Thread by @Ayjchan

Many scientists have known for a long time that the logic in Proximal Origin is fundamentally flawed.

David Relman published a counter response in PNAS in Nov 2020.

How one genetically engineers a virus depends on what sequences are in their toolkit.
pnas.org/content/117/47…

Yet 4 of the 5 Proximal Origin authors continue to push this flawed logic in their recent @CellCellPress review on #OriginOfCovid

"There is no logical reason why an engineered virus would utilize such a suboptimal furin cleavage site"

pubmed.ncbi.nlm.nih.gov/34480864/

In short, these scientists speculated that what we see in SARS-CoV-2 is not how a scientist would logically engineer a novel S1/S2 FCS into a SARSr-CoV and they contended that there is no evidence of research at the WIV that artificially inserted complete FCSs into coronaviruses.

Barely 5 days after the Holmes et al. critical review was published in @CellCellPress the DEFUSE proposal was leaked online, providing evidence that the WIV & collaborators had a roadmap for inserting FCSs into SARS-like viruses.

@CellCellPress I wrote in July: "we have little insight to the viruses and virus sequences available to scientists and the experiments being conducted in labs prior to the.. Covid-19 outbreak — these would have a great influence on the types of insertions being made"
ayjchan.medium.com/a-response-to-…

@CellCellPress People who don't know better could easily buy into the Proximal Origin flawed argument that SARS2 must not be genetically engineered since it's not how they think scientists would've engineered it.

But scientists who engineer organisms/viruses know this reasoning is bunk.

@CellCellPress It worries me that top voices advising US intelligence & defense are not able to comprehend that labs in other nations have private databases of virus samples & sequences.

Without access to these data, how could we predict exactly how scientists are engineering novel viruses?

@CellCellPress The correct answer at the time and even today is: We don't have access to the data that would enable us to confidently determine whether or not the SARS-CoV-2 S1/S2 FCS insertion is natural or artificial.

+Even if it is natural, it doesn't mean the virus did not leak from a lab.

@CellCellPress The difference between early 2020 and today is that we know there is a way to investigate. The EcoHealth Alliance must have communications, data and/or documents (drafts) relating to their Defuse proposal and the section on detecting and inserting cleavage sites into SARSrCoVs.