Streptococcus pneumoniae type 7F capsular polysaccharide

The Streptococcus pneumoniae type 7F capsular polysaccharide is a serotype-specific carbohydrate polymer that forms the outermost layer (capsule) of the bacterium S. pneumoniae. This capsule is the dominant surface structure and serves as a major virulence factor, protecting the bacterium from host immune responses, particularly by interfering with opsonophagocytic clearance mechanisms. It is included in pneumococcal conjugate vaccines (PCVs), such as PCV21 and PCV13. In these vaccines, purified type-specific capsular polysaccharides are chemically conjugated to carrier proteins like CRM197 to enhance immunogenicity.

Antibody production via vaccination; Opsonization and phagocytosis of bacteria.