With the recent news about mad cow disease, I've been reading about prions, which are thought to cause that disease.

What is a prion? AHD defines it as "A microscopic protein particle similar to a virus but lacking nucleic acid, thought to be the infectious agent responsible for scrapie and certain other degenerative diseases of the nervous system."

But if it lacks nucleic acid, how does it replicate? (The AHD definition of "infection" requires replication, saying, "Invasion by and multiplication of pathogenic microorganisms in a bodily part or tissue.")

And if it doesn't replicate, how does it differ from a simple poison or toxin? And anyway, what's the difference between a poison and a toxin?

I am a bit clueless, too, and am looking to read more on prions. However, in an article in our local paper today, telling about a local University of Chicago scientist who is working on a vaccine, I read the following:

"The crux of the problem is the cause of the illness: inanimate proteins called prions that are fundamentally different from the viruses and bacteria that cause other diseases and demand a different line of attack."

The article goes on to say the prions are nearly identical to normal body proteins. Normally treatments for infections involve the disruption of the cell wall or outer membrane. However, in this case we just have a protein that's resistant to heat, acids and most anything. There is little known about prions, according to the article, such that scientists don't know what function the wayward proteins normally play. Since the prions appear normal to the body, it may be impossible to stimulate the body's natural immune defenses against it.

The only differences between the prions (bad proteins) and their normal counterparts are their shapes, which the immune system can't discern. To function properly porteins must fold into precise shapes. Experts believe that the folding goes awry in prions, and may serve as templates to transforming normal proteins into deformed ones. This, Wordnerd, may be how the prions replicate, so to speak. The bad proteins stick together, thus forming fibers, which may be what causes brain damage in the disease.

Now, this is all from a Chicago Tribune article, and I definitely need to read more to validate it. A couple of interesting points are that treatment of prions may aid in the treatment of Alzheimer's disease and treatment may involve unusual and radical solutions. For example, it may include genetically modifying cows so that they can no longer contract the disease nor pass it on.

I think this particular Prions thread just replicated itself mysteriously !

Perhaps the other one could be disinfected by the appropriate admintibiotic, just to remove confusion?

Done, hab.