Therapeutic window for treatment of prion disease defined by timed depletion of Prion protein

There is no effective treatment preventing the progression of neurodegenerative diseases such as prion and Alzheimer’s diseases. These fatal diseases of the central nervous system, involve progressive accumulation of a misfolded protein long before overt clinical signs of disease. Removal of prion protein early in the pathological process appears to halt the progression however, it is not known whether intervention at later disease stages could be effective. We investigated the potential for intervention throughout the course of prion disease, by developing a mouse model in which Prnp expression can be manipulated in a tissue specific and time dependent manner. Depleting Prnp from neuronal populations in CNS throughout the preclinical phase substantially prolonged incubation. The pathology was dramatically altered to a pattern of astrocytic associated prion deposition. However once overt clinical symptoms of disease were apparent Prnp depletion did not alter disease progression. This study establishes a wide window for intervention, and suggests timely treatment could delay the onset of clinical disease potentially well beyond the lifetime of an individual.