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A Murine Model of Group B Streptococcus Vaginal Colonization
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A Murine Model of Group B Streptococcus Vaginal Colonization

Published on: November 16, 2016

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Hemolytic Membrane Vesicles of Group B Streptococcus Promote Infection

Blair Armistead1,2, Phoenicia Quach2, Jessica M Snyder3

  • 1Department of Global Health, University of Washington, Seattle, Washington, USA.

The Journal of Infectious Diseases
|August 30, 2020
PubMed
Abstract

Insights

Group B streptococci (GBS) use membrane vesicles to deliver their granadaene toxin. These hemolytic MVs promote GBS virulence, immune evasion, and severe neonatal disease.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Group B streptococci (GBS) are Gram-positive bacteria linked to adverse pregnancy outcomes and neonatal infections.
  • The GBS β-hemolysin/cytolysin (granadaene) is a key virulence factor, typically surface-associated.

Purpose of the Study:

  • To investigate the role of GBS membrane vesicles (MVs) in delivering the β-hemolysin/cytolysin (granadaene).
  • To determine the contribution of MV-associated granadaene to GBS virulence and pathogenesis.

Main Methods:

  • Characterization of GBS-derived membrane vesicles (MVs) for pigmentation and hemolytic activity.
  • Assessment of MV-induced cytotoxicity on immune cells (neutrophils, T cells, B cells).
  • Evaluation of hemolytic MVs' impact on GBS oxidative killing and a neonatal mouse infection model.

Main Results:

  • GBS MVs were found to be pigmented and hemolytic, confirming functional granadaene presence.
  • MVs from hyperhemolytic GBS strains caused increased immune cell death compared to nonhemolytic strains.
  • Hemolytic MVs impaired GBS oxidative killing and worsened neonatal mouse GBS infection outcomes.

Conclusions:

  • GBS MVs serve as a vehicle for deploying the granadaene virulence factor.
  • MV-mediated granadaene delivery contributes to immune evasion and enhanced GBS pathogenesis.
  • This highlights a novel mechanism for GBS virulence factor dissemination and disease progression.
Keywords:
granadaenegroup B streptococcushemolysinimmune evasionmembrane vesicles

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