Discovery of a recombinant Babesia canis supernatant antigen that protects dogs against virulent challenge infection.

Unlabelled: Soluble parasite antigens (SPA) in supernatants of in vitro cultures of Babesia canis can be used to vaccinate dogs against virulent B. canis infection. The moment that immunity becomes apparent coincides with the appearance of antibodies against SPA in the serum of the vaccinated animals.