Prion proteins can be found in the muscles of infected sheep, reports a new study in the June issue of Nature Medicine.
Variant Creutzfeldt-Jakob disease in humans might result from consumption of animal products contaminated with prions. Olivier Andréoletti and his colleagues found that the prion protein PrPSc accumulates in the muscle cells of experimentally and naturally infected sheep for several months before the clinical manifestation of disease. The infectivity of PrPSc in muscle is approximately 5,000-fold lower than in the brain, the researchers found.
Although prion proteins had previously been shown to accumulate in the muscles of rodents and humans, this is the first demonstration of muscle infectivity in a species that enters the human food chain.