The complement regulator factor H binds to the surface protein OspE of Borrelia burgdorferi

Spirochete bacteria of the Borrelia burgdorferi sensu late complex cause Ly me borreliosis, The three pathogenic subspecies Borrelia garinii, Borrelia afzelii, and Borrelia burgdorferi sensu stricto differ in their disease pro files and susceptibility to complement lysis. We investigated whether compl ement resistance of Borreliae could be due to acquisition of the main solub le inhibitors of the alternative complement pathway, factor H and the facto r H-like protein 1. When exposed to nonimmune EDTA-plasma, the serum-resist ant B. afzelii and B. burgdorferi sensu stricto strains bound factor H/fact or H-like protein 1 to their surfaces. Assays with radiolabeled proteins sh owed that factor a bound strongly to the B. burgdorferi sensu stricto strai n, To identify factor H ligands on the borrelial surface, we analyzed a pan el of outer surface proteins of B. burgdorferi sensu stricto with the surfa ce plasmon resonance technique. The outer surface lipoprotein OspE was iden tified as a specific ligand for factor H. Using recombinant constructs of f actor H, the binding site for OspE was localized to the C-terminal short co nsensus repeat domains 15-20. Specific binding of factor H to B, burgdorfer i sensu stricto OspE may help the pathogen to evade complement attack and p hagocytosis.