ANALYSIS OF EXPRESSION OF CAGA AND VACA VIRULENCE FACTORS IN 43 STRAINS OF HELICOBACTER-PYLORI REVEALS THAT CLINICAL ISOLATES CAN BE DIVIDED INTO 2 MAJOR TYPES AND THAT CAGA IS NOT NECESSARY FOR EXPRESSION OF THE VACUOLATING CYTOTOXIN

Colonization of the mucosa of the stomach and the duodenum by Helicoba cter pylori is the major cause of acute and chronic gastroduodenal pat hologies in humans, Duodenal ulcer formation strongly correlates,vith the expression of an antigen (CagA) that is usually coexpressed with t he vacuolating cytotoxin (VacA), a protein that causes ulceration in t he stomach of mice, However, the relationship between these two virule nce factors is unknown. To define whether CagA and VacA are coexpresse d in all clinical isolates and their relationships, we collected 43 cl inical isolates of H. pylori and studied their genetic and phenotypic properties, Based on this analysis, most of the strains could be class ified into two major types, Type I bacteria had the gene coding for Ca gA and expressed the CagA protein and the vacuolating cytotoxin. Type II bacteria did not have the gene coding for CagA and did not express either the CagA. protein or the vacuolating cytotoxin, Type I and type II bacteria represented 56 and 16%, respectively, of the 43 clinical isolates, while the remaining 28% had an intermediate phenotype, expre ssing CagA independently of VacA or vice versa, This finding shows tha t although it is present in most cytotoxic strains, CagA is not necess ary for the expression of the vacuolating cytotoxin.