Streptococcus pneumoniae capsular polysaccharide serotype 11A (Spn11A CPS)

Streptococcus pneumoniae capsular polysaccharide serotype 11A is a complex carbohydrate structure that encapsulates the S. pneumoniae bacterium, serving as its outermost defense layer. This polysaccharide functions as a primary virulence factor by shielding the pathogen from the host's immune system, specifically by inhibiting opsonization and subsequent phagocytosis by neutrophils [1]. In clinical medicine, serotype 11A has been identified as a significant cause of invasive pneumococcal disease (IPD), often increasing in prevalence as a "replacement" serotype after the implementation of lower-valent conjugate vaccines [2]. As a therapeutic target, the 11A polysaccharide is purified and conjugated to carrier proteins to form the basis of modern pneumococcal conjugate vaccines, which convert the carbohydrate into a T-cell-dependent antigen to ensure long-term immunological memory [3]. The primary pharmacological interventions targeting this molecule include the 20-valent pneumococcal conjugate vaccine (PCV20) and the 21-valent conjugate vaccine (Capvaxive), both of which are designed to elicit serotype-specific antibodies to prevent severe infections such as pneumonia, meningitis, and sepsis [4, 5].

Other names

Pneumococcal polysaccharide serotype 11ASerotype 11A capsular polysaccharidePn11A CPSStreptococcus pneumoniae serotype 11A antigenCPS11A

Stimulates the production of serotype-specific IgG antibodies that bind to the bacterial capsule, facilitating opsonization and subsequent phagocytosis and killing by host immune cells [3, 4].