MSU researchers show how new viruses evolve and, in some cases, become deadly

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Justin Meyer and Devin Dobias examine the growth of bacteria in the Lenski lab. (view larger image)

Researchers at Michigan State University (MSU) have demonstrated how a new virus evolves and sheds light on how easy it can be for diseases to undergo dangerous mutations.

The scientists showed for the first time how the virus, Lambda, evolved to find a new way to attack host cells, an innovation that took only four mutations to accomplish. This virus infects bacteria—in particular, the common E. coli bacterium. Lambda isn’t dangerous to humans, but this research demonstrated how viruses evolve complex and potentially deadly new traits, said Justin Meyer, MSU graduate student, who co-authored a paper  with Richard Lenski, MSU AgBioResearch scientist and MSU Hannah distinguished professor of microbiology and molecular genetics. The paper appeared In the January 27, 2012, issue of Science.

“The viruses and bacteria reproduce so quickly that we can watch evolution in action,” Lenski said.  “We can even study evolutionary changes that require several mutations and involve the interaction between different species.”

This paper follows recent news that scientists in the United States and the Netherlands produced a deadly version of bird flu. Even though bird flu is a mere five mutations away from becoming transmissible between humans, it’s highly unlikely that the virus could naturally obtain all of the beneficial mutations at once. However, it might evolve sequentially, gaining benefits one by one if conditions are favorable at each step, he added.

Meyer and his colleagues’ ability to duplicate the results of their research—conducted at BEACON, MSU’s National Science Foundation Center for the Study of Evolution in Action—implied that adaptation by natural selection, or survival of the fittest, had an important role in the viruses’ evolution.

When the genomes of the adapted virus were sequenced, they always had four mutations in common. The viruses that didn’t evolve the new way of entering cells had some of the four mutations but never all four together, said Meyer, who holds the Barnett Rosenberg Fellowship in the MSU College of Natural Science.

“In other words, natural selection promoted the viruses’ evolution because the mutations helped them use both their old and new attacks,” Meyer said. “The finding raises questions of whether the five bird flu mutations may also have multiple functions, and could they evolve naturally?”

Additional authors of the paper are Devin Dobias, former MSU undergraduate (now a graduate student at Washington University in St. Louis); Ryan Quick, MSU undergraduate; Jeff Barrick, a former Lenski lab researcher now on the faculty at the University of Texas; and Joshua Weitz on the faculty at Georgia Tech.

Funding for the research was provided in part by MSU AgBioResearch and the National Science Foundation.

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