CagA and VacA: Virulence factors of Helicobacter pylori in thai patients with gastroduodenal diseases

Background. The aim of this study was to assess the seroprevalence of cytot oxin-associated gene A (cagA) and vacuolating cytotoxin gene A (vacA) of He licobacter pylori in selected Thai populations with specific gastroduodenal diseases. Materials and Methods. The immunoblot assay was used to detect serum antibo dies against CagA and VacA obtained from the following patients: 87 cases o f nonulcer dyspepsia (NUD), 61 cases of duodenal ulcer (DU), 49 cases of ga stric ulcer (GU), and 10 cases of gastric cancer (GC). Results. Serum antibodies to CagA were detected in 75.4% of all patients (7 0.1% of NUD, 78.7% of DU, 77.6% of GU, and 90% of GC). Although the prevale nce of CagA seropositivity in GC patients was higher than in the other thre e groups, the difference was not statistically significant (p > .05). Conclusions. The high seroprevalence of the CagA-positive H. pylori strain in patients with peptic ulcer, GC, and NUD indicates that this strain is co mmon in Thai patients with gastroduodenal diseases. Furthermore, phenotypic classification of H. pylori into type 1 (CagA-positive, VacA-positive) and type 2 (CagA-negative, VacA-negative) is not a useful marker for screening patients with severe forms of gastroduodenal diseases.