Mysterious virus discovered in Brazilian lake

It is called Yaravirus and intrigues scientists: this virus infecting amoebas does not have any of the usual characteristics of already known viruses, and has 90% of genes never identified until now. A discovery showing the astonishing diversity of the world of viruses which never ceases to amaze scientists.

Christened Yaravirus, named after the queen ofAmazon Yara, the new virus discovered by a Franco-Brazilian team in the artificial lake of Pampulha, near Belo Horizonte in Brazil, belongs to a still unknown line, this is what reveals a new study published on the pre-publication site bioRxiv. Out of 74 Genoa that this virus infects amoebas (a protozoan living in water), 68 are not found in any database phylogenetic, which means that 90% of its genome is unknown. Researchers compared his genome with 8,535 others metagenome and found no match. " Such a proportion of orphan genes (which do not code for any protein known functional, editor's note) has never been observed in an amoeba virus since the discovery of Pandoraviruses "Note the authors.

A miniature pandoravirus?

Discovered in 2013, the pandoravirus are giant viruses as big as a bacterium (about 1 micrometer) and containing several thousand genes. Pandoraviruses thus have 2,500 genes, where conventional viruses, such as those of HIV or from influenza, have only ten. These giant viruses, most of whose genes are not found in any other virus, are a big mystery for scientists wondering about the usefulness of all these additional genes. But the case of Yaravirus is even more astonishing, since it barely measures 80 nanometers in diameter, 10 times less than pandoraviruses, and has none of their usual characteristics. " Here we have identified a whole new type of amoeba virus ", Say the researchers.

Completely atypical viruses

This discovery shows once again the amazing diversity of viruses. In 2019, researchers from the University ofAgriculture and technology from Tokyo (Tuat) discovered in pig droppings a new type of enterovirus having no structural protein, which means that it is theoretically incapable of producing viral particles and therefore of entering a cell. A little embarrassing since a virus just needs a host to be able to replicate and spread. Researchers believe that these viruses, called EV-G and type 2, use a "helper virus" to help them get inside the cell. Some so-called viruses multi-party virus they have a genome fragmented into different viral particles. To reproduce, the virus therefore uses a group of several cells to manufacture its viral particles.

Giant viruses, like Megaviruses, have genes that are normally found in plants, animals, and other cellular organisms, but not in viruses. However, some of these genes play a key role in the translation ofDNA in proteins, which is normally useless for viruses which do not need to make proteins themselves since they make them produced by the cells of the host which they parasitize. Today, around 9,000 cash viruses are listed in databases genetic. But scientists estimate that there are several million of them.

Will old viruses resurface with global warming?

Article by Nathalie Mayer published on 25/01/2020

The whole planet aspen under threat from the new coronavirus appeared a few days ago in China. And the discovery of researchers in the Himalayan ice cream is not made to reassure us. Several previously unknown viruses have been discovered. Voluntarily, this time, and under control. But the global warming and the melting might ice cream soon change the situation?

It was in 2015. 5 years ago already. A team of American and Chinese researchers was leaving for Tibet. Objective: drill the Himalayan glaciers to then analyze the carrots thus extracted in search of bacteria and other viruses that they could contain. In pre-edition of their article, we learn that they have unearthed no less than 33 viruses, including 28 previously unknown to science.

They were discovered in ice no less than 15,000 years old. About 50 meters deep. And to ensure that these samples are not contaminated by their exposure toair modern researchers have followed protocols very precise and rigorous. Especially since the microorganism concentrations elders in such carrots are extremely small compared to those in the current environment. The researchers were thus led to establish new procedures forsampling ultra-clean applicable to viruses.

They had to settle in a cold room brought to minus 5 ° C and saw the outermost layer of the carrots – a thickness of 0.5 cm – using a sterilized band saw. Then, the carrots were washed with ethanol in order to remove yet another probably contaminated layer of 0.5 cm. And the next 0.5 cm was cleaned with sterile water.

For the researchers, it is no great surprise that they then uncovered several previously unknown virus. Viruses quite different from one carrot to another – one dating back 15,000 years, the other only 520 years old. Differences no doubt revealing of climatic conditions, also, dissimilar at the time of their deposit. These differences therefore provide important information to researchers on how viruses may or may not thrive depending on environmental conditions.

A tweet published a few days ago on this subject made much talk. © @LPLdirect, Twitter

Should we fear the melting of the ice?

And the opportunity for scientists to draw public attention to a new issue that they face today: the melting ice, the result of global warming. "In the best of cases, the melting of the ice will make us lose precious microbial and viral data which could inform us about the past climatic regimes of our Planet", explain the researchers in their article. But also the probable evolution of the populations of Microorganisms with the climatic variations to come. "In the worst case, global warming – and the new mining of previously inaccessible regions – could be behind a release of "new"agents pathogens in our environment. "

A fear not so crazy in look of some recent examples. In 2016, in the depths of Siberia, a 12-year-old child died after being contracted anthrax – which we know more under the name ofanthrax. A strain, it seems, released by a reindeer carcass on the occasion of the wave of heat that hit the region in the summer of 2016.

In 2017, researchers had discovered, in the permafrost, a giant virus 30,000 years old. And they had managed, under control, to reactivate it to infect a single-celled amoeba. Proof that viruses can survive at least 30,000 years. Like a sword of Damocles over our heads because modern doctors, of course, have never had to treat this type of infection. Without going back that far, melting ice could give a second chance to the viruses that have spread, for example, the devastating 1918 spanish flu. Keep in mind, however, that most microorganisms trapped in ice are not dangerous for humans.

In brief: old viruses will reappear with the melting of the poles

The frozen lakes of the poles trap bacteria, viruses and mushrooms that Man has not known. In response to climate change, the ice is melting and may well return to the surface of the Earth millions of years old viruses.

Article by Delphine Bossy published on 12/14/2012

If men find mammoths in permafrost, the ice hides many other organisms. Viruses, bacteria or fungi are trapped in frozen lakes ofArctic and D'Antarctic. If they were reissued in theatmosphere, some of them may well become dangerous. The immune system of a human being is adapted to his environment: he would surely be incapable of defending himself against certain viruses dating for example from 3 million years ago! Thus, in the current context of climate change, the scientific community warns: caps melt, we should expect the arrival of new diseases.

In 2009, a Spanish scientific team sampled the water from the frozen Limnopolar lake in Antarctica. Posted in Science, their results reveal the existence of more than 10,000 species from 12 different families, some of which were previously unknown to scientists. Even without talking about the global warming, areas like Siberia are already seen as potential hubs for bacteria. Periodically, lakes melt, emit and drop bacteria or viruses. These are often the Migrator birds who then scatter them. Shoham and Rogers have shown that a virus reappeared successively in the 1930s, the 1960s and in 2006.

Some viruses do not survive after thawing, but others adapt very well. This is typically the big flu problem. of the pandemics flu have struck periodically in history. Last century, there was the Spanish flu in 1918, the Asian flu in 1957 and the Hong Kong flu in 1968. But between these pandemics, where did the virus reside? Some suggest that he was trapped in the ice in Siberia. Pandemics are difficult to predict, and it is almost impossible to trace their source. Global warming therefore risks increasing the number of pathogens, diseases and viruses both for humans and other organisms.

This will also interest you

What are the differences between bacteria and viruses? They are microbes. They are very small and they are easily confused. However, bacteria and viruses are two very different things. And to fight effectively against those who cause diseases, it is better to identify them clearly.

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