Capsular polysaccharides of Streptococcus pneumoniae (serotypes 1, 5, 6A, 6B, 7F, 9V, 14, 19A, 19F, 23F) (CPS (SIILPCV10))

Capsular polysaccharides (CPS) are the primary virulence factors of Streptococcus pneumoniae, forming a thick carbohydrate layer that protects the bacterium from host immune recognition. These polysaccharides inhibit opsonization by complement and prevent phagocytosis by leukocytes, enabling the pathogen to survive in the bloodstream and cause invasive diseases such as pneumonia, meningitis, and sepsis (Henriques-Normark & Tuomanen, 2013). The SIILPCV10 vaccine, known commercially as Pneumosil, targets ten specific serotypes (1, 5, 6A, 6B, 7F, 9V, 14, 19A, 19F, and 23F) that are major contributors to childhood mortality in low- and middle-income countries (PATH, 2020). In the vaccine, these polysaccharides are conjugated to the CRM197 carrier protein to overcome the poor immunogenicity of pure polysaccharides in young children. This conjugation facilitates a T-cell dependent immune response, leading to the production of high-affinity antibodies and the establishment of long-term immunological memory (WHO, 2019). By targeting these CPS antigens, the vaccine significantly reduces the burden of invasive pneumococcal disease and nasopharyngeal carriage of the included serotypes.

Other names

Pneumococcal capsular polysaccharidesS. pneumoniae CPSPneumosil antigens10-valent pneumococcal conjugate vaccine antigens

Induction of serotype-specific IgG antibodies and opsonophagocytic activity (OPA) through a T-cell dependent immune response following conjugation to a carrier protein (CRM197).