Nontypeable Haemophilus influenzae: challenges in developing a vaccine

Nontypeable Haemophilus influenzae (NTHi) is a gram-negative coccobacillus that is one of the bacteria that form the commensal flora of the upper resp iratory tract in humans. This bacterium is an important human pathogen caus ing a broad spectrum of disease in both adults and children, including inva sive and localised infections. The challenges in developing a bacterial pro tein antigen into an effective vaccine are, firstly, understanding what fac tors constitute an effective protective immune response for the host, and s econdly, to design an effective delivery system that can target and induce the required immune response in humans that will prevent the variety of inf ections caused by NTHi. (C) 1999 Elsevier Science B.V. All rights reserved.