Scientists find the pathological prion protein in skeletal muscles of hamster with scrapie

In the May 2003 issue of EMBO reports, researchers from the German Robert Koch Institute in Berlin report finding the pathological prion protein PrPSc in a wide range of skeletal muscles after feeding hamsters with prion-infected food. PrPSc is believed to be an essential - if not the sole - constituent of the agent that causes BSE in cattle, scrapie in sheep and Creutzfeldt-Jakob disease.

The researchers fed Syrian hamsters with food pellets that contained mashed-up brain tissue from scrapie-infected hamsters. These hamsters developed symptoms of scrapie as expected and were put down at the terminal stage of the disease. The researchers used a highly sensitive method (Western blot analysis) to analyse concentrated extracts from different muscles in the animals. They subsequently detected the pathological prion protein in various types of skeletal muscle of the terminally-ill animals. A control group of uninfected hamsters did not show pathological prion protein in their muscle tissue.
"These results support and expand on recent observations by Stanley ,Prusiner and his colleagues, who found scrapie agent in the hind limb muscles of mice whose brains had been injected with prions," says Michael Beekes, researcher at the Robert Koch Institute in Berlin. Until recently, PrPSc has normally been found in the central nervous system or in the lymphatic system, for instance, but never in skeletal muscle.
"However, we have to clearly state that these results in mice and hamsters do not necessarily mean that skeletal muscles of cows or sheep infected with BSE or scrapie, respectively, actually do contain prions. At present, the experiments only suggest that more research needs to be done in this area," added Beekes. (EP)
Reference: Thomzig, A., Kratzel, C., Lenz, G., Krüger, D. & Beekes, M. Widespread PrPsc-accumulation in muscles of hamster orally infected with scrapie. EMBO reports 4, 5, (2003). (Advanced online publishing on April 11, 2003; published in print May 1, 2003.)
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