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Prions are unique proteins responsible for transmissible spongiform encephalopathies (TSEs), causing holes in the nervous system. They lack nucleic acid and resist decontamination, posing a potential threat to the food supply. TSEs have been linked to contaminated tissue consumption in animals and humans.
Prions are unique proteins that appear to be responsible for a family of diseases collectively called transmissible spongiform encephalopathies (TSEs), including scrapie in sheep, kuru in humans and “mad cow disease” in cows. These prion diseases are all caused by disruption of the nervous system, which is readily apparent following an autopsy or autopsy. Looking at the tissue of the nervous system, it becomes clear that it has literally been eaten up by these rogue proteins, causing characteristic holes to form.
The existence of prions has been hypothesized as early as the 1960s, when researchers first formulated the so-called “protein only” hypothesis to explain TSEs. These researchers noted that irradiating potentially infectious tissue did not appear to kill the organism responsible, suggesting that it did not contain nucleic acid, which is susceptible to radiation. The theory met with great opposition until the 1980s, when researcher Stanley Prusiner coined the term “prion” to describe the highly unusual proteins he had discovered; these proteins did not contain nucleic acid, the backbone of all living organisms on Earth.
The word is taken from the longer term “infectious protein particle”. Despite the fact that prions lack nucleic acid and therefore in theory cannot reproduce, these proteins do, exhibiting strange folding patterns that subvert otherwise healthy proteins. The protein they are made from is found in many animals, which explains why these diseases affect a wide range of species. Animals and humans can get TSE by ingesting prions in things like infected tissue and through contaminated blood products.
These little proteins are quite stubborn. They resist many techniques used to decontaminate food, raising concerns about the safety of the food supply. Prions cannot be irradiated, and very high temperatures and pressures are required to remove them—much higher temperatures than consumers would normally use to cook a steak. Fortunately, they appear to reside primarily in nervous system tissue, although consuming meat from TSE-infected animals could be potentially dangerous.
These proteins made headlines in the 1990s, when numerous cases of Creutzfeldt-Jakob disease (CJD) began to be linked to prions and the consumption of contaminated tissue from cattle and sheep in the UK. Cases of TSEs have been clearly documented in food animals in Europe, and researchers suspect that TSEs may also be a problem in the United States, perhaps explaining the increased rate of so-called downer cows, cows that for some reason are unable to resist the massacre. Such cattle are not expected to enter the food supply due to concerns about prion diseases and other conditions that could pose a threat to human health.
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