DIAGNOSIS OF TOXOPLASMA ABORTION IN EWES BY POLYMERASE-CHAIN-REACTION

Eighteen oestrus-synchronised ewes were infected experimentally with 1 500 sporulated oocysts of Toxoplasma gondii between 80 and 90 days of gestation. The infection induced pyrexia and specific antibody in all the ewes, One ewe resorbed its fetus, five ewes aborted and 12 deliver ed live, congenitally-infected lambs whose pre-colostral serum was ant ibody-positive. Tissues from the aborted fetuses and placentae from th e live lambs were examined for toxoplasma infection by polymerase chai n reaction (PCR) amplification of the B1 gene and by mouse inoculation . Using a simple protocol of tissue preparation without DNA extraction and a nested format, PCR was as sensitive as mouse inoculation, Place ntal cotyledon gave a higher sensitivity of detection than brain, lung or liver, and 16 of 19 placentae were positive by PCR Compared with 1 3 of 18 by mouse inoculation. In mock-infected tissues, as few as 10 t achyzoites could he detected. The PCR could be applied to tissues unfi t for mouse inoculation.