The case against COVID coming from a lab

We can’t rule out the possibility that the new coronavirus came from a lab. As we heard earlier, the closest known bat virus is 96% similar to the COVID19 virus, but that 4% difference is a big genetic sticking point. The new coronavirus also has an additional piece of genetic material in its spike protein; this is called a furin cleavage site and it makes the new virus much better adapted to spreading among humans. So is this by human design? Virologists like David Robertson from the University of Glasgow, here talking to Chris Smith, nevertheless say “no”...

David - When we compare the new human virus to the closest bat virus, it's about 4% different. That's relatively genetically close, but in terms of time, that represents many decades. And so that's telling us that the last shared ancestor was some considerable time ago. What this is telling us is there are circulating viruses, probably in bats, that we haven't sampled yet, that gave rise to this new human virus.

Chris - Surely though, if that ancestor for this SARS COV-2 which is causing the pandemic was frequent enough in its population to jump into people, why have we not found it then?

David - To directly answer that we can't be sure how frequent it is. It could have been a one-off, or a very small population of bat viruses that accidentally or incidentally got into humans; or alternatively we just haven't sampled well enough. There is a quite extensive lineage of viruses in the bat that just hasn't been sampled.

Chris: - Your hypothesis then would be, if we were to hunt carefully enough, we might find a species - probably a bat - that's harbouring the more direct ancestor of what is COVID?

David - Yes almost certainly, I think that's what all the data's pointing towards.

Chris - Along the way though, David, there've been interesting sort of spinoffs of this, where initially people tried to implicate snakes as being part of the equation; and then attention focused on these scaly mammals, the pangolins. How do these other species fit into this picture, then?

David - Well, some of them are just really poor analysis and the misinterpretation of some of the signals in the data. But the pangolins - we have recovered viruses that are close to the human virus. But it's not that the virus in the animal reservoir has adapted to humans per se, it's that it's a bit of a generalist and that's allowed it then to jump to several species.

Chris - People have mentioned that the spike on the outer coat of the virus has some special characteristics that, they're arguing, set it apart or make it stand out. What are they getting at?

David - The main one is there's a furin cleavage site in the spike protein, and that's a little bit of additional sequence. And that's unique to the SARS COV-2 lineage. There's no animal equivalent of that sequence. But what we do know is that because these viruses can generate hybrids, they what we call 'recombine', and that's probably what's happened in this case.

Chris - Does that furin cleavage site make a difference to the way the virus behaves, then?

David - We believe it's increasing the ability of the virus to bind to the human receptor, making it much more transmissible.

Chris - Is there a possibility then, based on the uniqueness of their structure and how effective it is, that this is the work of human hands - nature didn't endow us with this?

David - I would say it's very unlikely, because so many of the properties of this new virus we just didn't know about. We just didn't know what the closest relative viruses were. We still don't know. For a human to engineer a virus that's so unique and complicated, and in unexpected ways... it's just very unlikely. If you were to engineer a virus, you would have started with the first SARS virus and you would work from there. You wouldn't invent some novel virus with parts that we'd never seen before. It just seems very implausible.

Chris - What about if it was an accident? As in, someone's working on different coronaviruses and they just by chance happen to mix them up, and as you've said, they very often trade bits of genetic information between themselves. Could they not disclose this because it's so good at what it does, it would just naturally pop out and outgrow all the others and off it goes?

David - Well, I think first the overwhelming evidence is that these events can occur naturally. And so if you discover that you have viruses that are in reservoirs, that can transmit to humans, they have all the parts quite naturally. I think that's where the weight of the scientific evidence points towards.

The missing person at the centre of this story is Zhengli Shi, director of the Center for Emerging Infectious Diseases at the Wuhan Institute of Virology, nicknamed ‘batwoman’ in the Chinese press. A lot of what we know about these bat coronaviruses comes from research from her centre - and, as might be expected, claims that the new coronavirus escaped from a lab generally involve her as well, not least because many of the coronaviruses that are closely related to SARS-CoV-2 were discovered and worked on there by Shi and her team. Shi has said on the record that she “never expected this kind of thing to happen in Wuhan, in central China,” but that the allegation that the virus came from her lab, quote “totally contradicts the facts”. We can’t get in touch with her at the moment - very few can - but Maureen Miller from Columbia University worked with her, and has an idea what she might say…

Maureen - Well, first I don't want to put words in her mouth, but I do understand how frustrating it must be to have spent an entire career trying to prevent exactly the same kind of scenario that we're seeing right now, and people not heeding warnings, people not conducting more studies like we did in Yunnan province, where we found a bat that had a virus that could cause disease in humans. We have the technology to be able to do that. We know the global hotspots. We could be surveilling those areas.