Molecular characterization of Borrelia burgdorferi sensu lato strains by pulsed-field gel electrophoresis.

The large restriction fragment patterns (LRFP) and linear plasmid profiles of eight tick isolates of Borrelia burgdorferi sensu lato were investigated with pulsed-field gel electrophoresis (PFGE). The whole cell lysate was examined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The MluI LRFP differentiates two species of Borrelia burgdorferi sensu lato (Borrelia burgdorferi sensu stricto and Borrelia garinii). LRFP is a suitable method to demonstrate genetic hetero- or homogeneity of isolates within one species without subsequent hybridization utilizing diverse probes. Different strains with similar or identical LRFP can be further discriminated by plasmid profile analysis. Our results show that each strain analyzed had a different plasmid profile. Therefore the linear plasmid profile has a potential application as a strain typing procedure. SDS-PAGE of whole-cell lysate supports the findings of homology within the B. burgdorferi sensu stricto species and the heterology within the B. garinii species.