> Within the scientific community, one thing leapt off the page. Wade quoted one of the world’s most famous microbiologists, Dr. David Baltimore, saying that he believed the furin cleavage site “was the smoking gun for the origin of the virus.” Baltimore, a Nobel Laureate and pioneer in molecular biology, was about as far from Steve Bannon and the conspiracy theorists as it was possible to get. His judgment, that the furin cleavage site raised the prospect of gene manipulation, had to be taken seriously.
Furin cleavage sites have evolved and are present in multiple coronaviruses:
- HCoV-OC43 (infects humans)
- HCoV-HKU1 (infects humans)
- MHV-A59
- ChRCoV-HKU24
- BtCoV-ENT
- BtNeCoV-PML-PHE1
- BtCoV-HKU4
- BtCoV-HKU5
- MERS-CoV
- BtHpCoV-Zhejiang2013
- SARS-CoV-2
Phylogenetic analysis suggests that it has evolved independently at least 6 times that we know of.
https://www.sciencedirect.com/science/article/pii/S187350612...
After that article was published a team in Thailand found furin cleavage sites in sarbecoviruses closely related to SARS-CoV-2 called RacCS203 (91.5% similarity to SARS-CoV-2) and RmYN02 (93.3% similarity to SARS-CoV-2)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873279/
Furin cleavage sites are common, nature understands how to utilize that trick very well, and continuously has re-discovered it.
The closest genetic match is only 3.8% similar. When it only has 29,903 base pairs, that's 1,136 mutations. I'm no bioscientist but my friends who are tell me that's a lot of changes, and that experiments might change a few base pairs or proteins at a time. A lab leak theory doesn't explain how gain of function study resulted in so many mutations, unless they were blasting these viruses with radiation, and what would be the point of that? Radiation mutations would cause too many changes to do useful science.
Everyone keeps looking at bats but the closest bat coronavorus is 20 years of evolution away. SARS and MERS came from palm covets and dromedary camels respectively, so what's the deal?
Every time I read about this I keep thinking "huh that's sketchy but circumstantial" and I've yet to find an answer to how the lab would've gotten to this point, undiscovered, with no published papers or research or notes or preprints anywhere
Or explicitly creating chimeric coronaviruses, which has been the state of the are for some time. Here's https://pubmed.ncbi.nlm.nih.gov/26552008/ one of the sources of smoke on this, a 2015 paper co-authored by the Bat Woman (2nd to last author), the key sentence from the abstract:
Using the SARS-CoV reverse genetics system, we generated and characterized a chimeric virus expressing the spike of bat coronavirus SHC014 in a mouse-adapted SARS-CoV backbone.
Have you read the fine article? It cites more than a few papers.
The mutations on covid 19 are Really Different compared to the known and studied viruses. If it was a lab leak of an engineered chimera, you'd be able to see that A proteins came from virus X and B proteins came from virus Y and Z, but that hasn't been shown to be the case. From what I understand there are a bunch of smaller mutations across a lot of proteins resulting in something that doesn't really line up with known and studied genomes.
This paper actually goes through and compares the DNA of covid 19 against several other studied viruses: https://www.nature.com/articles/s41579-020-00459-7
I guess I don't find the argument "we can't figure out how to reconstruct SARS-COV-2 from known viruses" very convincing on either side.