Group B Streptococcus serotype II capsular polysaccharide (GBS II CPS)

Group B Streptococcus (GBS) serotype II capsular polysaccharide is a major surface-exposed carbohydrate and a key virulence factor of Streptococcus agalactiae (Wessels et al., 1989, PubMed ID: 2451101). It functions primarily by preventing the deposition of complement C3b on the bacterial surface, thereby inhibiting opsonophagocytosis and allowing the pathogen to survive within the host bloodstream (Edwards et al., 1982, PubMed ID: 7042336). This polysaccharide is one of several distinct serotypes that account for the majority of invasive GBS disease globally, including neonatal sepsis, meningitis, and pneumonia (Bianchi-Jassir et al., 2020, PubMed ID: 32199451). Because it is highly immunogenic when conjugated to carrier proteins, it is a primary component in multi-valent glycoconjugate vaccines currently in clinical development, such as Pfizer's GBS6 (NCT03765073). These vaccines are designed to be administered to pregnant women to induce high levels of maternal IgG, which are then transferred across the placenta to protect the neonate during the first months of life (Absalon et al., 2021, PubMed ID: 34161447). Targeting this polysaccharide is essential for broad-spectrum protection against GBS, as serotype II is prevalent in many geographic regions. The structural uniqueness of the serotype II repeating unit necessitates its specific inclusion in polyvalent vaccine formulations to ensure comprehensive coverage against diverse GBS strains.

Other names

Streptococcus agalactiae serotype II capsular polysaccharideGBS type II polysaccharideType II GBS CPSGroup B Streptococcal type II polysaccharide

Induction of protective, serotype-specific opsonophagocytic antibodies through active immunization.