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Dernière mise à jour : Mai 2018

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Conservation of the prion proteins in Vertebrates

INRA Prod. Anim., 14(2), 91-96.


INRA Laboratoire de Génétique des Poissons, 78352 Jouy-en-Josas Cedex

Adresse actuelle :
Jeune Equipe INRA Morphogenèse du système nerveux des Chordés, CNRS, UPR 2197 DEPSN, Institut Fessard, Avenue de la Terrasse, 91198 Gif-sur-Yvette


The word prion (which stands for proteinaceousinfectious agent) has originally been coined in 1982 toname the presumed, and unconventional, etiologicalagent of the transmissible spongiform encephalopathies,a group of neurodegenerative diseases whichaffect the central nervous system of humans and othermammals. Since that time, this word’s meaning haswidened enormously, so that it is now used to designatea vast group of divergent proteins, sometimes even inunicellular organisms like the baker’s yeast. This paperis aimed at reviewing the problem of the existence of“prions”, or PrP genes in non-mammalian vertebrates.At present, definite PrP genes have been found in severalbird species, and in one turtle. However, the proteinsencoded by these genes are divergent from themammalian ones. In fishes, there is presently no evidencefor a PrP. Our group has looked for PrP gene(s)in trout and medaka, by various means (screen of atrout expression library with an anti-PrP antibody, of acDNA medaka brain library with mouse and sheep DNAprobes, and by PCR) and never got a positive result.Searches in fish -especially zebrafish- databases wereunable to detect a sequence with similarities to knownprions. It can be concluded from these negative resultsthat an eventual fish PrP gene is probably very divergentfrom those characterised in mammals; and that itwould be extremely unlikely to share the pathologicalproperties of these latter molecules. In a more generalperspective, it appears that the problem of the nomenclatureof the so-called “prion” proteins needs an updateand a clarification.

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