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The Moraxella catarrhalis porin-like outer membrane protein CD is an adhesin for human lung cells

Melissa M Holm1, Serena L Vanlerberg, Ian M Foley

  • 1Department of Microbiology and Immunology, Medical College of Ohio, Toledo, Ohio 43614-5806, USA.

Infection and Immunity
|March 25, 2004
PubMed

Insights

Moraxella catarrhalis outer membrane protein CD (OMPCD) acts as an adhesin, facilitating bacterial binding to human lung cells. Disrupting the ompCD gene reduces this adherence and impacts bacterial growth and serum resistance.

Area of Science:

  • Microbiology
  • Immunology
  • Bacterial Pathogenesis

Background:

  • Moraxella catarrhalis is a significant human pathogen.
  • Outer membrane proteins (OMPs) are crucial for bacterial interactions and are potential vaccine targets.
  • Outer membrane protein CD (OMPCD) of M. catarrhalis has characteristics of a vaccine antigen.

Purpose of the Study:

  • To investigate the role of OMPCD in M. catarrhalis adherence to human lung cells.
  • To characterize the function of OMPCD as a potential vaccine candidate.

Main Methods:

  • Isolation and characterization of transposon mutants in M. catarrhalis strain O35E.
  • Microcolony formation assays to assess bacterial binding to A549 human lung cells.
  • Construction of an isogenic mutant (O35E-ompCD) to confirm OMPCD's role.
  • Cloning of ompCD and expression in recombinant Escherichia coli to evaluate adherence properties.

Main Results:

  • Transposon mutants with insertions in ompCD exhibited reduced binding (approx. 10-fold) to A549 cells.
  • ompCD mutants displayed pleiotropic effects, including slower growth, increased serum sensitivity, and altered colony morphology (transparency).
  • Recombinant E. coli expressing OMPCD showed a 10-fold increase in adherence to A549 cells, confirming OMPCD's adhesin function.

Conclusions:

  • OMPCD is a key adhesin for Moraxella catarrhalis binding to human lung epithelial cells.
  • Disruption of ompCD significantly impacts bacterial virulence factors and adherence.
  • OMPCD represents a promising target for vaccine development against M. catarrhalis infections.

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