Polyribosyl-ribitol-phosphate capsular polysaccharide (PRP)

Polyribosyl-ribitol-phosphate capsular polysaccharide (PRP) is a linear polymer composed of repeating units of β-D-ribofuranose and D-ribitol linked by phosphodiester bonds. It is the principal component of the polysaccharide capsule of Haemophilus influenzae type b (Hib), an encapsulated bacterium responsible for severe invasive diseases in children. The capsule enables Hib to evade innate immune responses, mainly by inhibiting phagocytosis and interfering with complement activation. PRP is poorly immunogenic by itself in infants, but when covalently conjugated to carrier proteins such as tetanus or diphtheria toxoid, it becomes a highly effective vaccine antigen, driving robust and protective antibody responses. Anti-PRP antibodies are essential for protection against Hib infection, and measurement of these antibodies is used as a correlate of vaccine-induced immunity. PRP is thus both a critical virulence determinant of Hib and the immunological target for all Hib conjugate vaccines in current use[2][3][4][5][6][7].

Other names

Polyribosyl ribitol phosphateHib capsular polysaccharideHaemophilus influenzae type b capsulePRP polysaccharide

Induction of anti-PRP antibody response via conjugation vaccines: the conjugated PRP stimulates T-cell dependent immune response, leading to protective antibody formation