Neisseria meningitidis Group A Polysaccharide Antigen

The Neisseria meningitidis group A polysaccharide antigen is a group-specific capsular polysaccharide found on the surface of *Neisseria meningitidis* serogroup A bacteria. This antigen is the primary virulence factor for this serogroup and forms the basis for several vaccines used to prevent invasive diseases such as meningitis and meningococcemia caused by *N. meningitidis* group A. The polysaccharide capsule is essential for bacterial survival in the host, protecting against immune responses. For serogroup A, the capsule consists of a homopolymer of (α1→6)-linked N-acetylmannosamine-1-phosphate residues. The purified group A capsular polysaccharide serves as an immunogen in both plain (polysaccharide) vaccines and conjugate vaccines (where it is linked to carrier proteins like diphtheria toxoid). These antigens stimulate protective immunity by inducing antibodies that target the bacterial capsule, preventing infection or reducing disease severity.

Other names

Meningococcal group A polysaccharideMeningococcal polysaccharide antigen group ANeisseria meningitidis group A capsular polysaccharide antigen

Induction of neutralizing antibodies against the capsular polysaccharide, leading to complement-mediated killing and opsonization of *Neisseria meningitidis* serogroup A.