Viruses up their game in arms race with immune system

In a classic example of the evolutionary arms race between a host and a pathogen, the myxoma virus—introduced to control the rabbit population in Australia in 1950—has developed a novel and deadly ability to suppress the immune response of its host rabbits. New research shows that viruses collected in the 1990s are much more effective at shutting down the immune systems of rabbits that have never been exposed to the virus than are viruses from the 1950s.