RT Journal Article SR Electronic T1 Major virulence factors, VacA and CagA, are commonly positive inHelicobacter pylori isolates in Japan JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 338 OP 343 DO 10.1136/gut.42.3.338 VO 42 IS 3 A1 S Maeda A1 K Ogura A1 H Yoshida A1 F Kanai A1 T Ikenoue A1 N Kato A1 Y Shiratori A1 M Omata YR 1998 UL http://gut.bmj.com/content/42/3/338.abstract AB Background—VacA and CagA proteins have been reported to be major virulence factors of Helicobacter pylori. However, antibodies against these proteins are frequently found in the sera of Japanese patients regardless of their gastroduodenal status. Aim—To evaluate the expression of VacA and CagA proteins by H pylori strains isolated in Japan. Methods—By using specific antibodies raised against recombinant VacA and CagA proteins, the expression of VacA and CagA was evaluated in 68 H pylori strains isolated from Japanese patients; a vacuolating assay and genotyping of thevacA gene were also used in the evaluation. The results were analysed in relation to the gastroduodenal diseases of the hosts. Results—VacA and CagA proteins were expressed in 59/68 (87%) and in 61/68 (90%) isolates respectively. The vacuolating assay was positive in 57/68 (84%) isolates, indicating that most immunologically VacA positive strains produced active cytotoxin. The prevalence of infection with strains expressing CagA and positive for vacuolating activity (Type I) was very high, 54/68 (79%), irrespective of the gastroduodenal status of the host. Conclusion—Most H pylori isolates in Japan are positive for vacuolating cytotoxin and CagA, and thus these virulence factors cannot be used as markers to discern the risk of developing serious gastroduodenal pathologies in the hosts. However, the high prevalence of infection with strains positive for vacuolating cytotoxin and CagA may contribute to the characteristics of H pylori infection in Japan.