Viruses can cause global pandemics, but where did the first virus come from?

Viruses such as Ebola, influenza and Zika make headlines. They grab our attention with their potential to cause widespread disease and death.

Health workers get ready to spray insecticide in advance of the 2016 Summer Olympics, in Rio de Janeiro, Brazil, to combat the mosquitoes that transmit the Zika virus in this Jan. 26, 2016 photo. (AP Photo/Leo Correa, File)

But where did these viruses first come from?

Unlike bacteria, viruses aren’t living organisms — they can’t reproduce on their own. Instead, they hijack cells to multiply, spread and cause disease.

But what if it wasn’t always this way?

Scientists studying a so-called giant virus called a Tupanvirus (named for the South American Guarani God of Thunder) found that it, unlike the viruses we encounter today, had an almost complete machinery to take care of itself.

This recent discovery has refuelled the debate over the origin of viruses.

Frozen viruses

There is no physical fossil record of viruses like there is for the dinosaurs.

One way scientists detect viruses, and study their origins, is to look for their genetic material— molecules of DNA or RNA — in animal tissues and soil.

Even though the movies might have you believe otherwise, viral genetic material has never been detected in fossilized plant leaves or in insects trapped in amber.

However, some ancient viruses have been detected in permafrost in Siberia, and there are hopes of discovering more as global warming continues to thaw ground that has been frozen for thousands of years. Until then, we remain limited in our ability to precisely reconstruct the origin of viruses.

Beautiful, but deadly. A colourized scanning electron micrograph magnified 20,000 times of Ebola virus particles (green) from a chronically infected African Green Monkey kidney cell (blue). (BernbaumJG/Wikimedia Commons), CC BY

The Conversation

Arinjay Banerjee is a PhD candidate in veterinary microbiology at the University of Saskatchewan.

Vikram Misra is a professor of veterinary microbiology at the University of Saskatchewan.

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