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Clinical and Developmental Immunology
Volume 2012, Article ID 349657, 12 pages
http://dx.doi.org/10.1155/2012/349657
Research Article

Contribution of the Infection-Associated Complement Regulator-Acquiring Surface Protein 4 (ErpC) to Complement Resistance of Borrelia burgdorferi

1Institute of Medical Microbiology and Infection Control, Frankfurt University Hospital, Paul-Ehrlich-Straße 40, 60596 Frankfurt, Germany
2Department of Infection Biology, Leibniz Institute for Natural Products Research and Infection Biology, Beutenbergstraße 11a, 07745 Jena, Germany
3Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany
4Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
5Friedrich Schiller University of Jena, 07737 Jena, Germany

Received 22 June 2011; Accepted 5 October 2011

Academic Editor: Franc Strle

Copyright © 2012 Claudia Hammerschmidt et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Borrelia burgdorferi evades complement-mediated killing by interacting with complement regulators through distinct complement regulator-acquiring surface proteins (CRASPs). Here, we extend our analyses to the contribution of CRASP-4 in mediating complement resistance of B. burgdorferi and its interaction with human complement regulators. CRASP-4 (also known as ErpC) was immobilized onto magnetic beads and used to capture proteins from human serum. Following Western blotting, factor H (CFH), CFH-related protein 1 (CFHR1), CFHR2, and CFHR5 were identified as ligands of CRASP-4. To analyze the impact of native CRASP-4 on mediating survival of serum-sensitive cells in human serum, a B. garinii strain was generated that ectopically expresses CRASP-4. CRASP-4-producing bacteria bound CFHR1, CFHR2, and CFHR5 but not CFH. In addition, transformed spirochetes deposited significant amounts of lethal complement components on their surface and were susceptible to human serum, thus indicating that CRASP-4 plays a subordinate role in complement resistance of B. burgdorferi.