When scientists study virology, they’re often investigating birds and mammals. This is largely due to the constant development of varying strains of RNA viruses, notably bird and swine influenza. We hear very little about viruses from fish, frogs or reptiles.
Now in a new study from the University of Sydney, the China Centre for Disease Control and Prevention and the Shanghai Public Health Clinical Centre, scientists have discovered over 200 previously unknown RNA viruses in the three different species.
Extracting the RNA from the gills, guts, livers and lungs of 190 different classes of vertebrate, from turtles and snakes to salamanders and jawless fish, the researchers were surprised to find 214 previously undiscovered RNA viruses lurking inside the fish, frogs and reptiles.
Unlike DNA, RNA is derived from ribonucleic acid. RNA lends itself to many of the diseases we see impacting humanity today, including the common cold.
Fish, in particular, carry an amazing diversity of viruses, and virtually every type of virus family detected in mammals is now found in fish, said Edward Holmes, an evolutionary virologist at the University of Sydney, and co-author of the study. We even found relatives of both Ebola and influenza viruses in fish.
While human infection can’t be ruled out, it’s wise not to freak out about a whole new subsection of Ebola virus strains that we might not even need to worry about. Fish are very different to humans, and the viruses have been evolving alongside vertebrates this is the significant part.
Of the 214 viruses identified, all of them were found to be linked to vertebrate infection, with 24% of the viruses being recovered from the same species’ tissue.
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, Holmes said. 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.
This suggests that there are millions of RNA viruses that have yet to be discovered. And worryingly, that makes it even harder to predict which ones might eventually infect humans.
Dennis Publishing Limited