This volume reviews current work on new vaccines and defines the key immunological principles that govern vaccine development. The opening section describes current vaccines and those in late-stage clinical trials, surveys national and international immunization programmes and highlights future needs and opportunities in vaccine development. A major portion of the text examines the innate and adaptive immune systems, the roles of different immune responses in combatting infection, the mechanisms by which infectious agents invade or subvert immune responses and the most effective ways of enhancing or selectively inducing different immune responses. The authors also discuss vaccine design, including peptide-based vaccines, rDNA technology, genetic (DNA) preparations and methods for producing vaccine perparations in plants. The final section explores the prospects of immunotherapy for tumours, autoimmune diseases and fertility control.