HETEROGENEITY OF RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM IN THE UREASE GENE OF HELICOBACTER-PYLORI

Purpose: A molecular analysis of Helicobacter pylori, an organism which has very high urease activity, was carried out using its urease gene as a genetic marker. Methods: The genetic heterogeneity of clinical isolates of H. pylori was investigated by the Southern blot technique, using a urease gene beta-subunit probe. A 928-base pair portion of the urease gene was amplified by the polymerase chain reaction method. To analyze genetic polymorphism within the beta-subunit of the urease gene, the resultant products were digested with the restriction endonuclease HaeIII and the restriction fragment length polymorphism (RFLP) patterns were studied. Results: Southern blots of HaeIII-digested genomic DNA hybridized with the urease gene probe gave different patterns for 13 clinical isolates obtained from different patients. This polymorphism may be useful in epidemiological studies of relapses or polyinfection with H. pylori in the same patient. Patterns in single patients were identical despite differences in the site and time of isolating H. pylori, indicating that individuals are usually infected with a single genotype of an H. pylori strain. The polymerase chain reaction products from 13 clinical isolates of H. pylori taken from different patients were all the same size when visualized on an agarose gel, suggesting that there were no major insertions or deletions within the urease gene beta-subunit. Restriction fragments of the amplified products with HaeIII revealed seven RFLP patterns. Conclusion: Southern blots of genomic DNA from H. pylori isolates probed with a polymerase chain reaction generating the beta-subunit of the urease gene may prove useful in epidemiological studies.