Prion particle is an infectious agent causing neurodegenerative diseases in humans and animals, such as Creutzfeldt-Jakob disease, kuru, Gerstmann-Straussler-Scheinker syndrome, and fatal familial insomnia in humans; mad cow disease, scrapie, and feline spongiform encephalopathy in animals. This particle is devoid of nucleic acid and seems to be composed of protein. The normal prion protein (PrPC) is converted into its abnormal isoform (PrPSc) posttranslationally. The conversion of PrPC into PrPSc involves a conformational change whereby the a-helical content decreases and the amount offi-sheet increases. The formation of PrPSc requires an unknown protein X which might junction as a molecular chaperone. Many prion characteristics have been revealed in these last two decades, such as physical, chemical, strain, molecular biology, and immunological characteristics. Some investigators revealed the topological forms of prion protein in the endoplasmic reticulum membrane and their role in the pathophysiological process of the disease. But still prion diseases continue to raise many unanswerable questions to be investigated. One of the unanswerable questions is prion multiplication. Many prion multiplication models are suggested by investigators; one constant finding is that prion replication requires the interaction of PrPC-PrPSc. The studies of pathogenesis of prion diseases need much more attention to develop an effective therapy for these neurodegenerative diseases. Diagnosis of prion diseases is based on the clinical and histopathological findings, and immunochemical tests of some proteins in cerebrospinal fluid. Immunochemical tests of proteins in cerebrospinal fluid are important in developing premortem diagnosis of prion diseases.
- Conformational change
- Creutzfeldt-Jakob disease