US drugmaker Merck has bought the rights to an experimental Ebola vaccine being developed by NewLink Genetics, the companies claimed.
The agreement gives Merck an exclusive worldwide agreement to research, develop, manufacture and distribute NewLink's rVSV-EBOV Ebola vaccine, originally developed by Canada's Public Health Agency.
Licensed by the Canadian government to the US firm NewLink, rVSV-EBOV is one of two experimental Ebola vaccines identified by the WHO as showing promising results when tested on monkeys.
The other vaccine, ChAd3, is made by British company GlaxoSmithKline and the US National Institute of Allergy and Infectious Diseases (NIAID).
There is no licensed treatment or vaccine against the Ebola virus, which has killed around 5,500 people in the outbreak centered in West Africa, according to the World Health Organization's latest data.
Total cases this year have climbed to more than 15,000 in the worst Ebola epidemic since the virus was first identified in 1976.
Julie Gerberding, president of Merck Vaccines, said the agreement with NewLink marked a significant step in fighting the scourge.
"Effective Ebola vaccines will be a critical component of comprehensive prevention and control measures for people at risk of Ebola virus infection and to stem future outbreaks globally," she said in a statement.
"Merck is committed to applying our vaccine expertise to address important global health needs and, through our collaboration with NewLink, we hope to advance the public health response to this urgent international health priority."
Clinical trials on NewLink's rVSV-EBOV vaccine are being conducted at the National Institutes of Health, the Walter Reed Army Institute of Research and in a WHO-coordinated collaborative effort in Switzerland, Germany, Kenya and Gabon, the companies said.
Merck will pay $30 million upfront to NewLink when the agreement takes effect and $20 million at the beginning of effectiveness trials for the licensed vaccine, expected to begin in the first quarter of 2015, according to the New Jersey-based global drug company's regulatory filing.
NewLink, a biopharma company headquartered in Iowa, will be eligible to receive royalties on the sale of vaccines in certain markets.
Shares in Dow component Merck were down 0.7 percent in early-afternoon trade, while NewLink shares leaped 2.8 percent.