IMMUNOLOGICAL RESPONSES OF THE MAMMALIAN HOST AGAINST TAPEWORM INFECTIONS. II. SPECIES SPECIFICITY OF HEXACANTH EMBRYOS IN PROTECTING RABBITS AGAINST TAENIA PISIFORMIS

Rabbits vaccinated by intramuscular injection with the viable eggs or the activated embryos of Taenia pisiformis, T. ovis or T. hydatigena, were subsequently challenged per os with eggs of T. pisiformis.

A single intramuscular injection of viable eggs or activated embryos of T. pisiformis induced a relatively solid immune response to the establishment and also to the long-term survival of the challenge infection of T. pisiformis.

A single intramuscular injection of the activated embryos of both T. ovis and T. hydatigena also induced some resistance to the establishment and long-term survival of a challenge infection with T. pisiformis but no significant immune response to a similar challenge infection was detected in those rabbits vaccinated with the viable eggs of these two sheep metacestodes.

IMMUNOLOGICAL RESPONSES OF THE MAMMALIAN HOST AGAINST TAPEWORM INFECTIONS. 3. SPECIES SPECIFICITY OF HEXACANTH EMBRYOS IN PROTECTING SHEEP AGAINST TAENIA OVIS

Sixty lambs were divided into three groups each comprising twenty animals. Half the lambs in each group were vaccinated with the viable eggs and half with the activated embryos of Taenia ovis, T. hydatigena or T. pisiformis. These lambs together with ten control animals were subsequently challenged with eggs of T. ovis.

Only one of the lambs in the group immunized with T. ovis completely resisted the challenge infection, but almost all of these lambs developed a solid resistance to the challenge infection, preventing it from reaching maturity at the site of election.

No lamb in the group vaccinated with T. hydatigena completely resisted the challenge infection of T. ovis, but some animals harboured significantly fewer cysticerci of T. ovis than control sheep or those vaccinated with T. pisiformis.

The injection of viable eggs or activated embryos of T. pisiformis induced no resistance to either the establishment or the subsequent survival of the challenge infection of T. ovis.