More than 5,500 unknown viruses discovered in the ocean

The RNA virus differ from classical viruses DNA in the sense that they evolve much faster. In us humans they cause illnesses ranging from colds to… COVID-19 or even Ebola. But they also infect plants or animals that are dear to us. And their presence in our environment remains relatively understudied. Especially because viruses are missing RNA the barcode genetics – unique short pieces of DNA – that distinguish one species from another.

Today, however, an analysis of genetic material contents in the oceans reveal the presence of several thousand previously unknown RNA viruses. Viruses so diverse that they simply double the number of biological groups of viruses that are thought to exist, so to speak Ohio State University researchers (United States). Microbiologists’ trick: working on a protein shared by all RNA viruses. Or more precisely on the embarrassed RdRp encoding it. Because this gene has minor differences that can help distinguish one type of virus from another. And then it doesn’t show up in other viruses or cells.

The researchers examined a database RNA sequences of plankton collected by theTara Ocean’s Expedition† Because plankton is a common host for RNA viruses. About 35,000 samples from over 120 different regions around the world. And they identified more than 44,000 sequences of the gene encoding the viral protein that interests them.

A new light on life

The researchers are continuing their work by trying to determine the evolutionary links between all of these sequences. Assuming that the more similar the genes are, the more likely the viruses they carry are closely related. Thanks to’artificial intelligence and in-depth analysis using 3D representations of sequence structures, they identified 5,504 new RNA viruses. And increases the number of known biological groups of viruses from five to ten. They even think they have found Taraviricota – a group present in all oceans -, the missing link in the evolution of RNA viruses that scientists have long sought, by linking together two different known branches of RNA viruses that differed in their way of replication†

This work is not only important because RNA viruses can be deadly to humans. They are also important because they shed light on the evolution of life on Earth. The RdRp gene is arguably one of the oldest genes in the world. It existed before life needed DNA.

RNA viruses also play a central role in ecosystems. By infecting all kinds of organisms, they affect the environment and food webs on a chemical level. So they could play a role in how the oceans adapt to the global warming† About how the oceans absorb and store about half of the oceans carbon that emit our activities into the atmosphere.

Note that for now, researchers don’t know which organisms infect these new RNA viruses. Particularly because the fragments of taken available to them are incomplete and extremely difficult to decipher. They still hope to be able to determine in the future what types of genes may be missing and how they evolved over time. To better understand how these RNA viruses work.