2023-04-22 06:00:00
A virus infecting plankton has been discovered on the surface of the seas and oceans thanks to expeditions by the Tara Oceans Foundation.
Par Johanna Amselem
© LOIC VENANCE / AFP
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PMore than two-thirds of the world’s population under the age of 50 are affected by the herpes virus type 1, according to figures published by the World Health Organization. This infection causes cold sores and sometimes genital herpes. The expeditions of the Tara Oceans Foundation have made it possible to discover a new type of virus: mirusviruses (in Latin, “dead” can be translated as strange). This discovery was made at the Genoscope in Évry, where the genomes collected by the Tara Océans foundation are sequenced.
“Tara Oceans has transformed our understanding of plankton ecology. Our study shows that this incredible expedition also allows us to answer fundamental questions of evolution. There is still so much to discover and understand about mirusviruses. There is no known culture, we have no image of their virus particle, and we have not yet begun to study them anywhere other than in the oceans! ” underlined Morgan Gaïa, expert in virus evolution at the CEA and first author.
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Chimeric viruses
According to a study published on April 19 in the scientific journal Nature, distant neighbors of the herpes virus have been discovered on the surface of the seas and oceans. These DNA viruses were present from the equator to the poles, they play a role in regulating plankton. These chimeric viruses are halfway between the giant viruses and the herpes virus. While the former only infect single-celled organisms, the latter only infects animals, including humans. “These viruses have an amazing evolutionary history, halfway between the herpes virus, which infects half of the world’s human population, and the giant viruses, a completely distinct group of viruses also abundant in the oceans”, details CNRS press release.
Before completing: “Herpes viruses are very widespread in animals (half of the world’s human population is infected with the herpes virus), but completely absent from the rest of life, leaving the question of their origin unresponsive. This finding confirms that the ancestors of herpes viruses once infected single-celled marine organisms. “In 2018, our research team observed an unusual evolutionary signal in the tsunami of sequencing data from Tara Oceans. Monitoring this signal has enabled us to discover and then characterize a major group of DNA viruses: the mirusviruses. »
“The publication of this discovery in the journal Nature is the beginning of a new adventure, because it gives the scientific community the keys to detecting and studying mirusviruses in many ecosystems”, summarizes Tom Delmont, expert in microbial ecology at the CNRS and last author of this work. This discovery should therefore make it possible to better understand ocean diversity.
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