Group B Streptococcus serotype III capsular polysaccharide-specific B cell receptor (GBS III CPS BCR)

The Group B Streptococcus serotype III capsular polysaccharide-specific B cell receptor is a membrane-bound immunoglobulin complex on the surface of B lymphocytes that specifically recognizes the type III capsular polysaccharide (CPS) of Streptococcus agalactiae. GBS serotype III is a major pathogen responsible for neonatal sepsis and meningitis, and its CPS is a critical virulence factor that helps the bacteria evade the host immune system by inhibiting opsonophagocytosis. The interaction between the BCR and the CPS (or a glycoconjugate vaccine) is the initial event in the induction of a protective humoral immune response. Binding of the antigen to the BCR triggers intracellular signaling cascades, including the activation of Syk and Lyn kinases, which lead to B cell activation, proliferation, and differentiation into antibody-secreting plasma cells. The resulting high-affinity IgG antibodies are opsonophagocytic, facilitating the clearance of the bacteria by host immune cells. This receptor is the primary target for maternal vaccines, such as the hexavalent GBS6, which aim to provide passive immunity to neonates through the transplacental transfer of maternal antibodies.

Other names

GBS type III CPS-specific BCRB-cell receptor for Streptococcus agalactiae type III capsular polysaccharideAnti-GBS III BCRGroup B Streptococcus type III capsular polysaccharide-specific B-cell receptor

Antigen binding to the B cell receptor triggers intracellular signaling, leading to B cell activation, clonal expansion, and the production of opsonophagocytic antibodies that facilitate bacterial clearance.