Pneumococcal capsular polysaccharide (PPS) (PPS)

Pneumococcal capsular polysaccharides are essential virulence factors located on the surface of Streptococcus pneumoniae, a major human pathogen (NCBI, 2022). These complex carbohydrates form a protective capsule that shields the bacteria from the host's immune system by inhibiting complement-mediated opsonization and subsequent phagocytosis (PubMed, 2021). There are over 100 known serotypes of S. pneumoniae, each defined by the unique chemical structure of its capsular polysaccharide. In the context of pharmacology, these polysaccharides serve as the primary antigenic components in both polysaccharide and conjugate vaccines (CDC, 2023). By introducing these antigens to the immune system, vaccines stimulate the production of serotype-specific antibodies that enhance bacterial recognition and clearance. This immune response is critical for preventing invasive pneumococcal diseases such as pneumonia, meningitis, and sepsis (FDA, 2021). While pure polysaccharide vaccines are effective in adults, they are poorly immunogenic in infants, leading to the development of conjugate vaccines where the polysaccharide is linked to a carrier protein. The diversity of these polysaccharides necessitates the inclusion of multiple serotypes in a single vaccine formulation to provide broad protection.

Other names

Streptococcus pneumoniae capsular polysaccharidePneumococcal antigenCPSPneumococcal polysaccharide

Induction of B-cell mediated humoral immunity and production of serotype-specific opsonizing antibodies (IgG) that facilitate phagocytosis and clearance of Streptococcus pneumoniae (StatPearls, 2023; CDC, 2023).