Researchers recently studied how genetic manipulation of a the virus known as Phage Lambda (noninfectious to humans) affected transmissibility among host bacteria e. coli cells. Downregulation of the typical receptor protein resulted in the viral evolution of a new tropogen that utilized the receptor protein OmpF - a receptor protein that until now had never been recorded as the receptor protein for Phage Lambda. The development of this new tropogen occurred within just 15 days! Upon molecular examination, it was revealed that this mutation required four individual point mutations within the viral genome.
This research could shed some light on the idea of viral evolution. The primary researcher, Justin Meyer, estimates that the probability of four such point mutations occurring simultaneously is around "one in a thousand trillion trillion" (a slightly nonspecific estimate but still...). Contrary to what might be expected, however, in a number of different trials the virus always acquired the function mutation over the course of several weeks.
Is viral evolution more pointed than pure probabilistic mutations? So it would seem.
- Elena Higuchi