Regeneron will work with the U.S. government to develop antibody treatments for the new coronavirus from China, disclosing Tuesday an expansion of a partnership that previously yielded an experimental drug cocktail for the Ebola virus.

The Tarrytown, New York-based biotech is one of roughly a dozen drugmakers now working on treatments for the coronavirus that emerged late last year in Wuhan, China. Most are smaller companies unlikely to possess sufficient funds to run large-scale tests, although Johnson & Johnson and Gilead have announced initial efforts in recent weeks.

The biotech hopes to replicate its past success in quickly advancing a treatment for Ebola. But, as that experience showed, proving a new antiviral isn’t easy.