Objective: To investigate the association between the diversity of urease gene and urease activity of clinical isolates of Helicobacter pylori (H. pylori). Methods: Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of urease gene and rapid urease activity test were used to study the urease activity of different clinical isolates of H. pylori. Results: H. pylori clinical isolates were divided into 4 types according to their PCR-RFLP results of urease gene and urease activity. Type Ⅰ , possessing strong urease activity (0. 11) and presented 1 fragment of 1. 7 kb by PCR-RFLP, had close relations with gastric ulcer; type Ⅱ , with the weakest urease activity (0. 07) and 2 fragments (1. 3 and 0. 4 kb respectively) , was associated with duodenal bulb ulcer; type Ⅲ , with the strongest urease activity (0. 12) and 2 fragments (0. 4 and 0. 17 kb) with or without 1 fragment (0. 23 or 0. 37 kb) , was responsible for gastritis; type Ⅳ , with weak urease activity (0. 09) and 2 fragments (1. 5 and 0. 2 kb), was shown to be related to both gastric and duodenal bulb ulcers. Conclusion: The diversity of urease gene decides different urease activities of different clinical isolates of H. pylori, hence the different possibilities of pathogenesis due to this bacteria.
Summary: The vacuolated effect of Helicobacter (H. pylori) and its relationship to vacuolated cytotoxin antigen (VacA) were investigated by the method of cytotoxic test and SDS-pobyacrylamide gel electrophoresis (SDS-PAGE). Of the 62 clinical isolates, the broth culture filter (BCF) of 43 strains caused the Vero cell intracytoplasmically vacuolated. H. pylori strains were divided into H. pylori (Toxin +) group with vacuolated effect and H. pylori (Toxin -) group without vacuolated effect. The analysis of the BCF of H. pylori (Toxin +) and that of H. pylori (Toxin -) was studied by SDS-PAGE and Scan reader. A kind of protein with 87 ku molecular weight was recognized in the BCF of 30.23 % (13/43) H. pylori (Toxin +) strains but in none of that of H. pylori (Toxin -) strains, the difference was statistically significant (P<0.05). There was a significant and concordant relationship between OD of the protein band with 87 ku molecular weight and titer of vacuolated activity of H. pylori(Toxin +) (r=0.67 and P<0.05 by linear regression analysis). H. pylori strains were divided into H. pylori (Toxin +) group with vacuolated effect and H. pylori (Toxin -) group without vacuolated effect. The vacuolated effect of H. pylori (Toxin +) was caused by the protein with 87 ku molecular weight (VacA)
