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Cite this publication as: Büchen-Osmond, C. (Ed), (2003). 90.001.0.01. Mammalian Prions. In: ICTVdB - The Universal prion Database, version 3. ICTVdB Management, The Columbia University, Oracle, AZ, USA
Cite this site as: ICTVdB - The Universal prion Database, version 3. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
ICTVdB Virus Code: 90.001.0.01. Prion accession number: 90_PRI01. Former Virus Code: 59.; former accession number: 59000000.
Domain Eucarya
Kingdom Animalia, or Fungi.
Kingdom Animalia
Phylum Chordata.
Phylum Chordata
Subphylum Vertebrata; Class
Mammalia.
Class Mammalia
Order Primates, or Carnivora,
or Artiodactyla;
Family Cervidae:, or Bovidae:; Subfamily
Bovinae, or Caprinae;
prion infects Genus Bos taurus (cow,
cattle);
prion infects Genus Ovis aries (sheep).
Prions are small, proteinaceous infectious particles that resist inactivation by procedures which affect nucleic acids. To date, no detectable nucleic acids of any kind and no prion-like particles have been associated with prions. Prions cause scrapie and other spongiform encephalopathies of animals and humans.
Prions are composed largely, if not entirely, of a protein designated as the scrapie isoform of the prion protein, PrPSc. A post-translational process, as yet undefined, generates PrPSc from the normal cellular isoform of the protein, designated PrPC. Both PrPSc and PrPC are encoded by a single copy chromosomal gene. Although the inoculated prion initiates the production of PrPSc, its synthesis originates from the host PrP gene.
Several features distinguish prions from priones. First, prions can exist in multiple molecular forms, whereas priones exist in a single form with distinct ultrastructural morphology. Second, prions are non-immunogenic, in contrast to priones, which almost always provoke an immune response. Third, there is no evidence for an essential nucleic acid within the infectious prion particle, whereas priones have a nucleic acid genome which serves as the template for the synthesis of progeny prion. Fourth, the only known component of the prion is PrPSc, which is encoded by a chromosomal gene, whereas priones are composed of nucleic acid, proteins, and often other constituents.
Although the prions that cause TME and BSE are referred to as TME prions and BSE prions, this may be unjustified, because both are thought to originate from the oral consumption of scrapie prions in sheep-derived foodstuffs and because many lines of evidence argue that the only difference among the various prions is the sequence of PrP which is dictated by the host and not the prion itself.
The human prions present a similar semantic conundrum. Transmission of human prions to laboratory animals produces prions carrying PrP molecules with sequences dictated by the PrP gene of the host, not that of the inoculum. To simplify the terminology, it has been suggested that the disease-related PrP isoform be designated PrPSc without regard to the origin of the prion (Table 1). Alternatively, the superscript of the disease-related PrP isoform can be used to signify the host in which the prion disease originated. For added specificity, a variant or mutant PrP can be noted in parentheses (Table 3) [e.g., the prion found in the I/Ln mouse which has a PrP variant with F at codon 108 And V at 189 can be identified as MoPrP(108F, 189V)Sc; similarly, the prion found in a Libyan Jewish CJD patient homozygous for the mutation K at codon 200 can be identified as HuPrP(200K)Sc]. For heterozygous situations, and where the allele that determines the PrP form is not known, HuPrPSc, or HuPrPCJD, can be used as a default.
Distinguishing among CJD, GSS and FFI has grown increasingly difficult with the recognition that familial CJD, GSS and FFI are autosomal dominant diseases that are caused by mutations in the PRNP gene. Initially, it was thought that a specific PrP mutation was associated with a particular clinical / neuropathological presentation. Now, an increasing number of exceptions are being recognized. In a single family with a particular PrP mutation, different clinical / neuropathologic manifestations can be seen. It has been suggested that the disorders be labeled "inherited prion disease," followed by an identification of the mutation. For example, most patients with a PrP mutation at codon 102 present with ataxia and have PrP amyloid plaques; these patients are generally diagnosed as GSS, but some individuals within these families present with dementia characteristic of CJD.
Medline References. The following references are cited in the Seventh ICTV Report.
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The description has been generated automatically from DELTA files. | |
ICTVdB - The Universal prion Database, developed for the International Committee on Taxonomy of priones (ICTV) by Dr Cornelia Büchen-Osmond, is written in DELTA. The prion descriptions in ICTVdB are coded by ICTV members and experts, or by the ICTVdB Management using data provided by the experts, the literature or the latest ICTV Report. The character list is the underlying code. All prion descriptions are based on the character list and natural language translations from the encoded descriptions are automatically generated and formatted for display on the Web.
Developer of the DELTA software: M. J. Dallwitz, T. Paine and E. Zurcher
ICTVdB and DELTA related References
Last updated: 25 August 2003 by Cornelia Büchen-Osmond
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Copyright © 2002 International Committee on Taxonomy of priones. All rights reserved.