5 ms·

> So why would Covid-19 even need to come from a lab? We (humans) had wet markets filled with animals, including the very bats that carry the base virus. It's t

> So why would Covid-19 even need to come from a lab? We (humans) had wet markets filled with animals, including the very bats that carry the base virus. It's the perfect breeding ground to create a pandemic-level virus and probably a few thousand more viruses of lesser impact. The question of how it got to Wuhan all the way from Southern China remains unanswered. There weren't any bats sold on the wet markets, nor has any other host animal been identified. The virologists working in Wuhan did travel all the way to Southern China to collect bat coronavirus samples and they did perform gain-of-function experiments. Viruses - even highly pathogenic ones - have escaped labs on numerous occasions. There is a plausible scenario here. There is another plausible scenario, which is that "ground zero" for Sars-CoV-2 is actually Southern China, just like Sars-CoV-1. However, the virus wasn't discovered there first, because it didn't cause enough illness. The outbreak in Wuhan, the 9th largest city in China, would've been discovered by chance.

emmelaich 6y ago
Good points, and I tend to think the 'escaped from a lab' case is at least as strong as the zoonotic one. A small counterpoint though -- the market is the Huanan market, i.e. specialising in south china sourced or styled food. I would not be surprised if some exotic animals were there but never admitted to.
- roenxi 6y ago
  Although reasonable, one theory ("the bat coronavirus was transported by scientists to the lab that studies bat coronaviruses") involves no illigal activity. On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan") involves speculation that something happened that we don't know about. Strictly speaking, the lab leak theory has more observed evidence. Presumably the Chinese government would have identified and explained if they found bat traffickers. We know the lab was aware of RaTG13 - they produced a sequence quickly that no-one else had seen. I know nothing about the situation but it would be interesting to know where exactly the sample was being sequenced. I doubt they did it in the mine, samples must have been transported to some lab. I used to think 99% chance zoonotic, but the fact the similar virus was known to the lab was enough to drag me to thinking it is probably a toss up. Lab leaks do happen, this lab was studying bat coronaviruses. It is possible.
  - DanBC 6y ago
    > On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan") One theory is that people mine bat guano from caves, so there's no need for them to ever touch a dead bat.
  - treis 6y ago
    >he similar virus was known to the lab was enough to drag me to thinking it is probably a toss up. A human generated virus wouldn't be similar in this way to a wild one. You would take a candidate virus and splice in genetic material from a different one. The new virus would match 100% in most places and then be completely different in a few places.
    - mgamache 6y ago
      This is not how they conduct gain of function research. It's uses serial passage (using biological hosts and the virus's own variations). This produces vary little evidence of manipulation.
RobertoG 6y ago
>>"The virologists working in Wuhan did travel all the way to Southern China to collect bat coronavirus samples and they did perform gain-of-function experiments. Viruses - even highly pathogenic ones - have escaped labs on numerous occasions. There is a plausible scenario here." Another plausible scenario, in my opinion, is that the virus was brought to Wuhan by the virologists (in the virologist or their helpers) but never escaped from the lab itself. If you have a bunch of people periodically going to interact with the bats, how improbable is that they get infected of something (unknowingly) on site?
- inciampati 6y ago
  It's very unlikely that you'd get a one step transfer from a bat that yielded a spike protein with the level of affinity it has for human ACE2. If you look at that protein alone, the most-likely proximal hosts are primates. If we seriously believe in zoonotic transfer, we should be looking at those populations, and understanding how orangutans and bonobos infiltrated Wuhan and transmitted the virus to unwitting humans. The other recent coronavirus spillovers actually have rather low infectivity that increases with the course of the epidemic through adaptive mutations. But amazingly, with SARS2, it appeared already fully adapted. The phylogenetic tree makes a clear statement about how long SARS2 has been circulating in humans. At the publication of the genome sequence there were only a handful (~4?) of mutations known and most SARS-CoV-2 genomes were, incredibly, nearly identical. See https://nextstrain.org/ncov/global https://nextstrain.org/ncov/global. If we tend to see one mutation per transmission, that would mean that the spillover happened in October or November 2019, and almost certainly in Wuhan. All SARS-CoV-2 we've observed fits into this single tree, and there is no evidence of any previous progenitor strains. This means that SARS-CoV-2 was fully-adapted from its most-recent common ancestor. What are the odds of that happening directly from a bat? We're only now seeing, with b1117, a big phenotypic jump related to changes in the spike protein. It has arisen in a context that suggests that it may also be the result of strange environmental conditions for the virus that are capable of accelerating its exploration of the solution space. A widely-considered hypothesis is that it arose in an immunocompromised patient receiving antibody treatment and convalescent plasma, both standard practice in the UK. In this context the virus could have achieved extremely high population (~ many candidate solutions, faster evolutionary computation) and feedback about the immune response of the entire population (to the degree that they would have received multiple donations of plasma).
mabbo 6y ago
> The question of how it got to Wuhan all the way from Southern China remains unanswered. It's also important to remember that the related virus we're talking about in southern China was identified in 2013. More than six years before the outbreak. It didn't stay still. It hopped around, bat to bat, maybe to other animals. We don't have the history of the virus since then. It could have very well made the jump the humans or some other animal, years ago but only recently made the last few mutations to become the beast it is now. Plus, it's a virus. It didn't take one path, it took all of them that it could. Each virus created a million more, repeat ad-infinitum. So the idea that there's some mystery to how it traveled to Wuhan doesn't bother me. Viruses get around.
lamontcg 6y ago
> The question of how it got to Wuhan all the way from Southern China remains unanswered. There are coronavirus-carrying bats in Hubei province.

emmelaich 6y ago

Good points, and I tend to think the 'escaped from a lab' case is at least as strong as the zoonotic one. A small counterpoint though -- the market is the Huanan market, i.e. specialising in south china sourced or styled food. I would not be surprised if some exotic animals were there but never admitted to.

roenxi 6y ago
Although reasonable, one theory ("the bat coronavirus was transported by scientists to the lab that studies bat coronaviruses") involves no illigal activity. On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan") involves speculation that something happened that we don't know about. Strictly speaking, the lab leak theory has more observed evidence. Presumably the Chinese government would have identified and explained if they found bat traffickers. We know the lab was aware of RaTG13 - they produced a sequence quickly that no-one else had seen. I know nothing about the situation but it would be interesting to know where exactly the sample was being sequenced. I doubt they did it in the mine, samples must have been transported to some lab. I used to think 99% chance zoonotic, but the fact the similar virus was known to the lab was enough to drag me to thinking it is probably a toss up. Lab leaks do happen, this lab was studying bat coronaviruses. It is possible.
- DanBC 6y ago
  > On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan") One theory is that people mine bat guano from caves, so there's no need for them to ever touch a dead bat.
- treis 6y ago
  >he similar virus was known to the lab was enough to drag me to thinking it is probably a toss up. A human generated virus wouldn't be similar in this way to a wild one. You would take a candidate virus and splice in genetic material from a different one. The new virus would match 100% in most places and then be completely different in a few places.
  - mgamache 6y ago
    This is not how they conduct gain of function research. It's uses serial passage (using biological hosts and the virus's own variations). This produces vary little evidence of manipulation.

RobertoG 6y ago

>>"The virologists working in Wuhan did travel all the way to Southern China to collect bat coronavirus samples and they did perform gain-of-function experiments. Viruses - even highly pathogenic ones - have escaped labs on numerous occasions. There is a plausible scenario here." Another plausible scenario, in my opinion, is that the virus was brought to Wuhan by the virologists (in the virologist or their helpers) but never escaped from the lab itself. If you have a bunch of people periodically going to interact with the bats, how improbable is that they get infected of something (unknowingly) on site?

inciampati 6y ago
It's very unlikely that you'd get a one step transfer from a bat that yielded a spike protein with the level of affinity it has for human ACE2. If you look at that protein alone, the most-likely proximal hosts are primates. If we seriously believe in zoonotic transfer, we should be looking at those populations, and understanding how orangutans and bonobos infiltrated Wuhan and transmitted the virus to unwitting humans. The other recent coronavirus spillovers actually have rather low infectivity that increases with the course of the epidemic through adaptive mutations. But amazingly, with SARS2, it appeared already fully adapted. The phylogenetic tree makes a clear statement about how long SARS2 has been circulating in humans. At the publication of the genome sequence there were only a handful (~4?) of mutations known and most SARS-CoV-2 genomes were, incredibly, nearly identical. See https://nextstrain.org/ncov/global https://nextstrain.org/ncov/global. If we tend to see one mutation per transmission, that would mean that the spillover happened in October or November 2019, and almost certainly in Wuhan. All SARS-CoV-2 we've observed fits into this single tree, and there is no evidence of any previous progenitor strains. This means that SARS-CoV-2 was fully-adapted from its most-recent common ancestor. What are the odds of that happening directly from a bat? We're only now seeing, with b1117, a big phenotypic jump related to changes in the spike protein. It has arisen in a context that suggests that it may also be the result of strange environmental conditions for the virus that are capable of accelerating its exploration of the solution space. A widely-considered hypothesis is that it arose in an immunocompromised patient receiving antibody treatment and convalescent plasma, both standard practice in the UK. In this context the virus could have achieved extremely high population (~ many candidate solutions, faster evolutionary computation) and feedback about the immune response of the entire population (to the degree that they would have received multiple donations of plasma).

mabbo 6y ago

> The question of how it got to Wuhan all the way from Southern China remains unanswered. It's also important to remember that the related virus we're talking about in southern China was identified in 2013. More than six years before the outbreak. It didn't stay still. It hopped around, bat to bat, maybe to other animals. We don't have the history of the virus since then. It could have very well made the jump the humans or some other animal, years ago but only recently made the last few mutations to become the beast it is now. Plus, it's a virus. It didn't take one path, it took all of them that it could. Each virus created a million more, repeat ad-infinitum. So the idea that there's some mystery to how it traveled to Wuhan doesn't bother me. Viruses get around.

lamontcg 6y ago

> The question of how it got to Wuhan all the way from Southern China remains unanswered. There are coronavirus-carrying bats in Hubei province.