Genetic characterization and functional status of oipA gene in Helicobacter pylori isolates from Iranian patients with different gastric pathologies

Helicobacter pylori is the primary cause of chronic gastritis, peptic ulcer disease, and gastric cancer, with disease outcome strongly influenced by strain-specific virulence factors. The outer inflammatory protein A (OipA) adhesin promotes epithelial adhesion and IL-8 induction through phase-variable CT dinucleotide repeats in its 5′ signal sequence, which switch the gene between functional (ON) and non-functional (OFF) states. Herein, 40 H. pylori isolates from Iranian patients undergoing endoscopy were examined. Virulence genotypes ( cagA , vacA alleles, babA2 , and oipA ) were determined by PCR. An oipA PCR amplicon was obtained in 29 isolates, which was successfully sequenced to assess the CT repeat-containing signal peptide region. Phylogenetic relationships were reconstructed using the Neighbor-Joining method. oipA was functional in 21/29 (72.4%) isolates. ON status was significantly associated with vacA s1 ( P = 0.004), cagA positivity ( P = 0.028), and inversely with vacA s2 and s2/m2 genotypes ( P = 0.004). ON isolates predominantly carried 10–17 CT repeats, while OFF isolates showed longer tracts (median 15). No direct correlation was found between oipA status and clinical manifestations. The present study demonstrates a high frequency of oipA ON status among Iranian H. pylori isolates, supporting its association with selected virulence genotypes. Larger cohorts and geographically diverse investigations are required to confirm the biological and clinical relevance of oipA phase variation.