Immunoparasitology: its contribution to development of new parasite vaccines.

Immunoparasitology--the study of the immunology of host-parasite relationships--can post some notable research successes over the past decade. Progress towards prophylactic molecularly-defined vaccines against human parasitic diseases such as falciparum malaria, schistosomiasis mansoni and cutaneous leishmaniasis, as well as economically-important veterinary parasites, has been good. However, new vaccines are not coming as easily as might be hoped mainly because of several deficiencies in knowledge on the immunology of host-parasite relationships and the unknown relevance of well-characterized model systems to real-life parasitic diseases. In some models, the immunology of resistance and the immunology of disease are understood in broad outline. The availability of isolated antigens and their epitopes has improved quantitation of host immune responses to various life cycle stages of parasites and enabled vaccination efficacy or diagnostic potential to be assessed. One of several major challenges facing the immunoparasitologist interested in vaccine development is overcoming genetically-based unresponsiveness to "oligoepitope", defined-antigen vaccines particularly at the level of helper TH and cytotoxic (Tc) T cells.