Alright. I can verify the meaning and significance. I have a PhD in chemical biology, and have done (non-pathogenic) gain of function research. This is the sort of result that I would expect someone to have found if I were given the charge to insert a furin cleavage site into a virus. Proof: https://bmcbiochem.biomedcentral.com/articles/10.1186/1471-2... ,in which I stack-overflow-copy-paste ideas for beneficial mutations from sequences in distant species.