Prion agent diversity and species barrierVincent Béringue1, Jean-Luc Vilotte2 and Hubert Laude1
1 Institut National de la Recherche Agronomique (INRA), UR892, Virologie et Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
2 INRA, UR339, Génétique Biochimique et Cytogénétique, F-78350 Jouy-en-Josas, France
Received 25 March 2008; accepted 30 May 2008; published online 03 June 2008
Abstract - Mammalian prions are the infectious agents responsible for transmissible spongiform encephalopathies (TSE), a group of fatal, neurodegenerative diseases, affecting both domestic animals and humans. The most widely accepted view to date is that these agents lack a nucleic acid genome and consist primarily of PrP, a misfolded, aggregated form of the host-encoded cellular prion protein (PrP) that propagates by autocatalytic conversion and accumulates mainly in the brain. The BSE epizooty, allied with the emergence of its human counterpart, variant CJD, has focused much attention on two characteristics that prions share with conventional infectious agents. First, the existence of multiple prion strains that impose, after inoculation in the same host, specific and stable phenotypic traits such as incubation period, molecular pattern of PrP and neuropathology. Prion strains are thought to be enciphered within distinct PrP conformers. Second, a transmission barrier exists that restricts the propagation of prions between different species. Here we discuss the possible situations resulting from the confrontation between species barrier and prion strain diversity, the molecular mechanisms involved and the potential of interspecies transmission of animal prions, including recently discovered forms of TSE in ruminants.
Key words: prion / strain / misfolding / species barrier / PrP
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© INRA, EDP Sciences 2008