Structural analysis of the O-acetylated O-polysaccharide isolated from Salmonella paratyphi A and used for vaccine preparation

Ravenscroft, Neil; Cescutti, Paola; Gavini, Massimiliano; Stefanetti, Giuseppe; MacLennan, Calman A.; Martin, Laura B.; Micoli, Francesca

doi:10.1016/j.carres.2014.12.002

Cited by 36 publications

(23 citation statements)

References 29 publications

(34 reference statements)

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“…A protective S. enterica serovar Paratyphi A glycoconjugate LPS vaccine required acetylation, which is likely dependent on the described rhamnose acetylation modification (34, 35). Based on the data presented here linking rhamnose acetylation to the family 2 gtr operon, this can now be attributed to the family 2 gtr operon harbored by the S .…”

Section: Discussionmentioning

confidence: 99%

Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition

et al. 2017

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Salmonella enterica serovar Typhi is a human-restricted Gram-negative bacterial pathogen responsible for causing an estimated 27 million cases of typhoid fever annually, leading to 217,000 deaths, and current vaccines do not offer full protection. The O-antigen side chain of the lipopolysaccharide is an immunodominant antigen, can define host-pathogen interactions, and is under consideration as a vaccine target for some Gram-negative species. The composition of the O-antigen can be modified by the activity of glycosyltransferase (gtr) operons acquired by horizontal gene transfer. Here we investigate the role of two gtr operons that we identified in the S. Typhi genome. Strains were engineered to express specific gtr operons. Full chemical analysis of the O-antigens of these strains identified gtr-dependent glucosylation and acetylation. The glucosylated form of the O-antigen mediated enhanced survival in human serum and decreased complement binding. A single nucleotide deviation from an epigenetic phase variation signature sequence rendered the expression of this glucosylating gtr operon uniform in the population. In contrast, the expression of the acetylating gtrC gene is controlled by epigenetic phase variation. Acetylation did not affect serum survival, but phase variation can be an immune evasion mechanism, and thus, this modification may contribute to persistence in a host. In murine immunization studies, both O-antigen modifications were generally immunodominant. Our results emphasize that natural O-antigen modifications should be taken into consideration when assessing responses to vaccines, especially O-antigen-based vaccines, and that the Salmonella gtr repertoire may confound the protective efficacy of broad-ranging Salmonella lipopolysaccharide conjugate vaccines.

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Section: Discussionmentioning

confidence: 99%

Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition

et al. 2017

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“…The lack of binding, by ELISA ( Fig 5B ) and by FACS (data not shown), against S . Paratyphi OAg, which has also been found O-acetylated on C–2/C–3 Rha [ 38 ] (total OAc 68%), may hint for the presence of a structural epitope, specific for S . Typhimurium OAg chain.…”

Section: Discussionmentioning

confidence: 99%

Strain Selection for Generation of O-Antigen-Based Glycoconjugate Vaccines against Invasive Nontyphoidal Salmonella Disease

Lanzilao¹,

Stefanetti²,

Saul³

et al. 2015

PLoS ONE

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Nontyphoidal Salmonellae, principally S. Typhimurium and S. Enteritidis, are a major cause of invasive bloodstream infections in sub-Saharan Africa with no vaccine currently available. Conjugation of lipopolysaccharide O-antigen to a carrier protein constitutes a promising vaccination strategy. Here we describe a rational process to select the most appropriate isolates of Salmonella as source of O-antigen for developing a bivalent glycoconjugate vaccine. We screened a library of 30 S. Typhimurium and 21 S. Enteritidis in order to identify the most suitable strains for large scale O-antigen production and generation of conjugate vaccines. Initial screening was based on growth characteristics, safety profile of the isolates, O-antigen production, and O-antigen characteristics in terms of molecular size, O-acetylation and glucosylation level and position, as determined by phenol sulfuric assay, NMR, HPLC-SEC and HPAEC-PAD. Three animal isolates for each serovar were identified and used to synthesize candidate glycoconjugate vaccines, using CRM197 as carrier protein. The immunogenicity of these conjugates and the functional activity of the induced antibodies was investigated by ELISA, serum bactericidal assay and flow cytometry. S. Typhimurium O-antigen showed high structural diversity, including O-acetylation of rhamnose in a Malawian invasive strain generating a specific immunodominant epitope. S. Typhimurium conjugates provoked an anti-O-antigen response primarily against the O:5 determinant. O-antigen from S. Enteritidis was structurally more homogeneous than from S. Typhimurium, and no idiosyncratic antibody responses were detected for the S. Enteritidis conjugates. Of the three initially selected isolates, two S. Typhimurium (1418 and 2189) and two S. Enteritidis (502 and 618) strains generated glycoconjugates able to induce high specific antibody levels with high breadth of serovar-specific strain coverage, and were selected for use in vaccine production. The strain selection approach described is potentially applicable to the development of glycoconjugate vaccines against other bacterial pathogens.

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“…The 1 H and 13 C nuclear magnetic resonance (NMR) spectra were recorded in D 2 O on a Bruker Avance DPX-400 instrument. The electrospray ionization mass spectrometry (ESI-MS) analysis of oligosaccharide fractions were performed on a VG Quattro MS/MS spectrometer as described in [16,17].…”

Section: Methodsmentioning

confidence: 99%

Structure elucidation of a pectin fromDendrobium nobileLindl. and its immunological activity

Wang

Zhang

Luo

2018

Biotechnology & Biotechnological Equipment

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In this study, an RG-I pectin DNP-W6 was isolated from the stems of Dendrobium nobile Lindl. (Orchidaceae). It contained mannose, glucose, galactose, galacturonic acid and rhamnose in a molar ratio of 0.6: 1.0: 1.5: 1.1: 1.0. Its structural features were revealed by chemical, physical and spectral analysis. The results suggested that DNP-W6 possessed a backbone of a disaccharide of !4)-a-GalAp-(1!2)-a-Rhap-(1!, with approximate 50% substitution at O-4 of the rhamnopyranosyl residues. The side chains were neutral chains including galactosyl, mannosyl and glucosyl chains. The acetyl content was estimated to be 8.9%. The immunological results indicated that DNP-W6 and its derivatives exhibited different immunological activities in vitro, showing that the side chains and acetyl groups had an important effect on the expression of immunological activities.

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Structural analysis of the O-acetylated O-polysaccharide isolated from Salmonella paratyphi A and used for vaccine preparation

Cited by 36 publications

References 29 publications

Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition

Salmonella enterica Serovar Typhi Lipopolysaccharide O-Antigen Modification Impact on Serum Resistance and Antibody Recognition

Strain Selection for Generation of O-Antigen-Based Glycoconjugate Vaccines against Invasive Nontyphoidal Salmonella Disease

Structure elucidation of a pectin fromDendrobium nobileLindl. and its immunological activity

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