zlacker

>>ruarai+(OP)
This is definitely not my area of expertise but:

role of furin cleavage site in covid:

https://www.nature.com/articles/s41392-020-0184-0

"In fact, no influenza virus with a furin cleavage site has ever been found in nature,"

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435492/

Where did this mutation come from?

>>waynes+Dp1
It's never been found in an influenza virus in nature, but covid isn't an influenza virus. Is this never found in coronaviruses in nature?

>>bugzz+Up1
From that second link:

> Although they only emerge under artificial conditions in influenza viruses, these furin cleavage sites are found within several branches of the coronavirus family tree. However SARS‐CoV‐2 is the only lineage B coronavirus found with one, and the only other coronaviruses known to have them are only at most 60% identical to this novel coronavirus.