DEVELOPMENT OF A HIGHLY INFECTIVE BABESIA BIGEMINA VACCINE OF REDUCED VIRULENCE |
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| Authors: | R J Dalgliesh L L Callow L T Mellors W McGregor |
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| Institution: | Queensland Department of Primary Industries Animal Research Institute, Tick Fever Research Centre, Wacol, Queensland, 4076 |
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| 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 . |
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