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Title: PRELIMINARY RESULTS OF ATTEMPTS TO TRANSMIT THE U.S. SCRAPIE AGENT TO CATTLE

Author
item Cutlip, Randall
item MILLER JANICE M - 3630-24-00
item RACE RICHARD E - NIH,NIAID,HAMILTON,MT.
item JENNY ALLEN L - USDA,APHIS,NVSL,AMES,IA
item Lehmkuhl, Howard
item ROBINSON MARK M - USDA,ARS,ADRU,PULLMAN,WA

Submitted to: International Workshop on Bovine Spongiform Encephalopathy
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Epidemiological evidence that bovine spongiform encephalopathy (BSE) in Great Britain was acquired through feeding rendered sheep by-products to cattle caused great concern in the livestock and related industries in the United States. Therefore, this project was undertaken to determine if the U.S. scrapie agent(s) would transmitted to cattle and cause a disease resembling BSE. For this purpose, groups of young male calves were intracerebrally or orally inoculated with a pooled suspension of raw brain from sheep with scrapie or fed rendered by-product prepared from sheep with scrapie in the flock. Progressive signs of neurologic disease were seen in all calves that were inoculated intracerebrally and held for more than one year after inoculation. Stiffness, lethargy, incoordination, and decreased appetite preceding recumbency were the common signs. There was no evidence of aggressiveness, hyperexcitability, hyperesthesia (tactile or auditory) or hypermetria of limbs as has been reported for BSE. Microscopic examination of sections of the brain from affected calves did not reveal the primary lesions reported for BSE. All calves that were inoculated intracerebrally with raw scrapie brain had PrP-res in the brain that was detectable either by immunohistochemistry or immunoblotting. PrP was not demonstrated in brains of calves that were exposed orally to either raw brain or rendered product. Two years after inoculation of mice, isolation of infectious agent has been successful only from the brain of one intracerebrally inoculated calf. Calves that were inoculated orally or fed rendered by-product remain normal 4 years after exposure, and lesions, PrP-res, or infectious agent have not been found in those examined one year after exposure.