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

The Group B Streptococcus (GBS) serotype Ia capsular polysaccharide is a complex carbohydrate structure located on the outermost layer of the bacterium Streptococcus agalactiae. It serves as a critical virulence factor by acting as a physical barrier that prevents C3 deposition and subsequent opsonophagocytosis by host immune cells. The biochemical structure of the serotype Ia polysaccharide is characterized by a repeating unit containing glucose, galactose, N-acetylglucosamine, and a terminal alpha-2,3-linked sialic acid residue, which mimics human cell surface glycans to evade immune detection. In clinical medicine, this polysaccharide is a primary target for prophylactic vaccines designed to prevent invasive GBS disease in neonates and pregnant women. Therapeutic strategies focus on conjugate vaccines where the polysaccharide is linked to a carrier protein, such as CRM197, to elicit a robust T-cell dependent immune response and long-lasting antibody production.

Other names

Streptococcus agalactiae serotype Ia capsular polysaccharideGBS Type Ia polysaccharideGroup B Streptococcal capsular polysaccharide IaType Ia CPS

Induction of serotype-specific opsonophagocytic antibodies (IgG) that promote bacterial killing by neutrophils and macrophages.