Streptococcus pneumoniae serotype 4 capsular polysaccharide (Spn4 CP) (Spn4 CP)

The capsular polysaccharide of Streptococcus pneumoniae serotype 4 is a high-molecular-weight carbohydrate polymer that encapsulates the bacterial cell wall. It functions as a primary virulence factor by inhibiting opsonization and subsequent phagocytosis by host immune cells, thereby allowing the pathogen to survive and disseminate within the bloodstream and tissues (Source: PubMed, PMID: 11854167). Chemically, the serotype 4 polysaccharide is distinct, consisting of a repeating tetrasaccharide unit that includes an unusual 2,11-linked N-acetyl-D-fucosamine residue (Source: PubChem, CID: 139031040). This molecule is a key component in several multi-valent pneumococcal vaccines, where it is often conjugated to a carrier protein like CRM197 to enhance immunogenicity, particularly in infants (Source: FDA, Prevnar 13 Package Insert). By targeting this antigen, vaccines stimulate the production of serotype-specific antibodies that neutralize the bacteria's protective layer, facilitating its destruction by the immune system. Clinical monitoring of vaccine efficacy against this target typically involves measuring serum IgG levels and opsonophagocytic activity (Source: WHO Technical Report Series). Serotype 4 has historically been a major contributor to invasive pneumococcal disease, including meningitis and bacteremia, making its inclusion in vaccine formulations a public health priority (Source: CDC, Pneumococcal Disease).

Other names

Pneumococcal polysaccharide serotype 4S. pneumoniae type 4 capsular polysaccharidePn4 antigenCPS4

Active immunization inducing the production of serotype-specific opsonizing antibodies (IgG) that facilitate phagocytosis and clearance of the bacteria (Source: PubMed, PMID: 11854167).