title: Toxoplasmosis in sheep III. Further evaluation of the ability of a live Toxoplasma gondii vaccine to prevent lamb losses and reduce congenital infection following experimental oral challenge.
abstract: The aim of this study was to compare the ability of a live incomplete strain (Strain 48) and a live complete strain (Strain 89) of Toxoplasma gondii to protect against abortion and congenital infection following an oral challenge of T. gondii oocysts. Sixty-nine two-tooth ewes were immunised pre-tupping with live Strain 48 of T. gondii tachyzoites and seventy ewes were immunised with Strain 89. Eighty-two serologically negative ewes served as controls. At mid-pregnancy half of the ewes were challenged orally with T. gondii oocysts (2x10(5)/ewe). The ewes vaccinated with Strain 48 were significantly (p<0.05) protected against the effects of experimental challenge and the rate of congenital infection was also significantly (p<0.15) reduced. The ewes vaccinated with Strain 89 were also significantly (p<0.05) protected. The serological response to challenge as measured by both the Dye test and the Indirect Haemagglutination test varied considerably between the two vaccinated groups.
authors: Wallaceville Animal Research Centre, MAFTech, Ministry of Agriculture and Fisheries, Private Bag, Upper Hutt, New Zealand.
authors: M F
authors: MF
authors: Wilkins
authors: E
authors: E
authors: O'Connell
authors: W A
authors: WA
authors: Te Punga