Elucidating the Structural and Minimal Protective Epitope of the Serogroup X Meningococcal Capsular Polysaccharide.

Despite the considerable progress toward the eradication of meningococcal disease with the introduction of glycoconjugate vaccines, previously unremarkable serogroup X has emerged in recent years, recording several outbreaks throughout the African continent. Different serogroup X polysaccharide-based vaccines have been tested in preclinical trials, establishing the principles for further improvement. To elucidate the antigenic determinants of the MenX capsular polysaccharide, we generated a monoclonal antibody, and its bactericidal nature was confirmed using the rabbit serum bactericidal assay. The antibody was tested by the inhibition enzyme-linked immunosorbent assay and surface plasmon resonance against a set of oligosaccharide fragments of different lengths. The epitope was shown to be contained within five to six α-(1-4) phosphodiester mannosamine repeating units. The molecular interactions between the protective monoclonal antibody and the MenX capsular polysaccharide fragment were further detailed at the atomic level by saturation transfer difference nuclear magnetic resonance (NMR) spectroscopy. The NMR results were used for validation of the

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Copyright © 2021 Pietri, Tontini, Brogioni, Oldrini, Robakiewicz, Henriques, Calloni, Abramova, Santini, Malić, Miklić, Lisnic, Bertuzzi, Unione, Balducci, de Ruyck, Romano, Jimenez-Barbero, Bouckaert, Jonjic, Rovis and Adamo.

Déclaration de conflit d'intérêts

MT, BB, DO, PH, LS, EB, MRR and RA are employees of GSK group of companies. MRR and RA are inventors of patents related to this topic. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.