Prevention of scrapie transmission in sheep, using embryo transfer

TitlePrevention of scrapie transmission in sheep, using embryo transfer
Publication TypeJournal Article
Year of Publication1993
AuthorsFoote WC, Clark W, Maciulis A, Call JW, Hourrigan J, Evans RC, Marshall MR, de Camp M
JournalAm J Vet Res
Pagination1863 - 8
Date PublishedNov
ISSN0002-9645 (Print) 0002-9645 (Linking)
Accession Number8291764
KeywordsAnimals, Embryo Transfer, Embryo, Mammalian / microbiology, Female, Maternal-Fetal Exchange, Pregnancy, Prions / isolation & purification, Scrapie / microbiology / *prevention & control / *transmission, Sheep, Time Factors, Uterus / microbiology

Reciprocal embryo transfers were made between scrapie-inoculated and scrapie-free sheep (Cheviot and Suffolk breeds) to measure scrapie transmission via the embryo (using offspring from embryos of scrapie-inoculated donors and scrapie-free recipients) and via the uterus (using offspring from embryos of scrapie-free donors and scrapie-inoculated recipients taken by cesarean section). Two control groups of offspring, 1 from scrapie-free parents (negative) and 1 from scrapie-inoculated parents (positive), also were included. All sheep were observed for clinical signs of scrapie until death or for a minimum of 60 months. Final diagnosis was made on the basis of histopathologic findings or results of mouse inoculation and/or proteinase-K-resistant protein analysis. Thirty to 61% of the scrapie-inoculated donor/recipient sheep within groups developed scrapie within 8 to 44 months after inoculation. None of the scrapie-free donor/recipients, including those gestating embryos from scrapie-inoculated donors, developed scrapie. Also, none of the offspring observed to > or = 24 months of age from reciprocal cross, via embryo (0/67), or via the uterus (0/25), or from the negative-control group (0/33) developed scrapie. Fifty-six of the offspring via embryo, 19 of these via the uterus, and 31 negative controls survived to > or = 60 months of age. Of the 21 sheep in the positive-control group, 2 (9.5%) developed scrapie, 1 at 31 months of age and 1 at 42 months of age. In the Cheviot offspring, the percentage of sheep carrying the short incubation allele ranged from 24 to 44% and the percentage in the Suffolk offspring ranged from 61 to 83%.(ABSTRACT TRUNCATED AT 250 WORDS)

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