A strategic approach to vaccine development: animal models, monitoring vaccine efficacy, formulation and delivery.

One of the most pressing issues in animal and human medicine currently is the need to develop new and more effective vaccines, against an ever increasing range of infectious diseases. Traditional vaccines have involved the use of killed microorganisms, live attenuated cultures or antigenic extracts. In spite of extensive research, there have been very few newly developed vaccines for humans or animals, over the past 20 years. Recent developments in our understanding of the pathways of immunity required to produce protection against different infections, allow immunological principles to be incorporated into the design new and better vaccines. This paper outlines the key variables that need to be taken into consideration when developing a new vaccine. Three critical areas will be considered in the review: (1) use of an appropriate experimental animal model of infection; (2) targeting appropriate immune markers for protection; (3) design of optimal vaccine formulation and delivery systems.