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Transmissible spongiform encephalopathies (TSEs) most commonly known as prion diseases are invariably fatal neurological disorders that affect humans and animals. These disorders differ from other neurodegenerative conformational diseases caused by the accumulation in the brain of misfolded proteins, sometimes with amyloid properties, in their ability to infect susceptible species by various routes. While the infectious properties of amyloidogenic proteins, other than misfolded prion protein (PrP TSE ), are currently under scrutiny, their potential to transmit from cell to cell, one of the intrinsic properties of the prion, has been recently shown in vitro and in vivo . Over the decades, various cell culture and laboratory animal models have been developed to study TSEs. These assays have been widely used in a variety of applications but showed to be time consuming and entailed elevated costs. Novel economic and fast alternatives became available with the development of in vitro assays that are based on the property of conformationally abnormal PrP TSE to recruit normal cellular PrP C to misfold. These include the cell-free conversion assay, protein misfolding cyclic amplification (PMCA) and quaking induced conversion assay (QuIC), of which the PMCA has been the only technology shown to generate infectious prions. Moreover, it allows indefinite amplification of PrP TSE with strain-specific biochemical and biological properties of the original molecules and under certain conditions may give rise to new spontaneously generated prions. The method also allows addressing the species barrier phenomena and assessing possible risks of animal-to-animal and animal-to-human transmission. Additionally, its unprecedented sensitivity has made possible the detection of as little as one infectious dose of PrP TSE and the biochemical identification of this protein in different tissues and biological fluids, including blood, cerebral spinal fluid (CSF), semen, milk, urine and saliva during the pre-clinical and clinical phases of the disease. The mechanistic similarities between TSEs and other conformational disorders have resulted in the adaptation of the PMCA to the amplification and detection of various amyloidogenic proteins. Here we provide a compelling discussion of the different applications of this technology to the study of TSEs and other neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

We report protease-resistant prion protein (PrPres) in spontaneous lymphoreticular tumors of mice infected with the agent of variant Creutzfeldt-Jakob disease (vCJD). PrPres may accumulate in lymphoreticular system tumors of asymptomatic persons with vCJD. The statistical power of estimates of vCJD prevalence might be increased by expanding screening to include samples of lymphoreticular neoplasms. [ABSTRACT FROM AUTHOR]

BACKGROUND: The long-standing goal of a preclinical diagnostic test for transmissible spongiform encephalopathy (TSE) has recently become urgent because of the discovery that humans with variant Creutzfeldt-Jakob disease can transmit disease via blood transfusions. STUDY DESIGN AND METHODS: The misfolded protein diagnostic (MPD) assay employs a pyrene-labeled palindromic sequence of prion peptides that undergoes a cascade of coil to β-sheet conversion in the presence of the misfolded prion protein (PrPTSE). The ability of the assay to detect PrPTSE in brain, serum, and plasma was tested. The basic protocol involved a several-hour incubation of 200-µL sample volumes with the peptide reagent in 96-well plates, after which fluorescence was monitored by a fluorescence plate reader with an excitation wavelength of 350 nm and emission scanning wavelength range of 365 to 600 nm. RESULTS: Target specificity for PrPTSE was documented by correlation of assay signal with Western blot signals in brain tissue from TSE-infected, normal, and knockout mice and negative assay signals by use of reagents with different peptide sequences. When applied to plasma or serum, the assay discriminated between samples from a variety of experimental and natural TSE infections compared to uninfected controls, with a sensitivity threshold of approximately 1 infectious dose per mL in pooled plasma from TSE-infected mice. CONCLUSIONS: The MPD assay is a sensitive and specific test for the detection of PrPTSE that may be useful in both preclinical and clinical diagnosis of TSE diseases of animals and humans. [ABSTRACT FROM AUTHOR]