Borrelia persica and B. baltazardi sp. nov.: experimental pathogenicity for some animals and comparison of the ultrastructure.

The ultrastructure of cells of Borrelia persica was compared with that of cells of a new isolate of Barrelia (Borrelia "x"). This organism (B. "x") was isolated in a region of Iran where B. persica is already known to exist. The morphology of the cells of the two strains differed in mean cell length and cell diameter. Cells of B. persica were covered by a regularly structured surface layer, while those of B. "x" possessed an amorphous surface coat. Furthermore, the strains differed in their experimental pathogenicity for animals. It is concluded that the new isolate represents a new species of the genus Borrelia, and Borrelia baltazardi sp. nov. is proposed.