pylori obtained from Korea compared to the United States.
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发表时间：
1996-07
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通讯作者：
S. Miehlke;K. Kibler;Jong G. Kim;N. Figura;Small Sm;D. Y. Graham;M. Go
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文献类型：
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作者：
S. Miehlke;K. Kibler;Jong G. Kim;N. Figura;Small Sm;D. Y. Graham;M. Go
目的幽门螺杆菌是十二指肠溃疡发病的重要因素，也与胃腺癌的发病有关。已有研究表明，cagA基因是幽门螺杆菌毒力更强菌株的标志。方法对我国60株临床分离株[胃癌患者34例，十二指肠球部溃疡患者26例]进行cagA基因检测。用两套不同的cagA基因引物对基因组DNA进行聚合酶链式反应扩增。第一套cagA引物从cagA基因的中间区扩增出297个碱基的产物。之前在休斯顿地区的患者群体(21名DU患者，20名无症状胃炎患者)中建立的第二套引物扩增了cagA基因下游1.4kb的区域。结果韩国Hp分离株(33/34 CA，26/26 DU)和休斯顿地区Hp分离株(20/21 DU，16/20无症状性胃炎)中59/60(98.3%)和36/41(88%)存在预期的cagA基因扩增产物。使用第二套cagA引物，只有1/60(1.7%)来自韩国的Hp分离株(1/34 CA，0/26 DU)和36/41(88%)来自休斯顿地区的Hp分离株(20/21 DU，16/20 GST)(p<；0.001)有预期的1.4kb产物。Western印迹分析表明，韩国Hp分离株均表达cagA。结论cagA基因在韩国人胃腺癌或十二指肠溃疡患者Hp分离株中的高表达，提示cagA基因在Hp菌株中普遍存在，因此不能作为区分Hp菌株与特定疾病的单一标志。我们的数据进一步表明，幽门螺杆菌菌株基因组中可能存在等位基因变异，不同的幽门螺杆菌种群可能在不同的地理区域循环。
OBJECTIVE Helicobacter pylori is an important factor in the development of duodenal ulcer disease and has been implicated in the pathogenesis of gastric adenocarcinoma. It has been suggested that the cagA gene is a marker for more virulent strains of H. pylori. METHODS We determined the prevalence of the cagA gene in 60 clinical isolates [34 from gastric carcinoma patients (CA), 26 from duodenal ulcer patients (DU)] from Korea, a country with a high incidence and mortality from gastric cancer. Genomic DNA was polymerase chain reaction-amplified by using two different primer sets for the cagA gene. The first cagA primer set amplifies a 297-bp product from the midregion of the cagA gene. The second primer set, which was previously established in a patient population from the Houston area (21 DU patients, 20 from individuals with asymptomatic gastritis) amplified a 1.4-kb region further downstream in the cagA gene. RESULTS The expected 297 bp polymerase chain reaction amplicon for cagA was identified in 59/60 (98.3%) H. pylori isolates from Korea (33/34 CA, 26/26 DU), and in 36/41 (88%) isolates from the Houston area (20/21 DU, 16/20 asymptomatic gastritis) (NS). Using the second cagA primer set, the expected 1.4-kb product was found in only 1/60 (1.7%) H. pylori isolates from Korea (1/34 CA, 0/26 DU), and in 36/41 (88%) of isolates from the Houston area (20/21 DU, 16/20 GST) (p < 0.001). Western blot analysis showed that all Korean H. pylori isolates expressed cagA. CONCLUSIONS The high prevalence of the cagA gene in H. pylori isolates from Korean patients with gastric adenocarcinoma or duodenal ulcers indicates that the cagA gene is common in H. pylori strains, and therefore, is not reliable as a single marker for the discrimination of H. pylori strains with respect to a specific disease. Our data further suggest that allelic variations in the genome of H. pylori strains may exist and that distinct H. pylori populations may circulate in different geographic regions.