PREVALENCE OF VACUOLATING CYTOTOXIN PRODUCTION AND DISTRIBUTION OF DISTINCT VACA ALLELES IN HELICOBACTER-PYLORI FROM CHINA

Studies of Helicobacter pylori from the West have linked production of vacuolating cytotoxin and a particular signal sequence (sla) allele o f the underlying vacA gene to peptic ulcer disease (PUD). Among Chines e H. pylori most isolates from both PUD and gastritis patients were to xigenic (35/46 and 29/35, respectively). Polymerase chain reaction and DNA sequencing showed that 95 of 96 isolates carried vacA sla alleles . Ln the mid-region, 78 of 96 isolates carried m2; 14 were m1-like but only 87% identical (DNA-level) to classical mi and were designated m1 b; the other 4 were unusual hybrids (m1b-type proximal, m2-type distal ). isolates with mlb and m1b-m2 alleles produced higher levels of vacu olating activity than did isolates with m2 alleles (P < .01). There wa s no association between any vacA allele and disease. These results su ggest that the composition of H. pylori gene pools varies geographical ly and that other as-yet-unknown polymorphic H.pylori genes are import ant in PUD.