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The yersiniabactin transport system is critical for the pathogenesis of bubonic and pneumonic plague

Jacqueline D Fetherston1, Olga Kirillina, Alexander G Bobrov

  • 1Department of Microbiology, Immunology, and Molecular Genetics, MS415 Medical Center, University of Kentucky, Lexington, KY 40536-0298, USA.

Infection and Immunity
|February 18, 2010
PubMed

Insights

The Yersinia pestis yersiniabactin (Ybt) system is crucial for iron acquisition and virulence in plague models. While essential for bubonic plague, its role in pneumonic plague differs between Ybt synthesis and transport.

Area of Science:

  • Microbiology
  • Pathogenesis
  • Bacterial Iron Acquisition

Background:

  • Iron acquisition is vital for bacterial pathogens like Yersinia pestis.
  • The yersiniabactin (Ybt) siderophore system is a primary iron uptake mechanism for Y. pestis.
  • Ybt facilitates iron acquisition from host proteins like transferrin and lactoferrin.

Purpose of the Study:

  • To investigate the role of the Ybt system in Yersinia pestis virulence.
  • To compare the importance of Ybt siderophore synthesis versus transport in different plague models.
  • To identify other virulence factors involved in pneumonic plague pathogenesis.

Main Methods:

  • Construction and testing of Y. pestis mutants deficient in Ybt transport or synthesis.
  • Evaluation of mutant virulence in mouse models of bubonic (subcutaneous injection) and pneumonic (intranasal instillation) plague.
  • Assessment of bacterial growth under iron-restricted conditions in vitro.
  • Comparison of virulence loss between Ybt mutants and a pgm deletion mutant.

Main Results:

  • Ybt system mutants were avirulent in the bubonic plague model.
  • In the pneumonic plague model, Ybt biosynthetic mutants showed significantly reduced virulence (24-fold higher LD50) compared to transport mutants.
  • In vitro, Ybt transport mutants exhibited a more severe growth defect under iron limitation than biosynthetic mutants.
  • A deletion mutant of the pgm locus showed a greater loss of virulence than the Ybt biosynthetic mutant.

Conclusions:

  • The Ybt system is essential for Y. pestis virulence in bubonic plague.
  • Differential roles of Ybt synthesis and transport are evident in pneumonic plague.
  • The pgm locus encodes a significant virulence factor for pneumonic plague, independent of Ybt.

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