To study the human prion diseases, transgenic (Tg) mice expressing chimeric prion proteins (PrP) comprised of mouse and human PrP sequences have been produced. By mutating the residues individually that differ between human and mouse PrP, we have produced Tg mice that are progressively more susceptible to human prions as evidenced by shorter and shorter incubation times. We propose to develop Tg mice even more sensitive human prions and use these as well as existing Tg mice for the detection of human prions. The bioassay data will be compared to measurements of both the protease-sensitive (s) PrPSc as well as protease-resistant (r) PrPSc. We shall also study the tissue distribution of prion infectivity as well as sPrPSc and rPrPSc in both people and animal models. Our studies may elucidate some of the factors that feature in the transmission of prions between humans and animals. Currently, the Tg mice that are most susceptible to human prions are those expressing a chimeric Mo/Hu PrP, which differs from MoPrP at just six residues. These Tg mice are susceptible to prions from patients who died of sporadic (s) Creutzfeldt- Jakob disease (CJD), in just 80 days. We plan to study systematically the effect of each of these six residues on susceptibility to prion infection, and determine how the expression level of the transgene impacts the incubation time to disease onset after inoculation. We shall also use guinea pigs as models for human prion diseases, having recently demonstrated that they uniquely reproduce the pathological features of variant (v) CJD. The large brain and blood volumes of the guinea pig makes them useful for CNS imaging studies as well as investigations of prions in blood and lymphoid tissues. Several studies suggest that the distribution of prions in brain and lymphoid tissues are quite different in sCJD versus vCJD patients. Whether guinea pigs will reproduce these differences in prion distribution remains to be established. While only four cases of vCJD occurred in the UK last year, the possibility that vCJD prions have contaminated the human blood supply cannot be ignored. Besides measuring prion titers by bioassays in Tg mice, we plan to measure the levels of both sPrPSc and rPrPSc. Recent advances in methods for measuring particularly sprpsc usjng tne amyloid seeding assay (ASA) are encouraging.
Over 95% of total PrPSc in humans with sCJD appears to be sPrPSc that was not measurable until we first developed the conformation-dependent immunoassay (GDI) subsequently the ASA. Combining our new, highly sensitive Tg mice for measuring CJD infectivity with measurements of both sPrPSc and rPrPSc should give important insights into the pathogenesis of human prion disease in the CNS as well as systemic tissues.
|Wan, William; Stubbs, Gerald (2014) Heterogeneous seeding of HET-s(218-289) and the mutability of prion structures. Prion 8:|
|Silber, B Michael; Gever, Joel R; Rao, Satish et al. (2014) Novel compounds lowering the cellular isoform of the human prion protein in cultured human cells. Bioorg Med Chem 22:1960-72|
|Stöhr, Jan; Condello, Carlo; Watts, Joel C et al. (2014) Distinct synthetic A? prion strains producing different amyloid deposits in bigenic mice. Proc Natl Acad Sci U S A 111:10329-34|
|Watts, Joel C; Giles, Kurt; Patel, Smita et al. (2014) Evidence that bank vole PrP is a universal acceptor for prions. PLoS Pathog 10:e1003990|
|Watts, Joel C; Prusiner, Stanley B (2014) Mouse models for studying the formation and propagation of prions. J Biol Chem 289:19841-9|
|Watts, Joel C; Condello, Carlo; Stöhr, Jan et al. (2014) Serial propagation of distinct strains of A? prions from Alzheimer's disease patients. Proc Natl Acad Sci U S A 111:10323-8|
|Wan, William; Stubbs, Gerald (2014) Fiber diffraction of the prion-forming domain HET-s(218-289) shows dehydration-induced deformation of a complex amyloid structure. Biochemistry 53:2366-70|
|Wan, William; Stubbs, Gerald (2014) Fungal prion HET-s as a model for structural complexity and self-propagation in prions. Proc Natl Acad Sci U S A 111:5201-6|
|Kurouski, Dmitry; Lu, Xuefang; Popova, Ludmila et al. (2014) Is supramolecular filament chirality the underlying cause of major morphology differences in amyloid fibrils? J Am Chem Soc 136:2302-12|
|Li, Zhe; Gever, Joel; Rao, Satish et al. (2013) Discovery and Preliminary SAR of Arylpiperazines as Novel, Brainpenetrant Antiprion Compounds. ACS Med Chem Lett 4:397-401|
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