More than 200 previously-unknown pathogens in a category whose members cause diseases like influenza and hemorrhagic fevers have been discovered by researchers, in a study that involved 190 different vertebrates. These specimens included a wide range, from jawless fish like lampreys to reptiles such as turtles, and some were found to contain RNA viruses that have never been categorized.
Since RNA viruses cause a wide range of illnesses in people and livestock, previous studies focused mostly on diseases that infected mammals and birds. The new research, in an attempt to study how RNA viruses have evolved, expanded the survey to take in other vertebrate classes which included fish, amphibians and reptiles.
Edward Holmes, an evolutionary virologist at the University of Sydney in Australia and a co-author of the study, says that RNA viruses are much more widespread than originally thought.
In previous studies, RNA viruses were found in newts and salamanders, but scientists did not have enough knowledge back then to identify the ones that infected other vertebrates. Because of this, Holmes and his colleagues studied almost 200 vertebrate animals and analyzed the RNA extracted from their organs. In the research, Holmes’ team discovered 214 new RNA viruses- with most of them belonging to virus families known to infect birds and mammals.
While they may be related to deadly diseases, it doesn’t mean that they automatically pose a threat to human health. Holmes says that while viruses may belong to the same family, those viruses in fish would not be able to infect humans because humans and fish are very different. This is due to RNA viruses evolving with their hosts. As vertebrates evolved from aquatic creatures and moved towards land, so did these microorganisms that ancient vertebrates hosted, and which have eluded scientific scrutiny until now.
These findings could help scientists to identify viruses that could be harmful to humans in the future, says Mya Breitbart, an environmental virologist from the University of South Florida in St. Petersburg. Lead study author Yong-Zhen Zhang, a virologist at the Chinese Center for Disease Control and Prevention in Beijing, also said that the study just scratches the surface of the huge number and variety of viruses out there. Yong-Zhen Zhang’s team collected samples that are mainly confined to China, and viruses whose RNA sequence has no similarity to any other virus are not included in the analysis. This means vertebrates from other parts of the world could be hosting other unknown viruses that have yet to be discovered.