PHÂN TÍCH GEN CAGA VÀ PHÁT SINH CHỦNG LOẠI HELICOBACTER PYLORI Ở BỆNH NHÂN VIÊM DẠ DÀY TẠI BỆNH VIỆN 19-8

Abstract

Objective: This study aimed to analyze the molecular characteristics and phylogenetic relationships of the CagA gene in Helicobacter pylori (H. pylori) strains isolated from gastric patients at 19-8 Hospital, Hanoi, Vietnam. Subjects and methods: Twenty-three H. pylori-positive gastric biopsy samples were selected by urease test and PCR. Samples were screened for CagA gene presence using diagnostic primers CagA-F and CagA-R (383 bp product). CagA-positive samples were amplified at the 3' region (~1.2 kb) using primer pairs Cag1/Cag2bR, followed by Sanger sequencing and analysis with Genedoc 2.7 and MEGA XII. Results: The CagA gene was detected in 20 out of 23 isolates (86.95%). All 20 strains carried the EPIYA-D motif, characteristic of the East Asian CagA genotype, a high-virulence variant strongly associated with gastric atrophy and gastric cancer. Nucleotide similarity among the Vietnamese strains ranged from 93.7% to 100%, and from 92.9% to 97.3% when compared to East Asian reference strains (Vietnam, Korea, Japan, etc.). However, it was only 79.7% to 83.0% with Western strains (Italy, Algeria, France). Phylogenetic analysis (Neighbor-Joining, 1000 bootstrap replicates) confirmed that all 20 study strains clustered within the East Asian clade, closely related to strains from Vietnam, Korea, Japan, and Southeast Asia. Conclusion: All H. pylori isolates from Vietnamese patients presenting at Hospital 19-8 harbored the East Asian CagA genotype with the EPIYA-D motif, which reflects the region-specific genetic features and is associated with high risk for precancerous changes and gastric cancer development. These results provide molecular evidence for prognostication and clinical management of H. pylori infection in Vietnamese patients.