During the 1990s, a biowarfare expert named Ken Alibek defected from the Soviet Union and testified to Congress that the Soviet Union had been working on developing Ebola as a weapon. I was a virologist, and I was working at U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) in western Maryland, not far from where I grew up. At the time, the only biosafety level 4 (BSL4) labs in the U.S. were at the CDC and USAMRIID, and there was interest from the Department of Defense to study Ebola. We certainly were doing things to develop different countermeasures like vaccines, treatments, and we were trying to understand the virus.

That got us to a point—to the point of taking some of the better ideas and showing that they worked or didn’t work. But that’s where it stopped. There wasn’t money or interest or time to take those products across the finish line.

But I’ve never been somebody who toes the line. I just looked at Ebola as a challenge. I’m not the kind of scientist who sits at a desk. I’ve got to be in the middle of it, in the space suit in the lab, in the thick of it. When I do this work, I take it personally. You go through all those times when it doesn’t work, it doesn’t work, it doesn’t work, and it’s so frustrating, so mentally draining, so demeaning, physically and mentally.

But after 9/11, everything changed. There was increased funding. It was fortunate for me, because Ebola was my main area of interest. When all the money became available, we started looking at developing a vaccine. The idea came from Heinz Feldmann, then at the Public Health Agency of Canada (now at the National Institute of Allergy and Infectious Diseases), and the first big success we had was in 2002 or 2003. We did two back-to-back studies, and this was the first vaccine that completely protected monkeys from Ebola.

Everything about the disease in monkeys is so much like in humans. So even though you can’t say for 100% it’s going to work in humans, you know the odds are 99% that if it works for monkeys, it will probably work for people.

I remember walking in that room where I was used to seeing dead monkeys, and five, six, seven, eight, twelve—all the monkeys are healthy, no signs of disease. In my field and what I do, that’s the greatest feeling you can imagine.

When I started doing some of the first studies [on drug treatments] in the ’90s, I would get excited because something I tried worked in guinea pigs or mice or something. Then you’d get excited: “Oh man, this is going to be great.” But there’s a quantum leap from rodents to nonhuman primates like monkeys. It turns out rodents aren’t very good models for Ebola infection. All of a sudden you do it in monkeys, and all of the monkeys died. We had so many failures in the 1990s. It was a terrible feeling.

I’ve got shelves and shelves and shelves and shelves of stuff that slow or inhibit growth of Ebola in culture. Dozens of those protect mice or guinea pigs. Only two worked in nonhuman primates, out of all the studies done in the BSL4 lab—and those are ZMapp done by [Dr. Gary Pignac Kobinger (born 1969)] in Canada and TKM-Ebola, which I worked on with biotech company Tekmira.

When you do have success, like when we did the TKM-Ebola study, there is no greater feeling. There is no greater feeling than walking in when you know it’s going to work, you’ve got healthy animals—that feeling is awesome. When we did our first study with TKM-Ebola on monkeys, I was like, It would be good if we get 50% protection, it’s a home run. I didn’t expect 100% protection.

In this Ebola outbreak, we know at least four to five people got the TKM drug, and all have survived. But we don’t want to say the drug was the reason they survived. While we hope they helped in patients, we can’t say for sure because the patients got so many other things. There are so many confounding variables, so how can you say any one thing made the difference?

But it’s a great feeling knowing I was involved in the development of something that hopefully saved somebody. And if it saved one person, it matters. —as told to Alice Park