ANALYSIS OF THE EXPRESSION OF CAGA, VACA AND THE VACUOLATING ACTIVITYIN 167 ISOLATES FROM PATIENTS WITH EITHER PEPTIC-ULCERS OR NONULCER DYSPEPSIA

Objectives: The goals of this study were: 1) to examine the prevalence of cytotoxin-associated protein (CagA), vacuolating cytotoxin (VacA), and the vacuolating cytotoxin activity (VCA) in vitro of infecting He licobacter pylori isolates and 2) to clarify the relation between the expression of these virulence factors and the occurrence of peptic ulc eration. Methods: One hundred sixty-seven clinical isolates of H. pylo ri from patients with peptic ulcer disease (gastric ulcer, 62 cases; d uodenal ulcer, 48 cases) and nonulcer dyspepsia (57 cases) were studie d regarding their genetic and phenotypic properties. Results: Type 1 b acteria, which had both CagA and VCA, and type 2 bacteria, which did n ot express either CagA or VCA, represented 62.9% and 7.8%, respectivel y; the remaining 29.4% had an intermediate phenotype, expressing eithe r CagA independent of the presence of VCA (CagA(+)VCA(-)) or vice vers a (CagA(-)VCA(+)). CagA(+)VCA(-) and CagA(-)VCA(+) bacteria represente d 17.4% and 12.0%, respectively, both of which were more numerous than the type 2 category. The proportion of the CagA-positive isolates was significantly higher in both the duodenal ulcer (97.9%) and gastric u lcer (83.9%) patients than in the non-ulcer dyspepsia patients (61.4%) (p < 0.01). On the other hand, the proportion of VacA/VCA-positive is olates was not significantly different between peptic ulcer disease an d non-ulcer disease and non-ulcer dyspepsia. Conclusions: The currentl y used classification of this bacterium based on the concomitant expre ssion of CagA and VacA/VCA into the two major types is not adequate. T he CagA-positive phenotype thus may be important as a virulence marker for peptic ulcer disease independent of the presence of VacA/VCA. (C) 1998 by Am. Coll. of Gastroenterology.