By Helen Branswell, The Canadian Press Published Wednesday, October 16, 2013 5:42PM CST Last Updated Wednesday, October 16, 2013 5:44PM CST

TORONTO -- Scientists at Canada's National Microbiology Laboratory are continuing to fine-tune a possible treatment for Ebola virus infection, one of the deadliest known to humankind.

In a newly published article, the Winnipeg-based scientists reported that their combination therapy saved three of four cynomolgus macaques and four of four rhesus macaques when it was given three days after the animals were infected with Ebola Zaire, the deadliest strain.

The scientists hope to test the drug cocktail in humans beginning in late 2014 or early 2015, if they can get approval from Canadian and U.S. drug regulators.

The work builds on earlier research which showed a cocktail of three cloned antibodies saved four of four primates when given 24 hours after infection and two of four treated 48 hours after infection.

This time the researchers added interferon-alpha, a chemical made by the immune system, to the treatment regime.

Two of four primates survived when they were given the chemical one day after infection, and then the antibody cocktail four days later.

In order for a treatment to be useful against the five types of Ebola viruses or their cousin, the Marburg virus, it must be something that can enhance survival when given days after infection, which is when cases would typically come to light.

"The concept of combining different treatments to improve efficacy and extend the treatment window is certainly interesting and the data look promising," Tom Geisbert, an expert in viral hemorrhagic fevers, said of the work. Geisbert is a researcher at the University of Texas Medical Branch in Galveston.

The senior author of the study is Gary Kobinger, head of the special pathogens program at the Winnipeg lab. The laboratory is part of the Public Health Agency of Canada.

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Canadian national lab scientists in Winnipeg work to fine-tune possible Ebola virus therapy