Ravenscroft N, Cescutti P, Gavini M, Stefanetti G, Maclennan CA, Martin LB, Micoli F Structural analysis of the O-acetylated O-polysaccharide isolated from Salmonella paratyphi A and used for vaccine preparation Carbohydrate Research404 (2015)
108-116
The structure was elucidated in this paper NCBI PubMed ID:2566578 Publication DOI:10.1016/j.carres.2014.12.002 Journal NLM ID:0043535 Publisher: Elsevier Correspondence: francesca.micolinovartis.com Institutions: Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa, Novartis Vaccines Institute for Global Health, Via Fiorentina 1, I-53100 Siena, Italy, Department of Life Sciences, Blg. C11, Universita di Trieste, via L. Giorgieri 1, 34127 Trieste, Italy
Salmonella paratyphi A is increasingly recognized as a common cause of enteric fever cases and there are no licensed vaccines against this infection. Antibodies directed against the O-polysaccharide of the lipopolysaccharide of Salmonella are protective and conjugation of the O-polysaccharide to a carrier protein represents a promising strategy for vaccine development. O-Acetylation of S. paratyphi A O-polysaccharide is considered important for the immunogenicity of S. paratyphi A conjugate vaccines. Here, as part of a programme to produce a bivalent conjugate vaccine against both S. typhi and S. paratyphi A diseases, we have fully elucidated the O-polysaccharide structure of S. paratyphi A by use of HPLC-SEC, HPAEC-PAD/CD, GLC, GLC-MS, 1D and 2D-NMR spectroscopy. In particular, chemical and NMR studies identified the presence of O-acetyl groups on C-2 and C-3 of rhamnose in the lipopolysaccharide repeating unit, at variance with previous reports of O-acetylation at a single position. Moreover HR-MAS NMR analysis performed directly on bacterial pellets from several strains of S. paratyphi A also showed O-acetylation on C-2 and C-3 of rhamnose, thus this pattern is common and not an artefact from O-polysaccharide purification. Conjugation of the O-polysaccharide to the carrier protein had little impact on O-acetylation and therefore should not adversely affect the immunogenicity of the vaccine.
O-polysaccharide, O-acetylation, bacterial polysaccharide structure, Salmonella paratyphi A
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(later renamed to: Salmonella enterica ssp. enterica sv. paratyphi A (NVGH307))
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