The overall objectives of this proposal are twofold: (l) to identify and characterize carbohydrate and protein antigens of Leishmania major involved in induction of host-protective immune responses or which are key molecules obligatory for initiating infection of the host macrophage; (2) to clone, characterize and express genes for the protein antigens in order to allow production of these molecules for vaccination studies in our mouse-L.major model system. Specifically, the glycolipid molecule on the surface of the amastigote which is the receptor for the host macrophage will be biochemically characterized in terms of its composition, synthesis, transport to the macrophage surface and association with host MHC molecules. The role of this glycolipid in determining tissue tropism and as a potential vaccine molecule will be studied. These studies will provide new information on a key parasite molecule which is critical for the host-parasite interaction and will assess this molecule as a vaccine. In addition, stage-specific and strain specific cDNA sequences will be isolated and characterized in terms of their transcription, gene structure and sequence. These sequences which represent good candidates to encode host protective antigens will be expressed to allow indentification of the encoded protein and vaccination studies in mice. Polymorphic gene sequences will be used as genomic markers for the genotypic taxonomy of Leishmania. The molecular karyotyping of Leishmanis using pulsed field gradient gel electrophoresis to separate chromosomes will permit the analysis of the genetic content of individual chromosomes. These molecular genetic studies will integrate with the immunochemical studies to provide fundamental new insights into antigens and genes of Leishmamis which are critically involved in determining the host parasite relationship. This proposal thus emphasizes the use of both glycolipid and protein molecules in the development of a defined Leishmania vaccine. This reflects the belief that for genetically diverse parasites and hosts a multivalent vaccine will be necessary to achieve protection.
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