Streptococcus pneumoniae capsular polysaccharide serotype 31 (Spn31 CPS)

Streptococcus pneumoniae capsular polysaccharide serotype 31 is a complex carbohydrate polymer that constitutes the outermost protective layer of the serotype 31 pneumococcus. It serves as a primary virulence factor by shielding the bacterium from the host's innate immune system, specifically by inhibiting opsonization and subsequent phagocytosis by neutrophils and macrophages. Serotype 31 has been identified as an emerging cause of invasive pneumococcal disease (IPD), including pneumonia, meningitis, and bacteremia, particularly in adults and immunocompromised individuals. Due to its high case fatality rate and its absence from earlier generations of pneumococcal vaccines like PCV13 and PCV20, it has become a key target for next-generation vaccines. Current therapeutic strategies involve the use of conjugate vaccines, such as the 21-valent (PCV21) and 24-valent (PCV24) formulations, which link the polysaccharide to a carrier protein to induce a T-cell-dependent immune response. Vaccination leads to the production of serotype-specific IgG antibodies that facilitate bacterial clearance through the opsonophagocytic pathway.

Other names

Pneumococcal polysaccharide serotype 31Spn31 capsular polysaccharideS-31-psStreptococcus pneumoniae type 31 capsular polysaccharide

Active immunization; induction of serotype-specific IgG antibodies that facilitate opsonization and phagocytic clearance of the bacteria.