Streptococcus pneumoniae capsular polysaccharide-protein conjugate

The Streptococcus pneumoniae capsular polysaccharide-protein conjugate is a vaccine antigen composed of the bacterium’s capsular polysaccharides covalently linked to an immunogenic carrier protein, most commonly CRM197. This conjugation enhances the immune response, especially in young children and other populations with less mature or compromised immune systems. The capsular polysaccharide is a major virulence factor, protecting bacteria from host immune clearance. Linking CPS to proteins like CRM197 recruits helper T cells via peptide presentation. This enables class switching from IgM to other immunoglobulins (notably IgG), generation of memory B cells, mucosal immunity, reduced colonization rates for targeted serotypes, herd protection effects, and longer-lasting immunity after repeated exposures.

Other names

Pneumococcal Conjugate VaccinePCV

The conjugate vaccine elicits a T-cell dependent immune response, leading to the production of IgG antibodies against the capsular polysaccharide of Streptococcus pneumoniae. These antibodies promote opsonophagocytosis and clearance of the bacteria.