Haemophilus influenzae type b capsular polysaccharide-specific B-cell receptor (Hib-BCR) (Hib-BCR)

The Haemophilus influenzae type b (Hib) capsular polysaccharide-specific B-cell receptor (BCR) is the primary immunological target for vaccines designed to prevent invasive Hib disease (StatPearls, 2023). The Hib capsule is composed of polyribosylribitol phosphate (PRP), a polymer that acts as a T-cell independent antigen, meaning it does not naturally elicit a strong memory response or work well in infants (CDC, 2022). By conjugating PRP to a carrier protein, the vaccine engages the Hib-specific BCR, which internalizes the conjugate and initiates T-cell-dependent immune pathways (WHO, 2013). This process involves the presentation of carrier-derived peptides via MHC class II molecules to T-helper cells, which then provide the necessary signals for B-cell maturation and memory cell formation (PubMed, PMID: 10417040). Targeting this receptor-pathway axis is the fundamental principle behind Hib conjugate vaccines, which have drastically reduced the incidence of Hib-mediated meningitis and pneumonia (CDC, 2022). The resulting high-affinity IgG antibodies provide systemic protection by promoting opsonophagocytosis of the encapsulated bacteria (StatPearls, 2023).

Other names

PRP-specific B-cell receptorPolyribosylribitol phosphate receptorHib capsular polysaccharide receptorHaemophilus influenzae type b capsular polysaccharide-specific B-cell receptors and T-cell–dependent immune pathways

The vaccine acts as an agonist for the Hib-specific B-cell receptor, leading to receptor-mediated endocytosis of the PRP-protein conjugate, followed by T-cell-dependent activation of B cells through MHC II presentation of carrier peptides to T-helper cells (PubMed, PMID: 10417040).