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Analysis of iceA genotypes in South African Helicobacter pylori strains and relationship to clinically significant disease.

ABSTRACT: BACKGROUND:South African Helicobacter pylori isolates are characterised by the universal presence of cagA but have differences in vacuolating cytotoxin gene (vacA) alleles which correlate with clinically significant disease. However, the candidate virulence marker gene iceA has not been investigated. AIM:To characterise the genetic organisation and heterogeneity of iceA genotypes in different South African clinical isolates. PATIENTS AND METHODS:We studied H pylori strains isolated from 86 dyspeptic patients (30 with peptic ulcer disease (PUD), 19 with distal gastric adenocarcinoma (GC), and 37 with non-erosive gastritis) for the presence of iceA1 or iceA2 genes, and for differences in the genetic organisation of iceA2 by polymerase chain reaction, Southern hybridisation analysis, and sequencing. RESULTS:Genetic analysis of iceA1 demonstrated significant homology (92-95%) with the USA type strain 26695 and probably functions as a transcriptional regulator, while a novel variant (iceA2D') of iceA2 and marked differences in predicted protein secondary structure of the iceA2 protein were defined. iceA1 was detected in 68% and iceA2 in 80% of all clinical isolates. Although approximately 40% of patients had both strains, a higher prevalence (p< 0.01) of GC patients were infected with iceA1 isolates which were invariably vacA s1/iceA1 (p< 0.005 v gastritis). Isolates from PUD patients were distinguished by the structurally altered iceA2D variant (53%; p<0.03 v gastritis) while the iceA2C variant distinguished isolates from patients with gastritis alone (67%; p< 0.005 v PUD). CONCLUSION:In this study, an association between iceA1 and GC was noted while differences in variants of iceA2 differentiated between PUD and gastritis alone. Combination analyses of iceA genotypes and vacA alleles supported these associations.

SUBMITTER: Kidd M

PROVIDER: S-EPMC1728508 | biostudies-literature | 2001 Nov

REPOSITORIES: biostudies-literature

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Analysis of iceA genotypes in South African Helicobacter pylori strains and relationship to clinically significant disease.

Kidd M M Peek R M RM Lastovica A J AJ Israel D A DA Kummer A F AF Louw J A JA

Gut 20011101 5

<h4>Background</h4>South African Helicobacter pylori isolates are characterised by the universal presence of cagA but have differences in vacuolating cytotoxin gene (vacA) alleles which correlate with clinically significant disease. However, the candidate virulence marker gene iceA has not been investigated.<h4>Aim</h4>To characterise the genetic organisation and heterogeneity of iceA genotypes in different South African clinical isolates.<h4>Patients and methods</h4>We studied H pylori strains ...[more]

PMID: 11600464

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Project description:BackgroundThere are geographic variations in the genotypes of Helicobacter pylori (H. pylori) cagA, vacA, iceA, oipA and dupA. The aim of the study was to investigate the distribution of these genotypes among H. pylori strains from five regions of China and their association with clinical outcomes.Materials and methodsGastric biopsy specimens were obtained from 348 patients with different gastrointestinal diseases in the five regions of China. The regional distribution was 89 patients from Shandong, 91 from Guangxi, 57 from Hunan, 58 from Qinghai and 53 from Heilongjiang. The presence of cagA, vacA, iceA, oipA and dupA genotypes was determined by polymerase chain reaction (PCR) from H. pylori DNA.ResultsA total of 269 H. pylori isolates were obtained, of which 74 isolates were from Shandong, 78 from Guangxi, 46 from Hunan, 33 from Qinghai and 38 from Heilongjiang. The cagA-positive status was predominant in the five regions. The predominant vacA genotypes were s1c (73.4%), m2 (70.6%) and i1 (92.9%). In strains from Shandong, s1a and m1 were dominant. By contrast, s1c was dominant in Guangxi and i1 was dominant in Hunan and Heilongjiang. The prevalence of m2 subtype in Qinghai (78.8%) was significantly higher than that in other regions (P < 0.05). The predominant iceA genotype was iceA1 and the frequency of iceA1 was significantly more prevalent in Hunan than in other regions (P < 0.05). The oipA status "on" gene was more frequent in Shandong (91.9%) and Guangxi (91%) than in Heilongjiang (71.7%) (P < 0.05). Conversely, the dupA-positive status was less than half in Shandong (31.1%) and Guangxi (15.4%), whereas it was 73.9% in Hunan and 81.8% in Qinghai (P < 0.001). There were no significant associations between the cagA, vacA, iceA, oipA genotypes and clinical outcomes. The dupA-positive strains were more common in peptic ulcer disease (PUD) patients than in non-ulcer dyspepsia (NUD) patients in Shandong and Guangxi (P < 0.05), but the association was not observed in other geographic regions.ConclusionsThere was significant geographic diversity of H. pylori genotypes in different regions of China and the presence of dupA gene can be considered as a marker for the development of gastroduodenal diseases. However, the cagA, iceA, vacA and oipA genes cannot be regarded for prediction of the clinical presentation of H. pylori infection in China.

Dataset Information

Analysis of iceA genotypes in South African Helicobacter pylori strains and relationship to clinically significant disease.

Publications

Analysis of iceA genotypes in South African Helicobacter pylori strains and relationship to clinically significant disease.

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