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Borrelia recurrentis characterization and comparison with relapsing-fever, Lyme-associated, and other Borrelia spp
S J Cutler1, J Moss, M Fukunaga
1Department of Medical Microbiology, Charing Cross Hospital, London, United Kingdom. rabm001@cxwms.ac.uk
Abstract:
Borrelia recurrentis, the cause of louse-borne relapsing fever, has until recently been considered noncultivable, which has prevented characterization of this spirochete. We successfully cultivated 18 strains from patients with louse-borne relapsing fever and present the initial characterization of these isolates. Electron microscopy revealed spirochetal cells with pointed ends, an average wavelength of 1.8 microns, an amplitude of 0.8 micron, and 8 to 10 periplasmic flagella. The G+C ratio was 28.4 mol%. Whole DNA-DNA hybridizations showed similarity between the isolates of B. recurrentis but not with Borrelia hermsii, Borrelia parkeri, Borrelia turicatae, or the Lyme-associated borreliae. Sequencing studies of both the flagellin and 16S RNA genes revealed that the greatest similarity was between B. recurrentis and Borrelia duttonii. Analysis of the sodium dodecyl sulfate-polycarylamide gel electrophoresis profiles of strains revealed four groups based on the position of a major protein band (one of the groups showed some heterogeneity and was subdivided into four subgroups). Pulsed-field gel electrophoresis revealed five distinct patterns.
Insights
Borrelia recurrentis, the cause of louse-borne relapsing fever, is now cultivable. This breakthrough allows initial characterization of the spirochete, differentiating it from other Borrelia species.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Borrelia recurrentis, responsible for louse-borne relapsing fever, was previously considered non-cultivable.
- This lack of cultivation hindered detailed characterization of the spirochete.
Purpose of the Study:
- To successfully cultivate Borrelia recurrentis strains.
- To perform initial characterization of these newly cultivated isolates.
- To compare B. recurrentis isolates with other Borrelia species.
Main Methods:
- Cultivation of 18 Borrelia recurrentis strains from patients.
- Electron microscopy for morphological analysis.
- DNA-DNA hybridization for genetic relatedness.
- Gene sequencing (flagellin, 16S rRNA) for phylogenetic analysis.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiling.
- Pulsed-field gel electrophoresis (PFGE) for genomic fingerprinting.
Main Results:
- Successful cultivation of 18 Borrelia recurrentis strains.
- Electron microscopy revealed characteristic spirochetal morphology (pointed ends, 8-10 periplasmic flagella).
- DNA-DNA hybridization confirmed intraspecies similarity within B. recurrentis and distinctness from other Borrelia species.
- Gene sequencing showed highest similarity to Borrelia duttonii.
- SDS-PAGE identified four distinct protein profile groups, and PFGE revealed five distinct genomic patterns.
Conclusions:
- Borrelia recurrentis can be successfully cultivated, enabling its study.
- Initial characterization confirms B. recurrentis as a distinct species within the Borrelia genus.
- These findings provide a foundation for further research into louse-borne relapsing fever pathogenesis and treatment.