title: Atypical/Nor98 scrapie infectivity in sheep peripheral tissues.
abstract: Atypical/Nor98 scrapie was first identified in 1998 in Norway. It is now considered as a worldwide disease of small ruminants and currently represents a significant part of the detected transmissible spongiform encephalopathies (TSE) cases in Europe. Atypical/Nor98 scrapie cases were reported in ARR/ARR sheep, which are highly resistant to BSE and other small ruminants TSE agents. The biology and pathogenesis of the Atypical/Nor98 scrapie agent in its natural host is still poorly understood. However, based on the absence of detectable abnormal PrP in peripheral tissues of affected individuals, human and animal exposure risk to this specific TSE agent has been considered low. In this study we demonstrate that infectivity can accumulate, even if no abnormal PrP is detectable, in lymphoid tissues, nerves, and muscles from natural and/or experimental Atypical/Nor98 scrapie cases. Evidence is provided that, in comparison to other TSE agents, samples containing Atypical/Nor98 scrapie infectivity could remain PrP(Sc) negative. This feature will impact detection of Atypical/Nor98 scrapie cases in the field, and highlights the need to review current evaluations of the disease prevalence and potential transmissibility. Finally, an estimate is made of the infectivity loads accumulating in peripheral tissues in both Atypical/Nor98 and classical scrapie cases that currently enter the food chain. The results obtained indicate that dietary exposure risk to small ruminants TSE agents may be higher than commonly believed.
authors.affiliation: UMR INRA ENVT 1225, Interactions Hôtes Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, Toulouse, France. o.andreoletti@envt.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Andréoletti
authors.forename: Leonor
authors.initials: L
authors.lastname: Orge
authors.forename: Sylvie L
authors.initials: SL
authors.lastname: Benestad
authors.forename: Vincent
authors.initials: V
authors.lastname: Beringue
authors.forename: Claire
authors.initials: C
authors.lastname: Litaise
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Simon
authors.forename: Annick
authors.initials: A
authors.lastname: Le Dur
authors.forename: Hubert
authors.initials: H
authors.lastname: Laude
authors.forename: Hugh
authors.initials: H
authors.lastname: Simmons
authors.forename: Séverine
authors.initials: S
authors.lastname: Lugan
authors.forename: Fabien
authors.initials: F
authors.lastname: Corbière
authors.forename: Pierrette
authors.initials: P
authors.lastname: Costes
authors.forename: Nathalie
authors.initials: N
authors.lastname: Morel
authors.forename: François
authors.initials: F
authors.lastname: Schelcher
authors.forename: Caroline
authors.initials: C
authors.lastname: Lacroux
mesh_terms: D000483:Alleles; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D005838:Genotype; D051379:Mice; D018620:PrPSc Proteins / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D012608:Scrapie / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics / Q000473:pathology*; D014018:Tissue Distribution
chemical_list: D018620:PrPSc Proteins