Abstracts (complete list) - Wissenschaft Online

Pia Herzberger, Corinna Siegel, Christine Skerka, Volker Fingerle, Ulrike Schulte-
Spechtel, Bettina Wilske, Volker Brade, Reinhard Wallich, Peter F. Zipfel, Peter Kraiczy
Serum resistance of human pathogenic Borrelia spielmanii sp.
nov. correlates with binding of complement regulators factor
H and FHL-1
B. spielmanii sp. nov. has recently been identified as a novel human pathogenic
genospecies that cause Lyme disease in Europe. In order to elucidate immune evasion
mechanisms of B. spielmanii as a means of evading the innate immune system we have
compared the ability of isolates obtained from Lyme disease patients and tick isolate PC-
Eq17 to escape from complement-mediated bacteriolysis. Applying a growth inhibition
assay, we show that four B. spielmanii isolates, including PC-Eq17, are serum-resistant
whereas a single isolate, PMew, was more sensitive to complement-mediated lysis. All
isolates activate complement in vitro as demonstrated by covalent attachment of C3 ,
however, deposition of later activation products C6 and C5b-9 was restricted to the
moderately serum-resistant isolate PMew and serum-sensitive B. garinii isolate G1.
Furthermore, serum adsorption experiments revealed that all B. spielmanii isolates
acquire the host alternative pathway regulators factor H and FHL-1 from human serum.
Both complement regulators retain their factor I-mediated C3b inactivation activity
when bound to spirochetes. In addition, two distinct factor H and FHL-1 binding
proteins, BsCRASP-1 and BsCRASP-2, were identified that are approximately 23 to 25
kDa in size. A further factor H-binding protein, BsCRASP-3, was exclusively found in the
tick isolate PC-Eq17. In conclusion, this is the first report describing an immune evasion
mechanism utilized by B. spielmanii sp. nov. and demonstrates capture of human
immune regulators to resist complement-mediated killing. This work was funded by the
Deutsche Forschungsgemeinschaft DFG, Project Kr3383/1-1 and Wa533/7-1.