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Cultivation Methods of Spirochetes from Borrelia burgdorferi Sensu Lato Complex and Relapsing Fever Borrelia
Published on: November 25, 2022
Relapsing fever spirochetes Borrelia recurrentis and B. duttonii acquire complement regulators C4b-binding protein
1Haartman Institute, Department of Bacteriology and Immunology, P.O. Box 21, University of Helsinki, FIN-00014 Helsinki, Finland. taru.meri@helsinki.fi.
Infection and Immunity
|June 23, 2006
Summary
Borrelia spirochetes causing relapsing fever evade the immune system. These bacteria capture human complement regulators, Factor H and C4b-binding protein, to resist complement-mediated killing.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Relapsing fever is a severe septic illness caused by Borrelia spirochetes, with epidemic and endemic forms.
- Borrelia species exhibit immune evasion strategies, persisting in the bloodstream despite antibody development, leading to relapses and high mortality.
- Understanding these immune evasion mechanisms is crucial for developing effective treatments against relapsing fever.
Purpose of the Study:
- To investigate the serum resistance of Borrelia recurrentis (epidemic) and Borrelia duttonii (endemic) relapsing fever pathogens.
- To determine if these spirochetes utilize immune evasion strategies involving complement regulators.
- To identify the specific complement regulators bound by relapsing fever Borrelia species.
Main Methods:
- In vitro assessment of serum resistance (complement resistance) for Borrelia recurrentis and Borrelia duttonii.
- Analysis of the binding of host complement regulators, specifically Factor H and C4b-binding protein, to the surface of these spirochetes.
- Functional assessment of bound complement regulators to confirm their activity.
Main Results:
- Borrelia recurrentis and Borrelia duttonii demonstrated resistance to complement-mediated lysis in vitro.
- Both pathogens were found to acquire the alternative complement pathway regulator, Factor H, onto their surfaces.
- Relapsing fever spirochetes specifically bound the classical complement pathway regulator, C4b-binding protein, which retained its function when bound.
Conclusions:
- This study provides the first evidence of complement evasion mechanisms in Borrelia recurrentis and Borrelia duttonii.
- The capture of host Factor H and C4b-binding protein represents a novel immune evasion strategy employed by these relapsing fever pathogens.
- These findings highlight the sophisticated ways Borrelia spirochetes evade host immune responses, contributing to disease persistence and severity.
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