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Updated: May 13, 2026
04:25
Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
Structure determination of Streptococcus suis serotype 14 capsular polysaccharide
Marie-Rose Van Calsteren1, Fleur Gagnon, Cynthia Calzas
1Food Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC J2S 8E3, Canada. marie-rose.vancalsteren@agr.gc.ca
Summary
The capsular polysaccharide from Streptococcus suis serotype 14 was analyzed, revealing a unique repeating unit structure with implications for bacterial biosynthesis pathways.
Area of Science:
- Microbiology
- Biochemistry
- Glycobiology
Background:
- Streptococcus suis serotype 14 (S. suis 14) is a significant pathogen.
- Understanding the capsular polysaccharide (CPS) is crucial for vaccine development and pathogenesis studies.
Purpose of the Study:
- To determine the detailed structure of the S. suis 14 CPS.
- To elucidate the repeating unit sequence and its linkage patterns.
- To propose a correlation between the CPS structure and its biosynthesis genes.
Main Methods:
- Purification and chemical modification of S. suis 14 CPS.
- Sugar composition and absolute configuration analysis.
- Lectins binding assays (Sambucus nigra lectin).
- Mild acid hydrolysis for desialylation.
- Periodate oxidation, borohydride reduction, and Smith degradation.
- Nuclear magnetic resonance (NMR) spectroscopy ((1)H and (13)C).
- Mass spectrometry (MS).
Main Results:
- The S. suis 14 CPS is composed of D-Galactose, D-Glucose, D-GlcNAc, and D-Neu5Ac in a specific ratio.
- The terminal sialic acid (Neu5Ac) is linked via an α2-6 linkage to galactose.
- The repeating unit sequence was determined as [6)[Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3)]Gal(β1-3)Gal(β1-4)Glc(β1-](n).
- The sialic acid-containing side chain is identical to that of S. suis serotype 2 CPS but lacks rhamnose.
Conclusions:
- The detailed structure of S. suis 14 CPS was elucidated.
- The S. suis 14 CPS shares structural similarities with other bacterial CPS, suggesting conserved biosynthetic mechanisms.
- A proposed correlation exists between the determined CPS structure and the genes within the S. suis serotype 14 cps locus responsible for its biosynthesis.
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