Polyribosylribitol phosphate capsular polysaccharide antigen (PRP)

The polyribosylribitol phosphate (PRP) capsular polysaccharide antigen is a highly immunogenic, linear bacterial polysaccharide composed of repeating ribose and ribitol phosphate units. It forms the capsule of *Haemophilus influenzae* type b, conferring resistance to phagocytosis and serving as a major virulence determinant in invasive Hib disease. PRP is the principal target of Hib conjugate vaccines, which stimulate a T-cell dependent, long-lasting, and protective antibody response, crucial for effective prevention of Hib-related meningitis, pneumonia, and sepsis in children. The antigen itself is not a protein or receptor but is essential for immune recognition and vaccine design Key points: - PRP is not a receptor, enzyme, or protein, but a carbohydrate antigenic determinant. - It is functionally essential and a validated target for disease prevention, especially through its use in conjugate vaccines.

Other names

Hib capsular polysaccharideHib PRPHaemophilus influenzae type b capsular antigenpolyribosylribitol phosphate

Induction of anti-PRP antibody response (IgG and IgA), leading to opsonization and complement-mediated killing of Hib Generation of immune memory against Hib infection