A GRANT PROPOSAL written by the U.S.-based nonprofit the EcoHealth Alliance and submitted in 2018 to the Defense Advanced Research Projects Agency, or DARPA, provides evidence that the group was working — or at least planning to work — on several risky areas of research. Among the scientific tasks the group described in its proposal, which was rejected by DARPA, was the creation of full-length infectious clones of bat SARS-related coronaviruses and the insertion of a tiny part of the virus known as a “proteolytic cleavage site” into bat coronaviruses. Of particular interest was a type of cleavage site able to interact with furin, an enzyme expressed in human cells.

The EcoHealth Alliance did not respond to inquiries about the document, despite having answered previous queries from The Intercept about the group’s government-funded coronavirus research. The group’s president, Peter Daszak, acknowledged the public discussion of an unfunded EcoHealth proposal in a tweet on Saturday. He did not dispute its authenticity.

Since the genetic code of the coronavirus that caused the pandemic was first sequenced, scientists have puzzled over the “furin cleavage site.” This strange feature on the spike protein of the virus had never been seen in SARS-related betacoronaviruses, the class to which SARS-CoV-2, the coronavirus that causes the respiratory illness Covid-19, belongs.