Streptococcus agalactiae capsular polysaccharide (GBS CPS)

Streptococcus agalactiae capsular polysaccharide (GBS CPS) is the primary virulence factor of Group B Streptococcus, a leading cause of invasive disease in neonates and immunocompromised adults. The CPS forms a protective layer that masks underlying cell wall components and inhibits the deposition of complement factor C3b, thereby preventing opsonophagocytosis by host leukocytes (Source: PubMed, PMID: 30634447). There are ten known serotypes (Ia, Ib, II–IX), with serotypes Ia, Ib, II, III, and V accounting for the majority of global disease (Source: WHO, 2021). As a therapeutic target, GBS CPS is utilized in the development of conjugate vaccines where the polysaccharide is chemically linked to a carrier protein to enhance immunogenicity. These vaccines aim to induce high titers of maternal IgG, which are then transplacentally transferred to provide passive immunity to the newborn (Source: Pfizer, 2023). Clinical development focuses on multivalent formulations, such as hexavalent vaccines, to ensure broad protection against the most prevalent circulating serotypes (Source: ClinicalTrials.gov, NCT03765073).

Other names

Group B Streptococcus capsular polysaccharideGBS polysaccharideType-specific polysaccharideS. agalactiae CPS

Induction of serotype-specific opsonophagocytic antibodies that facilitate bacterial clearance by host immune cells.