Neisseria meningitidis serogroup A polysaccharide capsule antigen (MenA CPS)

Neisseria meningitidis serogroup A polysaccharide capsule antigen (MenA CPS) is a surface-expressed, high-molecular-weight polymer that forms the core virulence determinant of serogroup A strains of Neisseria meningitidis, a leading cause of epidemic bacterial meningitis and sepsis[1][6]. The capsule consists of repeating units of O-acetylated (1→6)-linked 2-acetamido-2-deoxy-α-D-mannopyranosyl phosphate, specifically O-acetylated at the C3 and C4 positions of the sugar moiety[2][3][4]. This O-acetylation is essential for both structural stability and immunogenicity, making it critical for the effectiveness of MenA polysaccharide-based conjugate vaccines[3][4][6]. The capsule is biosynthesized by enzymes encoded in a genetic locus named cps, with the serogroup A-specific enzymes (notably the O-acetyltransferase CsaC/MynC) responsible for its characteristic chemical structure[1][2][3]. Antibodies targeting MenA CPS confer complement-mediated bactericidal activity and are protective, forming the basis for the MenA polysaccharide conjugate vaccines that have nearly eliminated epidemic MenA disease in regions where they are widely used[6].

Other names

Neisseria meningitidis serogroup A capsular polysaccharideMenA capsuleMenA polysaccharideSerogroup A meningococcal polysaccharide

Induction of protective antibodies via immunization (vaccines use MenA CPS to elicit humoral immune responses, specifically targeting the polysaccharide capsule and leading to complement-mediated bactericidal activity)[6]. Direct bactericidal activity following antibody binding (complement activation)[6].