Scientists show prions mutate and adapt to host environment

Scientists from the Florida campus of The Scripps Research Institute have shown that prions, bits of infectious protein that can cause fatal neuro-degenerative disease such as bovine spongiform encephalopathy (BSE) or "mad cow disease," have the ability to adapt to survive in a new host environment.

In this regard, although they lack DNA and RNA, they behave much like viruses, producing distinct self-perpetuating structural mutations that provide a clear evolutionary advantage.

The study was published 14 December 2010, in the online Early Edition the journal Proceedings of the National Academy of Sciences.

"We found that when a particular prion strain is transferred from brain cells to a different cell line, its properties gradually change, giving rise to a variant strain that is better adapted to this new cellular environment," said Charles Weissmann, the head of Scripps Florida's Department of Infectology, who led the study.

"If those same prions are subsequently transferred to another cell line, they change again, adapting to these new host cells. And if returned to the brain, the prions gradually regain their original properties. We found physical evidence that, at least in one case, the fold of the prion changed when its properties changed."

Darwinian evolution without DNA
These new findings come approximately one year after Weissmann and colleagues published a study in the 1 January 2010 edition of the journal Science that showed that prions were capable of Darwinian evolution.