Virologists have identified 5,504 new virus species floating in seawater samples. The viruses were found using a machine learning algorithm to examine 35,000 water samples from around the world, reports Viswam Sankaran for the Independently.
Researchers suspect that only a tiny fraction of the viruses that can harm animals, plants and humans have been studied. The find could change scientists’ understanding of how these submicroscopic infectious agents drive ecological processes in the planet’s oceans. Details of the study were published in this month Science.
The most studied viruses are viruses that contain DNA as the genetic material; Viruses identified in the new study are RNA viruses, reports Rachael Rettner for live science.
“RNA viruses are best known for the diseases they cause in humans, from the common cold to COVID-19. They also infect plants and animals important to humans.” study authors write in a blog post for The conversation. “RNA viruses evolve much faster than DNA viruses. While scientists have cataloged hundreds of thousands of DNA viruses in their natural ecosystems, RNA viruses are relatively unexplored.”
During a four-year Tara Oceans global research project, the team collected RNA sequences from plankton. Plankton are aquatic organisms that are critical to ocean food webs and often harbor RNA viruses The conversation. Analysis narrowed down the RNA sequences to those containing the RdRp gene, which is required for virus replication. This gene evolved in RNA viruses over billions of years and is not found in other types of viruses or cells Independently.
“RNA viruses are clearly important in our world, but we typically only study a tiny fraction of them – the few hundred that harm humans, plants and animals. We wanted to study them systematically at a very large scale and explore an environment where nobody is. We had looked carefully, and we were lucky because virtually every species was new, and many were really new,” says study author Matthew Sullivan , an Ohio State University microbiologist, in a Explanation.
However, since the RdRp gene dates back to when life was first discovered on Earth, the position of the sequence has changed many times, making it nearly impossible to rely on a family tree alone to identify the sequences , explains a statement.
Using machine learning to organize the data, the team found 5,504 new RNA virus species, which were grouped into five existing RNA virus strains, or classification levels. Because so many new viruses were identified, the team proposed five additional classification categories.
The five known RNA virus strains are within the Orthornaviruses Kingdom. However, the researchers proposed five new classifications for some of the new viruses that, with the discovery, do not fit into the existing five phyla. The new tribes include Taraviricota, pomiviricota, Paraxenoviricota, Wamoviricota and arctiviricota, per statement. Most of the newly identified species belong to a new proposed phylum called Taraviricota.
“There is so much new diversity here – and a whole tribe that Taraviricota, have been found throughout the oceans, suggesting they are ecologically important,” Sullivan said in a statement.
After geographically mapping the genetic sequences, the team found that the new strain, Taraviricota (named after the Tara Oceans expedition) was more common in temperate and tropical waters. In contrast, the arctiviticota was found in the Arctic Ocean, the conversation reports. The team suspects the same Taraviricota could be the missing link in the evolution of RNA viruses, connecting two branches of RNA viruses that differed in their replication.
Overall, the new find could help virologists understand the evolutionary history of RNA viruses – and even provide insight into the early development of life on Earth. By further mapping where these RNA viruses are found, scientists can understand how the viruses interact with other organisms on Earth conversation.
“RdRp is said to be one of the oldest genes – it existed before DNA was needed. So we’re not only tracing the origin of viruses, we’re also tracing the origin of life,” study author Ahmed Zayed, also a microbiologist at Ohio State University, said in a statement.