Molecular vaccines against parasites.

Prophylactic vaccines can be expected to be one of the major practical outputs of parasitology research. Various groups within Australia have pursued the vaccine objective for several years, with particular emphasis on blood-stage falciparum malaria in man, intestinal helminths of sheep and cattle, cutaneous myiasis (blowfly strike) in sheep, cysticercosis in sheep and cattle, bovine babesiosis, and cattle ticks. Other vaccine programmes are concerned with giardiasis, filariasis, toxoplasmosis, fascioliasis, coccidiosis in poultry, cutaneous leishmaniasis and schistosomiasis japonica. For many years, the only available vaccine against a parasite in Australia has been the attenuated Babesia bovis vaccine produced by the Tick Fever Research Centre of the Queensland Department of Primary Industries. Strategies for achieving molecular vaccines are generally similar within the various research groups. They involve analysis of the immunology and immunochemistry of a model or in-vitro system; development of functional monoclonal antibodies; analysis of antibody specificities in clinically and/or functionally defined polyclonal sera; screening of cDNA or genomic expression libraries; peptide synthesis; identification of an appropriate vaccination schedule involving adjuvants or new recombinant DNA-based antigen delivery systems. Outlined below are five of the major vaccine programmes.