Would we have gone from one extreme to the other? This is the impression that the publication of new elements questioning the transparency of the Wuhan Institute of Virology (WIV), in China, may give. But specialists remain very cautious.
What are the possible origins of the epidemic?
Tracing the course of SARS-CoV-2 supposes explaining its emergence and then its spread. There may be several possibilities:
– the appearance and then the spread of the virus in a natural way (zoonosis);
– accidental spread of a virus studied in the laboratory (escape);
– the modification of a virus in the laboratory, to give it new properties, then its dissemination, voluntary or not.
Answering these questions requires scientific investigation. For this, for a year and a half, specialists have analyzed the sequences of the genome of the virus, to compare it to others. They are also working to identify the first patients with Covid-19 and to study their environment, especially the animals with which they have been in contact.
Why is its origin still not established?
Exploring the zoonotic trail requires luck. “Finding the host animal is like looking for a needle in a haystack, summarizes Etienne Simon-Lorière, researcher in virology at the Institut Pasteur. Especially since in China, there are huge areas in which to collect. “
Additionally, the pandemic’s “patient zero” is unknown. The oldest known patient dates from the beginning of December 2019 in Wuhan. However, the original strain dates back to September or October of that same year, phylogenetic analyzes show. “We don’t know where she appeared. If the first people infected were young people, maybe they had no symptoms ”, suggests Virginie Courtier, research director in biology at the National Center for Scientific Research (CNRS). To make matters worse, RNA virus infections often don’t leave a lasting mark in the long term.
Why has animal origin been taken for granted for a long time?
Cases of transmission of an animal virus to humans are the most frequent. This is how specialists estimate that the transmission of the SARS-CoV-1 coronavirus to humans occurred through the civet, and that of MERS-CoV, through the dromedary. Ebola, the Marburg virus or the Nipah virus are thought to emanate from bats. However, the Wuhan Institute of Virology was already alerting in 2017 to the risks of the appearance of new diseases linked to bats. Indeed, in the regions neighboring the epicenter of the epidemic, there are many rural areas where men are naturally exposed to them and their coronaviruses. SARS-CoV-2 is also very close to one of them, called RaTG13.
This lead was supported by the discovery of several coronaviruses close to SARS-CoV-2 in Thailand, Cambodia and southern China. “We can say that several decades ago, the ancestor of the virus circulated in bats”, concludes Virginie Courtier.
Why is this thesis no longer the only one defended?
The missing link remains unknown. The pangolin trail, which doesn’t share the same ecosystem as the bats, has cooled off. The idea that humans have infected themselves directly from bats is also being considered, as is that of an infection with two viruses that would have mixed together. So many theoretical explanations that have not been supported by documented cases.
“The zoonosis hypothesis was the big favorite at the start of the epidemic, summarizes Etienne Decroly, research director in virology at the CNRS. But a year later, 80,000 samples were tested to find the intermediate host, and these analyzes failed to identify the animal responsible for this zoonosis. Scientific rigor therefore requires that we explore other hypotheses initially considered less probable. “
What are the arguments of the laboratory’s thesis?
Since 1979, the Wuhan Institute of Virology has housed the China Center for Virus Culture Collection (CCVCC – “Chinese Center for the Collection of Viral Cultures”, in French), which it presented in 2018 as “The largest virus bank in Asia”. China has been studying coronaviruses even more closely since the SARS-CoV-1 epidemic in 2002-2004. However, in 2012, six miners who left to clean up bat droppings in a cave in the Yunnan mountains developed severe pneumonia linked to a coronavirus, reveals the Wuhan Institute of Virology in early 2020. More intriguing, it is only ‘in July 2020 that the institute admitted that it was on this occasion that RaTG13, very close genetically to SARS-CoV-2, was collected. “They should have said it straight away”, wonders Virginie Courtier.
The suspicion was heightened in mid-May after the disclosure by an internet user, The Seeker, from three academic works that cast doubt on the number of WIV coronaviruses and the existence of species crossing experiences. “These allow us to understand how zoonosis occurs from a molecular point of view, which would allow us to monitor bat viruses that are problematic for humans, and to put in place countermeasures”, explains M. Decroly, but these experiments worry part of the scientific community.
How can a virus escape from a laboratory?
It is not excluded that the virus naturally contaminated WIV employees. “People go into a cave, collect viruses, put them in culture at the same time, recombinations – or not – take place, and one escapes. It’s possible “, confirms Mr. Simon-Lorière. Often human error is the cause, for example when a laboratory technician accidentally spills a vial on it and disinfects himself poorly. In 2004, SARS-CoV-1 had thus escaped twice, fortunately without seriousness, from the Beijing Institute of Virology, following negligence.
It can also be an employee who throws waste in a contaminated area, or a technician who sells the corpse of an animal to make ends meet, etc. This risk is all the more conceivable given that the bat coronaviruses are handled in P3 or even P2 laboratories, with less strict security than a P4. In 2018, American experts were already alerting the Pentagon to the work carried out in Wuhan and their security flaws. The Chinese Center for Disease Control and Prevention itself admitted in 2019 that the control of the reliability of its laboratories was flawed.
So, were the early 2020 conspiracy theories fair?
No. Let’s remember: one of the first rumors evoked “A military biological weapon” in Wuhan’s P4 and involved George Soros, a Jewish billionaire and scapegoat for the conspirators. Another, broadcast by a “yellow vest”, attributed the creation of the virus to the Pasteur Institute, after an erroneous reading of a scientific patent. As for the 2008 Nobel Prize for Medicine, now ostracized from science, Luc Montagnier, he defended the idea that the SARS-CoV-2 virus had been obtained by crossing with HIV.
“We spoke at the time of a little monstrous virus, made in the laboratory by mad scientists, and it was not based on anything, reframes Guy Gorochov, head of the center of immunology and infectious diseases at the Pitié-Salpêtrière hospital, interviewed in 2020 on these theses. On the other hand, the possibility that this virus entered by an unnatural way, such as a laboratory, before infecting laboratory workers, that is a hypothesis that cannot be ruled out. “
So the thesis of the leak of a laboratory is now established?
Well… neither. Mme Broker Note: “At first, I used to say to my friends, ‘Watch out, it can also be the lab.’ But now I tell them, “Be careful, that can also be natural.” ” Even if the flight thesis is once again on the rise, it lacks the essential: definitive proof. And it will probably be difficult to have any.
At the level of its genome, “There is no obvious clue [que le virus ait été manipulé], notes Etienne Decroly. But it is not easy to differentiate a natural virus from a natural virus that has been slightly modified. ”
Is SARS-CoV-2 related to WIV natural collections? To find out, the scientific community would have to have access to the institute’s sample bank, which Beijing refuses. As is, “It’s impossible to conclude”, says Mr. Gorochov, who judges the Chinese attitude “Suspicious”.
Why is China obstructing WHO investigations?
The SARS-CoV-1 epidemic had been experienced as a snub. Since then, numerous investments have transformed the Middle Empire into a Mecca for virology, with the city of Wuhan as a showcase. If the hypothesis of a laboratory leak is confirmed, whether on the international or domestic scene, “It would be a political earthquake for Beijing”, prognosis Marc Julienne, researcher at the French Institute of International Relations.
Especially since the Chinese Communist Party (CCP) is preparing to celebrate its 100e anniversary. “Nothing can taint the good festivities, details Emmanuel Véron, associate geographer at the National Institute of Oriental Languages and Civilizations (Inalco). The CCP, which is already not focused on transparency and adversarial debate, will especially not let them get in. “
Ironically, it is not certain that Beijing knows the exact origin of the virus, the local power in Wuhan having tried to quell the first cases, and many officials having been redacted. What annoy the researchers. For Mr. Decroly, it is essential to understand, “And avoid a SARS-CoV-3 pandemic in the next ten years”.
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