Lone Star tick-infecting Borreliae are most closely related to the agent of bovine borreliosis

Although Borrelia theileri, the agent of bovine borreliosis, was described at the turn of the century tin 1903), its relationship with borreliae causi ng Lyme disease or relapsing fever remains undescribed. We tested the previ ously published hypothesis that spirochetes infecting Lone Star ticks (Ambl yomma americanum) may comprise B. theileri by analyzing the 16S ribosomal D NAs (rDNAs) and flagellin genes of these spirochetes. IZ. theileri, the Amb lyomma agent, and B. miyamotoi formed a natural group or clade distinct fro m but most closely related to that of the relapsing fever spirochetes. B. t heileri and the Amblyomma agent were 97 and 98% similar at the nucleotide l evel within the analyzed portions of the 16S rDNA and the flagellin gene re spectively, suggesting a recent divergence. The agent of bovine borreliosis might be explored as a surrogate antigen for the as-yet-uncultivatable Amb lyomma agent in studies designed to explore the etiology of a Lyme disease- like infection associated with Lone Star ticks.