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Contribution of Streptococcus pyogenes M87 protein to innate immune resistance and virulence

Yujiro Hirose1, Piotr Kolesinski2, Masanobu Hiraoka3

  • 1Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 5650871, Japan; Department of Pediatrics, University of California at San Diego, La Jolla, CA, 92093, USA.

Microbial Pathogenesis
|June 20, 2022
PubMed

Insights

The M87 protein of Streptococcus pyogenes enhances bacterial survival against immune cells and promotes severe infections. Deleting this emm87 gene reduced mortality in a mouse model, highlighting its role in pathogenesis.

Area of Science:

  • Microbiology
  • Immunology
  • Pathogen Research

Background:

  • Streptococcus pyogenes is a major human pathogen identified by its emm gene, which encodes the M protein.
  • The M/emm87 strain's prevalence is increasing in invasive infections, but the role of its M87 protein in virulence is unknown.

Purpose of the Study:

  • To investigate the role of the M87 protein in Streptococcus pyogenes pathogenesis.
  • To determine how the M87 protein interacts with the host immune system.

Main Methods:

  • Targeted mutagenesis to create emm87 deletion mutants.
  • Assays for bacterial resistance to neutrophil and whole blood killing.
  • Measurement of IL-1β release from macrophages.
  • Assessment of epithelial cell adherence and nasal colonization.
  • Evaluation of bacterial loads and mortality in a murine systemic infection model.

Main Results:

  • The M87 protein enhances resistance to immune cell killing and promotes IL-1β release.
  • Deletion of emm87 did not affect bacterial adherence or colonization.
  • Loss of emm87 significantly reduced mortality and bacterial burden in a mouse model of systemic infection.

Conclusions:

  • The M87 protein is a virulence factor for Streptococcus pyogenes.
  • emm87 contributes to pathogenesis by modulating interactions with innate immune cells, impacting bacterial survival and host response.
Keywords:
M proteinStreptococcus pyogenesVirulence factoremm87

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