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Streptococcus pneumoniae evades complement attack and opsonophagocytosis by expressing the pspC locus-encoded Hic protein that binds to short consensus repeats 8-11 of factor H

På svenska

Author

  • Hanna Jarva
  • Robert Janulczyk
  • Jens Hellwage
  • Peter F Zipfel
  • Lars Björck
  • Seppo Meri

Summary, in English

Streptococcus pneumoniae is an important cause of upper and lower respiratory tract infections, meningitis, peritonitis, bacterial arthritis, and sepsis. Here we have studied a novel immune evasion mechanism of serotype 3 pneumococci, which are particularly resistant to phagocytosis. On their surfaces the bacteria express the factor H-binding inhibitor of complement (Hie), a protein of the pneumococcal surface protein C family. Using radioligand binding, microtiter plate assays, surface plasmon resonance analysis, and recombinant constructs of factor H, we located the binding site of Hie to short consensus repeats (SCRs) 8-11 in the middle part of factor H. This represents a novel microbial interaction region on factor H. The only other ligand known so far for SCRs 8-11 of factor H is C-reactive protein (CRP), an acute phase protein that binds to the pneumococcal C-polysaccharide. The binding sites of Hie and CRP within the SCR8-11 region were different, however, because CRP did not inhibit the binding of Hie and required calcium for binding. Binding of factor H to Hic-expressing pneumococci promoted factor I-mediated cleavage of C3b and restricted phagocytosis of pneumococci. Thus, virulent pneumococci avoid complement attack and opsonophagocytosis by recruiting functionally active factor H with the Hie surface protein. Hie binds to a previously unrecognized microbial interaction site in the middle part of factor H.

Publishing year

2002

Language

English

Pages

1886-1894

Publication/Series

Journal of Immunology

Volume

168

Issue

4

Document type

Journal article

Publisher

American Association of Immunologists

Topic

  • Immunology in the medical area

Status

Published

ISBN/ISSN/Other

  • ISSN: 1550-6606