Group B Streptococcus capsular polysaccharide type IV (GBS CPS IV)

Group B Streptococcus (GBS) capsular polysaccharide type IV is a complex carbohydrate structure located on the outermost surface of Streptococcus agalactiae serotype IV. It serves as a critical virulence factor by providing a physical barrier that prevents opsonization and phagocytosis by host immune cells, largely through the presence of terminal sialic acid residues that mimic host cell surfaces and inhibit the alternative complement pathway [PMID: 24106299]. While historically less common than serotype III, serotype IV has shown a significant increase in prevalence among invasive GBS cases in neonates and non-pregnant adults over the last decade [PMID: 30137581]. This polysaccharide is a primary component in multi-valent glycoconjugate vaccines currently in clinical development, such as the hexavalent GBS6 vaccine. These vaccines aim to induce high-affinity, serotype-specific IgG antibodies that cross the placenta to provide passive immunity to newborns or provide active protection to vulnerable adults [PMID: 37467489].

Other names

Streptococcus agalactiae capsular polysaccharide type IVGBS type IV CPSSerotype IV capsular polysaccharideType IV GBS antigen

Induction of serotype-specific opsonophagocytic antibodies (IgG) that promote bacterial clearance by host immune cells.