Molecular modeling provides insights into the loading of sialic acid-containing antigens onto CRM197: the role of chain flexibility in conjugation efficiency and glycoconjugate architecture.

Kuttel, Michelle M. and Ravenscroft, Neil and Berti, Francesco (2021) Molecular modeling provides insights into the loading of sialic acid-containing antigens onto CRM197: the role of chain flexibility in conjugation efficiency and glycoconjugate architecture., Glycoconjugate Journal, 38, 411–419, Springer.

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Abstract

Vaccination is the most cost-effective way to control disease caused by encapsulated bacteria; the capsular polysaccharide (CPS)is the primary virulence factor and vaccine target. Neisseria meningitidis (Nm) serogroups B, C, Y and W all contain sialic acid, a common surface feature of human pathogens. Two protein-based vaccines against serogroup B infection are available for human use while four tetravalent conjugate vaccines including serogroups C, W and Y have been licensed. The tetravalent Menveo® conjugate vaccine is well-defined: a simple monomeric structure of oligosaccharides terminally conjugated to amino groups of the carrier protein CRM197. However, not only is there a surprisingly low limit for antigen chain attachment to CRM197, but different serogroup saccharides have consistently different CRM197 loading, the reasons for which are unclear. Understanding this phenomenon is important for the long-term goal of controlling conjugation to prepare conjugate vaccines of optimal immunogenicity. Here we use molecular modeling to explore whether antigen flexibility can explain the varying antigen loading of the conjugates. Because flexibility is difficult to separate from other structural factors, we focus on sialic-acid containing CPS present in current glycoconjugate vaccines: serogroups NmC, NmWand NmY. Our simulations reveal a correlation between Nm antigen flexibility (NmW> NmC > NmY) and the number of chains attached to CRM197, suggesting that increased flexibility enables accommodation of additional chains on the protein surface. Further, in silico models of the glycoconjugates confirm the relatively large hydrodynamic size of the saccharide chains and indicate steric constraints to further conjugation.

Item Type:	Journal article (paginated)
Uncontrolled Keywords:	Neisseria meningitidis; Capsular polysaccharide; Molecular modeling; Antigen conformation; Conjugation efficiency; Glycoconjugate structure
Subjects:	Computing methodologies > Modeling and simulation Computing methodologies > Modeling and simulation > Simulation types and techniques Computing methodologies > Modeling and simulation > Simulation types and techniques > Molecular simulation Applied computing > Physical sciences and engineering > Chemistry
Date Deposited:	03 Dec 2021 10:52
Last Modified:	03 Dec 2021 10:52
URI:	https://pubs.cs.uct.ac.za/id/eprint/1465

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