I recently attended a virology lecture where this question was asked.

The answer was that this is very unlikely. In fact, the evolutionary direction of all known viruses is the opposite: from high towards low virulence. High virulence is observed in viruses which have recently jumped from one species to another and can be thought of as temporary maladaptation to the new species. As the virus adapts, the damage it does in the course of its reproduction process becomes less and less severe. Eventually, many viruses end up causing mild symptoms similar to the common cold, warts etc.