[throwanem]

These are great questions, and thank you for asking them!

1. Yes. The claim based on the misreading of the 2019 paper is that SARS-CoV-2 is actually a lab-created combination of another coronavirus and the human immunodeficiency virus, or HIV. If that were true, the genome of SARS-CoV-2 would incorporate large parts of the HIV genome verbatim. It does not; comparing these genomes for identical or nearly identical subsequences via BLAST, by far the tool most widely used for this purpose, shows no such similarity.

2. Viral recombination occurs when multiple related strains of a given virus infect the same cell at the same time. That can be done in vitro, but I haven't seen any papers from WIV describing such experiments. Notably, the frequently cited 2019 paper describes a totally different kind of experiment, which could not under any circumstances have produced a virus with the genome which SARS-CoV-2 has been observed to have.

3. For that to happen would require two different strains of the same virus to independently develop the same mutation allowing them to cross over and infect humans, and to simultaneously infect the same worker in the lab, and to then recombine in such a way as to produce SARS-CoV-2.

That is not impossible, but it is about as likely to occur as it is for every atom in your body to simultaneously transmute into gold.

[legolas2412]

Thanks for your answer. I'll like to point out that 3 is slightly eased off if the two viruses are already able to jump to humans. In this case, it could be the SARS coronavirus and the pangolin virus whose receptor proteins are similar to ncov19. Then all that is required is for the two viruses to jump over and then recombine. Definitely a possibility.

I find the wet market theory full of such improbabilities too. How is ncov19 relatively close to two known viruses, 1) the sars like bat virus it was 96% similar to, and 2) the pangolin virus with which it has resembling receptor proteins. Seems a lot of coincidence for these two to combine, both of which can jump to humans, and 300 meters from a leading Coronavirus research lab.

I know I'm just repeating the conspiracy theory, but just explaining my position. The virus was found initially at the wet market, and there is no proof of its origin being there. Plus it seems perfectly feasible for it come out of the lab and not be a deliberately engineered virus, atleast not one using the 2019 paper's chimera virus techniques.

[throwanem]

Compared to other families of viruses, coronaviruses recombine unusually often and are unusually likely to produce viable new strains that way. Those traits make them unusually capable of producing zoonoses, which is one of the reasons why they're a subject of particular interest among infectious disease researchers.

Those same traits also produce a high degree of similarity between a lot of genomically differentiable strains of coronavirus, especially since spike proteins tend to be strongly conserved for their direct effect on virulence - a significant mutation there is likely to be maladaptive, if it changes the protein structure enough for cells to no longer uptake a virion that expresses it. So it's not really a surprise to see that two different strains have similar spike proteins, and doesn't really give much basis for inference about relatedness between them.

Another important point is that coronaviruses are so common specifically in bats, which are both extremely plentiful and unusually accommodating hosts for many kinds of viruses including coronaviruses, very often with multiple strains infecting a single host at once. That gives coronaviruses - which, remember, are already good at recombining to produce new strains, every one being possibly able to jump species - more chances at that kind of recombination than they would have otherwise.

Too, bats shed virus in feces the same way humans do, and bat guano is so effective a fertilizer that wars have started over access to supplies of it. So it's not difficult or unlikely to postulate a chain of events like this:

- a recombination event in a bat produces a virus capable of infecting humans,

- which is then deposited in feces used to fertilize a human food crop,

- which is then harvested and taken to a city market to be sold,

- and all it takes for someone to get sick from there is not washing their hands often enough while they're cooking.

To be clear, I'm not saying this is what happened. Nobody knows that yet. But precisely because nobody knows that yet, it's important to consider the relative likelihoods of various ways that the pathogen might have developed into a form that can infect humans, and then reached the point of actually doing so.

That's what I'm doing here. Each stage of this postulated chain of events relies only on things that are already known to frequently occur, and have been so known since long before SARS-CoV-2 was even known to exist.

The result is unprovable, of course, just as with every other theory of this disease's origin that anyone has advanced so far. But it doesn't rely on any unusually small probabilities, and so it seems a lot likelier to me than the combination of a lab accident of a kind known to have happened only a few times in the last two decades, and a simultaneous superinfection of a single researcher with two different strains of coronavirus.

[legolas2412]

Thanks that was very educational.

[throwanem]

Happy to! I hope it's been useful.