Streptococcus pneumoniae type 9N capsular polysaccharide (CPS 9N)

The Streptococcus pneumoniae type 9N capsular polysaccharide is a serotype-specific carbohydrate polymer forming the capsule of S. pneumoniae. It is a major virulence factor, protecting the bacterium from host immune responses. The repeating unit is a linear pentasaccharide: →4)-α-D-GlcpA-(1→3)-α-D-Glcp-(1→3)-β-D-ManpNAc-(1→4)-α-D-Glcp-(1→4)-β-D-GlcpNAc(1→. Type-specific immunity relies on recognition of unique epitopes on the capsule, making it a target for vaccines against pneumococcal disease.

Other names

Pneumococcal type 9N capsular polysaccharideS. pneumoniae serotype 9N capsuleType 9N CPS

Vaccines elicit type-specific antibodies that opsonize bacteria expressing the 9N capsule, promoting phagocytosis and clearance. Antibodies can also neutralize the capsule's antiphagocytic properties.