From the Capsular Polysaccharide to a Conjugate Vaccine Containing Haemophilus influenzae Type b Synthetic Oligosaccharide

Abstract

Haemophilus influenzae type b was a leading cause of bacterial meningitis, pneumonia and other infections in children under five years of age. Such an important world health problem prompted the discovery and introduction almost 25 years ago of a new vaccine, the so-called glycoconjugate vaccine. The bacterial capsular polysaccharide, chemically modified by a covalent linkage to a bacterial protein, became the ideal pharmaceutical preparation for the induction of a suitable immune response in infants, which then protects them against the deadly disease. Almost 10 years ago, a successful attempt to produce a vaccine with a synthetic oligosaccharide became the first vaccine based on a fully synthetic carbohydrate molecule. This vaccine, under the name Quimi-Hib, was first licensed in Cuba for use in infants. Since then, more than 34 million doses have been produced and used in several countries, proving that the synthetic approach is feasible. The present chapter reviews the most salient features of this development.