Abstract

cagA gene, a marker for the cag pathogenicity island (CagPAI) and a virulent factor in Helicobacter pylori infection codes for 120 to 145 kDa protein that is associated with cytotoxin production and more severe clinical outcomes. The aim of this study was to determine whether any correlation exists between H. pylori CagA protein and the endoscopic findings among dyspeptic patients from South-western, Nigeria and also to investigate the evolutionary relationships among H. pylori cagA gene with the GenBank strains. A total of one hundred and twenty four H. pylori positive isolates were amplified for the detection of cagA by polymerase chain reaction (PCR) and H. pylori isolates positive for cagA were further evaluated for protein expression using western blotting analysis. Also, DNA sequencing, blasting and phylogenetic analysis were performed on twelve selected isolates positive for cagA. cagA gene was detected in all the 124 samples (100%) and protein expressions of cagA by western blotting analysis was 88.7% (110/124). There was a high prevalence (91.7%) of expressed cagA strains in patients with positive endoscopic lesions than those with normal endoscopic findings (85.7%); however, association was not statistically significant (P>0.05). Also, the expressed cagA had no statistically significant association with all the positive endoscopic findings (P>0.05). Phylogenetic analysis of the selected H. pylori cagA gene showed high similarity with some GenBank strains of western cagA H. pylori. This study shows that CagA is high among dyspeptic patients in Nigeria but with no statistically significant association with the endoscopic findings.

Key words: Protein expression, CagA, protein, GenBank, dyspeptic.