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Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.

ABSTRACT: The Group B Streptococcus capsular polysaccharide type IX was isolated and purified, and the structure of its repeating unit was determined. Type IX capsule ? 4)[NeupNAc-?-(2 ? 3)-Galp-?-(1 ? 4)-GlcpNAc-?-(1 ? 6)]-?-GlcpNAc-(1 ? 4)-?-Galp-(1 ? 4)-?-Glcp-(1 ? appears most similar to types VII and V, although it contains two GlcpNAc residues. Genetic analysis identified differences in cpsM, cpsO, and cpsI gene sequences as responsible for the differentiation between the three capsular polysaccharide types, leading us to hypothesize that type V emerged from a recombination event in a type IX background.

SUBMITTER: Berti F

PROVIDER: S-EPMC4156066 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.

Berti Francesco F Campisi Edmondo E Toniolo Chiara C Morelli Laura L Crotti Stefano S Rosini Roberto R Romano Maria Rosaria MR Pinto Vittoria V Brogioni Barbara B Torricelli Giulia G Janulczyk Robert R Grandi Guido G Margarit Immaculada I

The Journal of biological chemistry 20140702 34

The Group B Streptococcus capsular polysaccharide type IX was isolated and purified, and the structure of its repeating unit was determined. Type IX capsule → 4)[NeupNAc-α-(2 → 3)-Galp-β-(1 → 4)-GlcpNAc-β-(1 → 6)]-β-GlcpNAc-(1 → 4)-β-Galp-(1 → 4)-β-Glcp-(1 → appears most similar to types VII and V, although it contains two GlcpNAc residues. Genetic analysis identified differences in cpsM, cpsO, and cpsI gene sequences as responsible for the differentiation between the three capsular polysacchari ...[more]

PMID: 24990951

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Project description:UnlabelledThe use of pneumococcal capsular polysaccharide (PPS)-based vaccines has resulted in a substantial reduction in invasive pneumococcal disease. However, much remains to be learned about vaccine-mediated immunity, as seven-valent PPS-protein conjugate vaccine use in children has been associated with nonvaccine serotype replacement and 23-valent vaccine use in adults has not prevented pneumococcal pneumonia. In this report, we demonstrate that certain PPS-specific monoclonal antibodies (MAbs) enhance the transformation frequency of two different Streptococcus pneumoniae serotypes. This phenomenon was mediated by PPS-specific MAbs that agglutinate but do not promote opsonic effector cell killing of the homologous serotype in vitro. Compared to the autoinducer, competence-stimulating peptide (CSP) alone, transcriptional profiling of pneumococcal gene expression after incubation with CSP and one such MAb to the PPS of serotype 3 revealed changes in the expression of competence (com)-related and bacteriocin-like peptide (blp) genes involved in pneumococcal quorum sensing. This MAb was also found to induce a nearly 2-fold increase in CSP2-mediated bacterial killing or fratricide. These observations reveal a novel, direct effect of PPS-binding MAbs on pneumococcal biology that has important implications for antibody immunity to pneumococcus in the pneumococcal vaccine era. Taken together, our data suggest heretofore unsuspected mechanisms by which PPS-specific antibodies could affect genetic exchange and bacterial viability in the absence of host cells.ImportanceCurrent thought holds that pneumococcal capsular polysaccharide (PPS)-binding antibodies protect against pneumococcus by inducing effector cell opsonic killing of the homologous serotype. While such antibodies are an important part of how pneumococcal vaccines protect against pneumococcal disease, PPS-specific antibodies that do not exhibit this activity but are highly protective against pneumococcus in mice have been identified. This article examines the effect of nonopsonic PPS-specific monoclonal antibodies (MAbs) on the biology of Streptococcus pneumoniae. The results showed that in the presence of a competence-stimulating peptide (CSP), such MAbs increase the frequency of pneumococcal transformation. Further studies with one such MAb showed that it altered the expression of genes involved in quorum sensing and increased competence-induced killing or fratricide. These findings reveal a novel, previously unsuspected mechanism by which certain PPS-specific antibodies exert a direct effect on pneumococcal biology that has broad implications for bacterial clearance, genetic exchange, and antibody immunity to pneumococcus.

Dataset Information

Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.

Publications

Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.

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