Forced evolution: Can we mutate viruses...( HOUSTON -- Nov. 10 2008 -- It sounds...)

HOUSTON -- Nov. 10, 2008 -- It sounds like a science fiction movie: A killer contagion threatens the Earth, but scientists save the day with a designer drug that forces the virus to mutate itself out of existence. The killer disease? Still a fiction. The drug? It could become a reality thanks to a new study by Rice University bioengineers.

The study, which is available online and slated for publication in the journal Physical Review E, offers the most comprehensive mathematical analysis to date of the mechanisms that drive evolution in viruses and bacteria. Rather than focusing solely on random genetic mutations, as past analyses have, the study predicts exactly how evolution is affected by the exchange of entire genes and sets of genes.

"We wanted to focus more attention on the roles that recombination and horizontal gene transfer play in the evolution of viruses and bacteria," said bioengineer Michael Deem, the study's lead researcher. "So, we incorporated both into the leading models that are used to describe bacterial and viral evolution, and we derived exact solutions to the models."

The upshot is a newer, composite formula that more accurately captures what happens in real world evolution. Deem's co-authors on the study include Rice graduate student Enrique Muoz and longtime collaborator Jeong-Man Park, a physicist at the Catholic University of Korea in Bucheon.

In describing the new model, Deem drew an analogy to thermodynamics and discussed how a geneticist or drug designer could use the new formula in much the same way that an engineer might use thermodynamics formulas.

"Some of the properties that describe water are density, pressure and temperature," said Deem. "If you know any two of them, then you can predict any other one using thermodynamics.

"That's what we're doing here," he said. "If you know the recombination rate, mutation rate and fitness function, our formula can analytically pre
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