Identification of a third genomic group of Borrelia burgdorferi through signature nucleotide analysis and 16S rRNA sequence determination.

As part of a continuing effort to assess genetic variation among isolates of Borrelia burgdorferi we have determined the 16S rRNA signature nucleotide makeup of two tick isolates from the USSR. Signature nucleotides were identified via reverse transcriptase primer extension sequencing of select regions of the 16S rRNA molecule. In addition, the near complete 16S rRNA sequence of one of the isolates, R-IP3, was determined and utilized in a phylogenetic assessment. The sequence was aligned with the 16S rRNA sequences of other B. burgdorferi isolates as well as with other Borrelia species. Distance matrix analyses were performed and a phylogenetic tree was constructed. These analyses demonstrate that these isolates belong to a third previously unidentified genomic group of B. burgdorferi.