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Say hello to cousin Ebola: Viruses are alive and are our distant relatives, researchers claim

Scientists identified hundreds of proteins shared by viruses and cells
Argue modern viruses and cells share 'sibling' ancestors
Say viruses merit a place on the tree of life

Published: 18:10 EST, 28 September 2015 | Updated: 19:09 EST, 28 September 2015

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Viruses deserve a place on the tree of life and are they're 'siblings' of humans' genetic ancestors, a new study has claimed.

While centuries of scientists have held that viruses are not living things, University of Illinois researchers found that viruses and cells share hundreds of common protein structures.

That, they say, is solid evidence that the two share closely-related ancestors.

Viruses such as Ebola (pictured) deserve a place on the tree of life and are they're 'siblings' of humans' genetic ancestors, a new study has claimed.

'This tells you that you can build a tree of life, because you've found a multitude of features in viruses that have all the properties that cells have,' said lead researcher Gustavo Caetano-Anollés, crop sciences and genomic biology professor at University of Illinois.

In the study, appearing in Science Advances journal, Caetano-Anollés and his graduate student, Arshan Nasir, argue that early viruses were remarkably similar to the cells from which humans and modern organisms descended.

Historically, scientists have had difficulty determining where viruses come from, because there are so many kinds, and they evolve or mutate incredibly quickly.

Many scientists say that viruses aren't even part of the tree of life—suggesting that they can't be alive if they don't have metabolisms and they can't independently reproduce.

But that argument overlooks the way that viruses can form networks, the authors argue.

When viruses infect cells, taking over in order to reproduce, they act very similar to many parasitic bacteria—which are fully accepted as living.

'Viruses now merit a place in the tree of life,' Caetano-Anollés said.

'Obviously, there is much more to viruses than we once thought.'

The authors say the early viruses, 'proto-virocells,' coexisted with ancient cells until early viruses started to adapt.

Adenovirus one of a large group of viruses causing disease of the upper respiratory tract and conjunctiva. Researchers argue rgue that early viruses were remarkably similar to the cells from which humans and modern organisms descended.

They shrank until they lost all resemblance to their cousins, and started to wrap themselves in protein for protection.

By the time those proto-virocells transformed into modern viruses like Ebola, which has only a handful of genes, they were virtually unrecognizable.

The researchers say their methodology has its shortcomings—they relied on protein structure and not actual sequences, meaning they skipped over short-term evolution patterns that could be worth noting. But the statistical models they used accommodated for that type of data.

Ultimately, they say their findings lay a solid and important groundwork for further research in the area.

'[W]e hope that our study will initiate further discussions of this topic and that a consensus regarding viral evolution will be reached in the near future,' they wrote.