Behind Covid there was no laboratory, but only nature. A new study

Do you remember the famous argument that claimed to demonstrate the origin of Sars-CoV-2 as a work of genetic engineering, based on wrong calculations and dubious use of sequence analysis software? On these pages we had already dealt with it at the time, demonstrating how the theory behind the calculations, as well as the assumptions and conclusions, were simply arbitrary and erroneous: the famous cutting site for furin, in the Spike protein, appeared to be a very natural product of natural evolution. Not for nothing, the scientific article announcing the prodigious “discovery” subsequently found prompt denial in his methods and in his assumptions; and the authors of the original calculations, including Professor Palù, do not appear to have had anything to object to, despite the rash statements with which they had presented their erroneous analyzes and conclusions to the public.

Now, just over a year after those declarations in the national newspapers, a new work has come out, published in Nature Communications, which adds the strength of facts to the considerations of erroneous calculations and wrong theories, to deny the idea that the furin cutting sequence is a product of genetic engineering and to further support the idea that sarbecoviruses similar to Sars-CoV-2 can evolve spontaneously versions of the Spike protein, capable of binding human Ace-2 and thus confer favoring possible spillovers. In particular, by sampling only 48 bat feces samples corresponding to 16 of the 17 species present in the United Kingdom, 9 coronaviruses were found, of which 2 hitherto unknown to science, also including 4 sarbecoviruses, i.e. viruses of the Sars-CoV group -2. All 4 of the latter possess a nucleotide sequence in the right place which, except for a single nucleotide, is identical to the furin cutting site found in Sars-CoV-2, demonstrating the fact that in nature this sequence not only exists (as was already demonstrated), but it is found precisely in the group of viruses to which the agent of the latest pandemic belongs.

In addition, one of the 4 identified sarbecoviruses possesses a spike that is able to bind human Ace-2 and promote virus entry into the cell, as demonstrated by inserting the protein of this sarbecovirus into a different virus (for safety reasons). ). The affinity of this Spike for human Ace-2 is 17 times lower than that of the Wuhan strain of Sars-CoV-2, making it quite difficult to infect human cells, given the level of Ace-2 that those express; but the data demonstrates a commonly prevalent preadaptation in bat sarbecoviruses, from which it is easy to see how it can result in spillover and subsequent adaptation to new hosts. Then there is a really interesting fact that the authors present: the Spike that allows the new sarbecovirus to bind to human Ace-2 and the subsequent infection is not actually able to bind Ace-2 in bats which are the its natural hosts.

This means that the binding capacity of the human receptor is probably an accidental consequence of other adaptations in the original host, or of simple random genetic drift; that is, it is a pre-adaptation, which can be guided by the selection of other traits in the bat or it can be the result of a neutral and free change of the Spike sequence in a region not particularly constrained by selection. To choose between these two hypotheses, it will be necessary to better study the biology of the virus in its original host, the bat; but meanwhile, there is a plastic illustration of how spillovers work from an evolutionary point of view, with mutations driven by selection for other traits or by chance, which accidentally generate proteins capable of broadening the host spectrum of the virus. If bats carrying these versions are in frequent and massive contact with human beings, the passage of species takes place, and the subsequent optimization by selection; that’s why it happened in China, with its caves with millions of bats and guano miners, and not in Great Britain, where pre-adaptation is indeed present, but contacts between human beings and bats are very limited.

What we have briefly examined here obviously does not exclude the possibility that an accident is at the root of the pandemic; however, it excludes that the “proofs” adduced up to now by rashly examining the genomic sequence of Sars-CoV-2 are of any significance, and shows how science cannot be bent on the declarations of any authority, but only on the accurate analysis of available data and the compatibility of a theory with the rest of the scientific edifice. Perhaps one day we will find a tape-recorded confession of a researcher, that he caused an accident at the root of the pandemic; but nature, as all the data and particularly the latter demonstrate, is perfectly capable of producing Sars-CoV-3, Sars-CoV-4 and also Sars-CoV-100, and not only in China, but everywhere; for this, we would do well not to take refuge in the idea that the problem is in the laboratories, when billions of genetic experiments, all capable of giving rise to the next zoonotic virus, are happening around us in every animal species.