Streptococcus pneumoniae serotype 33F capsular polysaccharide (Spn33F CPS)

The Streptococcus pneumoniae serotype 33F capsular polysaccharide is a complex carbohydrate polymer that encapsulates the 33F strain of the pneumococcus bacterium (CDC, 2023). This polysaccharide is a vital virulence factor that enables the pathogen to evade the host's innate immune response by inhibiting opsonization and phagocytosis (PubMed, PMID: 30201714). Due to its high immunogenicity, it is utilized as a key antigenic component in several multi-valent pneumococcal conjugate vaccines, including PCV15 (Vaxneuvance), PCV20 (Prevnar 20), and PCV21 (Capvaxive), as well as the polysaccharide vaccine PPSV23 (FDA, 2021; FDA, 2024). Upon vaccination, the immune system generates serotype-specific IgG antibodies and memory B cells that target this specific polysaccharide structure. These antibodies facilitate the clearance of the bacteria through opsonophagocytic killing, thereby providing protection against invasive pneumococcal diseases such as bacteremia, meningitis, and pneumonia (StatPearls, 2023). The 33F serotype has gained clinical importance due to its prevalence in post-vaccination epidemiological shifts, making its inclusion in modern vaccines a priority for public health (PubMed, PMID: 34153254).

Other names

Pneumococcal polysaccharide serotype 33F33F CPSStreptococcus pneumoniae type 33F capsuleSpn33F polysaccharide

Induction of serotype-specific opsonophagocytic antibodies that facilitate bacterial clearance by the immune system (FDA, 2021; PubMed, PMID: 30201714).