Researchers at Michigan State University have successfully demonstrated how a new virus is capable of evolving and mutating.
In the current issue of Science, the researchers showed - for the first time - how a virus known as "Lambda" evolved to find a new way to attack host cells, which ultimately took four mutations to accomplish.
This virus infects bacteria, specifically, the common E. coli bacterium. Although Lambda isn't dangerous to humans, the new research highlights how viruses are capable of evolving complex and potentially deadly new traits.
"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," explained MSU graduate student Justin Meyer. "But when we re-ran the evolution experiment, we saw the same thing happen over and over."
Meyer noted that the publication of his paper, co-authored with Professor Richard Lenski, follows recent news that scientists in the United States and the Netherlands managed to produce 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 the virus could naturally obtain all of the beneficial mutations all at once. Nevertheless, it might evolve sequentially, gaining benefits one-by-one, if conditions are favorable at each step.
Indeed, Meyer's "Lambda" research implies that adaptation by natural selection, or survival of the fittest, plays an important role in the evolution of a virus. To be sure, when the genomes of the adaptable 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.
"In other words, natural selection promoted the virus' evolution because the mutations helped them use both their old and new attacks," Meyer explained. "The finding raises questions of whether the five bird flu mutations may also have multiple functions, and could they evolve naturally?"