Capsular polysaccharide of Streptococcus pneumoniae (CPS (less commonly abbreviated as "PnC" in some vaccine contexts))

Capsular polysaccharide of Streptococcus pneumoniae is a surface-exposed, high-molecular-weight polymer of repeating sugar units that forms a hydrophilic capsule surrounding the bacterium. It is the major virulence determinant of S. pneumoniae, providing protection against host immune defenses by inhibiting complement-mediated opsonization, phagocytosis, and trapping in neutrophil extracellular traps[5][8][9]. Over 98 structurally distinct serotypes have been identified, defined by differences in the CPS structure, and these serotypes strongly affect the bacterium’s invasiveness, epidemiology, and ability to cause disease[5][7][8]. The CPS is currently the principal target of pneumococcal vaccines, which elicit serotype-specific immunity by generating anti-capsular antibodies[5][9]. While highly effective, vaccine strategies are challenged by serotype diversity, serotype replacement, and genetic plasticity of the capsule biosynthesis locus[7][8].

Other names

Pneumococcal capsular polysaccharidePneumococcal capsulePneumococcal CPS

Induction of serotype-specific antibodies that enhance opsonophagocytic killing Antibody-mediated neutralization and enhanced clearance by immune cells