Approaches to vaccines against bovine Theileriosis

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Morphological changes of sporozoites, schizonts and merozoites in the life cycle of T.sergenti were observed to use as the vaccine sources, we attempted to produce monoclonal antibodies against each stage of T.sergent.1. Merozoites. Thirteen monoclonal antibodies against merozoites of T.sergenti were prepared for analysis of their structural proteins. All monoclonal antibodies stained the piroplasm, but not aninfected erythrocytes by indirect fluorescent antibody test. Western blot analysis showed that 6 hybridomas tested recongnized palypeptides with molecular weights of 32,000 or 23,000. These antibodies reacted with cell membrane of merozoites by immuno electron microscopical observations, but did not react with veil and bar-structure of infected erythrocytes. The onset of intraerythrocytic multiplication was marked by the appearance of rhopties, microneme and inner membrane. It was suggested that four dividing forms in intraerythrocytic merozoites had common anatigens and infective ability, because this merozoite had the same instructural features as the sporozoites.2. Sporozoites. In the lumen of the gut of vector ticks, gametocytes appeared with in 48 hours after repletion. The sporozoites in the salivary glands of infected adult and nymph ticks maintained at 25゜C were induced by feeding ticks on rabbit after 30 days repletion. Infection level of sporozoites was high in nymph than adult ticks. A kinete penetrated to acini in the salivary glands formed syncytium and it produced over ten thousand sporozoites by budding. We tried to prepared monolonal antibody against the sporozoites.3. Schizonts, 15 cattle were inoculated sporozoites to detect schizonts in lymphocytes, schizont like protozoa were observed only in 5 cases. Althouht attenuated schizont vaccine for T.annulata were reported, shizonts of T.sergenti were not harvested sufficient volume to use for a immunoligical studies.