Culture-derived parasites in vaccination of cattle against tick-borne diseases.
The major economically important tick-borne diseases of cattle are theileriosis, babesiosis, anaplasmosis, and cowdriosis. Culture-derived attenuated schizonts of Theileria annulata have proved to be safe for all types of cattle and they protect against tick-borne theileriosis. T. parva was also successfully grown in vitro; however, inoculation of cattle with allogeneic schizont-infected cells resulted in rejection and destruction of the parasites together with the host cells. The number of schizont-infected cells needed for immunization is greater than for T. annulata theileriosis. Culture-propagated Babesia bovis and B. bigemina were used for large scale vaccination in the field. An avirulent population of Babesia spp. was obtained by in vitro cloning; inoculation of cattle did not induce clinical babesiosis, but produced specific antibodies. Culture-derived exoantigens of Babesia spp. proved to be completely safe for cattle, however, they conferred less protection than live parasites. Cell-cultured Cowdria ruminantium was highly infective for susceptible animals but, attenuated in vitro, could offer a potential source for vaccination. Anaplasma marginale, successfully grown in tick cell culture, may be developed for vaccines. Factors that should be considered in the developing of vaccines against tick-borne diseases include: the protective immune response to the pathogenic parasite developmental stages, virulence, immunological strain differences, and antigenic variations in cattle and in culture.
Shkap
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V
Kimron Veterinary Institute, P.O. Box 12, Bet Dagan, 50250, Israel. shkap@agri.huji.ac.il
Pipano
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E
D000712:Anaplasmosis / Q000276:immunology / Q000517:prevention & control; D000818:Animals; D016793:Babesia bovis; D001404:Babesiosis / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary; D001428:Bacterial Vaccines; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000517:prevention & control; D016995:Ehrlichia ruminantium; D006357:Heartwater Disease / Q000276:immunology / Q000517:prevention & control; D016052:Protozoan Vaccines; D016796:Theileria annulata; D013801:Theileriasis / Q000276:immunology / Q000517:prevention & control; D017282:Tick-Borne Diseases / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*
D001428:Bacterial Vaccines; D016052:Protozoan Vaccines