RNA viruses: How viruses contribute to evolution – Wikipedia

Research ship Tara in Paris – on a 125,000-kilometre voyage, scientists conducted research on RNA viruses around the world. Photo: imago / Alexis Sciarde

RNA viruses can cause diseases such as Covid-19. However, they can also contribute to development – this has led, for example, to the fact that people are especially adept at processing starch.

At least since the Corona pandemic, nearly every child has known about the RNA viruses that can lead to Covid-19, influenza, rabies, and a number of other diseases. However, these tiny creatures, which cannot be seen even under a natural microscope, are much more than just pathogens that cause infections to humans, animals and plants, on which research has mostly focused so far. Even if they cannot reproduce on their own, but use living organisms as hosts for this purpose, it is clear that viruses play a very important role not only in nature today, but also in the evolution of life.

Not much is known about RNA viruses so far

A group led by Matthew Sullivan of The Ohio State University in Columbus, USA, now shows in Science how little is known about these global players: In water samples from all of the world’s oceans, the team not only found the genomes of RNA viruses from the five previously known strains of viruses, But he also discovered five new viral strains previously unknown to science.

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Terry Jones, who and his group at the Institute of Virology at Charity University Hospital in Berlin analyzed genetic material for new or long-extinct viruses, but was not involved in Ohio State University research. “However, in their remarkable study, American colleagues examined and analyzed not just one bucket, but many seawater samples from all the world’s oceans,” continues the Charité virologist.

Seawater gives a glimpse into the past

These water samples were collected over three and a half years and 125,000 kilometers around the world by the French research vessel Tara between 2009 and 2013. The researchers took water samples from 210 sites on the expedition from water depths of up to 1,000 metres. Using newly developed bioinformatics strategies, Matthew Sullivan and his team extracted genetic information for enzymes called “RNA-dependent RNA polymerases” (RdRP) from these samples.

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RNA polymerases, in turn, translate information about genomic DNA into a closely related but clearly distinguishable RNA molecule in humans, animals, plants and microorganisms. This RNA in turn contains a template by which proteins and thus the central biomolecules of living organisms are produced. Unlike animals, plants, fungi and microorganisms, the genome of RNA viruses is not made up of DNA but rather of RNA. In order to duplicate this RNA genome, not only coronaviruses, but most RNA viruses use RdRP, which Matthew Sullivan and his group have now researched in seawater samples for the Tara expedition.

One previously unknown strain of the virus was the Taraviricota virus. According to the analyzes of the American team, these pathogens appear to be outdated. “This study is an important contribution to ancient and central questions about the evolution of RNA viruses: the ancestors of these Taraviricota viruses could have appeared at the time when life was On Earth the war has just begun, and it has also evolved. The so-called reactionary elements, American researchers then doubt in their scientific article.

Effect on saliva in our oral cavity

These retro elements, in turn, occur in the DNA genomes of animals and plants and under certain conditions can leave their traditional place and jump to another location in the genome. During this process, retroelements are first translated into RNA like any other genetic information. A special enzyme called “reverse transcription,” which occurs in retroviruses such as HIV, which causes AIDS, then converts this RNA back into DNA, which can be incorporated into an entirely different site in the genome.

These jumping elements, for example, activated the amylase gene in the genome in the salivary glands of the human oral cavity, which is not active there in many other mammals. In turn, with the help of this amylase, humans can digest the starch found in many plants, such as cereals and potatoes, better than many animals. So the elements of jumping mean a clear advantage for people. It also shows how important the evolution of viruses is to the development of animal and plant species.

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