Rapid virus evolution witnessed in lab

U.S. researchers say they have observed how a new virus evolves and how diseases can quickly gain dangerous mutations. Scientists at Michigan State University showed for the first time how a virus called "Lambda" evolved to find a new way to attack host cells, a change accomplished in just four mutation steps. While Lambda isn't dangerous to humans, the research demonstrated how viruses evolve complex and potentially deadly new traits, researcher Justin Meyer said in an MSU release Thursday. "We were surprised at first to see Lambda evolve this new function, this ability to attack and enter the cell through a new receptor -- and it happened so fast," Meyer said. "But when we re-ran the evolution experiment, we saw the same thing happen over and over." This study follows recent news that scientists in the United States and the Netherlands produced a deadly version of bird flu just five mutations away from becoming transmissible between humans. While it's highly unlikely the bird flu virus could naturally obtain all of the beneficial mutations all at once, it might evolve sequentially, gaining benefits one by one, Meyer said. When the genomes of the adaptable Lambda virus were sequenced, they always had four mutations in common, he said. "In other words, natural selection promoted the virus' 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?"