Carl Zimmer in the New York Times:
Viruses regularly evolve new ways of making people sick, but scientists usually do not become aware of these new strategies until years or centuries after they have evolved. In a new study published on Thursday in the journal Science, however, a team of scientists at Michigan State University describes how viruses evolved a new way of infecting cells in little more than two weeks.
The report is being published in the midst of a controversy over a deadly bird flu virus that researchers manipulated to spread from mammal to mammal. Some critics have questioned whether such a change could have happened on its own. The new research suggests that new traits based on multiple mutations can indeed occur with frightening speed.
The Michigan researchers studied a virus known as lambda. It is harmless to humans, infecting only the gut bacterium Escherichia coli. Justin Meyer, a graduate student in the biology laboratory of Richard Lenski, wondered whether lambda might be able to evolve an entirely new way of getting into its host.