COVID-19 Day 85: Coronavirus came from bats. There’s more where that came from.

In the podcast “ This week in Evolution “ virologist Vincent Racaniello and geneticist Nels Elde discussed the origin and evolution of COVID-19. They discount the lab-derived origins of SARS-CoV2 (SARS2) for the simple fact that there are probably thousands of unknown bat coronavirus and that SARS2 likely came from an as-yet-unidentified bat species.

There are billions of bats in Asia. There are hundreds of thousands of bat colonies/roosts, each containing hundreds of thousands of bats. There are over a hundred species of horseshoe bats alone ( scientists believe hundreds more) and different strains of coronavirus can evolve in different colonies and species. It is therefore very likely that SARS2 evolved in one of these bat populations but nearly impossible to discover which one without sending scientists all over Southern China (where most virologists think SARS originated) to literally get viral samples from each colony to achieve certainty as to the origin of SARS2.

It would be logistically easier to get blood samples from all over China and identify human populations with COVID-19 antibodies that haven’t experienced a known outbreaks of COVID-19. It would be possible to backtrack and find the regional “home” of SARS2 this way. But the Chinese Government would have to devote considerable resources to do it and given the divisive geopolitical environment, there isn’t much motivation to do so.

Ebola, SARS, MERS, and now COVID-19 are all contagious diseases that evolved from bat viruses. This fact is exactly why it is vital that China and the world devote more resources to study bat coronavirus. We can’t stop natural animal viruses from mutating and infecting humans, but we should develop better means of warning ourselves when this happens.

Genomic sequencing has determined that the coronavirus strain that became the world-wide pandemic can be traced back to around October of 2019. COVID-19 could and probably existed in China before October but those earlier strains did not break out of their local communities like the Wuhan strain did. Again, extensive genetic testing of regional populations could determine this but we have other, more pressing priorities.

Another bat coronavirus mutated and infected civit cats (a mongoose/weasel-like mammal) before mutating and infecting humans sparking the SARS1 pandemic in the early 2000s. This is why virologists like those at the Wuhan Institute of Virology were focused on researching bat coronavirus. Speculation of a lab-based accidental release aside, the most accepted origin of SARS2 is through a bat or an unidentified animal that was in close proximity to humans.

SARS2 also bears some similar features to pangolin coronavirus but it is not a close match. The Chinese authorities reported that both animals were sold in the Wuhan Market but now that report has been largely discounted for lack of evidence that either horseshoe bats or pangolins were ever sold at the market.

Bats are unique among mammals in that they fly. This makes them some of the best insectivores in the world, some bats eat their body-weight in insects a night, helping to control pest insects. Because of this ability, they are able to cover a wide geographic area every night. And some bat species migrate during the year, further increasing their ability to disperse pathogens.

Brett Weinstein, a scientist who studied the evolution of bats, is more inclined to believe the lab-accident theory of COVID-19. He believes SARS2 or its immediate precursor could have accidentally infected a researcher at the Wuhan Institute of Virology and that individual accidentally infected people while shopping at the Wuhan Market.

Prof. Weinstein is quick to warn that this is a hypothesis, without documented proof, but he’s perplexed why other scientists are quick to dismiss this possibility without further investigation. Granted, the Chinese Government would have an incentive to not allow an independent investigation into this hypothesis. He stresses, this is all the more reason for scientists not to dismiss it out of hand.

Truth be told, I favor the lab-accident hypothesis myself. No, I don’t have proof. But I like it because it’s a narrative rich with human hubris and carelessness. Something you could easily imagine a techno-thriller created out of, like ‘The Andromeda Strain’. It’s much more exciting than a story about the randomness of nature. Oh wait, there was this movie about a worldwide pandemic started from bat poop, ‘Contagion’.


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