Distribution of the prion protein in sheep terminally affected with BSE following experimental oral transmission

This study has examined the distribution of PrPSc in sheep by immunocytoche mistry of tissues recovered from terminally affected animals following thei r experimental infection by the oral route with BSE. Despite a wide range o f incubation period lengths, affected sheep showed a similar distribution o f high levels of PrPSc throughout the central nervous system. PrPSc was als o found in the lymphoid system, including parts of the digestive tract, and some components of the peripheral nervous system. These abundant PrPSc dep osits in sheep in regions outside the central nervous system are in direct contrast with cattle infected with BSE, which show barely detectable levels of PrPSc in peripheral tissues. A number of genetically susceptible, chall enged animals appear to have survived.