Viruses are masters of evolution, allowing them to outstrip immune responses and rapidly adapt to new hosts. This is one of the secrets of their success. However, this genetic plasticity may, in some cases, pose a problem.
Some viruses, such as HIV and HCV, establish lifelong infections and many years may pass before they have the opportunity to transmit to a new host. In this situation, can a virus become too adapted to the specific environment of their current host?
We discuss the various scenarios in which viruses may become 'short sighted'; being so well adapted to one host that they become a 'rusty' at transmitting to new hosts. We also propose the possible mechanisms viruses may have to avoid this short-sightedness.
I really enjoyed collaborating with Katrina to put this article together. It proved to be quite a mental workout (evolutionary biology is not in my comfort zone), but the writing process has given me a different perspective on persistent viral infections and how the host environment may shape their evolution.
This work was supported by the Wellcome Trust, Royal Society, The Natural Environment Research Council and The European Research Council
Image courtesy of Frances Cacino.