Deposition patterns of disease-associated prion protein in captive mule deer brains with chronic wasting disease

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) in captive and free-ranging cervids in the USA; its origin is obscure . Archival formalin-fixed and paraffin-embedded specimens of 16 captive mul e deer brains with CWD were analyzed using immunocytochemistry for the dise ase-associated prion protein (PrP). The most prominent pattern of PrP depos ition were plaque-like structures, a substantial proportion of which were f lorid plaques surrounded by a rim of spongiform vacuoles. The percentage of florid plaques was highly variable according to region, ranging from 0% to 52.7%. The highest percentage was observed in the medulla and basal gangli a, the lowest in the cerebral cortex. Only three brains contained no florid plaques. There were also punctate synaptic-type and perivascular deposits, particularly in areas of severe spongiform change, and subpial and subepen dymal plaque-like deposits, whereas cerebellar involvement was mild. Thus, CWD brain pathology prominently features florid PrP plaques, as does varian t Creutzfeldt-Jakob disease (vCJD), but differs in other characteristics fr om vCJD.