The objective of this proposal is to use genetic engineering methodologies for the development of safe and effective subunit vaccines for preventing infection by human malarial parasites. Plasmodium falciparum and P. vivax, the most common forms of human malaria, are highly prevalent worldwide and cause considerable morbidity and mortality. An increase in drug resistance by the Plasmodia has emphasized the need for an effective immunoprohylaxis against this organism. Currently however, no vaccine for malaria exists. We plan to investigate the immunological properties of various parasite surface antigens produced in genetically engineered yeast. Similar expression systems are currently being used for the production of other vaccines (Hepatitis B Virus surface antigens) and also for enzymes and hormones for therapeutic use in humans. Purified recombinant proteins will be used for immunogenicity studies in rodents and sub-human primates with a view to their eventual clinical trial in humans. In addition, the availability of these recombinant antigens will contribute to our understanding of basic aspects of pathogenesis and fundamental mechanisms of immunity.