Jenks P J, Mégraud F, Labigne A
Unité de Pathogénie Bactérienne des Muqueuses, Pasteur Institute, Paris, France.
Gut. 1998 Dec;43(6):752-8. doi: 10.1136/gut.43.6.752.
The development of clinical disease after infection with Helicobacter pylori has been reported to be associated with expression of the cagA gene. Recently, it has been shown that cagA is part of a multigene locus, described as the cag pathogenicity island (PAI). The role of this region in determining clinical outcome remains to be established.
To investigate whether the presence of cagA is always associated with the presence of the complete cag PAI and to evaluate the distribution of selected cag genes in 73 H pylori strains isolated from patients in France.
Clinical strains of H pylori were screened for selected genes of the cag PAI by polymerase chain reaction and colony hybridisation.
Of 64 strains that harboured the cagA gene, 57 (89%) also contained the entire cag PAI. The entire cag PAI was found in 85% (48/56) and 53% (9/17) of duodenal ulcer and non-ulcer dyspepsia isolates, respectively. Eight strains had deletions within the cag PAI, including deletion of the cagA gene in one isolate; the deletions were not associated with the insertion sequence IS605. Of eight strains lacking the cag PAI, four were isolated from patients with duodenal ulcer.
The cag PAI is not a uniform, conserved entity. Although the presence of the cag PAI is highly associated with duodenal ulcer, the clinical outcome of infection with H pylori is not reliably predicted by any gene of the cag PAI.
据报道，幽门螺杆菌感染后临床疾病的发生与cagA基因的表达有关。最近研究表明，cagA是一个多基因位点的一部分，该位点被称为cag致病岛（PAI）。该区域在决定临床结果方面的作用仍有待确定。
研究cagA的存在是否总是与完整的cag PAI的存在相关，并评估从法国患者中分离出的73株幽门螺杆菌菌株中选定的cag基因的分布情况。
通过聚合酶链反应和菌落杂交对幽门螺杆菌临床菌株进行cag PAI选定基因的筛查。
在64株携带cagA基因的菌株中，57株（89%）也含有完整的cag PAI。在十二指肠溃疡和非溃疡性消化不良分离株中，分别有85%（48/56）和53%（9/17）发现了完整的cag PAI。8株菌株的cag PAI内存在缺失，其中1株分离株的cagA基因缺失；这些缺失与插入序列IS605无关。在8株缺乏cag PAI的菌株中，有4株是从十二指肠溃疡患者中分离出来的。
cag PAI并非一个统一、保守的实体。虽然cag PAI的存在与十二指肠溃疡高度相关，但幽门螺杆菌感染的临床结果不能通过cag PAI的任何基因可靠预测。
