Various images of Yaravirus under an electron microscope
Various images of Yaravirus under an electron microscope
Image: Boratto, et al (bioRxiv)

Scientists in Brazil say they’ve made a mysterious discovery. They claim to have found a virus made of genetic material never before seen elsewhere. But you likely have nothing to fear from this virus: It seems to only hunt amoebas.

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The find is detailed in a paper released last month on the preprint website bioRxiv. Research showcased on bioRxiv hasn’t yet gone through peer review, and the data on the virus’s genetic structure, or genome, hasn’t been made public yet. This doesn’t mean the findings aren’t legitimate (nor does something being peer reviewed mean it’s definitely “true”), it just means a little more skepticism is warranted upfront.

According to the paper, the DNA-based virus was found in amoebas living in the muddy waters of an artificial lake in the town of Belo Horizonte, Brazil, called Pampulha. The early name given to the virus—Yaravirus brasiliensis—is a reference to Yara, an important mythical figure among the indigenous tribes that once resided in Brazil, the authors wrote.

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They were unable to find any likely relatives to Yaravirus after searching publicly available databases of viruses. And when they dug deeper, they found that more than 90 percent of its genes had never been documented before or had any connections to other known genes. Genes with no known evolutionary history are called ORFan genes in microbiology (pronounced orphan), potentially making Yaravirus an almost entirely orphan microbe.

“Here we report the discovery of Yaravirus, a new lineage of amoebal virus with a puzzling origin and phylogeny,” the authors wrote.

Scientists have found all sorts of viruses living inside amoebas, the usually single-celled lifeforms that move using finger-like projections from their body.

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These viruses have all been much bigger, genetically speaking, than the viruses that infect plants, animals, and people, leading to their classification as giant viruses. Giant viruses aren’t just bigger—they’re much more complex, allowing them to do things other viruses typically can’t do. Where in the history of life these viruses arose, including whether giant viruses could represent close relatives to the ancestor that gave rise to all viruses, is still unknown.

The researchers behind this new paper had previously discovered another group of giant viruses, called tupanviruses. But to make things even weirder, Yaravirus is far too small to be a giant virus, heightening the mystery of where exactly it came from. Provided the researchers are correct in their analysis, that could mean Yaravirus is either a very strange member of the giant virus family or the first known virus of its kind.

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In any case, the authors wrote, the discovery “reflects the variability existing in the viral world and how much potential of new viral genomes are still to be discovered.”

Science writer at Gizmodo and pug aficionado elsewhere

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