Merck & Co. has obtained the rights to an experimental Ebola vaccine developed by NewLink Genetics Corp., another sign of the scramble by pharmaceutical companies and other groups to find new ways to combat the deadly viral outbreak centered in West Africa.

The companies said Merck will pay NewLink $30 million upfront, plus an additional $20 million when new clinical trials to test the vaccine’s efficacy get under way, which is expected by the first quarter of 2015. Merck also will pay royalties to NewLink on sales of the product if it is approved for sale, excluding Africa and certain low-income countries.

There are currently no vaccines approved to protect against Ebola virus.

NewLink, of Ames, Iowa, has been developing a vaccine dubbed rVSV-EBOV, which NewLink licensed from the Public Health Agency of Canada. The vaccine uses a weakened strain of a different virus, vesicular stomatitis, which typically afflicts cattle. The weakened viral strain is modified to express an Ebola virus protein to help trigger an immune response to Ebola. Early-stage testing of the vaccine has begun at the Walter Reed Army Institute of Research in the U.S., to assess the vaccine’s safety and appropriate dosage.

The U.S. National Institutes of Health is planning a larger, human study in early 2015 to test rVSV-EBOV as well as another experimental Ebola vaccine co-developed by the NIH and GlaxoSmithKline PLC. Johnson & Johnson also is developing an experimental vaccine in partnership with Bavarian Nordic of Denmark.