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.

>>tshadd+qq1
I'm not waynesonfire, but seriously, what is up with people making deliberately misleading claims (e.g. highlighting it is not found in influenza viruses, even though covid virus is not influenza), and then providing a link that specifically debunks the implication they are trying to make.

It's like people just depend on nobody following the links they post.

>>hn_thr+Jr1
> However SARS‐CoV‐2 is the only lineage B coronavirus found with one

It's unusual even for coronavirus.

>>ekianj+os1
It's really only unusual for lineage B coronaviruses:

> Although they only emerge under artificial conditions in influenza viruses, these furin cleavage sites are found within several branches of the coronavirus family tree.

Even the original quote, "In fact, no influenza virus with a furin cleavage site has ever been found in nature" leaves out something important:

> the fact remains that every highly pathogenic avian influenza virus, defined by having a furin cleavage site, has either been found on commercial poultry farms that create the pseudo‐natural conditions necessary for serial passage, or created in laboratories with gain‐of‐function serial passage experiments.

That is, the authors are defining "in nature" not to include commercial poultry farms.