H. influenzae was first described by Pfeiffer in 1892, and it was not until 1918 that H. influenzae was distinguished from influenza virus. H. influenzae is a small, inactive, gram-negative bacillus that can be divided into encapsulated and non-encapsulated types. To date, six capsular polysaccharides of H. influenzae have been identified: types a, b, c, d, e, and f. They are present in the nasopharynx of approximately 75% of healthy children and adults and are considered normal flora.
Invasive disease caused by H. influenzae appears to occur only in humans. About 95% of these invasive diseases are caused by H. influenzae type b (Hib), and a small proportion of H. influenzae infections are caused by types a (Hia) and f. Age is a major risk factor for invasive Hib-related disease, with children younger than 2 years at greatest risk. Hib can cause respiratory diseases such as otitis media, sinusitis, and bronchitis.
Because H. influenzae invasive disease is almost entirely restricted to one serotype, this makes Hib a prime candidate for a vaccine antigen. Capsular polysaccharide covalently conjugated to carrier protein is an important component of various monovalent or multivalent childhood vaccines, which effectively prevents H. influenzae infection. Hib capsular polysaccharides, repeat polymers of phosphoribosyl ribitol (PRP), confer virulence by "shielding" deeper bacterial structures, such as lipopolysaccharide (LPS), from complement-lytic activities.
At CD BioGlyco, we have developed a One-stop Solution for Polysaccharide Conjugation, providing carrier protein design and polysaccharide antigen production services. We combine Hib capsular polysaccharide with a suitable Carrier Protein such as tetanus toxoid (TT) to stimulate a stronger and longer-lasting T cell immune response. Hib-PRP polysaccharides are activated with cyanogen bromide and ultrafiltered to remove by-products before conjugation. The addition of adipic acid dihydrazide (ADH) to activated PRP forms a covalent Hib-PRP-ADH product. The activated PRP-ADH is then conjugated to the carboxyl group of the TT protein by 1-ethyl-3-(3-dimethylaminopropyl)-carbodimide hydrochloride (EDC) and the Hib PRP-ADH is purified using a chromatographic column.
Fig.1 Flowchart of Hib antigen production. (CD BioGlyco)
CD BioGlyco is an expert in the field of Polysaccharide Vaccine Development and has been recognized by scientists in many countries. We provide clients with one-stop services from carrier protein design to polysaccharide conjugation and characterization. Please feel free to contact us for more information about our polysaccharide conjugation service.
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