Vaccination of sheep against Taenia ovis. The response to various dose rates of antigens obtained by incubation of oncospheres in vitro.

Activated oncospheres of Taenia ovis were incubated in vitro for 14 days and the antigens produced were collected and concentrated. Tenfold serial dilutions of the antigens were emulsified with Freund's incomplete adjuvant and injected intramuscularly into sheep. When subsequently challenged with T ovis eggs, these sheep displayed a level of immunity that was related to the amount of antigen injected. The calculated dose-response curve indicated that for the vaccine to be 90 per cent effective, the secretion from approximately 4600 T ovis oncospheres need to be injected into each sheep.