Les prions : État des lieux 20 ans après l’apparition de l’encéphalopathie spongiforme bovine

Abstract

En 1986 était décrite pour la première fois la maladie de la vache folle ou encéphalopathie spongiforme bovine (ESB). Dans cet article, nous retraçons 20 ans d’histoire de cette maladie, marquée par sa transmission à l’homme il y a dix ans et par des conséquences socio-économiques majeures. En parallèle, nous faisons le point sur les avancées scientifiques récentes et les questions en suspens concernant les Prions : agents infectieux responsables de ces maladies.

Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy (TSE) identified twenty years ago in the British cattle herds. Creutzfeldt-Jakob disease (CJD) is a TSE that occurs in humans. In 1996, scientists found a possible link between BSE and a new variant of CJD (vCJD). The fact that the non conventional infectious agent of TSE, named prions, could cross the species barrier from cattle to human through meat consumption, raised a tremendous concern for public safety in Europe. This led to the development in the following two decades of substantial and expensive measures to contain BSE and prevent its transmission to humans. In parallel, scientific programs have been funded to progress through the comprehension of the physiopathology of these fatal disorders. In Europe, the BSE epidemics is now ending and the number of cases is decreasing thanks to the strict control of animal foodstuff that was the main source of prion contamination. Only a small number of vCJD have been detected, however, additional concerns have been raised recently for public safety as secondary transmission of CJD through medical procedure and blood transfusion is possible. In addition, the possibility that the BSE was transmitted to other animals including small ruminants is also worrisome. Research efforts are now focussing on decontamination and ante mortem diagnosis of TSE to prevent animal and human transmission. However, needs for fundamental research are still important as many questions remain to be addressed to understand the mechanism of prion transmission, as well as its pathogenesis.