MicrobeWorld

Viruses can be transmitted to completely new host species that they have not previously infected. Usually host defenses stop the infection before any replication and adaptation can take place. On rare occasions, a novel population of viruses arises in the new host. These interspecies infections can sometimes be deduced by sequence analyses, providing a glimpse of the amazing and unpredictable paths of virus evolution. One example is a plant virus that switched hosts and infected vertebrates.