5 500 nouvelles espèces de virus à ARN découvertes dans l’océan – Retracer les origines des virus et les origines de la vie

Des échantillons d’eau de mer fournissent un trésor de données sur les virus à ARN

Des échantillons d’eau de mer collectés dans le monde entier ont fourni un trésor de nouvelles données sur[{” attribute=””>RNA viruses, expanding ecological research possibilities and reshaping our understanding of how these small but significant submicroscopic particles evolved.

Combining machine-learning analyses with traditional evolutionary trees, an international team of researchers has identified 5,500 new RNA virus species that represent all five known RNA virus phyla and suggest there are at least five new RNA virus phyla needed to capture them.

The most abundant collection of newly identified species belong to a proposed phylum researchers named Taraviricota, a nod to the source of the 35,000 water samples that enabled the analysis: the Tara Oceans Consortium, an ongoing global study onboard the schooner Tara of the impact of climate change on the world’s oceans.

“There’s so much new diversity here – and an entire phylum, the Taraviricota, were found all over the oceans, which suggests they’re ecologically important,” said lead author Matthew Sullivan, professor of microbiology at The Ohio State University.

“RNA viruses are clearly important in our world, but we usually only study a tiny slice of them – the few hundred that harm humans, plants, and animals. We wanted to systematically study them on a very big scale and explore an environment no one had looked at deeply, and we got lucky because virtually every species was new, and many were really new.”

The study was published on April 7, 2022, in the journal Science.

Distribution of RNA Viruses Across the Ocean

This map shows the distribution of RNA viruses across the ocean. Wedge size is proportional to the average abundance of viruses present in that area, and wedge color indicates virus phyla. Credit: Reprinted with permission from Zayed et al., Science Volume 376:156(2022)

While microbes are essential contributors to all life on the planet, viruses that infect or interact with them have a variety of influences on microbial functions. These types of viruses are believed to have three main functions: killing cells, changing how infected cells manage energy, and transferring genes from one host to another.

Knowing more about virus diversity and abundance in the world’s oceans will help explain marine microbes’ role in ocean adaptation to climate change, the researchers say. Oceans absorb half of the human-generated carbon dioxide from the atmosphere, and previous research by this group has suggested that marine viruses are the “knob” on a biological pump affecting how carbon in the ocean is stored.

By taking on the challenge of classifying RNA viruses, the team entered waters still rippling from earlier taxonomy categorization efforts that focused mostly on RNA viral pathogens. Within the biological kingdom Orthornavirae, five phyla were recently recognized by the International Committee on Taxonomy of Viruses (ICTV).

“RdRp is supposed to be one of the most ancient genes – it existed before there was a need for

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