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Updated: Jul 31, 2026

Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Localization of surface immunogenic protein on group B streptococcus
S Rioux1, D Martin, H W Ackermann
1Unité de Recherche en Vaccinologie, Centre Hospitalier Universitaire de Québec et Université Laval, Ste-Foy, Québec, Canada G1V 4G2. Stephanie.Rioux@crchul.ulaval.ca
Group B Streptococcus (GBS) surface immunogenic protein (Sip) is accessible on intact bacterial cells. Antibodies recognize Sip, which is localized to specific regions on the GBS surface.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Group B Streptococcus (GBS) is a significant human pathogen.
- Understanding the surface localization of GBS proteins is crucial for vaccine development.
- The surface immunogenic protein (Sip) is a potential target for GBS therapeutics.
Purpose of the Study:
- To investigate the localization and accessibility of the GBS surface immunogenic protein (Sip).
- To determine if native Sip is exposed on the surface of intact GBS cells.
- To identify specific regions of Sip distribution on the GBS cell surface.
Main Methods:
- Flow cytometry was used to assess Sip accessibility on intact GBS cells.
- Immunogold electron microscopy was employed to visualize Sip localization.
- Antibodies generated against recombinant Sip were used for detection.
Main Results:
- Antibodies against recombinant Sip effectively recognized native Sip on the surface of various GBS strains across all nine serotypes.
- Immunogold electron microscopy confirmed Sip exposure on the intact GBS cell surface.
- Sip distribution was found to be restricted to polar sites and the septal region of GBS cells.
Conclusions:
- The surface immunogenic protein (Sip) is exposed and accessible on the surface of intact Group B Streptococcus cells.
- Sip exhibits a non-uniform distribution, preferentially localizing to specific cellular regions.
- These findings support Sip as a potential target for immunodiagnostics and therapeutics against GBS infections.
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