Three theories on Covid-19 origins and its link with Lyon

Research director for French state scientific body CNRS Etienne Decroly talks about the importance of finding the pandemic's origin 

24 November 2020
By Jane Hanks

Citizens’ health group Unacs is taking the government to court demanding clarification of the origins of Covid-19, which some claim came from a laboratory in Wuhan, China, that has strong ties to a research institute in Lyon. Jane Hanks spoke to Etienne Decroly, a research director for the French state scientific body CNRS, who has studied the subject.

Why is it so important to find out the origins of the disease?

It is vital to trace the origins and evolution of the molecular mechanisms involved in the emergence of this pandemic to prevent new ones in the future and to try to stop the transmission of the SARS-CoV-2 virus from circulating in animals which could then re-infect humans in the short or long term. Recently, the virus was in minks and we saw how quickly it could pass back to humans.

What is the likelihood this virus originally came from bats?

It is certain the ancestor of the virus came from bats.

The research I carried out with other scientists, studying the genetic material of the virus and comparing it with viruses in bats, concluded that SARSCoV-2 is a new infectious agent, capable of human-to-human transmission belonging to the SARS-CoV family originating from bats.

The question is how was this virus transmitted from these bats to the human population?

What is the strongest hypothesis?

It is generally accepted that coronavirus is most likely transmitted to humans from bats via an intermediate host species.

There have been two other coronavirus epidemics.

The first was SARS-CoV in 2002 and it is generally agreed the intermediate host was a civet, although there are some studies suggesting it passed directly from bats to man.

The intermediary animal for the second MERS-CoV in 2012 was probably a camel.

It was thought the intermediary host for Sars-CoV-2 was the pangolin but this hypothesis raises many questions.

The genome [an organism’s set of genetic instructions] of coronavirus found in pangolins is not close enough to be the direct parent of SARS-CoV-2.

The SARS-CoV-2 is likely to correspond to a combination of CoV between bats and pangolins, but these species inhabit different ecosystems, so it is difficult to imagine how their viruses could have merged. Also, the first infected patients did not attend the Wuhan market, and despite the search for viruses in animal species sold at this market, no intermediate virus has yet been identified.

To find how the virus was transmitted from bats to man, it is imperative we find the direct genetic ancestor of SARSCoV-2. We need to continue research into other animals in close contact to man.

Is this research being carried out?

It is difficult to know. It is most likely that it is, but no results have been published yet. But if they have, they should be presented to the international scientific community because it is very important. It is astonishing the United Nations has not looked into this. There is a great deal still to do in this domain.

What is the second hypothesis?

It is possible the virus was already circulating in the human population at a lower strength before 2020 and developed to become as infectious as it is today. It is not the most likely scenario but it is important to look closely into each theory.

There is a third hypothesis that it escaped from a laboratory?

This is possible because we know at least one laboratory at Wuhan was studying how coronavirus could move from one species to another.

When you do this type of experiment, there is a risk that a laboratory worker will become infected from a virus sample or that a sample dish might be thrown away without being sufficiently decontaminated.

We are not talking about something deliberate, but this type of accident has already occurred in different laboratories with other viruses.

I insist, this is not the main hypothesis, but again it needs to be looked into, because we have not yet found the closest ancestor to this virus in an animal.

How significant is this risk?

New techniques have allowed laboratories to synthesise and build a functional virus from scratch. They are very useful for scientists to develop vaccines or antivirals, or to understand the virus replication mechanism.

But sometimes modification of a virus can help it to cross the species barrier and so such experiments do come with an element of risk.

I believe it is a subject which needs public discussion because too few regulations pose too great a risk, but too many restrict vital research possibilities for society.

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