If you are like many of us (this author included), you may not know what a prion is or why it is important. A prion is an infectious agent that is composed primarily of protein. It infects and re-propagates by refolding abnormally into a structure, which converts normal molecules into an abnormal form.
If this seems a little out of the horror flick, Alien, to you, you are not that far from wrong. Prions, without even trying, are just as malicious, and have been known to cause at least twenty diseases that are fatal to humans and animals.
For the first time in history, scientists at the American Scripps Research Institute have demonstrated that “lifeless” prion proteins, devoid of all genetic material, can evolve just like higher forms of life. They can adapt to suit their environment and develop a resistance to drugs.
According to Charles Weissmann, head of Scripps Florida’s department of Infectology who led the study: “On the face of it, you have exactly the same process of mutation and adaptive change in prions as you see in viruses.”
The study was published in the journal, Science, and those scientists involved were very excited that their revelations might suggest new methods in developing therapies for diseases. The study involved transferring prion populations from brain cells to other cells and observing the new environment. When the prions were returned to the brain cells, the brain-adapted prions took over the population.
In the words of Professor John Collinge of the Medical Research Council Prion Unit:
“This … pattern of Darwinian evolution appears to be universally active. In viruses, mutation is linked to changes in nucleic acid sequence that leads to resistance. Now, this adaptability has moved one level down – to prions and protein folding, and it’s clear that you do not need nucleic acid (DNA or RNA) for the process of evolution. This is a timely reminder that prion concerns are not going away and that controls to stop abnormal prions being transmitted to humans through the food system or through blood transfusions must be vigorously maintained.”
One terrible example of prions at work during infections is the human form of mad cow disease known as vCJD. In this case, abnormal proteins convert the normal host prion protein into its deadly form by altering its shape.
Collinge referred to what he calls “the cloud hypothesis” which concerns the multitude of prion proteins found in the human body that he suggested some two years ago. He goes on to say:
“Now we know that the abnormal prions replicate, and create variants, perhaps at a low level initially. But once they are transferred to a new host, natural selection will eventually choose the more virulent and aggressive variants. The prion protein is not a clone, it is a quasi-species that can create different protein strains even in the same animal.”
Current work on prions clearly suggests that it would be better to nip the supply of prion proteins in the bud rather than wait and risk abnormal adaptations that could take over in a more virulent form.
This would be really scary fodder for a sci-fi/ horror flick, but unfortunately, it isn’t fiction.
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