Prion biology relevant to bovine spongiform encephalopathy

• Published in: Journal of animal science Vol. 83; no. 6; pp. 1455 - 1476
• Main Authors: Novakofski, J, Brewer, M. S, Mateus-Pinilla, N, Killefer, J, McCusker, R. H
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01.06.2005; American Society of Animal Science
• Subjects: amino acid sequences; Animal productions; animal proteins; Animals; Animals, Domestic; Biological and medical sciences; bovine spongiform encephalopathy; Cattle; chronic wasting disease; Decontamination; Deer; disease surveillance; disease transmission; Encephalopathy, Bovine Spongiform - diagnosis; Encephalopathy, Bovine Spongiform - genetics; Encephalopathy, Bovine Spongiform - transmission; Environment; feeds; food security; Fundamental and applied biological sciences. Psychology; genetic variation; Glycosylation; Goats; Humans; ingestion; literature reviews; meat and bone meal; molecular sequence data; pathogenesis; Prion Diseases - prevention & control; Prion Diseases - transmission; Prion Diseases - veterinary; prions; Prions - blood; Prions - pathogenicity; Prions - physiology; Prions - urine; protein conformation; proteinases; PrPSc proteins; Ruminantia; Scrapie - transmission; Sheep; Terrestrial animal productions; Vertebrates; Wasting Disease, Chronic - physiopathology; Wasting Disease, Chronic - transmission; Infection; Chronic Wasting Disease; Prion disease; Vertebrata; Mammalia; Bovine; Disease; Prion; Artiodactyla; Spongiform encephalopathy; Bovine Spongiform Encephalopathy; Ungulata
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/2005.8361455x

Bovine spongiform encephalopathy (BSE) and chronic wasting disease (CWD) of deer and elk are a threat to agriculture and natural resources, as well as a human health concern. Both diseases are transmissible spongiform encephalopathies (TSE), or prion diseases, caused by autocatalytic conversion of endogenously encoded prion protein (PrP) to an abnormal, neurotoxic conformation designated PrP[superscript sc]. Most mammalian species are susceptible to TSE, which, despite a range of species-linked names, is caused by a single highly conserved protein, with no apparent normal function. In the simplest sense, TSE transmission can occur because PrP[superscript sc] is resistant to both endogenous and environmental proteinases, although many details remain unclear. Questions about the transmission of TSE are central to practical issues such as livestock testing, access to international livestock markets, and wildlife management strategies, as well as intangible issues such as consumer confidence in the safety of the meat supply. The majority of BSE cases seem to have been transmitted by feed containing meat and bone meal from infected animals. In the United Kingdom, there was a dramatic decrease in BSE cases after neural tissue and, later, all ruminant tissues were banned from ruminant feed. However, probably because of heightened awareness and widespread testing, there is growing evidence that new variants of BSE are arising "spontaneously," suggesting ongoing surveillance will continue to find infected animals. Interspecies transmission is inefficient and depends on exposure, sequence homology, TSE donor strain, genetic polymorphism of the host, and architecture of the visceral nerves if exposure is by an oral route. Considering the low probability of interspecies transmission, the low efficiency of oral transmission, and the low prion levels in nonnervous tissues, consumption of conventional animal products represents minimal risk. However, detection of rare events is challenging, and TSE literature is characterized by subsequently unsupported claims of species barriers or absolute tissue safety. This review presents an overview of TSE and summarizes recent research on pathogenesis and transmission.