In the classic sense, prions, which are misfolded versions of the brain protein PrP, cannot mutate because they do not contain DNA or RNA. They can, however, give rise to variants with different properties, possibly due to differences in the folding, or shape, of the proteins. In the study, published December 31 in Science Express, researchers estimated the rate at which prion mutants can appear in cultured human nerve cells. In addition, the study suggests that once variants appear, they persist at low levels, giving rise to a heterogeneous prion population.
“On the face of it, you have exactly the same process of mutation and adaptive change in prions as you see in viruses,” said Dr. Charles Weissmann in a prepared statement. Weissmann, who is the head of the Scripps Florida Department of Infectology in Jupiter, Fla., led the study.