The Ebola virus causes a hemorrhagic fever that is usually deadly.
We don't pay all that much attention to animal tests of experimental treatments. So many approaches that look good early on never make it in the real world.
But, let's face it, when it comes to the deadly Ebola and Marburg viruses, you don't want to be testing the effectiveness of treatments in people for viruses that kill them 80 percent or more of the time.
So the military and researchers from biotech firm AVI BioPharma tried experimental drugs that jam the genetic machinery inside cells that the viruses need to reproduce.
When injected into monkeys starting within an hour of infection with the viruses, the treatments helped 60 percent of the animals infected with Ebola and all of those infected with Marburg survive.
There are no effective treatments for either virus, so even progress on medicines that would have to be given very quickly after infection is promising.
The experiments, just published online by Nature Medicine, were designed to mimic what would happen after someone gets infected accidentally in a research lab or hospital. Previous tests in mice suggest the treatments might still work if given later, but that hypothesis needs more study, the researchers say.
Earlier this year, another group of researchers taking a similar tack with a different experimental medicine that interferes with Ebola's ability to replicate also got promising results.
Under special rules, the Food and Drug Administration would evaluate the effectiveness of a new treatment for the deadly viruses based on animal experiments. Human tests would focus on the side effects of treatment.
AVI BioPharma says the agency has given the go-ahead for those trials to begin.