Abstract

Cag Pathogenicity Island (cag-PAI)-containing Helicobacter pylori strains induces signal transduction pathways resulting in tyrosine phosphorylation of proteins adjacent to the site of bacterial adhesion on host gastric epithelial cells. Polymerase chain reaction (PCR) assays were designed to test the presence of three nucleotide sequences corresponding to tyrosine phosphorylation motifs (TPMs) A, B, and C in H. pylori isolates from gastroduodenal patients in Iran. This cross-sectional descriptive study was performed on 164 antral gastric biopsy specimens which were obtained from patients undergoing upper gastrointestinal tract endoscopy. Initially, H. pylori strains were identified by rapid urease test (RUT) and ureC gene and then analyzed for the presence of cagA gene and TPM subtypes (A, B and C) by PCR with established specific primers. Statistical analyses were performed to find their association with gastroduodenal diseases. The PCR assays demonstrated that motif A was common (13.24% of the isolates), whereas motifs B and C were found in 6.62 and 5.30% of the isolates respectively. TPM-AB, TPM-BC and TPM-AC were found in 21.19, 10.60 and 3.97% of the isolates respectively. 16.56% of the isolates had all kinds of TPMs. Strains lacking a TPM were found in 22.52% of the isolates. The presence of TPM-C alone or in combination with other motifs has a direct diagnostic value but the higher proportion of these strains in gastric ulcer patients merits further investigation.

Key words: Helicobacter pylori, cagA, tyrosine phosphorylation motifs, gastroduodenal diseases.