title: Development of a highly infective Babesia bigemina vaccine of reduced virulence.
abstract: The virulence of a strain of Babesia bigemina was reduced by syringe passaging at 3 to 16-week intervals in a series of 7 calves. The calves were splenectomised 1 to 14 weeks after inoculation to induce the relapse parasitaemias used for passaging. Parasites taken at relapse from the last 3 calves in the series were inoculated into splenectomised calves from which highly parasitised blood for vaccine was obtained. The vaccine produced mild infections in 32 recipient cattle. When challenged either 5 weeks or 7 months after vaccination, the cattle had substantial immunity to a heterologous strain of B. bigemina.
mesh_terms: D000818:Animals; D001403:Babesia / Q000276:immunology* / Q000472:pathogenicity; D001404:Babesiosis / Q000276:immunology / Q000517:prevention & control*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000517:prevention & control*; D014611:Vaccination / Q000379:methods / Q000662:veterinary*; D014612:Vaccines / Q000276:immunology
chemical_list: D014612:Vaccines