Babesia bovis: vaccination trial with a dominant immunodiffusion antigen in splenectomised calves.

The dominant immunodiffusion antigen of Babesia bovis was prepared from the lysate of infected erythrocytes by cation exchange chromatography, gel filtration and preparative native acrylamide electrophoresis. It was seemingly free of other babesial antigens and tested as a vaccine. In vaccinated calves, compared to controls, there was a delay in parasitaemia and at times a statistically significant difference in parasite numbers. However, the vaccinates showed little difference in pathophysiological parameters or survival rates from the controls. It was concluded that serodominance cannot necessarily be correlated with protection.