How SARS2 was stitched together
Nowadays,SARS2 like viruses can be generated in lab within weeks https://t.co/uWAI0oMrIU
If this was possible in Wuhan 2018/19 is debatable.
However, Shi Zhengli had 2 grants to investigate which manipulations enable bat viruses to go pandemic.
1/x

This was pointed before by members of DRASTIC https://t.co/By9hljwjuY, @TheSeeker268 @ydeigin
CV: https://t.co/fXlqRIJoWO
Let's say the WIV did not have yeast artificial cromosomes yet, they would have had to rely on bacteria as described here:
https://t.co/F4C9HfVcXv
2/x
This method has now evolved using in vitro assembly and transcription, which significantly speeds up the process and reduces costs, as described here:
https://t.co/Qi180L3c9u
In either case, one would need a special kind of Type IIS endonucleases (DNA cleaving enzymes):
3/x
These relatively rare enzymes cut outside of their recognition site and can produce variable 4 nucleotide long DNA sticky ends. Different sticky ends enable an ordered assembly of the full viral genome by ensuring that always the right ends are stitched together by ligases.
4/x
Also, there should be not too many fragments, and fragments should not be longer than ~8 thousand bases.
All these parameters, that do not have any advantage in natural evolution, are miraculously also met by SARS2.
This backbone also enables super easy RBM/FCS manipulations.
5/x
Miraculously, the S1 spike, pangolin-derived RBM, and MERS-like FCS can all be conveniently replaced with simple BsaI digests and new inserts.
Such variants of RaTG13 could be produced for a few $100.
6/x
Lets take a look at RaTG13, the most likely template virus.
The restriction sites are much less irregular, the first fragment would have probably been to big (10.4kb)
Some sites were re-used (doesn't alter the protein sequence), others newly removed/introduced.
smoking gun#4?
7/7
Side note: all sticky ends derived from such a SARS2 digestion are different, which is required for proper reassembly. This in itself is not very unusual given there are 4^4 possible sticky ends.
Side note2: we see 1-2% mutations between RaTG13 and SARS2 on protein level, suggesting that the recombinant RaTG13-PangolinRBM-FCS CoV was subsequently cultured (=tested for infectivity) on human cells/in ACE2 transgenic animals. We could have lost a cleavage site there.
Side note3:
yes, this is no ultimate proof that SARS2 was build in a lab.
It's yet another BIG smoking gun inconsistant with natural evolution.
I picked a provokative title as virologists seem to be ok with condemning origin theories in @Nature with zero evidence these days.
Side note4:
wow, this has gone viral🙃.
I do not want to tell anybody how to interpret this.
Still, few personal notes:
-none of this indicates SARS2 was build as a weapon
-the aim of the project may have been understanding pandemics
-warnings were ignored & safety abysmal (BSL2)
-similarly risky research has been done in the US and Europe as well
-it has seen a boom since the pandemic
-it is done mostly unregistered, unregulated and under inappropriate safety conditions
-this mess could be much worse if the technology got into the hands of terrorists
😱
Side note5: for specialists:yes, some evidence suggests RaTG13 was manipulted/not the direct template of SARS2. RaTG13 could also be a cousin derived from different passaging experiments with the same, 98-99% RaTG13 identical ancestor (Ra4991?).
https://t.co/efJe7adVFX
1% difference on protein level is not that much.
Delta variant is ~1.5% different in S1 from first SARS2 samples, mutations can accumulate faster during lab passaging.
The reason that we do not know for sure is not the lack of evidence, it's the lack of access to the evidence!

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