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Title:   Author  item
                                            Hamir, Amiraliitem
                                            Kunkle, Robertitem
                                            Greenlee, Justinitem
                                            Richt, Juergen
  Submitted to: Journal of Veterinary Diagnostic Investigation
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 9/13/2008
                                    Publication  Date: 1/1/2009
                                    Citation: Hamir, A.N., Kunkle, R.A., Greenlee, J.J., Richt, J.A. 2009. Experimental Oral Transmission of United States Origin Scrapie to Neonatal Sheep. Journal of Veterinary Diagnostic Investigation. 21(1):64-68.Interpretive Summary: Scrapie, is a naturally occurring fatal disease of sheep and goats. This study documents experimental findings in tissues of susceptible and resistant new born lambs inoculated with a pool of U.S. sheep scrapie material. Nine Suffolk lambs were orally inoculated within 12 hours of birth with 1 ml of a 10 percent brain suspension consisting of a pool of scrapie-affected sheep brains. Inoculated animals were euthanized when advanced clinical signs of scrapie were observed. All susceptible sheep developed clinical signs of scrapie with a mean survival time of 24 months. None of the QR sheep succumbed to the disease. A previous study using a larger volume of the same inoculum in four-month-old Suffolk lambs documented longer survival periods (average 32 months) and only 5 of 9 inoculated sheep developed scrapie. This study demonstrates that neonatal QQ lambs have increased susceptibility to scrapie compared to older animals and that a smaller dose of inoculum (i.e. 1/30th the volume) induces a higher attack rate when compared to lambs inoculated at four months of age using the same inoculum.
                                Technical Abstract: Scrapie, a transmissible spongiform encephalopathy (TSE), is a naturally occurring fatal neurodegenerative disease of sheep and goats. This study documents incubation periods, pathological findings and distribution of abnormal prion proteins (PrP**Sc) by immunohistochemistry and Western blot in tissues of genetically susceptible and resistant neonatal lambs inoculated with a pool of U.S. sheep scrapie material. Nine Suffolk lambs with genotypes AA/RR/QQ (n = 5) and AA/RR/QR (n = 4) at codons 136, 154, and 171, respectively) were orally inoculated within 12 hours of birth with 1 ml of a 10% brain suspension consisting of a pool of scrapie-affected sheep brains. Inoculated animals were euthanized when advanced clinical signs of scrapie were observed. All AA/RR/QQ sheep developed clinical signs of scrapie with a mean survival time of 24 months. Spongiform lesions in the brains and PrP**Sc deposits in central nervous system (CNS) and lymphoid tissues were present in these sheep. None of the QR sheep succumbed to the disease. A previous study using a larger volume (30 ml of 10% brain suspension) of the same inoculum in four-month-old Suffolk lambs documented longer survival periods (average 32 months) and only 5 of 9 inoculated sheep developed scrapie. This study demonstrates that neonatal QQ lambs have increased susceptibility to scrapie compared to older animals and that a smaller dose of inoculum (i.e. 1/30th the volume) induces a higher attack rate when compared to lambs inoculated at four months of age using the same inoculum.


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