How likely are you to survive an Ebola infection? Not very likely, with mortality rates as high as 90 percent for certain strains of the virus.
Led by Gary Kobinger, immunologists at the Public Health Agency of Canada in Winnipeg gave 74 macaques an experimental Ebola vaccine, either directly after infecting them or 28 days beforehand.
When they monitored immune responses to the infection and vaccine, researchers noticed a specific antibody seemed correlated with survival. Survivors possessed, on average, eight times the amount of the antibody than the monkeys that died did. Antibody levels also allowed extremely accurate predictions as to whether or not a monkey would survive infection.
Kobinger clarified these antibodies aren’t necessarily responsible for fighting off the virus themselves; but they do seem to provide some sort of protection, at least long enough for the immune system to marshal all its forces. Kobinger did venture an estimate that the antibodies are responsible for 70 percent of viral clearance, with T cells providing about 20 percent.
This research, published on Oct. 31 in the Science Translational Medicine journal, could pave the way toward human trials of the vaccine. Kobinger also expressed confidence the predictive ability of the antibody would hold true in human subjects as well as monkeys.
“What this tells you is what can you look at with the immune response that can tell us if this person is protected,” he said.
The downside is that the power of these antibodies might not extend to all kinds of Ebola. Nancy Sullivan, an immunologist at the National Institute of Allergy and Infectious Disease, emphasized this caution while still pointing out the positive side of the research.
“The study supports the notion that for some gene-based vaccines, the antibodies are correlative of protection,” she said.
The road to curing Ebola remains a long and hard one, but scientists like Kobinger and his team are steadfastly forging ahead — one step at a time.