The study, published in the Journal of Clinical Investigation, demonstrated that the aerosol Ebola vaccine activated immune cells in the respiratory system of rhesus macaques and provided full protection against the virus. The study was conducted by researchers at the University of Texas Medical Branch in Galveston and the National Institutes of Health in Bethesda, Md. It was the first attempt to use an aerosol to vaccinate monkeys against a hemorrhagic viral fever, the study’s authors said.
“The initial several decades of attempts to develop a vaccine against the Ebola virus were unsuccessful,” said Alexander Bukreyev, a virologist from the University of Texas Medical Branch and one of the paper’s authors. “This is one of the few vaccines that works.”
But the success of the vaccine in monkeys is no guarantee that it will work in people. This year, an Ebola drug that had been effective in monkeys failed to help humans.
The new vaccine can be administered without help from a medical professional. So if it proves successful in humans, the vaccine will be particularly useful in developing countries where there is a severe scarcity of doctors and nurses, as there is in West Africa, where the worst Ebola epidemic in history has yet to be extinguished.
“The discussion in the field right now is if this Ebola outbreak will be some kind of game changer for vaccine development, or will it only be one more scare that will be forgotten,” said Dr. Igor Lukashevich, a medical virologist from the University of Louisville, who was not involved with the study. “This aerosolized form of the vaccine is really what the field needs right now.”
The study’s lead author, Michelle Meyer, a postdoctoral fellow at the University of Texas Medical Branch, said the respiratory tract may serve as a portal for the Ebola virus if it is exposed to droplets of infected bodily fluids.
In the study, the aerosol vaccine generated substantially more Ebola-immunity cells in the lungs than in the blood and spleen. The cells “in the lungs are acting as the first barrier for protection,” Dr. Meyer said. “That’s ideal to combat the virus at the site of infection.”
Four of the rhesus macaques used in the research were given one dose of the aerosol vaccine; four were given two doses; and two were given the vaccine in a liquid form. Two monkeys were not vaccinated, serving as controls.
Four weeks after their treatments, all 12 monkeys were injected with 1,000 times the fatal dose of the Ebola virus. A little over a week later, the two unvaccinated monkeys succumbed to the disease and were euthanized, but the vaccinated monkeys stayed healthy. At the end of the study, the researchers euthanized the surviving monkeys, examined their blood and tissues, and found no traces of the Ebola virus.