title: Neospora caninum: oocyst challenge of pregnant cows.
abstract: Three pregnant cows were each orally challenged at 10 weeks of gestation with 600 sporulated oocysts of Neospora caninum. The number of oocysts was limited by those available. In concurrent bioassays, one oocyst per os infected each of two gerbils. Challenged cattle developed Neospora-specific antibody, cell proliferation and gamma-interferon responses. N. caninum specific PCR demonstrated persisting infection in the brains of cows 4 months after calving. Abortion was not induced and there was no evidence of transplacental infection in the healthy calves born at full-term. This experiment suggests that the dose threshold for induction of abortion exceeds 600 oocysts.
authors.affiliation: Veterinary Parasitology, Liverpool School of Tropical Medicine and Faculty of Veterinary Science, University of Liverpool, Pembroke Place, Liverpool L3 5QA, UK. trees@liverpool.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Trees
authors.forename: M M
authors.initials: MM
authors.lastname: McAllister
authors.forename: C S
authors.initials: CS
authors.lastname: Guy
authors.forename: J W
authors.initials: JW
authors.lastname: McGarry
authors.forename: R F
authors.initials: RF
authors.lastname: Smith
authors.forename: D J L
authors.initials: DJ
authors.lastname: Williams
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology / Q000302:isolation & purification; D001681:Biological Assay; D001921:Brain / Q000469:parasitology; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000469:parasitology* / Q000635:transmission; D003048:Coccidiosis / Q000276:immunology* / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D016054:DNA, Protozoan / Q000302:isolation & purification; D005260:Female; D005333:Fetus / Q000276:immunology; D005849:Gerbillinae / Q000469:parasitology; D018445:Infectious Disease Transmission, Vertical; D008431:Maternal-Fetal Exchange; D018688:Neospora / Q000276:immunology*; D033661:Oocysts / Q000166:cytology / Q000276:immunology*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000276:immunology* / Q000469:parasitology / Q000662:veterinary*
chemical_list: D000913:Antibodies, Protozoan; D016054:DNA, Protozoan