Neisseria meningitidis group Y polysaccharide (None established in scientific convention; “MenY polysaccharide” is sometimes used in literature but not universally standardized.)

Neisseria meningitidis group Y polysaccharide is a capsular polysaccharide expressed on the surface of N. meningitidis serogroup Y strains[1][2][3][5][7]. Structurally, it consists of partly O-acetylated, repeating disaccharide units of sialic acid (N-acetylneuraminic acid, NeuAc) and D-glucose, linked by α-(2→6) and α-(1→4) glycosidic bonds[3][7]. This polysaccharide capsule enables the bacterium to evade the host immune response, particularly by resisting complement-mediated killing, and is therefore a major virulence factor[1][7]. Group Y polysaccharide is the immunological target for licensed vaccines (plain polysaccharide and conjugate types), which elicit bactericidal antibodies protective against invasive meningococcal disease caused by serogroup Y strains[1][5][7]. Capsule switching, where the bacterium can change its capsule type via genetic exchange, is a documented phenomenon and poses challenges for vaccine coverage and disease surveillance[5]. Conformational epitope expression is length-dependent; larger polysaccharide chains present more protective antibody targets, impacting vaccine efficacy[7]. No common abbreviation is universally accepted, though MenY polysaccharide appears sporadically in literature. The molecule is not a receptor, enzyme, transporter, or protein, but a unique carbohydrate antigen, so it falls primarily under “other: bacterial surface antigen” or “polysaccharide capsule” for molecular classification[1][3][7].

Other names

Group Y capsuleMenY polysaccharideNeisseria meningitidis serogroup Y capsular polysaccharideGYMP (in some biochemical literature)

Induction of bactericidal antibodies (vaccine mechanism); Antibody-mediated immune protection against encapsulated bacteria