Organization of ribosomal RNA genes in Borrelia burgdorferi sensu lato isolated from Ixodes ovatus in Japan

Borrelia burgdorferi sensu lato was obtained from adult ixodid ticks, Ixodes ovatus, collected in Nagano, Japan, and was named NT112. The genomic DNA was digested with enzymes, electrophoresed, blotted and hybridized with rRNA gene probes obtained from B. burgdorferi sensu stricto B31. The results showed that the borrelial chromosome contains a single rrs (16S rRNA gene) sequence and two copies of rrl/rrf (23S/5S rRNA genes) sequences. The rrl/rrf genes were tandemly repeated at intervals of 3.2 kb and were located separately from the rrs gene on the genome. Our findings indicate that the organization of rRNA genes in Borrelia from I. ovatus ticks is identical to that of B. burgdorferi sensu stricto.