Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2012
Publication Date: 12/1/2012
Citation: Franz, M., Eiden, M., Balkema-Buschmann, A., Greenlee, J., Schatzl, H., Fast, C., Richt, J., Hildebrandt, J.P., Groschup, M.H. 2012. Detection of PrP(Sc) in peripheral tissues of clinically affected cattle after oral challenge with bovine spongiform encephalopathy. Journal of General Virology. 93(Pt12):2740-2748. Interpretive Summary: Bovine spongiform encephalopathy (BSE), a fatal neurodegenerative disease that affects cattle, exotic ungulates, cats, and humans, is a transmissible spongiform encephalopathy (TSE). TSEs are caused by infectious proteins called prions that are resistant to various methods of decontamination and environmental degradation. BSE in cattle is a feedborne disease caused by ingesting feedstuffs contaminated with meat and bone meal containing tissue from infected cattle. Some countries have established feedbans to prevent mammal-derived proteins from entering the ruminant food chain. Furthermore, an effort has been made to identify the tissues that contain prions in cattle affected with BSE, called specified risk materials (SRMs) and eliminate them from the human food chain. In the past, SRM have been identified using techniques with limited sensitivity. In this manuscript, an ultra-sensitive technique was developed and applied to tissues from cattle with clinical signs of BSE. This technique, protein misfolding cyclic amplification (PMCA), amplifies miniscule amounts of material to detectable levels. PMCA was used to demonstrate abnormal prion in number of tissues that confirm previous results obtained through traditional techniques and validate the use of this PMCA protocol. In addition, positive results were obtained from a number of tissues in which abnormal prion had not previously been detected including esophagus, adrenal gland, rumen, and rectum. These tissues represent a previously unrecognized risk for BSE transmission. This new data demonstrates an expansion in the scientific knowledge that should be considered by regulatory officials when determining guidelines for ruminant feedbans and SRMs to protect animal and human health.
Technical Abstract: Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative prion disease that affects cattle and can be transmitted to human beings as new variant Creutzfeldt-Jakob disease (vCJD). A protease-resistant, disease-associated isoform of the prion protein (PrP**Sc) accumulates in the central nervous system and other tissues during the course of BSE. Many countries have defined bovine tissues that can accumulate PrP**Sc as specified risk materials (SRMs) that should not enter the human or animal food chains. Ultrasensitive techniques such as the protein-misfolding cyclic amplification (PMCA) have been developed to detect PrP**Sc when present in miniscule amounts not readily detected by other diagnostic methods such as immunohistochemistry or western blot. This study was done to determine when and where PrP**Sc can be found by PMCA in cattle orally challenged with BSE. A total of 48 different tissue samples from 15 infected cattle of the German pathogenesis study were examined by a standardized PMCA protocol. The protocol uses brain homogenate from bovine PrP transgenic mice (Tgbov XV) as substrate and three consecutive rounds of PMCA. PrP**Sc was demonstrated in brain, spinal cord, optic nerve, Peyer’s patches, nerve ganglia, and lymphoid tissue. Interestingly, positive results were also obtained for the first time from oesophagus, abomasum, adrenal gland, rumen, and rectum in cattle with clinical BSE. This new data demonstrates an expansion in the scientific knowledge that should be considered for determining SRM regulations, namely BSE prions were demonstrated for the first time in tissues that may represent a previously unrecognized risk in transmission of BSE.