DNMT1, as a critical enzyme affecting epigenetics through methylation of DNA cytosine-rich sequences, regulates gene expression. Exterior factors including long-term infections, in this study infection, could change host cells' epigenetics by affecting gene expression. This study investigated the statistical correlation between virulence genes and gene expression in gastric antral epithelial cells of gastric adenocarcinoma and gastritis patients. In a case-control study, 50 and 53 gastritis and gastric adenocarcinoma antral biopsies, including 23 and 21 patients with infection, respectively, were collected from hospitals in the west of Iran. Having extracted total RNA from gastric biopsy samples, cDNA was synthesized and virulence genes of were detected by using the PCR method. Relative real-time RT PCR was used to detect ΔΔCt fold changes of the gene expression in divided groups of patients based on infection and clinical manifestations. The results showed that along with increasing patients' age, the gene expression will increase in gastric antral epithelial cells of gastric cancer patients ( ≤ 0.05). On the other hand, the biopsy samples with infection of , , and genotypes revealed a direct correlation along with increased gene expression. This study revealed the correlations of pathogenicity island genes with increased DNMT1 gene expression.