On safari with PrP: prion diseases of animals.

Prions are infectious pathogens that cause fatal neurodegeneration in humans and animals and are composed largely, or entirely, of an aberrant isoform of the host-encoded prion protein (PrP). A post-translational process involving a conformational change in PrP is a significant feature of their replication. Differences in PrP sequences modify the incubation times, neuropathology and properties of prion 'strains'.