Serogroup C capsular polysaccharide of Neisseria meningitidis (MenC CPS)

The Serogroup C capsular polysaccharide of Neisseria meningitidis is a critical virulence factor consisting of a homopolymer of alpha-2,9-linked N-acetylneuraminic acid (sialic acid) (Frasch et al., 1985; PubChem CID 139561245). This capsule surrounds the bacterium, providing a physical barrier that prevents host-mediated phagocytosis and inhibits the alternative complement pathway, thereby allowing the pathogen to survive in the bloodstream (StatPearls, 2023). It is a primary target for immunization strategies against meningococcal disease, which can manifest as life-threatening meningitis or septicemia (CDC, 2022). While pure polysaccharide vaccines are poorly immunogenic in children under two years of age, conjugate vaccines—which chemically link the polysaccharide to a carrier protein—induce a robust T-cell dependent immune response (Pollard et al., 2001). These vaccines have been highly successful in reducing the incidence of serogroup C disease through both direct protection and the induction of herd immunity by reducing nasopharyngeal carriage (Ramsay et al., 2003). The efficacy of these interventions is typically measured using serum bactericidal antibody (SBA) assays (Borrow et al., 2001).

Other names

Neisseria meningitidis serogroup C polysaccharideMenC polysaccharidealpha-2,9-linked sialic acid polymerMeningococcal group C polysaccharideGCPS

Induction of serum bactericidal antibodies (SBA) that mediate complement-dependent bacterial killing (Borrow et al., 2001). Conjugation to carrier proteins (e.g., CRM197, tetanus toxoid) converts the T-cell independent polysaccharide into a T-cell dependent antigen, enabling immunological memory and efficacy in infants (Pollard et al., 2001).