VARIABILITY OF GENE ORDER IN DIFFERENT HELICOBACTER-PYLORI STRAINS CONTRIBUTES TO GENOME DIVERSITY

Considerable genomic microdiversity has been reported previously among Helicobacter pylori isolates, We have constructed genome maps of four unrelated H. pylori strains (NCTC11637, NCTC11639, UA802 and UA861) u sing pulsed-field gel electrophoresis (PFGE) with Notl and Nrul, hybri dization with extracted PFGE DNA fragments and probing with 17 gene pr obes. These strains of H. pylori were compared with a fifth unrelated H. pylori strain NCTC11638 mapped previously. Considerable diversity i n gene arrangement was evident among the five H. pylori maps, and no c onsistent gene clustering was found. The association of only four gene s, katA (catalase gene), vacA (vacuolating cytotoxin gene), hpaA (a pu tative adhesin gene), and pfr (bacterial ferritin gene) were generally conserved within approximately the same 25% of the genome; however, t he order of these genes also varied, Our study demonstrates that macro diversity, i.e. variability in gene order, in addition to microdiversi ty, is a characteristic of the H. pylori genome.