Evolution: The evolution of RNA viruses

Vertebrate RNA viruses evolved alongside their hosts over geological timescales, a paper published online in Nature this week reports. The study, which expands our understanding of RNA virus diversity, sheds light on the evolutionary history of this important group of viruses.

RNA viruses are a diverse group that cause many notable diseases in vertebrates, such as influenza, hepatitis C and Ebola virus disease, but to date most attention has been focused on RNA viruses of mammals and birds. In this study, Yong-Zhen Zhang and colleagues survey the RNA viruses of fish, reptiles and amphibians. They describe around 200 new viruses and find that every vertebrate-specific viral family known to infect mammals and birds - including influenza viruses, filoviruses and hantaviruses - is also present in amphibians, reptiles or fish.

The evolutionary history of these viruses broadly matches that of their hosts, which suggests that they may have first evolved many hundreds of millions of years ago, the authors conclude.