Detailed Investigation of the Immunodominant Role of O‐Antigen Stoichiometric O‐Acetylation as Revealed by Chemical Synthesis, Immunochemistry, Solution Conformation and STD‐NMR Spectroscopy for Shigella flexneri 3a1. Issue 31 (4th July 2016)

• Record Type: Journal Article
• Authors: Boutet, Julien; Blasco, Pilar; Guerreiro, Catherine; Thouron, Françoise; Dartevelle , Sylvie; Nato , Farida; Cañada, F. Javier; Ardá, Ana; Phalipon, Armelle; Jiménez‐Barbero, Jesús; Mulard, Laurence A.
• Is Part Of: Chemistry. Volume 22:Issue 31(2016)
• Page Start: 10892
• Page End: 10911
• Publication Date: 2016-07-04
• Subjects: antibodies -- carbohydrates -- epitope specificity -- glycosylation -- NMR spectroscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201600567
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Shigella flexneri 3a causes bacillary dysentery. Its O‐antigen has the {2)‐[α‐d ‐Glc p ‐(1→3)]‐α‐l ‐Rha p ‐(1→2)‐α‐l ‐Rha p ‐(1→3)‐[Ac→2]‐α‐l ‐Rha p ‐(1→3)‐[Ac→6]≈40 % ‐β‐d ‐Glc p NAc‐(1→} ([(E)ABAc CAc D]) repeating unit, and the non‐ O ‐acetylated equivalent defines S. flexneri X. Propyl hepta‐, octa‐, and decasaccharides sharing the (E′)A′BAc CD(E)A sequence, and their non‐ O ‐acetylated analogues were synthesized from a fully protected BAc CD(E)A allyl glycoside. The stepwise introduction of orthogonally protected mono‐ and disaccharide imidate donors was followed by a two‐step deprotection process. Monoclonal antibody binding to twenty‐six S. flexneri types 3a and X di‐ to decasaccharides was studied by an inhibition enzyme‐linked immunosorbent assay (ELISA) and STD‐NMR spectroscopy. Epitope mapping revealed that the 2C ‐acetate dominated the recognition by monoclonal IgG and IgM antibodies and that the BAc CD segment was essential for binding. The glucosyl side chain contributed to a lesser extent, albeit increasingly with the chain length. Moreover, tr‐NOESY analysis also showed interaction but did not reveal any meaningful conformational change upon antibody binding. Abstract : New vaccines : Different propyl oligosaccharides reflecting the SF3a O‐antigen sequence and their non‐ O ‐acetylated analogues (SFX) were synthesized from a fully protected BAc CD(E)A allyl glycoside. Specific monoclonal antibody binding to several S. flexneri types 3a and X di‐ to decasaccharides was studied by enzyme‐linked immunosorbent assay (ELISA) and saturation transfer difference (STD)‐NMR spectroscopy (see figure).