Streptococcus pneumoniae type 8 capsular polysaccharide (Spn8 CP) (Spn8 CP)

Streptococcus pneumoniae type 8 capsular polysaccharide is a complex carbohydrate structure that forms the protective outer layer of the serotype 8 pneumococcus. This polysaccharide is a critical virulence factor that enables the bacterium to evade the host's innate immune system by inhibiting complement deposition and phagocytosis (CDC, 2022). Serotype 8 is a major contributor to invasive pneumococcal disease (IPD), including pneumonia, bacteremia, and meningitis, particularly in adults (FDA, 2021). In the pharmaceutical context, this polysaccharide is the target antigen for several multi-valent vaccines, such as the 23-valent polysaccharide vaccine (PPSV23) and the 20-valent conjugate vaccine (PCV20). These vaccines are designed to elicit the production of serotype-specific antibodies, which are measured as biomarkers of protection in clinical trials (Merck, 2024). The binding of these antibodies to the polysaccharide facilitates the opsonization and subsequent destruction of the bacteria by immune cells.

Other names

Pneumococcal polysaccharide serotype 8S. pneumoniae serotype 8 capsular polysaccharideType 8 pneumococcal polysaccharidePn8PS

Vaccines containing the type 8 polysaccharide act as antigens to stimulate B-cells to produce serotype-specific IgG antibodies. These antibodies bind to the bacterial capsule, promoting opsonophagocytosis by neutrophils and macrophages, thereby neutralizing the pathogen (FDA, 2021; Merck, 2024).