Streptococcus pneumoniae capsular polysaccharide (serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F) (PnCP)

Streptococcus pneumoniae capsular polysaccharides (PnCP) are complex carbohydrate structures that form the outermost layer of the bacterium, serving as its primary virulence factor by inhibiting host complement deposition and phagocytosis (Geno et al., 2015, PMID: 25833486). This specific set of 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) represents the antigens included in the 13-valent pneumococcal conjugate vaccine (PCV13), which were selected based on their historical prevalence in causing invasive pneumococcal disease (IPD) globally (CDC, 2022). In a therapeutic context, these polysaccharides are used as vaccine antigens to stimulate the production of protective antibodies. When conjugated to a carrier protein, they induce a robust T-cell dependent immune response, leading to the production of opsonizing antibodies that target the bacteria for destruction by the immune system (FDA, 2010). This targeting has significantly reduced the incidence of life-threatening conditions such as pneumonia, meningitis, and febrile bacteremia (WHO, 2019).

Other names

Pneumococcal capsular polysaccharideCPSS. pneumoniae capsular antigen13-valent pneumococcal polysaccharidePCV13 serotypes

Induction of active immunity through the production of serotype-specific opsonizing antibodies. In conjugate vaccines, the polysaccharide is covalently linked to a carrier protein (such as CRM197) to convert the T-cell independent immune response into a T-cell dependent response, which enables immunological memory and efficacy in infants and young children (FDA, 2010; WHO, 2019).