Haemophilus influenzae type b Capsular Polysaccharide Conjugate (None)

Haemophilus influenzae type b (Hib) capsular polysaccharide conjugate is the active component in Hib conjugate vaccines, which are designed to prevent infections caused by the bacterium *Haemophilus influenzae* type b. This bacterium can cause severe diseases such as meningitis, epiglottitis, pneumonia, septic arthritis, and pericarditis—especially in young children. The target molecule is the capsular polysaccharide of *H. influenzae* type b known as polyribosylribitol phosphate (PRP), a high-molecular-weight polymer. In the vaccine formulation, this PRP is covalently linked (conjugated) to a carrier protein to enhance immunogenicity. Common carrier proteins include: Tetanus toxoid (PRP-T), Diphtheria toxoid (PRP-D), Mutant diphtheria toxin CRM197 (HbOC), Neisseria meningitidis outer membrane protein (PRP-OMP). The conjugation process transforms the otherwise poorly immunogenic polysaccharide into an antigen that elicits a robust T-cell dependent immune response. The PRP-protein conjugate stimulates the immune system by: presenting both B-cell and T-cell epitopes, inducing germinal center formation with antibody class switching and memory B cell production and generating high-affinity antibodies against Hib's capsule for long-term protection. This mechanism overcomes limitations of plain polysaccharide vaccines that do not induce strong or lasting immunity in infants. Used primarily for active immunization against invasive Hib disease in children aged 2 months to 5 years; also used as booster doses. Available alone or combined with other vaccines such as diphtheria/tetanus/pertussis or hepatitis B/inactivated poliovirus vaccines.

Other names

Hib conjugatePRP-conjugatePolyribosylribitol phosphate conjugate

Induces robust antibody response via T-dependent pathway