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United States Department of Agriculture

Agricultural Research Service

Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES Title: Serial passage of sheep scrapie inoculum in Suffolk sheep

Authors
item Hamir, Amirali
item Kunkle, Robert
item Richt, Juergen
item Greenlee, Justin
item Miller, Janice - ARS RETIRED

Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 17, 2008
Publication Date: January 1, 2009
Citation: Hamir, A.N., Kunkle, R.A., Richt, J.A., Greenlee, J.J., Miller, J.M. 2009. Serial Passage of Sheep Scrapie Inoculum in Suffolk Sheep. Veterinary Pathology. 46(1):39-44.

Interpretive Summary: Scrapie is a naturally occurring fatal disease of sheep and goats. Susceptibility to the disease is partly dependent upon the genetic makeup of the host. In a previous study, it was shown that sheep intracerebrally inoculated with a US scrapie agent (No. 13-7) developed scrapie and survived for an average of 19 months post-inoculation. In the present study, when this scrapie inoculum was further passaged for 3 successive generations, the survival time was reduced by approximately 8 months in scrapie susceptible Suffolk sheep. It is concluded that inoculum No. 13-7 appears to have been stabilized in susceptible Suffolks and may be considered a specific isolate of sheep scrapie agent in the United States and therefore it can be used to evaluate other isolates of sheep scrapie in this country.

Technical Abstract: Scrapie is a naturally occurring fatal neurodegenerative disease of sheep and goats. Susceptibility to the disease is partly dependent upon the genetic makeup of the host. In a recent study, it was shown that sheep intracerebrally inoculated with a US scrapie agent (No. 13-7) developed scrapie and survived for an average of 19 months post-inoculation (MPI). In the present study, when this scrapie inoculum was further passaged for 3 successive generations, the survival time was reduced by approximately 8 months in scrapie susceptible (QQ on prion protein gene [PRNP] at codon 171) Suffolk sheep. When the inoculum was further passaged in a Suffolk with susceptible genotype at PRNP codon 136 (AV) and 171 (QQ), it was not possible to further reduce the survival time. Therefore, it appears that in susceptible sheep (QQ at 171) PrP genetics at the 136 loci may not have significant influence in the survival time of sheep infected with this inoculum. It is concluded that inoculum No. 13-7 appears to have been stabilized in susceptible (171 QQ) Suffolks and may be considered a cloned isolate of sheep scrapie agent in the United States and therefore it can be used to evaluate other isolates of sheep scrapie in this country.

Last Modified: 8/29/2014
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