Where Does the Ebola Virus Hide Between Outbreaks?

Joe DeRisi standing in his lab
Photo by Steve Babuljak

Joe DeRisi, PhD, is a master detective of infectious diseases. No matter how obscure or complex, he says he’ll take on the challenge because “it could lead to new biology that we wouldn’t have discovered otherwise.”

That's precisely what happened when he stumbled on a clue to cracking the decades-long search for the place – or creature – where the Ebola virus hides between deadly outbreaks.

You might be thinking, “Isn't Ebola carried by bats?” In a recent episode of UC San Francisco’s Carry the One Radio, DeRisi – a UCSF professor of Biochemistry and Biophysics and co-president of the Chan Zuckerberg Biohub – revealed that the evidence isn’t as strong as you’d think.

Because the general consensus has settled on bats, most Ebola investigations have been biased to focus on the flying mammals. By taking on a seemingly unrelated case years ago, DeRisi’s team was able to take the field in a totally unexpected direction.

In 2009, DeRisi began studying an incurable disease that was killing reptiles raised in captivity, a disease that caused strange neurological symptoms ranging from vomiting to uncontrollable contortions. They found the culprit – a previously undescribed arenavirus – and uncovered something surprising: the Arenavirus’s glycoprotein, a viral “access badge” to the secure insides of a cell, actually belonged to the Ebola virus.

This fascinated DeRisi. After all, if the arenavirus could use Ebola’s access badge to infect reptiles, there was a pretty good chance that Ebola itself could infect reptiles as well.

In collaboration with an extremely secure infectious disease facility at the National Institutes of Health, DeRisi discovered exactly that: in a petri dish, Ebola can infect reptile cells with ease. Crucially, the cells survive the infection, making reptiles an excellent candidate for an Ebola “reservoir” species, a place where the virus can take shelter between outbreaks.

There’s another fascinating twist to the story: So far, there are no known examples of deadly viruses that can jump between reptiles and humans – except in folklore. The most common Ebola origin story from the 2014 outbreak involves a woman with a mysterious bag that, when opened, led to the infection and decimation of the whole village. Can you guess what was in the bag?

Since the late 1970s, scientists have scoured the globe to find the animal that carries the Ebola virus between outbreaks, with little success. DeRisi’s discovery may provide the key to unlocking this deadly mystery.

Hear the full story on Carry the One Radio: