Preclinical immunogenicity studies of Haemophilus influenzae type a glycoconjugate vaccine.

Haemophilus influenzae type a (Hia) disease is associated with fatality and morbidity, predominantly in children from Northern indigenous communities in Canada and Alaska. Symptoms include but are not limited to meningitis, sepsis, pneumonia, otitis media and bacteremia. A key virulence factor associated with Hia pathogenesis is the bacterial capsular polysaccharides. Prophylactic vaccines targeting the capsular polysaccharide (CPS) antigens is considered a promising intervention strategy given the effectiveness of polysaccharide-protein conjugate vaccines against diverse bacterial pathogens. In the same vein, we in this study have presented the development of Hia conjugate vaccine involving hydrazide-polyethylene glycol-hydrazide linker with rCRM197 as a carrier protein. Preclinical immunogenicity data indicated induction of robust serum bactericidal antibody responses at a 10-μg CPS antigen dose in rabbits like the PedvaxHIB® comparator, leading to evaluation of the Hia vaccine candidate in Phase I clinical trials.