Multiple Scrapie

While clinical and pathological observations of natural goat scrapie also indicate the existence of multiple field isolates, strain characterization of prions from goats... 

Parchi et al, 1996), sheep (Kascsak et al, 1985 Kascsak et al, 1986), and hamsters (Bessen and Marsh, 1994). At least 20 strains have heen extensively characterized and studied in experimental mouse models of scrapie (Bruce, 1996). It is especially challenging to explain TSE strains in terms of PrP-res formation because multiple strains have been described in species with one PrP genotype. Because the TSE appear to be a disease of protein folding, the answer may reside not in the PrP amino acid sequence but rather in the conformation of the protein. 

Transmissible spongiform encephalopathies Prion-caused diseases resulting in brain tissue developing multiple holds such that it resembles a sponge, includes Creutz-feldt-Jakob disease, mad cow disease, kuru, scrapie and others. 

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