Some neurological diseases are caused by protein infectious particles (PRIONS). These include several animal and at least 3 human diseases. One of these diseases, KURU, infects its victims when they eat the brain tissue of their enemies (a questionable activity at best). The best studied of these diseases is scrapies in sheep. The disease entity seems to be composed completely of PROTEIN and to entirely lack any nucleic acid. This poses a major problem given the significant role of DNA and RNA in life. Three theories are currently being considered to explain prions.
Those prions contain as yet undetected nucleic acid. Extensive purification and testing using the most sensitive methods available have failed to demonstrate any nucleic acid in purified, infectious prions.
That an unknown bacterium that is hard to cultivate and that passes through filters is responsible. Again, there is no proof for such an organism.
Those prions represent a type of protein that is able to convert a "normal" protein into a "prion protein". This theory is currently the most popular and there is some evidence accumulating to suggest that it is valid. This theory says that when the prion protein gets into the brain of a victim it binds to a normal or pre-prion protein and somehow converts it into a prion; the new-prion then proceeds to convert other natural proteins. As the number of prions increase destruction of the brain occurs, eventually killing the victim.
ARE THERE PRIONS IN OUR FUTURE?
This is a case of an Emerging Disease about which we understand too little to know whether to be scared-out-of-our-wits or just to be wary and concerned. The Press/TV/Tabloids find prions a good way to sell their services and they tend to hype it up for that purpose. However, there are scientists who are very concerned about the potential dangers of prions. The following are some points of information (tentative) to keep in mind:
There is still some serious debate within the scientific community as to the existence of prions and their role in diseases like the Mad Cow Disease.
Currently the preponderance of data support the idea of prions being "killer proteins".
Prions are very tough; they are not destroyed by autoclaving, cooking temperatures, most disinfectants or being buried in the soil for months.
They are slow acting, however there was a recent death in a young person after exposure only a couple of years previously.
No cases of Mad Cow Disease disease (in cattle) have been reported in the US, but Mad Cow-like diseases infect deer and elk in the US.
There is no treatment for prion diseases; it is a death sentence.
Prevention is uncertain. In UK they have killed and burned a significant percentage of the cattle. British beef can not be imported into most countries.
The disease seems to be spread by animals eating the remains of other animals, particularly of closely related species. However, it also seems to be spread by other means, yet unknown.
Feeding of animal parts to cattle and sheep is in the process of being banned in the US.
Prions
