Streptococcus pneumoniae capsular polysaccharides (serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 23F) (PCV13 antigens)

Streptococcus pneumoniae capsular polysaccharides are complex carbohydrate polymers that form the outermost layer of the bacterium and serve as its primary virulence factor. These polysaccharides shield the pathogen from host immune recognition by inhibiting opsonization and subsequent phagocytosis by macrophages and neutrophils (CDC, 2022). There are over 100 known serotypes of S. pneumoniae, each defined by a unique chemical structure of its capsule. The specific set of 13 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) represents the most prevalent strains associated with invasive pneumococcal disease, such as meningitis and bacteremia, prior to the introduction of conjugate vaccines (FDA, 2010). In a therapeutic context, these polysaccharides are used as antigens in conjugate vaccines, where they are covalently linked to a carrier protein like CRM197 to induce a T-cell dependent immune response, providing long-term immunological memory and protection across all age groups (StatPearls, 2023).

Other names

Pneumococcal capsular polysaccharidesPCV13 antigensStreptococcus pneumoniae capsulePneumococcal polysaccharides

Induction of serotype-specific opsonizing antibodies that bind to the bacterial capsule, facilitating phagocytosis and killing of the bacteria by host immune cells.