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Updated: Jun 12, 2026
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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
Structure determination of Streptococcus suis serotype 2 capsular polysaccharide
Marie-Rose Van Calsteren1, Fleur Gagnon, Sonia Lacouture
1Centre de recherche et de développement sur les aliments, Agriculture et Agroalimentaire Canada, Saint-Hyacinthe, QC J2S 8E3, Canada. marie-rose.vancalsteren@agr.gc.ca
Summary
The capsular polysaccharide (CPS) of Streptococcus suis serotype 2 was analyzed, revealing a unique repeating unit sequence. This finding aids in understanding bacterial pathogenesis and developing potential vaccines against Streptococcus suis infections.
Area of Science:
- Microbiology
- Carbohydrate Chemistry
- Structural Biology
Background:
- Streptococcus suis serotype 2 is a significant veterinary pathogen.
- The capsular polysaccharide (CPS) is a key virulence factor, influencing serotype identification and host-pathogen interactions.
Purpose of the Study:
- To isolate, purify, and chemically characterize the capsular polysaccharide (CPS) of Streptococcus suis serotype 2.
- To elucidate the precise repeating unit sequence of the S. suis serotype 2 CPS.
- To compare the S. suis CPS structure with those of other related bacterial species.
Main Methods:
- Isolation and purification of capsular polysaccharide.
- Chemical modification including desialylation and Smith degradation.
- Advanced analytical techniques: sugar analysis, absolute configuration determination, methylation analysis, 1H and 13C nuclear magnetic resonance (NMR), and mass spectrometry.
Main Results:
- The S. suis serotype 2 CPS composition was determined as D-Gal, 3; D-Glc, 1; D-GlcNAc, 1; D-Neu5Ac, 1; L-Rha, 1.
- The repeating unit sequence was established as [4)[Neu5Ac(alpha2-6)Gal(beta1-4)GlcNAc(beta1-3)]Gal(beta1-4)[Gal(alpha1-3)]Rha(beta1-4)Glc(beta1-]n.
- The backbone sequence showed identity to Streptococcus agalactiae and Streptococcus pneumoniae type 23F CPSs.
Conclusions:
- The determined structure of S. suis serotype 2 CPS provides critical insights into its molecular architecture.
- Structural similarities and differences were identified when compared to CPSs of Streptococcus agalactiae and Streptococcus pneumoniae.
- A tentative correlation was established between the S. suis CPS sequence and the genes within the cps locus responsible for its biosynthesis.
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