HAMILTON – Andrea Marzi celebrated Thursday night. The Rocky Mountain Laboratory staff scientist had good reason.
Earlier that day, her manuscript documenting a study that showed a single dose of an experimental Ebola vaccine would protect a macaque primate against the current and most deadly strain of the disease if given seven days before exposure was officially published.
“For me, this is a highlight of my career,” Marzi said. “I’m very excited about it.”
Conducted at the National Institutes of Health’s laboratory in Hamilton earlier this year, the study also found that primates were partially protected from the disease if given three days prior to exposure.
“That was a big surprise and very good surprise,” Marzi said. “We were all very excited about this data.”
The very same vaccine is now being used successfully in Africa to protect people from becoming infected with Ebola in the first human trials, currently occurring in Guinea.
So far, the vaccine has provided 100 percent protection to more than 4,000 people given the vaccine 10 days before exposure to the disease.
The vaccine was originally developed by RML Chief of Virology Dr. Heinz Feldmann more than a decade ago when he was working in Winnipeg at Canada’s National Microbiology Laboratory with immunologist Thomas Geisbert. In 2005, the scientists showed the vaccine protected monkeys against lethal doses of Ebola after a single injection.
During the recent and most deadly outbreak of the disease, Marzi and Feldmann worked together in Liberia studying the spread of the disease.
At the time, Marzi said there was no vaccine available.
No one knew for sure if the vaccine developed earlier by Feldmann would be efficient against the newest strain of the Ebola virus.
“We also were wondering that if we did have this vaccine, how long would it take before people were protected,” Marzi said.
When the researchers returned to Hamilton, they designed a study that would vaccinate macaques 7, 14, 21 and 28 days before they were exposed to the virus.
Earlier research showed the vaccine would likely be effective if provided two weeks before exposure to the disease, but a week seemed like too short of a period of time.
“We were pushing the limits in what we thought the minimum time would be,” Marzi said.
Even more encouraging, the vaccine also triggered an innate virus-fighting immune response that provided some protection against the disease after the first three days. The animals vaccinated more than a week before exposure developed antibodies, the adaptive immune response shown to be critical for protection.
Prior to the RML study, scientists didn’t know how monkeys vaccinated with the experimental Ebola vaccine would respond to the newest strain that spread across West Africa and infected more than 28,000 people.
Earlier tests had shown the vaccine would protect monkeys from the first recognized Ebola strain that appeared in 1976 and a second strain that emerged in central Africa in 1995.
The RML study concluded that the vaccine would likely provide equal protection against the different strains.
Last week, another study was published that focused on the early successes of the current human trials.
Marzi said the Hamilton-based study supports its findings.
The hope now is the research will help lead to a vaccine being licensed, which would allow for additional production of the product.
Before the latest outbreak of the disease that occurred in urban settings, the two earlier epidemics happened in rural areas where few people were impacted and the disease was easier to contain.
At the time the last outbreak, there were only 1,000 doses of the vaccine available in Canada, Marzi said.
“There was just not enough available to make a difference,” she said. “And then there was no proof that it would even work against the new virus. It is great that everyone has pulled together and the clinical trials have happened as quickly as they have.”
“Let’s hope and keep our fingers crossed that we’ll soon have an Ebola vaccine approved,” Marzi said. “We’re really excited that it is being used and seemed to work. It’s a good time to celebrate that.”