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Bovine plasma proteins increase virulence of Haemophilus somnus in mice

Roger S Geertsema1, Richard A Kimball, Lynette B Corbeil

  • 1Department of Pathology, School of Medicine, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8416, USA.

Microbial Pathogenesis
|November 28, 2006
PubMed

Insights

Bovine transferrin and lactoferrin enhance Haemophilus somnus virulence in mice. Transferrin provides iron by binding to outer-membrane proteins, while lactoferrin

Area of Science:

  • Veterinary Microbiology
  • Bacterial Pathogenesis
  • Host-Pathogen Interactions

Background:

  • Haemophilus somnus is a significant bovine pathogen causing septicemia.
  • Bovine serum and plasma proteins may influence bacterial virulence.
  • Understanding these interactions is crucial for developing effective treatments.

Purpose of the Study:

  • To investigate the role of bovine serum and plasma proteins in Haemophilus somnus virulence.
  • To determine the specific mechanisms by which these proteins affect bacterial pathogenicity.

Main Methods:

  • Mouse model of septicemia.
  • Pre-incubation of H. somnus with purified bovine proteins (transferrin, lactoferrin).
  • ELISA assays to assess protein binding.
  • Growth assays on iron-depleted media.

Main Results:

  • Fetal calf serum increased H. somnus virulence.
  • Bovine transferrin significantly increased virulence, supporting growth on iron-depleted media.
  • Bovine lactoferrin also increased virulence, but via an undetermined mechanism.
  • Transferrin binding to H. somnus was enhanced in iron-restricted conditions and involved iron-regulated outer-membrane proteins (IROMPs).

Conclusions:

  • Transferrin enhances H. somnus virulence by providing iron through binding to IROMPs.
  • Lactoferrin's role in virulence enhancement requires further investigation.
  • These findings highlight the importance of iron acquisition in H. somnus pathogenesis.

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