New approaches to vaccine development: memorandum from a WHO meeting.

Recent advances in immunology and cell biology may make it possible to improve existing vaccines and even, in future, to obtain vaccines against complex organisms, such as parasites.With the use of modern techniques, such as monoclonal antibodies, it is now possible to identify protective epitopes (antigenic determinants that can elicit a protective immune response) and, using chemical or DNA recombinant techniques, obtain these epitopes in the laboratory. Most of these potential vaccines, however, may not be able to stimulate a sufficient immune response. To achieve this, it may be necessary to couple the vaccines to carrier molecules and to inject them together with suitable adjuvants. Better knowledge of how antigens are presented to immunocompetent cells would help in the choice of carrier molecules and adjuvants to be used with future vaccines.