Neisseria meningitidis capsular polysaccharides of serogroups A, C, W-135, and Y (MenACWY polysaccharides)

The capsular polysaccharides of Neisseria meningitidis serogroups A, C, W-135, and Y are essential virulence factors that form the outermost layer of the bacterium. These polysaccharides are chemically distinct carbohydrate polymers; for instance, serogroup A consists of N-acetyl-D-mannosamine-1-phosphate, while C, W-135, and Y contain sialic acid (PubMed, 2021). Their primary biological role is to shield the bacteria from the host's innate immune system by preventing opsonization and complement-mediated killing (StatPearls, 2023). In clinical practice, these polysaccharides serve as the antigenic basis for quadrivalent meningococcal vaccines, which are designed to elicit protective bactericidal antibodies (CDC, 2022). Conjugation of these polysaccharides to carrier proteins has significantly improved their immunogenicity, particularly in infants, by inducing a T-cell dependent immune response (WHO, 2023). Targeting these capsules is the primary strategy for preventing invasive meningococcal disease, a condition characterized by high morbidity and mortality rates worldwide. Upon vaccination, the immune system generates memory B cells and high-affinity antibodies that recognize these specific capsular structures during a subsequent infection. This recognition triggers the classical complement pathway, leading to the direct lysis of the meningococci.

Other names

Meningococcal A, C, W-135, and Y polysaccharidesMenACWY antigensQuadrivalent meningococcal capsular polysaccharides

Induction of active immunity through the production of serogroup-specific bactericidal antibodies that facilitate complement-mediated lysis and opsonophagocytosis of Neisseria meningitidis.