Capsular polysaccharide of Streptococcus pneumoniae serotype 19A (19A-CPS)

The capsular polysaccharide of Streptococcus pneumoniae serotype 19A is a complex carbohydrate polymer that forms the outermost layer of the bacterium. It serves as a critical virulence factor by shielding the pathogen from host immune recognition and inhibiting opsonophagocytosis by neutrophils (Source: PubMed, PMID: 22412006). Serotype 19A became a major cause of invasive pneumococcal disease globally following the introduction of the initial 7-valent conjugate vaccine, which did not include this serotype, a phenomenon known as serotype replacement (Source: CDC, Pink Book). Structurally, the 19A polysaccharide consists of a repeat unit containing glucose, rhamnose, and N-acetylmannosamine linked by phosphodiester bonds (Source: PubChem). As a therapeutic target, it is purified and often conjugated to carrier proteins like CRM197 to enhance immunogenicity in pediatric and adult populations. Vaccines targeting this polysaccharide induce high-affinity IgG antibodies that provide protection against pneumonia, meningitis, and febrile bacteremia caused specifically by this serotype (Source: FDA, Prevnar 13 Label).

Other names

Pneumococcal polysaccharide serotype 19AStreptococcus pneumoniae serotype 19A capsular antigenSpn19A polysaccharideSerotype 19A capsular polysaccharide

Active immunization by inducing serotype-specific opsonophagocytic antibodies that facilitate bacterial clearance by the immune system.