Preliminary investigations into the immunization of lambs against infection with Taenia multiceps metacestodes.

Two trials were carried out to investigate the protective value of various antigens in the immunization of lambs against Taenia multiceps metacestode infections. The first trial involved groups of 5 or 6 lambs immunized with activated T. multiceps oncospheres; activated T. hydatigena oncospheres; T. multiceps coenurus fluid antigens, and two untreated control groups. All except one of the control groups were challenged orally with T. multiceps oncospheres 5 weeks later. The results of the trial were equivocal with 1 to 3 lambs from each group showing post-mortem evidence of infection. There was evidence that some lambs from this trial had previously been exposed to Taenia oncospheres, thus nullifying possible effects of immunization. A second trial used two groups of 5 "cestode free" lambs. One group was immunized with T. multiceps oncosphere-derived antigens prior to challenge and showed significant protection when compared with the sham-vaccinated controls.