Research published in Nature has found that many of the viruses infecting us today have ancient evolutionary histories that date back to the first vertebrates and perhaps the first animals in existence.

The study, a collaboration between the University of Sydney, the China Center for Disease Control and Prevention and the Shanghai Public Health Clinical Centre, looked for RNA viruses in 186 vertebrate species previously ignored when it came to viral infections.

The researchers discovered 214 novel RNA viruses (where the genomic material is RNA rather than DNA) in apparently healthy reptiles, amphibians, lungfish, ray-finned fish, cartilaginous fish and jawless fish.

This study reveals some groups of virus have been in existence for the entire evolutionary history of the vertebrates  it transforms our understanding of virus evolution.

For the first time we can definitely show that RNA viruses are many millions of years old, and have been in existence since the first vertebrates existed.

Fish, in particular, carry an amazing diversity of viruses, and virtually every type of virus family detected in mammals is now found in fish. We even found relatives of both Ebola and influenza viruses in fish.

This study emphasises just how big the universe of viruses  the virosphere  really is. Viruses are everywhere.