Anti-CagA IgG Antibody is Independent from Helicobacter pylori vacA and cagA Genotypes

Background: Helicobacter pylori strains have two classical virulence genes, the cytotoxinassociated A (cagA) gene and the vacuolating cytotoxin A (vacA) gene, which are located in the cag pathogenicity island (cagPAI). Serum immunoglobulin G (IgG) antibodies to H. pylori,especially, the CagA antigen may be a reliable marker for selection of dyspeptic patients for upper endoscopy. Methods: Serum sample of 129 dyspeptic patients with positive H. pylori, were tested for serum IgG Anti-CagA antibody by ELISA. The presence of the cagA and vacA genotypes were determined using polymerase chain reaction (PCR) on biopsy samples taken via endoscopy. Results: Positive serum IgG anti-CagA antibodies in patients with cagA+/vacA+ and cagA+/vacA- genotypes were 22/23 (95.6%) and 18/19 (94.7%), respectively. In addition, serum IgG anti-CagA antibodies in patients with cagA-/vacA+ and cagA-/vacA- genotypes were 22/47 (46.8%) and 33/40 (82.5%), respectively. Conclusions: It can be concluded that the serum IgG anti-CagA antibody alone could select patients with dyspepsia following upper endoscopy. The assessment of vacuolating cytotoxin activity of H. Pylori is, therefore, not required, even when vacA gene is positive. This hypothesis needs to be studied in a large number of patients with dyspepsia.