Disease-associated prion protein in the dental tissue of mice infected with scrapie.

Transmissible spongiform encephalopathies (TSEs) induce fatal neurodegenerative diseases in man and animals. The present study demonstrates immunohistochemically the presence of disease-associated prion protein (PrP(Sc)) in the epithelial cell rests of Malassez (ERM) of mice experimentally infected with ME7 scrapie by the intracerebral route. Mouse bioassay of scrapie-infected dental tissue revealed prolonged incubation periods, suggesting that there are relatively low amounts of infectious agent in dental tissue compared with the brain. These findings indicate that PrP(Sc) may spread from the brain to the ERM along the cranial nerves via the trigeminal ganglion that innervates the dental tissues. Dental tissue might therefore be a potential source of PrP(Sc) for horizontal transmission of TSEs.