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Binding of human factor H to outer membrane protein P5 of non-typeable Haemophilus influenzae contributes to

Jeroen D Langereis1, Marien I de Jonge, Jeffrey N Weiser

  • 1Department of Microbiology, University of Pennsylvania, Philadelphia, PA, USA; Department of Pediatrics, Laboratory of Pediatric Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands.

Molecular Microbiology
|August 6, 2014
PubMed

Insights

Non-typeable Haemophilus influenzae evades the immune system using outer membrane protein P5. This protein binds factor H, preventing complement C3 deposition and bacterial killing.

Area of Science:

  • Microbiology
  • Immunology
  • Bacterial Pathogenesis

Background:

  • Non-typeable Haemophilus influenzae (NTHi) is a common cause of respiratory infections.
  • NTHi must evade the human complement system to survive during infection.

Purpose of the Study:

  • To identify genes in NTHi that confer resistance to complement-mediated killing.
  • To elucidate the mechanism by which NTHi evades complement.

Main Methods:

  • Transposon sequencing (Tn-seq) screen to identify resistance genes.
  • Biochemical assays to confirm protein interactions and complement deposition.

Main Results:

  • Outer membrane protein P5 was identified as crucial for resistance to the alternative pathway of complement.
  • P5 directly binds the human complement regulatory protein factor H.
  • Factor H binding by P5 inhibits complement factor C3 deposition on the bacterial surface.
  • Variations in P5 surface-exposed regions influence factor H binding levels.

Conclusions:

  • Outer membrane protein P5 is a key factor in NTHi's evasion of complement-mediated immunity.
  • NTHi utilizes P5 to bind factor H, thereby preventing complement activation and bacterial killing.
  • Strain-specific variations in P5 may contribute to differential complement resistance.

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