the raccoon dog, a new suspect in the spread of the virus

The researcher in evolutionary biology at the CNRS, Florence Débarre, tracks on the Internet, Saturday March 4, samples taken from the Huanan market, in Wuhan, at the beginning of 2020. She has got into the habit of doing it in her free time since a year. She can’t find anything decisive when suddenly she stops. These samples, which had been produced by the Chinese Center for Disease Control and Prevention (CCCPM) and mentioned in a study published in February 2022, appear on the public and free database Gisaid (for global initiative on sharing avian influenza data) , founded by a group of international researchers.

The raccoon dog: missing link?

The researcher then shares this data with colleagues around the world. On Friday March 10, the obvious is obvious: “All the results reveal the presence of raccoon dogs at the Wuhan market, explains the researcher. We just found the scientific proof that there was. These dogs are small animals that look like a raccoon, and whose fur is very popular. But above all, they have the particularity of being mammals likely to be infected with Sars-Cov-2. However, underlines Florence Débarre, “they may have been intermediate hosts between bats – reservoirs of the virus – and humans. In the list of suspects, the raccoon dog was very high”she concludes.

The day before, Florence Débarre’s team had contacted one of the Chinese authors of the study to ask for permission to analyze the data. She then informs him of the result and also warns the World Health Organization (WHO). A few hours later, a mysterious event will occur. On Saturday March 11 in the early morning, the data is no longer accessible on the Gisaid database. Luckily, during the night, Florence Débarre had asked her colleagues to download them. “At that time, we hadn’t finished, because the mass of data was very large, 600 gigabytes. It took time, she points out. And from the moment we announced the result, there was a possibility that they would disappear.” So that’s what happened. But the team breathes, it had time to save them.

A major step forward

Several scientists from his team were then summoned by the WHO to present their results. Jean-Claude Manuguerra, virologist from the Institut Pasteur and co-president of SAGO (a scientific council created by the WHO to investigate in particular the origin of Sars-Cov-2) is invited to this meeting. “It was the end of a weekend where I had been working. I was tired, I wanted to relax a bit. And finally, we had two meetings, including one on Sunday. But I was happy because this discovery was a major step forward for our understanding of the start of the epidemic.” He too is impressed by what he discovers. “What is a little unexpected is that we find in the same place a large quantity of Sars-Cov-2 and a large quantity of DNA from animal species, some of which are sensitive to the coronavirus, and in particular to Sars -Cov-2.” The data collected makes it possible to produce a map that locates different areas of the market. “In some you find a lot of virus and a lot of raccoon dog DNA. And we find much less of them in other places where there are no such species. This strongly suggests that there were infected animals”estimates the virologist of the Pasteur Institute.

No irrefutable proof

At a press conference on March 17, the WHO is more reserved. Admittedly, it refers to a “significant step forward”but adds that “the data does not provide a definitive answer on how the pandemic started”. A caution shared by Étienne Decroly, research director at the CNRS at the University of Aix-Marseille and specialist in emerging viruses. “The key information is that in these samples there are genetic fragments that correspond to mammals that for a long time were considered not sold on the market. And among these animals is the raccoon dog. This therefore proves that there were indeed potential intermediate hosts there. [entre la chauve-souris et l’homme].” However, he notes that “these data do not prove that these dogs were infected with this virus”. In fact, the samples taken “are environmental levieshe says, carried out on the ground, on stalls or on cages”. And the researcher cites an example: “If you are sick with Covid and you cough on fish, by taking a sample from the fish, we will find genetic material from fish but also from Covid. This does not, however, prove that the fish were carriers of Covid and that they transmitted it in the fishmonger’s.

“To have indubitable proof, it would be necessary to find infected animals”, explains Jean-Claude Manuguerra. An almost impossible mission, because it is unlikely that the virus will continue to circulate in these species. Florence Débarre, like other scientists, nevertheless considers that this discovery should be the starting point for new, more targeted research. “We would have to take samples from wild raccoon dogs, or raised on farms, to see if they are close or not to those found on the market. We could also, she suggests, trace the supply chains of these animals, because the market stalls in Wuhan are identified and we know who managed them.”

A possible lab leak

But for this research to be carried out, China would still have to agree to cooperate, which is still not the case. Beijing persists in maintaining that the virus could have been imported from the United States via frozen products and that the Wuhan market was an amplifier of the pandemic, not the epicenter. In the absence of additional clues, according to virologist Jean-Claude Manuguerra, “the strongest evidence still argues in favor of the trail of transmission of the virus from animals to humans”. But that of a laboratory leak is not swept away. Even the WHO, which had dismissed it at first, recently reinstated it in the list of hypotheses to be considered.

This track, which scientists prefer to call “research accident”, was also revived last February by the statements of the boss of the FBI, qualifying it as “very probable”. A declaration which intervened a few days after the American department of Energy had supported it, while matching it with a level of confidence “weak” (on a scale going from weak, to moderate and strong).

These words, however, leave many scientists skeptical and bitter. Because they are based on a report whose content remains secret. “This document is classified and its existence is known only to sources who have seen it and told a Wall Street Journal reporter about it. We therefore do not know the arguments that were used to reach this conclusion., regrets Florence Débarre of the CNRS. Same annoyance with Jean-Claude Manuguerra, the co-president of SAGO: “We have a US Department of Energy that concludes its report with the existence of a weak hypothesis. In these cases: you shut up or you show what you have!”he is indignant, adding: “When we ask them if we can have access to these reports, it’s no! However, any agency, any scientist, any institution that has information that can help to know the origin of the virus must make it public. It is morally unacceptable not to do so.”

The WHO has also officially asked the United States to share their information. A request apparently heard by President Joe Biden who enacted a law at the end of March, allowing documents concerning the origins of the pandemic to be made public. But he, at the same time, specified that it had to be done “with respect to national security”, which raises fears that the Americans do not publish all the necessary information, under cover of military secrecy. But if the United States is singled out, scientists regret China’s opacity just as much. “There must be investigations to document the hypothesis of the research accident. This requires being able to enter the laboratories, to have access to the data, to be able to look at all those which have come back from the sequencers, etc. If this investigative work is not done, we cannot document this hypothesis”, emphasizes Étienne Decroly of Aix-Marseille University. And on this side, in three years, we have not progressed.

To alert the Radio France investigation unit:

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