Though we’ve yet to explore more than 80% of the world’s oceans, a new finding is shedding light on what lurks within Earth’s water: more than 5,500 new species of viruses.
The research, published Thursday in the peer-reviewed journal Science, found so many different types of RNA viruses that the team now proposes five new phyla, or divisions, of RNA viruses, as well as discovering a chain to an ancient virus.
“We were quite surprised actually,” Matthew Sullivan, professor of microbiology at Ohio State University and lead author of the study, said in an email to USA TODAY. “It was very exciting to find from every angle we looked that we had added likely at least five phyla to the five known phyla for RNA viruses!”
There are millions of viruses throughout the world, hundreds of which are able to infect humans, according to a study by the National Institute of Health in 2012. InJuly, scientists discovered more than 30 ancient viruses never seen before.
But there are two different types of viruses: DNA and RNA.
Though we know of RNA viruses like COVID-19, West Nile Virus and the flu, little is known about them because the only ones studied are the ones harmful to humans, animals or plants, Sullivan said. For this project, researchers wanted to study the viruses’ diversity rather than their impact.
To examine possible viruses, researchers analyzed 35,000 water samples taken from all oceans throughout the world. Samples included plankton, which are known to carry RNA viruses.
To see if any were actual viruses, researchers used “machine learning” to compare the genes to an ancient one known as RdRp, which has evolved in the billions of years it has been on Earth. Sullivan said RdRp acts as a “barcode gene” so researchers can asses virus diversity. There, they found more than 44,000 genes that are coded as virus protein before researchers discovered 5,504 new marine viruses.
The team noticed they all didn’t fit in any of the five already known phylas. So, they were put into five newly proposed phyla: Taraviricota, Pomiviricota, Paraxenoviricota, Wamoviricota and Arctiviricota.
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There were also trends in two of the new phyla. Taraviricota viruses were most abundantly found in tropical waters at or near the equator, and Arctiviricota were common near the Arctic Ocean, the team wrote in The Conversation.
Ahmed Zayed, a microbiology research scientist at Ohio State and co-author of the study, said the viruses’ connection to RdRp could help scientists understand how viruses evolved and how they played a role in life on Earth, because Taraviricota appeared to be the connector to past and present.
“RdRp is supposed to be one of the most ancient genes – it existed before there was a need for DNA,” Zayed said in a statement. “So we’re not just tracing the origins of viruses, but also tracing the origins of life.”
Scientists still need analyze the viruses’ full genetic makeup to understand how they influence marine life and their ecosystems, as well as their ecological importance. Sullivan also said it’s too early to tell whether the viruses are of any danger.
“At this point, it is very hard to predict the hosts for RNA viruses because they are very small genomes,” he said.
Follow Jordan Mendoza on Twitter: @jordan_mendoza5.