Major virulence factors, VacA and CagA, are commonly positive in Helicobacter pylori isolates in Japan.
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.


OBJECTIVE
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 the vacA gene were also used in the evaluation. The results in 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.


CONCLUSIONS
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.
Maeda
S
S
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Ogura
K
K
Yoshida
H
H
Kanai
F
F
Ikenoue
T
T
Kato
N
N
Shiratori
Y
Y
Omata
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000032:analysis*; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D001427:Bacterial Toxins / Q000032:analysis*; D001431:Bacteriological Techniques; D004415:Dyspepsia / Q000382:microbiology; D005260:Female; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007564:Japan; D008297:Male; D008875:Middle Aged; D013276:Stomach Ulcer / Q000382:microbiology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori