Haemophilus influenzae type b capsular polysaccharide (Hib PRP) (Hib PRP)

The Haemophilus influenzae type b (Hib) capsular polysaccharide, chemically identified as polyribosylribitol phosphate (PRP), is the primary virulence factor of the Hib bacterium (Source: StatPearls). It functions by shielding the bacterium from the host's innate immune system, specifically preventing C3b deposition and subsequent phagocytosis (Source: PubMed, PMID: 12654441). As a therapeutic target, PRP serves as the essential antigen in Hib vaccines designed to prevent invasive diseases such as meningitis, pneumonia, and epiglottitis (Source: WHO). Because pure PRP is a T-cell independent antigen and is poorly immunogenic in infants, it is typically conjugated to a carrier protein to elicit a T-cell dependent immune response (Source: CDC). This conjugation facilitates the production of high-titer anti-PRP IgG antibodies and the development of immunological memory, providing long-term protection against Hib infection (Source: NIH). The widespread implementation of these conjugate vaccines has resulted in a significant reduction in the global incidence of invasive Hib disease (Source: Lancet, PMID: 21181218).

Other names

Polyribosylribitol phosphatePRPHib capsular antigenHaemophilus influenzae type b polysaccharideHib antigen

Induces active immunity by stimulating the production of specific antibodies against the polyribosylribitol phosphate (PRP) capsule of Haemophilus influenzae type b. Conjugation to a protein carrier (e.g., tetanus toxoid) converts the polysaccharide into a T-cell dependent antigen, facilitating B-cell isotype switching and memory cell formation (Source: CDC, StatPearls).