International Journal of Medical Microbiology 298 (2008) S1, 284–286 SHORT COMMUNICATION BbCRASP-1 of the Lyme disease spirochetes induces antibodies to non-denatured structural determinants in humans Evelyn Rossmann a,1 , Veronique Kitiratschky a,1,2 , Heidelore Hofmann b , Markus M. Simon c , Peter Kraiczy d , Reinhard Wallich a,Ã a Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany b University Clinics for Dermatology and Allergology ‘Am Biederstein’, TU Munich, Germany c Metschnikoff Laboratory, Max-Planck-Institute for Immunobiology, Freiburg, Germany d Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Frankfurt/Main, Germany Abstract BbCRASP-1 is the dominant factor H and FHL-1 binding protein of Lyme disease spirochetes and is suggested to contribute to the persistence of the pathogen in mammals. Here, we show that serum samples from patients with Lyme disease contain antibodies generated to BbCRASP-1 that are exclusively directed to non-denatured structural determinants but not to denatured protein. r 2008 Elsevier GmbH. All rights reserved. Keywords: Borrelia burgdorferi; Lyme disease; Serodiagnosis; ELISA Introduction Pathogenic species of the Borrelia (B.) burgdorferi sensu lato complex express complement regulator- acquiring surface proteins (CRASP) that bind serum factor H (FH) and FHL-1 (Kraiczy et al., 2001, 2004; Alitalo et al., 2001). BbCRASP-1 is the dominant factor H and FHL-1 binding protein in vitro and is suggested to contribute to the persistence of the pathogen in mammals. High levels of BbCRASP-1 expression were observed in mouse skin at tick bite site at least for 72 h post-infection (von Lackum et al., 2005). In contrast, when heart and joint tissues from tick-infected C.B-17.SCID mice were tested at various time points post-infection (7–90 d), BbCRASP-1 expression was undetectable (Wallich et al., 2003; Lederer et al., 2005). However, in humans expression of BbCRASP-1 during infection is still debated (Wallich et al., 2003; Brooks et al., 2003; von Lackum et al., 2005). Here, we compared the reactivity of serum antibodies derived from Lyme disease patients for various B. burgdorferi antigens, including BbCRASP-1, VlsE, and OspC. The quality of antibodies generated during natural infection was analyzed by using non-denatured and denatured forms of the 3 recombinant outer surface proteins as targets in the Western blot and ELISA as confirmatory test systems. Materials and methods Sera obtained from Lyme disease patients met CDC criteria of Lyme disease and were collected at the Dermatology Clinic of the Technical University of Munich. ARTICLE IN PRESS www.elsevier.de/ijmm 1438-4221/$ - see front matter r 2008 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijmm.2008.02.002 Ã Corresponding author. Tel.: +49 6221 564 090; fax: +49 6221 565 611. E-mail address: wallich@uni-hd.de (R. Wallich). 1 These authors contributed equally to this work. 2 This work forms part of the MD thesis of V. Kitiratschky.