Neisseria meningitidis capsular polysaccharide W-135 (W-135 capsular polysaccharide)

Neisseria meningitidis capsular polysaccharide W-135 is a surface carbohydrate polymer composed of alternating partly O-acetylated units of sialic acid and D-galactose linked via α-(2→6) and α-(1→4) glycosidic bonds[3]. The W-135 capsule is a defining serogroup antigen, crucial for virulence, enabling the bacteria to evade host immune responses. It is synthesized by specific capsule polymerase enzymes (notably Csw), encoded in the cps locus, and anchored to the outer membrane via lipid and β-poly-Kdo linkers[2][3]. The capsular polysaccharide is the antigenic basis for the “W-135” designation and is the target of licensed multivalent meningococcal vaccines. Its expression is tightly regulated by genetic mechanisms, and its structural variability enables immune escape and capsule switching, posing challenges in vaccine development and disease control[1][2]. It is a carbohydrate antigen, not a protein (not a receptor, enzyme, or transporter), so molecular classification is "Other". It is the key antigen in licensed MenACWY vaccines, which protect against W-135-related meningococcal disease[5]. Capsule switching and genetic regulation can affect its detectability and vaccine coverage[1][2].

Other names

Serogroup W-135 polysaccharideGroup W-135 capsuleMeningococcal W-135 CPS

Vaccine-induced anti-capsular antibodies bind to W-135 polysaccharide, facilitating complement-mediated killing and preventing invasive disease