COMPARATIVE-ANALYSIS OF GENETIC-VARIABILITY AMONG BORRELIA-BURGDORFERI ISOLATES FROM EUROPE AND THE UNITED-STATES BY RESTRICTION ENZYME ANALYSIS, GENE RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM, AND PULSED-FIELDGEL-ELECTROPHORESIS

The genomes of 62 North American and European Borrelia burgdorferi iso lates were examined by restriction endonuclease analysis (REA), gene p robe restriction fragment length polymorphism, and pulsed-field gel el ectrophoresis (PFGE). Hybridization of restriction fragments with the immunologically relevant 83-kDa antigen gene revealed polymorphisms an d divided the isolates into three major groups. Group I included all b ut two of the American isolates and some of the European isolates. One of two Californian isolates (DN 127) and one Ixodes dammini isolate f rom New York (strain 25015), previously described as atypical, were di stinct from the isolates in the three groups. Plasmid profile analysis and REA, the method with the highest level of discrimination, reveale d extensive heterogeneity among isolates of the same major group. Our study demonstrates the usefulness of the 83-kDa antigen gene probe for dividing the isolates into major genogroups, whereas REA and plasmid profile analysis allow for a distinction of individual strains within these groups.