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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Publications at this Location » Publication #130604
Title: POLYMORPHIC DISTRIBUTION OF THE PRION PROTEIN (PRNP) GENE IN SCRAPIE-INFECTED SHEEP FLOCKS IN WHICH EMBRYO TRANSFER WAS USED TO CIRCUMVENT THE TRANSMISSIONS OF SCRAPIE

Author
item WANG, S - UTAH STATE UNIVERSITY
item COCKETT, N - UTAH STATE UNIVERSITY
item Miller, Janice
item SHAY, T - UTAH STATE UNIVERSITY
item MACIULIS, A - UTAH STATE UNIVERSITY
item SUTTON, D - USDA, APHIS, VS, NAHPS
item FOOTE, W - UTAH STATE UNIVERSITY
item HOLYOAK, G - OKLAHOMA STATE UNIVERSITY
item EVANS, R - UTAH STATE UNIVERSITY
item BUNCH, T - UTAH STATE UNIVERSITY

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2002
Publication Date: 4/1/2002
Citation: N/A

Interpretive Summary: The transmissible spongiform encephalopathies (TSEs) are a group of diseases that affect the brain and spinal cord of several mammalian species. The disease in sheep, known as scrapie, has been recognized for almost 300 years in some parts of Europe but was not seen in the United States until 1947. Several countries around the world, including the United dStates, have undertaken various kinds of control programs to eradicate scrapie, and most of them require the complete destruction of affected flocks. It is known that the genetic structure of a particular gene, called the prion gene, can influence susceptibility to scrapie. In the U.S. most scrapie infected sheep are of the Suffolk breed and the designated susceptibility gene for this breed is known as AA136, QQ171. In this study, the gene type was determined for Suffolks from a study in which embryos had been transferred from scrapie affected ewes to ewes in scrapie-free flocks. .Results showed that even when all of the donor ewes and more than half of their transferred embryos had the susceptible prion gene type, no transmissions of scrapie resulted. Sheep producers and animal health regulatory agencies will benefit from knowing that valuable bloodlines in scrapie infected flocks can be preserved, even from genetically susceptible ewes, by the transfer of embryos to ewes in scrapie-free flocks.

Technical Abstract: The genetic sequence of the ovine prion protein (PrP) gene between codons 102 and 175, with emphasis on ovine PrP gene codons 136 and 171, was determined in scrapie-exposed Suffolk embryo donors and in offspring from those donors that had been transferred to scrapie-free recipient ewes. The most common genotype was AA136,QQ171 (70% and 63% in the donor and offspring flocks, respectively), which is considered a high risk genotype in U.S. Suffolk sheep. Although embryos were collected from scrapie-positive donors and many embryos had the high risk genotype, no scrapie occurred in resulting offspring. Based upon the results of this study, we conclude that vertical transmission of scrapie can be circumvented using embryo transfer procedures even when offspring have the high risk genotype.