Meningococcal serogroup A capsular polysaccharide (MenA CP)

Meningococcal serogroup A capsular polysaccharide is a critical virulence factor produced by Neisseria meningitidis serogroup A, a primary cause of epidemic meningitis, particularly in the 'meningitis belt' of sub-Saharan Africa. Chemically, it is a homopolymer consisting of (1→6)-linked N-acetyl-D-mannosamine-1-phosphate units. This polysaccharide forms a protective capsule around the bacterium, allowing it to evade the host's innate immune system by resisting phagocytosis and complement-mediated lysis (Source: WHO, CDC). As a therapeutic target, it serves as the primary antigen in both pure polysaccharide and conjugate vaccines. While pure polysaccharide vaccines provide short-term protection in adults, conjugate vaccines—which link the polysaccharide to a carrier protein—induce a robust, long-lasting T-cell dependent immune response and are effective in infants and for establishing herd immunity (Source: PubMed, StatPearls).

Other names

Neisseria meningitidis serogroup A capsular polysaccharideGroup A meningococcal polysaccharideMenA polysaccharidealpha-(1->6)-linked N-acetyl-D-mannosamine-1-phosphate polymer

The polysaccharide acts as a T-cell independent antigen that, when conjugated to a carrier protein, induces a T-cell dependent humoral immune response, leading to the production of high-affinity IgG antibodies and immunological memory. These antibodies facilitate complement-mediated bacteriolysis and opsonophagocytosis of Neisseria meningitidis serogroup A bacteria.