According to research published in the journal Nature, over 5,000 new species of viruses have been identified in oceans around the world.
This study was conducted by a team of experts from Ohio State University, USA. They analyzed tens of thousands of water samples from various locations globally, searching for traces of RNA viruses, which use RNA as their genetic material. SARS-CoV-2 is a well-known example of an RNA virus.
The authors state that they undertook this research because RNA viruses have not been studied as thoroughly as DNA viruses in the past.
Experts identified approximately 5,500 new RNA virus species.
The diversity of the newly discovered viruses is so vast that the authors propose doubling the number of RNA virus taxonomic groups from 5 phyla to 10 phyla. The lead author of the study, Professor Matthew Sullivan from Ohio State University, stated: “We discovered a large number of new and diverse RNA viruses. Entirely new species within the phylum Taraviricota were found across the oceans.”
According to Professor Sullivan, studies on RNA viruses typically focus on specific RNA virus systems on Earth. “We wanted to conduct a systematic study on a very large scale and explore an environment that has not been deeply investigated by anyone,” Professor Sullivan declared.
He and his colleagues analyzed 35,000 water samples taken from 121 locations across the five oceans of the world. They examined genetic sequences extracted from small aquatic organisms known as plankton, which are common hosts for RNA viruses. They searched for RNA virus gene sequences by hunting for the RdRp gene. This gene is found in all RNA viruses but is absent in other cells and viruses. From this, they identified over 44,000 sequences carrying this gene.
The RdRp gene is billions of years old and has evolved multiple times. The evolutionary process of this gene occurred a long time ago, making it difficult for researchers to determine the evolutionary relationships between the sequences. They used machines to group them together and classify them into branches.
From this, experts identified approximately 5,500 new RNA virus species belonging to five existing phyla. Additionally, they proposed five new phyla: Taraviricota, Pomiviricota, Paraxenoviricota, Wamoviricota, and Arctiviricota.
According to The Conversation, species of viruses in the Taraviricota phylum are particularly abundant in temperate and tropical seas, while viruses belonging to the Arctiviricota phylum are prevalent in the Arctic Ocean.
The authors emphasize that understanding how the RdRp gene has diversified over time will help us grasp the early development of life on Earth.
“RdRp is considered one of the oldest genes. It existed before DNA formed. Therefore, we are not only tracing the origins of viruses but also seeking the origins of life,” said Ahmed Zayed, a microbiology expert at Ohio State University and co-author of the study.
