Brain pathology
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Prion diseases are progressive neurodegenerative disorders affecting humans and other mammalian species. The term prion, originally put forward to propose the concept that a protein could be infectious, refers to PrPSc , a misfolded isoform of the cellular prion protein (PrPC ) that represents the pathogenetic hallmark of these disorders. The discovery that other proteins characterized by misfolding and seeded aggregation can spread from cell to cell, similarly to PrPSc , has increased interest in prion diseases. ⋯ Because of their transmissibility, the phenotypic diversity of prion diseases can also be propagated into syngenic hosts as prion strains with distinct characteristics, such as incubation period, pattern of PrPSc distribution and regional severity of histopathological changes in the brain. Increasing evidence indicates that different PrPSc conformers, forming distinct ordered aggregates, encipher the phenotypic variants related to prion strains. In this review, we summarize the most recent advances concerning the histo-molecular pathology of human prion disease focusing on the phenotypic spectrum of the disease including co-pathologies, the characterization of prion strains by experimental transmission and their correlation with the physicochemical properties of PrPSc aggregates.