Depleting Neuronal PrP in Prion Infection Prevents Disease and Reverses Spongiosis

Abstract

The mechanisms involved in prion neurotoxicity are unclear, and therapies preventing accumulation of PrP Sc , the disease-associated form of prion protein (PrP), do not significantly prolong survival in mice with central nervous system prion infection. We found that depleting endogenous neuronal PrP c in mice with established neuroinvasive prion infection reversed early spongiform change and prevented neuronal loss and progression to clinical disease. This occurred despite the accumulation of extraneuronal PrP Sc to levels seen in terminally ill wild-type animals. Thus, the propagation of nonneuronal PrP Sc is not pathogenic, but arresting the continued conversion of PrP c to PrP Sc within neurons during scrapie infection prevents prion neurotoxicity.