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Identification of a novel virulence determinant with serum opacification activity in Streptococcus suis

Christoph G Baums1, Ute Kaim, Marcus Fulde

  • 1Institut fuer Mikrobiologie, Zentrum fuer Infektionsmedizin, Stiftung Tieraerztliche Hochschule Hannover, Bischofsholer Damm 15, D-30173 Hannover, Germany. christoph.baums@gmx.de

Infection and Immunity
|October 24, 2006
PubMed

Insights

Streptococcus suis serotype 2 possesses a novel surface protein, opacity factor of S. suis (OFS), which contributes to virulence. OFS is a key virulence determinant in invasive S. suis infections, though not essential for colonization.

Area of Science:

  • Microbiology
  • Pathogen Research
  • Molecular Biology

Background:

  • Streptococcus suis serotype 2 is a significant pathogen affecting both pigs and humans.
  • Microbial Surface Components Recognizing Adhesive Matrix Molecules (MSCRAMM) family proteins mediate host tissue interactions in streptococci.
  • The role of specific surface proteins in S. suis pathogenesis is an area of active investigation.

Purpose of the Study:

  • To identify and characterize a novel surface protein in S. suis serotype 2 with potential virulence functions.
  • To investigate the structural and functional properties of this new protein, named opacity factor of S. suis (OFS).
  • To determine the contribution of OFS to the pathogenesis of invasive S. suis infections in a porcine model.

Main Methods:

  • Identification and structural analysis of the novel OFS protein in S. suis.
  • Assessment of serum opacification activity in S. suis extracts and through heterologous expression.
  • Generation and characterization of an ofs knockout mutant in S. suis.
  • Experimental infection of piglets with the ofs mutant to evaluate virulence and colonization.

Main Results:

  • A novel MSCRAMM family protein, OFS, was identified in S. suis serotype 2, showing homology to fibronectin-binding protein A and serum opacity factor.
  • OFS demonstrated serum opacification activity, dependent on its presence and expression.
  • The C-terminal repeats of OFS differed from other MSCRAMMs, and recombinant OFS did not bind fibronectin.
  • The ofs knockout mutant exhibited significantly reduced virulence in piglets but maintained colonization ability.

Conclusions:

  • OFS is a novel surface protein of S. suis serotype 2 with serum opacification properties.
  • OFS functions as a significant virulence determinant in invasive S. suis infections.
  • OFS is not essential for bacterial colonization but plays a critical role in disease development.

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