Phylogenetic analysis of the genus Borrelia: a comparison of North American and European isolates of Borrelia burgdorferi.

We have sequenced the 16S rRNA molecules from four species of Borrelia and from six isolates of Borrelia burgdorferi via the reverse transcriptase primer extension method. The sequences were aligned and evolutionary relationships were determined, including the calculation of evolutionary distances and the construction of a phylogenetic tree. These analyses demonstrate significant divergence among B. burgdorferi isolates, with the European isolates G1 and G2 residing most distant from the main cluster. Signature nucleotides which distinguish B. burgdorferi from all other members of this genus and which distinguish the European isolates G1 and G2 from the North American isolates B31, Sh-2-82, and 1352 were identified. Finally, Southern blot analyses were performed to compare the restriction patterns of the genes coding for rRNA and to relate our data to the grouping scheme of Postic et al. (D. Postic, C. Edlinger, C. Richaud, F. Grimont, J. Dufresne, P. Perolat, G. Baranton, and P. A. D. Grimont, Res. Microbiol. 141:465-475, 1990).