Certainly could be. If it was manipulated it's somewhat immaterial to the response, as they are doing that work currently, and saying they only lost control of wild type virus and not one of their juiced up baddies isn't much of a comfort.
What does that mean really? No worries, could have been even worse, but wasn't, so carry on then? Keep building bigger nukes to blow up more atolls? Gotta do better than that Dr. Shi.
Depends on the perspective you take. If someone is purposefully designing a virus, from the ground up, and then it got out, that's different from researchers having a virus (whether it was known or not to be in a sample) and it unknowingly infects a worker and gets out. Let me make it clear, both are bad. But one is at entirely different level of bad. Having someone design it and it get out really gets at the level of nefarious purposes.
The story and body of research refutes this tho. We have had the capability to engineer novel virus from parts of naturally occurring viruses for some time. They can be further enhanced for infectiousness in the lab with selection pressure through repeated passes through model cells.
As far as detection.. we could identify restriction enzyme fingerprints (one paper did) but you can't necessarily distinguish between a natural sequence if you don't know which restriction enzyme that was specifically used.
Also, one of the papers laid out a seamless ligation technique developed by a collaborating researcher that leaves no nucleotide disturbances after insertion of the sequence for study into the target genome.
And we know there is money to do this because we have the receipts from the NIH and Ecohealth.
No, that's not the fingerprinting or engineering I'm getting at. The vast majority of coronavirus reverse genetics system rely on either a bacterial artificial chromosome or having the genome split across multiple plasmids and essentially performing a golden gate assembly of the genome prior to in vitro transcription and subsequent transfection/electroporation. Both of those approaches don't involve intraviral restriction digest sites that would be detectable. Coronaviruses are so large its nearly impossible to find appropriate restriction sites for single cutters, and on top of it, portions of the genome is known to be toxic to bacteria.
Where the fingerprints would be is that long stretches of open reading frames of SARS-CoV-2 are unique. The technology simply doesn't exist for researchers to "create" unique nucleotide/amino acid sequences to assemble a functional protein. So any virus that is engineered in the lab, given the current technology, would be a chimera, consisting of several highly (>99%) identical sequences to previously known viruses.
That doesn't occur with SARS-CoV-2.
The differences between the most closely related genome cannot be explained by serial passage through cell culture as you claim. The paper that best represent the pressure of serial passage was done in
1997 where they passaged the virus 600 times. Each passage was 3 days each, so 3x600 = 1800 days or just under 5 years of continual passaging in culture. Even after growing the virus in the lab, the S protein only differed by
2.1% from the original virus. The closest neighbor to SARS-CoV-2 differs by 4% across the entire genome. When you look at the closest neighbor to SARS-CoV-2, and even if I remove the RBD domain (invoking a purposeful recombination event), what is the nucleotide difference between the S domains? 6.17%. So if you wanted to invoke that serial passage created SARS-CoV-2, using the mutation rate, it would have taken nearly 15 years of continual serial passage in cell culture
So no, it doesn't add up that current techniques could have generated SARS-CoV-2. Its too divergent from any known virus, so they would have been stuck making up sequences of unknown function and pathogenicity.
Truth is, without a great deal of transparency from the Chinese, as well as identification of the reservoir population for a natural origin explanation, it will be difficult to come to a firm conclusion one way or the other.
I think once a closer neighbor to SARS-CoV-2 is discovered, which predict will be found at some point, I think it will be more clear the engineered virus theory is bunk. It already fails to explain the current genome outside of somebody guessing what a functional nucleotide sequence is. Trying to invoke serial passage isn't possible unless someone has been passaging the virus since one year after SARS-CoV-1 was discovered.