Neisseria meningitidis polysaccharide capsule antigen serogroup Y (N. meningitidis serogroup Y capsule antigen)

The **Neisseria meningitidis polysaccharide capsule antigen serogroup Y** is a surface-exposed polysaccharide that forms a capsule around the bacterium Neisseria meningitidis, serving as the principal virulence factor by protecting the organism from host immune mechanisms such as phagocytosis and complement-mediated lysis[6][2][3]. The capsule defines the serogroup (here, serogroup Y) and varies in chemical composition between serogroups, with serogroup Y defined by a specific pattern of sialic acid glycosylation[2][1]. The genetic determinants for synthesis and export of the capsule are clustered in the **cps locus**; in sialic acid–containing serogroups (including Y), capsule biosynthetic genes (cssA/B/C and csy for serogroup Y) are conserved in organization, with the specific polymerase (Csy) mediating serogroup-specific linkage and structure[3][1]. The capsule is the target of meningococcal vaccines and immunodiagnostics, and nearly all invasive disease cases are caused by encapsulated strains expressing serogroup-defining polysaccharides. Capsule switching and modification contribute to immune escape and present challenges for vaccine coverage[3][1]. The capsule is not a protein receptor, enzyme or transporter, but a high-molecular-weight carbohydrate antigen and is classified as a **bacterial polysaccharide antigen** and critical **therapeutic target** for prevention via vaccination[6][2][3].

Other names

Meningococcal serogroup Y capsule antigenNeisseria meningitidis serogroup Y capsular polysaccharideNmY capsule

Induction of serogroup-specific immunity via vaccine; Antibody-mediated opsonization and complement activation targeting the capsular polysaccharide; Chemoprophylaxis targets bacterial proliferation and carriage