Introduction: The Prion Protein
Prion proteins are found in the bodies of many animals, including humans. Although its natural function is debated, it was discovered that these proteins can change from their native form to a pathological one. The prion was first hypothesized by Stanley Prusiner, who coined the name as meaning "infectious protein", although it was first thought to be a slow virus.
From Philip Yam's book, The Pathological Protein:
From Philip Yam's book, The Pathological Protein:
Like bacteria, viruses, and other conventional disease agents, the pathological prion kills by making more of itself and overwhelming the body's defenses. But the prion replicates in a different way, by converting the normal prion protein. These newly transformed prions "inherit" the original prion's pathological properties and ability to recruit others... The idea that a protein could pass inheritance features violated the orthodoxy of molecular biology. Anything that reproduces, such as bacteria, viruses, yeast, and healthy human cells, needs nucleic acids - DNA and RNA - to do so, but prions go against this rule. (Yam, xiii)
He explains that this is what makes the prion so deadly- the lack of reliance on nucleic acids lets it withstand nearly all methods of sterilization. The prions form a group of unique diseases, some of which cross species barriers.
One of the difficulties of proving the prion theory was the central dogma of molecular biology, created by Francis Crick. He stated that the information can only flow in one direction, and that protein could never send information to anything else, it could only receive. The prion theory stated prions violated this, and could pass information to other proteins. Because of this, it was difficult for the theory to gain acceptance.
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Family of Prions
Sheep scrapie has been known for at least 200 years and was described as a transmissible disease over 100 years ago. Since then, three groups of transmissible spongiform encephalopathies or TSE diseases have been identified in humans including familial, infectious and sporadic types... ...The transmitted/iatrogenic group consists of kuru, iatrogenic Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD). For kuru and iatrogenic CJD, it is clear that the patients are exposed to TSE agent by contact with brain tissues or extracts contaminated by TSE agent... In 1996, authorities in the UK described vCJD, a new CJD which is now believed to be the human form of bovine spongiform encephalopathy (BSE). (Chesebro) |
Thesis Statement
Mad Cow Disease, or Bovine Spongiform Encephalopathy (BSE) has been one of the most influential diseases of the late twentieth century. Some may argue that because the death toll has been so much lower than other infectious diseases, it has not had as much of an impact. BSE has allowed researchers to discover connections, and may one day, cures for it and other diseases such as Alzheimer's and Parkinson's Disease. BSE has changed our farming practices, health regulations, and international relationships for several decades.