Neisseria meningitidis serogroup W-135 capsular polysaccharide antigen

The **Neisseria meningitidis serogroup W-135 capsular polysaccharide antigen** is a high-molecular-weight, cell-surface polymer composed of alternating sialic acid (N-acetylneuraminic acid, Neu5Ac) and D-galactose residues, linked via α-(2→6) and α-(1→4) glycosidic bonds[2][4][5][6]. It forms the outermost layer surrounding N. meningitidis of serogroup W-135 and is the key determinant of the bacterium's serogroup and virulence[1][4][5]. The capsule acts as a major virulence factor by providing resistance to complement-mediated killing and phagocytosis[3][4]. This antigen is also the principal target for protective antibodies, forming the critical epitope in available conjugate vaccines designed to prevent invasive disease caused by serogroup W-135 isolates[2][3][4]. The antigen's structure is highly similar to that of group Y, except for the galactose (in W-135) replacing glucose (in Y), which can impact antigenicity and immunity[2][5][6]. Antibodies to this polysaccharide require recognition of conformational epitopes only formed by long-chain, high-molecular-weight forms of the antigen[2][3], a key consideration for vaccine design. The capsule is genetically specified by a set of biosynthesis and export genes (notably the syn and ctr loci)[1], and its capacity for capsule switching poses epidemiological and vaccination challenges[1][4].

Other names

Neisseria meningitidis W-135 capsuleGroup W-135 capsular polysaccharideMenW-135 polysaccharideN. meningitidis W-135 polysaccharide antigen

Provides an immunogenic surface for vaccine-induced antibody development, leading to opsonization and/or direct complement-mediated killing of N. meningitidis W-135 Polysaccharide-protein conjugates convert T-cell-independent response to T-cell-dependent (higher efficacy)