Status: 03/23/2023 11:40 a.m
Genetic tests from Wuhan wildlife market show close mixing of raccoon dog and coronavirus DNA. Why are the dates only now known? And does this prove the animal origin of the pandemic?
What was discovered?
Virologists have come across previously unknown genetic analyzes from the wild animal market in Wuhan. These are from the beginning of 2020, i.e. the beginning of the pandemic. The genetic sequences were obtained from swabs taken at and near market stalls.
They were entered into the freely accessible genome database GISAID by researchers at the Chinese Center for Disease Control and Prevention (CCDC) and discovered and analyzed there at the beginning of March by scientists around the Frenchwoman Florence Débarre – almost by chance. This is how the researchers write it in one preprint studywhich was released on Monday.
What do the experts conclude from the data?
According to the researchers, an evaluation showed that market samples that had tested positive for SARS-CoV-2 also contained animal genetic material – including from raccoon dogs. According to the researchers, these animals are “susceptible to SARS-CoV-2 infection and can shed enough virus to transmit it to other species.” They have therefore long been suspected as intermediate hosts who could have transmitted the virus to humans.
As US media reports, the scientists conclude from the type of sampling that a raccoon dog infected with the corona virus could have been in the affected areas. Virologist Angela Rasmussen, who was involved in the analysis, said in “The Atlantic”: “This is a very strong indication that animals at the market were infected. There is no other reasonable explanation.”
Raccoon dogs were traded on the wild animal market in Wuhan – this is proven by the analyzes.
Image: dpa
However, the microbiologist Fabian Leendertz from One Health Institute in Greifswald emphasizes that this does not prove beyond a doubt that raccoon dogs were really infected. “It could also be that infected people carried the virus there. Or that another animal transmitted the virus.” However, it is important to realize that raccoon dogs were definitely being traded on the market – because this had long been denied by the Chinese authorities.
Why is this discovery only now?
It is an accidental find. After Débarre and her colleagues contacted the Chinese authors on March 9, they had the data deleted from GISAID two days later – but the western researchers had already downloaded the data. The reasons for the deletion are unknown.
Does this explain the origin of the corona virus?
No. But the findings, according to observers, support the thesis held by many scientists that the virus has a natural origin and did not come from a laboratory. “The preliminary result strongly supports my assumption that it originated in raccoon dogs or other carnivores such as civets, which has been expressed since the beginning of the pandemic,” explained the Berlin virologist Christian Drosten.
Leendertz also sees an “important piece of the puzzle” in the most recent publications. There will probably never be definitive proof of how the virus came into the world, because the animals are no longer alive. But the discovery makes the existing hypothesis more plausible.
What is the role of the Chinese authorities?
The fact that these data come to light so late and only by chance is likely to annoy many observers. The head of the World Health Organization (WHO), Tedros Adhanom Ghebreyesus, criticized China’s information policy. “This data could have been made available three years ago, and it should have been made available. We again call on China to be transparent by making data available and we call on China to conduct the necessary investigations and about to report the results.”
Leendertz calls the communication of the Chinese “extremely unfortunate”. This is possibly intended to protect fur production, which is a major industry in the country. Because raccoon dogs are mainly kept for their fur – which also ends up in European products.
According to the zoonoses expert who was involved in the WHO’s search for the SARS-CoV-2 origin, the WHO’s first report on investigating the origin of SARS-CoV-2 recommended that the samples also be taken from mammals – examine DNA. “I don’t know why that wasn’t done directly. That actually contradicts normal scientific practice.”
What follows from the discovery?
The new data provide a strong clue to the intermediate host. Now it is necessary to look at how the virus came into the world or was transmitted to the intermediate host: “What is missing now is to look further back – where do the wild animals that were traded there come from? Where did the raccoon dogs or other susceptible animals that were traded there, maybe the virus came from?” says Leendertz. The focus here is on bats or other small mammals. “A systematic study with a good sample size would be very useful, not just now – but for a long time.”