Neisseria meningitidis serogroups A, C, W, and Y capsular polysaccharides (ACWY capsular polysaccharides)

Capsular polysaccharides of Neisseria meningitidis serogroups A, C, W, and Y are surface-exposed sugar polymers that serve as major virulence factors, protecting the bacteria from host immune defenses. These polysaccharides are the targets of quadrivalent meningococcal conjugate vaccines, which elicit protective antibody responses that promote bacterial clearance through opsonization and complement activation. The chemical structure of each serogroup's polysaccharide is distinct, with serogroup A composed of N-acetyl mannosamine-1-phosphate, serogroup C of polysialic acid, and serogroups W and Y of sialic acid polymers with unique linkages. Conjugation to a carrier protein like tetanus toxoid or diphtheria toxoid enhances the immunogenicity of these polysaccharides, especially in infants and young children.

Other names

N. meningitidis A capsular polysaccharideN. meningitidis C capsular polysaccharideN. meningitidis W capsular polysaccharideN. meningitidis Y capsular polysaccharideMenA capsular polysaccharideMenC capsular polysaccharideMenW capsular polysaccharideMenY capsular polysaccharide

Vaccine-induced antibodies bind to the capsular polysaccharides, promoting complement activation and opsonophagocytosis, leading to bacterial clearance.