Phylogenetic tree of B. burgdorferi sensu lato strains based on 1,330 bp of 16S rRNA gene sequences (positions 34 to 1364). B. hermsii HS1 was used as an out-of-group control. Numbers at each of the branch nodes indicate results from bootstrap analysis. The accession numbers (in parentheses) of the 16S rRNA gene sequences of Borrelia strains used for comparison are as follows: B31 (U03396), DK7 (X85195), 20047 (D67018), PBi (X85199), DK1 (X85190), IP3 (M84815), HO14 (L40597), VS116 (X98232), UK (X98233), PotiB2 (X98228), 21038 (L46701), DN127 (L40596), Hk501 (D67023), Ya501 (D67022), and HS1(U42292).