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United States Department of Agriculture

Agricultural Research Service


item Johnson, W Carl - Carl
item Perryman, L
item Goff, Willard

Submitted to: Parasite Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Babesiosis is a tick-borne disease caused by a protozoa that reside in red blood cells of mammalian hosts; in this particular study, Babesia bovis in cattle. The parasites have been grown in culture for many years, which has facilitated the identification of parasite components that elicit an immune response from exposed cattle. Among the various preparations used as experimental vaccines, have included the use of culture fluid containing products from the parasite. While these preparations have induced partial protection, the fluid has not been well characterized. In this study, we determined the number of parasite proteins that accumulate in the fluid during culture, and identified several proteins previously found to be associated with the surface of the parasite. These proteins and others from the culture fluid can now be evaluated in terms of those eliciting the best immune response as potential improved vaccine components.

Technical Abstract: Babesia bovis merozoite proteins present as exoantigens in in vitro culture supernatants have been characterized. Bovine antisera to B. bovis exoantigens were used to immunoprecipitate {35S}-methionine metabolically labeled or lactoperoxidase-catalyzed radioiodinated B. bovis merozoite proteins. Twenty-four metabolically labeled proteins ranging in molecular weight from 24,000 to 225,000 daltons and nine radioiodinated proteins with molecular weights between 24,000 and 225,000 daltons were identified by SDS-PAGE electrophoresis. Monoclonal antibodies to B. bovis merozoite surface and internal proteins were also used to immunoprecipitate metabolically labeled exoantigens directly from in vitro culture supernatants. These results demonstrate epitopes from at least nine merozoite surface proteins present in the exoantigen fraction, among which include the recently characterized major surface antigen-1 and 2, rhoptry associated protein-1, and spherical body protein-2.

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