The drug, ZMapp, was even shown to be effective in later stages of the infection, trails showed.
Researchers, who published their findings in the medical journal Nature, said the results were a ” very important step forward”.
However, the limited supplies of the drug will not be able to help the 20,000 people reportedly infected during the outbreak in West Africa.
Dubbed the ‘secret serum’ – as it is still in the experimental stages of drug development – there has been no public data on the effectiveness of ZMapp.
But in their desperation, doctors have turned to the drug, as there is currently no cure for Ebola, which is responsible for more than 1,500 deaths in Guinea so far.
ZMapp is a combination of three antibodies – a part of the immune system which bind to viruses.
Clinical trials on 18 rhesus Ebola-infected macques showed 100 per cent survival. This include animals who were given the drug up to five days after infection – three days before the disease becomes fatal.
A significant step considering therapies have needed to been given before symptoms of the disease appeared in the past.
“The level of improvement was beyond my own expectation, I was quite surprised that the best combination would rescue animals as far as day five, it was fantastic news,” one of the study’s researchers, Dr Gary Kobinger from the Public Health Agency of Canada, said.
“What was very exceptional is that we could rescue some of the animals that had advanced disease.”
So will the drug be as effective in humans?
Well, results in human trails have been mixed. A liberian doctor and a Spanish priest both died from Ebola despite ZMapp treatment.
Yet a British citizen and two US doctors who contracted the infection have fully recovered after taking the experimental drug treatment.
Dr Kobinger acknowledged that, while the course of infection in humans is much slower, : “We know there is a point of no return where there is too much damage to major organs, so there’s a limit.”
The Researcher and his group wants to start clinical trials in people to truly assess the effectiveness of the ZMapp drug.