translated from Spanish: What are pandoraviruses and why some scientists doubt that they are actually viruses

Pandoraviruses are part of the family of giant viruses and can be up to 10 times larger than a common virus, even measuring as much or more than other small bacteria.

In addition, they have many more genes. Influenza A virus, for example, has a genome made up of about eight genes. A pandoravirus, such as salinus, can hold about 2,500.

Researching giant viruses has discovered things as surprising as they are often targeted by cannibal viruses, i.e. viruses that parasitistic other viruses.
And recently, one study found evidence that some pandoraviruses generate only possible membrane potential through energy production.

Giant viruses have been found to be targets for cannibal viruses, i.e. viruses that parasitistice other viruses

This study led by the Mediterranean University Hospital Institute for Infections in France rethinks the scientific dispute over whether pandoraviruses are a type of virus or if we are facing a biological group yet to be categorized.

However, other experts remain skeptical of this possibility, reasoning that there’s still a lot of research left to think about another biological classification.

Origin

“The first giant viruses were described in 2003 and the former was called mimivirus. Since then, so-called pandoraviruses have been discovered and their genomes studied,” World David Lamb, a scientist at Swansea University in Wales, UK, tells BBC World.

They are characterized by their size, greater than 200 nanometers, when common viruses are defined as being less than 200.

Giant viruses are observable under the light of an optical microscope, while the others can only be viewed with an electron microscope.

Giant viruses can be seen through a common optical microscope

But it was not until 2013 that the term pandoravirus was coined, when one of the largest was discovered, salinus, in Chile’s Tunquén wetland.

“It is called pandoravirus in reference to the ‘pandora’s box’, a mysterious box spoken of in Greek mythology. It was put this way because its genome encodes 80% of completely unknown proteins that make this type of virus like a box full of surprises. One of them, the recent finding of energy metabolism,” Professor Bernard La Scola of Aix-Marseille University in France explains to BBC Mundo.

Are they actually viruses?

Giant pandoraviruses and viruses, according to recent study researchers, have changed the definition of viruses in several ways.

For example the first time it was described that viruses could also be infected by other viruses was through the analysis of these giant entities.

Some giant viruses can measure as much or more than some small bacteria

Now, with the discovery of an electrical gradient, this group of scientists suspects that pandoraviruses might also be able to produce their own energy.

Energy production is associated with the living worldCell, but certainly not with viruses that, by definition, are not considered living beings, since they parasititate an organism and exploit its energy metabolism in order to replicate,” says La Scola.

“The findings question the definition of viruses and might suggest that pandoraviruses are simply not viruses,” the expert adds.

Much is unknown about pandoraviruses, but at the moment they pose no danger to humans

“Structurally, pandoraviruses remain viruses because of the way they replicate. There is still a lot of research to know if it could be anything else, but what is certain is that they are shed more and more light on biology,” Lamb says.

The study on the energy production of pandoraviruses is preliminary and has not yet been peer reviewed.

Potential danger?

Faced with the recent coronavirus pandemic, Scola recognizes that there is a growing tendency to classify viruses based on whether they can infect humans or not.

“But the world of viruses is very big. Pathogens are only a proportion something more studied. Right now there is no data to suggest that they may be dangerous,” concludes the expert.

Original source in Spanish

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