Disturbing

Even without DNA, prions can evolve like organisms, study says

To prove his theory, Weissmann took prion populations from infected brain cells and put them in cell cultures. After being transferred, the prions outcompeted the normal prion protein. And when those prions were transferred back into animal brains, they took over again.

To confirm the findings, the researcher tested the drug swainsonine, which can inhibit the formation of prions. In cell cultures where the drug was used, a drug- resistant substrain of prion evolved to become predominant. When the drug was withdrawn, the substrain that was susceptible to the drug again grew to become the dominate strain.

"The practical implications are that prions may develop drug resistance," he said.

It is kind of scary to think that abnormal proteins without DNA could still go through natural selection and acquire drug resistance. Prions are the cause of a variety of diseases, the best known of which is mad cow disease.