Haemophilus influenzae type b polyribosylribitol phosphate conjugated polysaccharide (PRP (for polyribosylribitol phosphate); “Hib” is used for the bacterium and vaccine but not specific to the conjugated polysaccharide[2])

Haemophilus influenzae type b polyribosylribitol phosphate conjugated polysaccharide is a chemically defined linear polymer consisting of repeated units of β-D-ribofuranose and D-ribitol linked via phosphate diester bridges. This polysaccharide forms the capsule of Hib, which enables the bacterium to evade host immune defenses. As a vaccine antigen, the PRP capsule is conjugated to carrier proteins, converting the poorly immunogenic T-cell independent polysaccharide into a highly effective T-cell dependent antigen, allowing even infants to mount protective antibody responses. These conjugate vaccines have dramatically reduced invasive Hib disease in countries where they are used[1][4][5][7].

Other names

Haemophilus influenzae type b capsular polysaccharide conjugateHib conjugate polysaccharidePRP-conjugate

PRP by itself induces a poor T-cell independent antibody response, especially in infants. Conjugation to carrier proteins elicits a T-cell dependent response, generating high-affinity anti-PRP antibodies and immunological memory[4][6].