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Title: Immunity to Toxoplasma gondii : studies with sheep and mice
Author: McColgan, Christina
ISNI:       0000 0001 3623 1810
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1987
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Toxoplasma is a major cause of ovine abortion in Great Britain and as yet there is no effective means of control. The work described in this thesis aimed to extend the knowledge of the ovine immune response to infection with Toxoplasma gondii. It was shown that 2000 Ml strain Toxoplasma oocysts administered orally before pregnancy induced total immunity against a subsequent challenge with 10,000 oocysts at mid gestation. Oocysts which had been treated with 5 or 10 krad of irradiation were also capable of inducing protective immunity although they were still pathogenic. Specific IgG antibody detected, by ELISA, as early as seven days after infection was found to be directed against certain Toxoplasma antigens by western blotting. It also had opsonising activity in vitro which enhanced phagocytosis of killed parasites by ovine mammary gland macrophages. In addition efferent lymph, collected following infection with Toxoplasma, contained a large number of blast cells, a considerable proportion of which were Ig negative and therefore presumed to be T cells. The results obtained in this study confirm that protective immunity to Toxoplasma can be induced in sheep. I propose that this immunity is dependent on the priming of T cells which stimulate B cells to secrete specific anti-toxoplasma antibody. Both this antibody and soluble factors released by the primed T cells activate the macrophage population thereby increasing their phagocytic and killing capacities.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Ovine abortion causes