Relative stability of meningococcal serogroup A and X polysaccharides

Berti, Francesco; Romano, Maria; Micoli, Francesca; Pinto, Vittoria; Cappelletti, Emilia; Gavini, Massimiliano; Proietti, Daniela; Pluschke, Gerd; MacLennan, Calman A.; Costantino, Paolo

doi:10.1016/j.vaccine.2012.08.021

Cited by 52 publications

(52 citation statements)

References 26 publications

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“…Approximately 200 mg of purified MenX PS was obtained from 1 L of fermentation broth, a productivity much higher than previously reported with MenX isolates (9.6-20 mg/L) (31,50,51). Studies on MenX PS and derived OS indicated that they are stable in aqueous solution (31,33), providing the opportunity to develop a fully liquid vaccine formulation with clear advantages in terms of cost and practical utilization compared with freeze-dried formulations that require reconstitution with water.…”

Section: Discussionmentioning

confidence: 99%

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Development of a glycoconjugate vaccine to prevent meningitis in Africa caused by meningococcal serogroup X

Micoli

Romano

Tontini

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Neisseria meningitidis is a major cause of bacterial meningitis worldwide, especially in the African meningitis belt, and has a high associated mortality. The meningococcal serogroups A, W, and X have been responsible for epidemics and almost all cases of meningococcal meningitis in the meningitis belt over the past 12 y. Currently no vaccine is available against meningococcal X (MenX). Because the development of a new vaccine through to licensure takes many years, this leaves Africa vulnerable to new epidemics of MenX meningitis at a time when the epidemiology of meningococcal meningitis on the continent is changing rapidly, following the recent introduction of a glycoconjugate vaccine against serogroup A. Here, we report the development of candidate glycoconjugate vaccines against MenX and preclinical data from their use in animal studies. Following optimization of growth conditions of our seed MenX strain for polysaccharide (PS) production, a scalable purification process was developed yielding high amounts of pure MenX PS. Different glycoconjugates were synthesized by coupling MenX oligosaccharides of varying chain length to CRM 197 as carrier protein. Analytical methods were developed for in-process control and determination of purity and consistency of the vaccines. All conjugates induced high anti-MenX PS IgG titers in mice. Antibodies were strongly bactericidal against African MenX isolates. These findings support the further development of glycoconjugate vaccines against MenX and their assessment in clinical trials to produce a vaccine against the one cause of epidemic meningococcal meningitis that currently cannot be prevented by available vaccines.

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Section: Discussionmentioning

confidence: 99%

“…The structure of MenX PS consists of N-acetylglucosamine-4-phosphate residues held together by α-(1-4) phosphodiester bonds without O-acetyl groups (28,(30)(31)(32)(33).…”

Section: Significancementioning

confidence: 99%

Development of a glycoconjugate vaccine to prevent meningitis in Africa caused by meningococcal serogroup X

Micoli

Romano

Tontini

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Solutions containing 2.5 mg/ml CPSA in sodium acetate buffer (50 mM sodium acetate, pH 4.8) were incubated at 73°C for 6 h, and 2 pool fractions (avDP 6 and 15, respectively) were purified by anionic exchange chromatography (Q-Sepharose column, GE Healthcare) using a sodium chloride gradient. The avDP and the dispersion of saccharide chains was determined by 31 P NMR and high performance anionic exchange chromatography-pulsed amperometric detection (HPAEC-PAD) analysis following an established protocol (26). If used in enzymatic reactions, hydrolyzed CPSA (CPSA hyd ) was dephosphorylated (CPSA hyd -deP) using acid phosphatase (Sigma) according to the manufacturer's guidelines.…”

Section: Methodsmentioning

confidence: 99%

Molecular Cloning and Functional Characterization of Components of the Capsule Biosynthesis Complex of Neisseria meningitidis Serogroup A

Fiebig

Freiberger

Pinto

et al. 2014

Journal of Biological Chemistry

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Background:The isolation of capsular polysaccharides from pathogenic bacteria for vaccine production is cost-intensive. Results: We describe the cloning, recombinant expression, and functional characterization of three enzymes from Neisseria meningitidis serogroup A that facilitate in vitro synthesis of the capsule polymer. Conclusion:The study presents a novel basis for efficient vaccine production. Significance: Economic vaccine production is prerequisite to combat meningococcal diseases.

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“…The monitoring of the anomeric proton at carbon 1 of the ManNAc-phosphate residue constituting the repeating unit of the serogroup A capsular polysaccharide provided a tool for evaluating levels of O-acetylation [28]. Two separate peaks, one of the O-acetylated form at lower-field signal (5.40 ppm) and the other of the non-O-acetylated form at upper-field signal (5.35 ppm) were resolved (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

Spontaneous point mutations in the capsule synthesis locus leading to structural and functional changes of the capsule in serogroup A meningococcal populations

Ispasanie

Micoli²,

Lamelas

et al. 2018

Virulence

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Whole genome sequencing analysis of 100 Neisseria meningitidis serogroup A isolates has revealed that the csaABCD-ctrABCD-ctrEF capsule polysaccharide synthesis locus represents a spontaneous point mutation hotspot. Structural and functional properties of the capsule of 11 carriage and two disease isolates with non-synonymous point mutations or stop codons in capsule synthesis genes were analyzed for their capsular polysaccharide expression, recognition by antibodies and sensitivity to bactericidal killing. Eight of eleven carriage isolates presenting capsule locus mutations expressed no or reduced amounts of capsule. One isolate with a stop codon in the O-acetyltransferase gene expressed non-O-acetylated polysaccharide, and was not recognized by anti-capsule antibodies. Capsule and O-acetylation deficient mutants were resistant to complement deposition and killing mediated by anti-capsular antibodies, but not by anti-lipopolysaccharide antibodies. Two capsule polymerase mutants, one carriage and one case isolate, showed capsule over-expression and increased resistance against bactericidal activity of both capsule- and lipopolysaccharide-specific antibodies. Meningococci have developed multiple strategies for changing capsule expression and structure, which is relevant both for colonization and virulence. Here we show that point mutations in the capsule synthesis genes substantially contribute to the repertoire of genetic mechanisms in natural populations leading to variability in capsule expression.

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Relative stability of meningococcal serogroup A and X polysaccharides

Cited by 52 publications

References 26 publications

Development of a glycoconjugate vaccine to prevent meningitis in Africa caused by meningococcal serogroup X

Development of a glycoconjugate vaccine to prevent meningitis in Africa caused by meningococcal serogroup X

Molecular Cloning and Functional Characterization of Components of the Capsule Biosynthesis Complex of Neisseria meningitidis Serogroup A

Spontaneous point mutations in the capsule synthesis locus leading to structural and functional changes of the capsule in serogroup A meningococcal populations

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