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cagA Subtypes (caga + subtype)
Selected AbstractsIdentification of Helicobacter pylori and the cagA genotype in gastric biopsies using highly sensitive real-time PCR as a new diagnostic toolFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2005Shiho Yamazaki Abstract The CagA protein is one of the virulence factors of Helicobacter pylori, and two major subtypes of CagA have been observed, the Western and East Asian type. CagA is injected from the bacteria into gastric epithelial cells, undergoes tyrosine phosphorylation, and binds to Src homology 2 domain-containing protein-tyrosine phosphatase SHP-2. The East Asian type CagA binds to SHP-2 more strongly than the Western type CagA. Here, we tried to distinguish the CagA type by highly sensitive real-time PCR with the objective of establishing a system to detect H. pylori and CagA subtypes from gastric biopsies. We designed primers and probe sets for Western or East Asian- cagA at Western-specific or East Asian-specific sequence regions, respectively, and H. pylori 16S rRNA. We could detect the H. pylori 16S rRNA gene, Western and East Asian- cagA gene from DNA of gastric biopsies. The sensitivity and specificity for H. pylori infection was 100% in this system. In Thai patients, 87.8% (36/41) were cagA -positive; 26.8% (11/41) were Western- cagA positive and 53.7% (22/41) were East Asian- cagA positive, while 7.3% (3/41) reacted with both types of cagA. These results suggest that this real-time PCR system provides a highly sensitive assessment of CagA type as a new diagnostic tool for the pathogenicity of H. pylori infection. [source] cagA gene variants in Malaysian Helicobacter pylori strains isolated from patients of different ethnic groupsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2005Mohamed Ramelah Abstract Helicobacter pylori infection of a distinct subtype of cagA may lead to different pathological manifestation. The aim of this study is to determine the presence of cagA gene and its variants in H. pylori infection among different ethnic groups and its effect on gastroduodenal diseases. Overall detection of cagA among the 205 clinical isolates of H. pylori was 94%. Variations in size of the 3, region of cagA gene were examined among 192 Malaysian H. pylori cagA -positive strains. Results showed that three cagA variants differing in fragment length of PCR products were detected and designated as type A (621,651 bp), type B (732,735 bp) and type C (525 bp). Although there was no association between any of the cagA subtypes with peptic ulcer disease (p > 0.05), an association between cagA subtypes with a specific ethnic group was observed. Specific- cagA subtype A strains were predominantly isolated from Chinese compared to Malays and Indians (p < 0.0005), and cagA subtype B strains were predominantly isolated from Malays and Indians compared to Chinese (p < 0.05). The cagA type A strains of H. pylori is commonly found in the Chinese patients who have a higher risk of peptic ulcer disease, thus indicating that it could be used as an important clinical biomarker for a more severe infection. [source] Distinctiveness of the cagA Genotype in Children and Adults with Peptic Symptoms in South ChinaHELICOBACTER, Issue 4 2009Juan Li Abstract Background:,Helicobacter pylori infection is different between children and adults, not only in infection rate but also in virulence genotypes. However, the 3, region of CagA, important in stomach carcinogenesis, still remains unclear in children. The present study aims to compare the frequency of cagA and the distribution of its subtypes between children and adults in South China. Materials and Methods:, One hundred and twenty-eight children and 99 adults with peptic symptoms were enrolled in our research. Histology, rapid urease test, and real-time polymerase chain reaction (PCR) assay were used to diagnose H. pylori infection. vacA s1 was detected by real-time PCR, and EPIYA motifs in the 3, region of CagA by conventional PCR and DNA sequencing. Results:,H. pylori infection was diagnosed in 53 children and 62 adults. vacA s1 was identified in 90.6% and 91.9% of infected children and adults, respectively. Furthermore, cagA was identified in 73.6% and 82.3% of infected children and adults, respectively. No patient with multiple cagA subtypes was observed. A higher prevalence of more virulent cagA genotype was found in children compared to adults (p < .05). Thirty-eight of 39 (97.4%) cagA -positive children were found to have EPIYA-ABD and only one (2.6%) with EPIYA-ABC. In adults, four types of EPIYA motifs , ABC (29.4%), ABD (64.7%), ABAB (2%), and AAD (3.9%) , were identified, and the ABD type was found more commonly in severe diseases, such as atrophic gastritis (53.3%) and gastric cancer (71.4%). Conclusion:,cagA genotypes in children and in adults are different, and EPIYA-ABD may have potential clinical implication in the development of gastric cancer in South China. [source] | ||||||||||