Genetic Diversity of thecagAgene ofHelicobacter pyloristrains from Sudanese Patients with Different Gastroduodenal Diseases

Abstract

Background: There is an increase in the prevalence of Helicobacter pylori infection in Sudan, accompanied by a high incidence of upper gastrointestinal malignancy. The cytotoxin-associated gene cagA gene is a marker of a pathogenicity island (PAI) in H. pylori and plays a crucial role in determining the clinical outcome of Helicobacter infections.Objective: This study aimed to determine the frequency and heterogeneity of the cagA gene of H. pylori and correlate the presence of cagA gene with clinical outcomes. Materials and methods:Fifty endoscopy biopsies were collected from Fedail and Soba hospitals in Khartoum state. DNA was extracted using the Guanidine chloride method followed by PCR to amplify 16S rRNA and cagA gene of H. pylori using specific primers. DNA amplicons of cagA gene were purified and sequenced. Bioinformatics and statistical analysis were done to characterize and to test the association between cagA gene and gastric complications. Results:CagA gene was detected in 20/37(54%) of the samples that were found positive for H.pylori. There was no association between endoscopy finding and the presence of the cagA gene (p = 0.225). Specific amino acid variations were found at seven loci related to strains from a patient with duodenitis, gastric ulcer, and gastric atrophy (R448H, T457K, S460L, IT463-464VA, D470E, A482Q, KNV490-491-492TKT) while mutations in cancerous strain were A439P, T457P, and H500Y. Conclusion:Disease-specific variations of cagA of H. pylori strains, in the region of amino acid residues 428-510, were evident among Sudanese patients with different gastroduodenal diseases.A novel mutation (K458N) was detected in a patient with duodenitis, which affects the positive electrostatic surface of cagA. Phylogenetic analysis showed a high level of diversity of cagA from Sudanese H. pylori strains.

Prevalence of Virulence Genes and Antigen Pattern in Helicobacter pylori-Infected Patients and the Level of Some Inflammatory Cytokines Compared with Non-infected Individuals

“…The present study showed that the prevalence of vacA, ureB, and cagA genes was 91.3%, 67.39%, and 50%, respectively. According to previous studies, cagA has a frequency of 71.4% in Turkey (39), 54% in Sudan (40), 62% in South Africa (41), and 77.27% in India (42). One of the most important virulence factors in H. pylori is an 89-kDa protein, VacA, which can cause cell depletion.…”