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Protection of mice by a pseudodiffuse strain of Staphylococcus aureus possessing polyvalent capsular type antigen

M Chomarat1, Y Ichiman, K Yoshida

  • 1Laboratoire de Bactériologie, Centre Hospitalier Lyon-Sud, France.

Journal of Medical Microbiology
|February 1, 1989
PubMed

Insights

Staphylococcus aureus strain MC31 exhibits pseudodiffuse growth and shares antigens with capsular types A, B, and C. Its cell-surface polysaccharide provides cross-protective immunity against these types.

Area of Science:

  • Microbiology
  • Immunology
  • Bacterial Pathogenesis

Background:

  • Staphylococcus aureus is a significant human pathogen.
  • Capsular polysaccharides play a crucial role in S. aureus virulence and immune evasion.
  • Understanding capsular type diversity is essential for developing effective vaccines.

Purpose of the Study:

  • To characterize the capsular type of Staphylococcus aureus strain MC31.
  • To investigate the immunoprotective potential of strain MC31's cell-surface polysaccharide.
  • To assess the cross-reactivity and cross-protection conferred by strain MC31 against other S. aureus capsular types.

Main Methods:

  • Serological assays using immune rabbit sera against known capsular types.
  • Mouse immunization with purified cell-surface polysaccharide from strain MC31.
  • Challenge experiments with lethal doses of homologous and heterologous S. aureus strains.
  • Passive protection assays using immune rabbit serum against strain MC31.
  • Absorption assays to quantify antigen cross-reactivity.
  • Electron microscopy using ferritin-labelled antisera.

Main Results:

  • Staphylococcus aureus strain MC31 demonstrated pseudodiffuse growth and reacted serologically with immune sera for capsular types A, B, and C, but not D.
  • Immunization with MC31 cell-surface polysaccharide conferred protection against lethal infection by homologous and heterologous strains of capsular types A, B, and C.
  • Passive protection assays indicated significant cross-protection, although higher titers of anti-MC31 serum were needed for heterologous protection.
  • Absorption studies revealed that MC31 polysaccharide required higher quantities to absorb homologous antibodies compared to homologous capsular polysaccharides.
  • Electron microscopy showed limited binding of ferritin-labelled antisera to the cell wall of strain MC31.

Conclusions:

  • Staphylococcus aureus strain MC31 possesses cell-surface antigens common to capsular types A, B, and C.
  • The cell-surface polysaccharide of strain MC31 induces protective immunity that extends to multiple capsular types.
  • Strain MC31 represents a potential candidate for developing a broadly protective S. aureus vaccine targeting common capsular antigens.

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