A Snag for Mutating Viruses to Extinction

In the New York Times, Carl Zimmer discusses a tack being taken to fight viruses. Viruses, he says, evolve rapidly to escape the reaches of the immune system and to adjust to a new tissue that they have invaded, but mutate too much and the viruses suffer. "[Some scientists] hope to cure infections by forcing viruses to evolve their way to extinction," Zimmer writes. However, a new paper coming out in Genetics from a team at the University of Texas, Austin, tested the impact of a high mutation rate on the long-term fitness of DNA bacteriophage T7. The researchers grew the phage up with a mutagen — producing four non-lethal mutations per generation — and saw that, after 200 generations, fitness had increased. "Failure of the theory challenges the quantitative basis of lethal mutagenesis and highlights the potential for adaptive evolution at high mutation rates," the researchers write.