Pathogenicity island cag, vacA and IS605 genotypes in Mexican strains of Helicobacter pylori associated with peptic ulcers

Abstract

BackgroundHelicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric cancer. Two major virulence factors of H. pylori have been described: the pathogenicity island cag (cag PAI) and the vacuolating cytotoxin gene (vacA). Virtually all strains have a copy of vacA, but its genotype varies. The cag PAI is a region of 32 genes in which the insertion of IS605 elements in its middle region has been associated with partial or total deletions of it that have generated strains with varying virulence. Accordingly, the aim of this work was to determine the cag PAI integrity, vacA genotype and IS605 status in groups of isolates from Mexican patients with non-peptic ulcers (NPU), non-bleeding peptic ulcers (NBPU), and bleeding peptic ulcers (BPU).MethodsThe cag PAI integrity was performed by detection of eleven targeted genes along this locus using dot blot hybridization and PCR assays. The vacA allelic, cag PAI genotype 1 and IS605 status were determined by PCR analysis.ResultsGroups of 16-17 isolates (n = 50) from two patients with NPU, NBPU, and BPU, respectively, were studied. 90% (45/50) of the isolates harbored a complete cag PAI. Three BPU isolates lacked the cag PAI, and two of the NBPU had an incomplete cag PAI: the first isolate was negative for three of its genes, including deletion of the cagA gene, whereas the second did not have the cagM gene. Most of the strains (76%) had the vacA s1b/m1 genotype; meanwhile the IS605 was not present within the cag PAI of any strain but was detected elsewhere in the genome of 8% (4/50).ConclusionThe patients had highly virulent strains since the most of them possessed a complete cag PAI and had a vacA s1b/m1 genotype. All the isolates presented the cag PAI without any IS605 insertion (genotype 1). Combined vacA genotypes showed that 1 NPU, 2 NBPU, and 1 BPU patients (66.6%) had a mixed infection; coexistence of H. pylori strains with different cag PAI status was observed in 1 NBPU and 2 BPU (50%) of the patients, but only two of these patients (NBPU and BPU) had different vacA genotypes.

The heterogeneic distribution of Helicobacter pylori cag pathogenicity island reflects different pathologies in multiracial Malaysian population

“…Discordance in the frequency of cag PAI intactness in many reports was due to the different cag PAI genes being examined. 13 , 25 , 26 Thus, results of the present study indicate that deletions can occur in all parts of the cag PAI and screening the entire genes in the cag PAI is essential for an accurate determination of the organization of the cag PAI region. For comparison with our results, we reviewed only studies that screened all the cag PAI genes.…”

Association of IS605 andcag-PAI ofHelicobacter pyloriIsolated from Patients with Gastrointestinal Diseases in Taiwan

“…However, a recent study has suggested that IS605 is not related to the cag -PAI status [26]. In a previous study involving the Taiwanese population, all isolates were reported as positive for the cag -PAI, but only 36% of these isolates carried an IS605 insertion [21].…”

The organization of Helicobacter pylori cag-pathogenicity island (cagPAI) genes in multiracial population with histopathological changes of gastric mucosa

“…In their study, few cagPAI genes (cagE, cagL, cagT and HP521) were examined to detect the intactness of cagPAI region. Discordant in the frequency of cagPAI intactness in many reports was due to the difference cagPAI genes that being examined [14,27,28]. Thus, results of the present study indicate that deletions can occur in all parts of the cagPAI and screening the entire genes in the cagPAI is needed to determine the accurate organization of the cagPAI region.…”