What exactly is a prion and why are cows mad at it?

Question

What exactly is a prion? How can something that isn't alive "eat" a cow's nervous system and how could something that isn't alive be passed along from one cow to another and apparently "multiply" themselves. I'm not sure that multiply is the right word, but at what rate do they replicate themselves.

Answer 1

A prion has been defined as "small proteinaceous infectious particles which resist inactivation by procedures that modify nucleic acids".

The discovery that proteins alone can transmit an infectious disease has come as a considerable surprise to the scientific community.

Prion diseases are often called spongiform encephalopathies because of the post mortem appearance of the brain with large vacuoles in the cortex and cerebellum. Probably most mammalian species develop these diseases.

Specific animal examples include:
* Scrapie: sheep
* TME (transmissible mink encephalopathy): mink
* CWD (chronic wasting disease): muledeer, elk
* BSE (bovine spongiform encephalopathy): cows

Humans are also susceptible to several prion diseases:
* CJD: Creutzfeld-Jacob Disease
* GSS: Gerstmann-Straussler-Scheinker syndrome
* FFI: Fatal familial Insomnia
* Kuru
* Alpers Syndrome

How they spread:
Ingested prions may be absorbed across the gut wall at Peyers patches. These are a part of the MALT, or mucosal associated lymphoid tissue. It is thought that the MALT presents microorganisms to the immune system in a contained and ideal fashion, facilitating a protective immune response. Prions could be taken up in the same way.

Lymphoid cells then phagocytose the particle and travel to other lymphoid sites such as nodes, the spleen and tonsils. The prion can replicate at these sites. Many of these sites are innervated and eventually the prion gains access to a nerve and then propagates back up the axon to the spinal cord and eventually the brain.

Hope that helps.

Answer 2

a prion is a protein that has folded into a different shape ( polymerizes into a fiber with a core consisting of tightly packed beta sheets to be exact), the prions the cows are mad at are causing Bovine Spongiform Encephalopathy because the protein in the cows brain have changed shape and so no longer "work" in the brain, so the brain becomes full of holes.

When another cow, or a person, eats a prion form a cow, it is passed along, because prions are able to convert other normal proteins into more prions, the important thing here is that the prions are not making the proteins, they are only changing them. Prions cause many diseases in humans, the one we can contract from cows is Creutzfeldt-Jakob disease, and once again is causes "swiss cheese" brains

Answer 3

Prions ARE NOT viruses. Please do not get confused. Usually prions are passed from one animal to another through feed supply. A lot of feedlot cattle farmers will buy feed for their cattle which contains ground up meat as a source of animal protein in it. This meat can be from cattle that died from "mad cow disease" previously. Cows don't know any better, or aren't given a choice.

Answer 4

A prion is an infectious agent composed only of protein.

Prions are believed to infect and propagate by refolding abnormally into a structure which is able to convert normal molecules of the protein into the abnormally structured form

Answer 5

Viruses are not considered alive, so think of it like a virus. Prion is debateable, but based on what you asked, it's a virus. Just like how AIDS or HIV can be passed and spread and infect cells but not be alive.

Answer 6

www.mad-cow.org/ - 24k Check these out to find out.https://lists.cs.columbia.edu/pipermail/ornet/2002-June/004721.html The second one is probably better for prion.Good luck