Evaluation of Conjugation of Haemophilus Influenzae Type b Capsular Polysaccharide with Neisseria Meningitides Serogroup B Outer Membrane Vesicle

The Haemophilus influenzae type b (Hib) infection is a leading cause of meningitis in infants and children in the developing countries, estimated that at least three million serious cases of disease worldwide are caused by Hib each year. The capsular of Hib, is the most important cause of its virulence. The capsular polysaccharide conjugated to a carrier protein is effective in the prevention of such infections. The routine vaccination against Hib has not been defined in the national immunization program of Iran. The aim of this study was to achieve an efficient method for producing vaccines against meningitis caused by haemophilus influenzae.
In this study, a derivative of Hib Polysaccharide (PRP) was conjugated to outer membrane vesicle (OMV) of Niesseria meningitides group B by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). Two methods, involving adipic acid dihydrazide (ADH) as a linker, were used. The polysaccharide activated with cyanogen bromide (CNBr) and EDAC separately. The first, ADH was bounded to PRP activated with CNBr to form PRPCNBr AH, second ADH was bounded to PRP activated with EDAC to form PRPEDAC AH. These derivatives were bound to OMV by EDAC to form PRPCNBr AH-OMV and PRPEDAC AH-OMV.
On the basis of the bounded protein to polysaccharide, the yield of conjugated PRPCNBr AH-OMV and PRPEDAC AH-OMV were calculated 63.3% and 47%, respectively.
The results indicated that average yield of conjugation with CNBr activator was higher than other activators, however more study required to other methods and comparing them together to achieve an effective conjugated vaccine.