Thanks to this find, the number of known tribes has doubled.

Researchers have discovered thousands of previously unknown RNA viruses thanks to an analysis of genetic material in the ocean. They write that in the magazine science† It’s an important find. For it greatly expands our understanding of these minor but important microscopic organisms.

RNA viruses

RNA viruses are viruses whose genetic material consists of RNA instead of DNA. RNA viruses are best known for the diseases they cause in humans, such as the flu, Ebola, hepatitis C and COVID-19. As the corona pandemic has unequivocally demonstrated, RNA viruses can cause deadly diseases. But RNA viruses also play a vital role in the ecosystem, as they can infect a wide variety of organisms.

Expand knowledge

However, much about RNA viruses is still unknown. That’s because they’re often barely studied. And that’s what researchers wanted to change in a new study. “RNA viruses are very important to our world,” said study researcher Matthew Sullivan. “But we often only study a small number – the few hundred that harm people, plants and animals. However, in our study, we wanted to study them systemically on a very large scale and explore an environment where no one had searched before.”

5500 new species

The researchers therefore decided to take samples of ocean water. And that provides a wealth of new data on RNA viruses. The team decided to extract sequences from genes expressed in organisms floating in the sea. They focused on a signature gene; Called RdRp, which evolved for billions of years in RNA viruses and is absent in other viruses or cells. In this way, the researchers discovered no fewer than 5,500 new RNA virus species. “There’s so much diversity here,” Sullivan says. “And we were lucky, because pretty much every species we found was new to science.”

tribes

Although the team discovered hundreds of new RNA virus species that could be introduced into existing strains, thousands were left out. The researchers therefore propose five new strains, which they Taraviricota† pomiviricota† paraxenoviricota† wamoviricota and arctiviricota to mention. Thanks to the discovery of no fewer than 5,500 new marine RNA viruses, the number of known strains has therefore doubled; from five to ten.

This map shows the distribution of RNA viruses across the ocean. The size of the wedge is proportional to the average amount of viruses present in that area. The color of the segment indicates the virus strain. Image: Zayed et al., Science Volume 376:156(2022)

In addition, the researchers found that two new strains are particularly abundant in vast oceanic regions. “We found the virus strain Taraviricota almost anywhere in the ocean,” Sullivan says. “This suggests that they are ecologically important.” In addition, arctiviricota commonly found in the Arctic Ocean; the part of the world where global warming is doing the most damage.

Climate change

Thanks to the study, we are expanding our knowledge of the diversity of viruses and their numbers in the ocean. And that is very important. This could help explain the role of marine microbes in the ocean’s adaptation to climate change, the researchers write. This is because oceans absorb about half of the carbon dioxide generated by humans from the atmosphere. And a previous study by the same researchers has already found that marine viruses are the “button” on a biological pump that influences how carbon is stored in the ocean.

Incidentally, the new data does not only reveal important information about RNA viruses. According to researcher Ahmed Zayed, the study also leads to a better understanding of the evolution of early life on Earth. “RdRp is believed to be one of the oldest genes – it existed before the need for DNA,” he says. “So we don’t just trace the origin of viruses, but also the origin of life.”