How viruses jump from one species to the other

COVID Chat
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It is believed that although the coronavirus has originated in bats; but it has been transmitted from pangolins to humans. In an elaborate conversation on CovidGyan, Uma Ramakrishnan, a scientist at the National Center for Biological Sciences, Bangalore, talks about the origin of the coronavirus, and how viruses jump from one species to the other.

Even though the genome of the SARS-CoV-2 virus is shown to have about 90% similarity with those of Bats, the article highlights key differences stating that the virus that caused COVID-19 in humans did not jump from bats but through an intermediary host that is from pangolins. Inorder to understand transmission of viruses, the researchers study the receptor-binding domain site of the spike protein, that acts as an entry point for virus to enter into human cells.

To understand how the coronavirus may have jumped from one species to another, the article also provides interesting perspectives from two possible hypotheses – recombination and mutation, followed by natural selection.

A brief discussion also can be found on a triggering issue about whether the coronavirus has been naturally evolved and not made in laboratories or genetically engineered.

To know more about in detail, visit the article on CovidGyan website.

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"However, we have to remember that there are many unknown viruses whose genome we have not sequenced.

But the fact remains that overall, SARS CoV-2 is most similar to Bat CoV RATG13."

This is a contentious issue, and the article touches, but does not dwell, upon it.

‘Most similar’ is 96.2%, which is, I gather, about as similar as chimpanzees and humans. Then the connection with pangolins is inferred as being a property of the Wuhan wet market, although the Chinese obsession with pangolins is actually to the scale, not the rest of the animal (which fact is omitted from the article).

I would have liked to have seen a more rigorous analysis of the mutation theory, linked to actual forensic evidence from Wuhan. Of course, we know that the administrative authorities shut the market itself down very shortly after people began falling ill, so definitive forensics are not possible, but at least the inferences need to be so.

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