International Journal of Medical Microbiology 298 (2008) S1, 292–294 SHORT COMMUNICATION Binding of complement regulatory protein factor H enhances serum resistance of Borrelia spielmanii sp. nov. Corinna Siegel a,1 , Pia Herzberger a,1,2 , Christine Skerka b , Volker Brade a , Volker Fingerle c , Ulrike Schulte-Spechtel c , Bettina Wilske c , Peter F. Zipfel b,d , Reinhard Wallich e , Peter Kraiczy a,Ã a Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Paul-Ehrlich-Straße 40, D-60596 Frankfurt, Germany b Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany c Max von Pettenkofer-Institut fu¨r Medizinische Mikrobiologie und Hygiene, Ludwig-Maximilians-University, Munich, Germany d Friedrich-Schiller-University, Jena, Germany e Institute of Immunology, University of Heidelberg, Heidelberg, Germany Accepted 27 December 2007 Abstract The European Borrelia species, B. spielmanii, has recently been shown to be associated with Lyme borreliosis/disease infections in humans. In order to elucidate complement susceptibility of diverse B. spielmanii species, we analyzed and compared two isolates obtained from patients with Lyme borreliosis for their ability to escape from complement- mediated bacteriolysis. Growth inhibition assays revealed striking differences between the two B. spielmanii isolates tested with regard to their complement sensitivity. B. spielmanii isolate A14S displayed a resistant phenotype, whereas isolate PSigII was highly sensitive to complement-mediated lysis. In addition, we demonstrate that B. spielmanii isolate A14S can bind complement regulator factor H at higher concentrations to the cell surface as compared to serum- sensitive isolate PSigII. The data presented here provide strong evidence for a correlation between factor H binding and serum resistance among the two isolates tested that can contribute to immune evasion of B. spielmanii from complement-mediated killing. r 2008 Elsevier GmbH. All rights reserved. Keywords: Borrelia spielmanii; Lyme borreliosis; factor H; Complement susceptibility; Immune evasion Introduction Lyme borreliosis is a multisystemic disorder caused by species of the Borrelia (B.) burgdorferi sensu lato complex which comprises at least 13 clearly delineated species or genomic groups including B. burgdorferi sensu stricto (s.s.), B. afzelii, B. garinii, B. japonica, B. valaisiana, B. lusitaniae, B. andersonii, B. bissettii, B. tanukii, B. turdi, B. sinica, B. spielmanii, and B. californiensis sp. nov. (Postic et al., 2007). In Central Europe, B. burgdorferi s.s., B. afzelii, and B. garinii are the most prevalent causative agents of Lyme borreliosis, while B. bissettii, B. lusitaniae, and B. valaisiana also appear to be associated with Lyme borreliosis. More ARTICLE IN PRESS www.elsevier.de/ijmm 1438-4221/$ - see front matter r 2008 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijmm.2007.12.007 Ã Corresponding author. Tel.: +49 69 6301 7165; fax: +49 69 6301 5767. E-mail address: Kraiczy@em.uni-frankfurt.de (P. Kraiczy). 1 These authors contributed equally to this work. 2 This work is part of the M.D. thesis by P. Herzberger.