THE ESSENTIAL
- Following numerous recombinations which coronaviruses are fond of, SARS-CoV-2 appears to have appeared in bats 40 to 70 years ago.
- The pangolin, which is responsible for transmitting the virus to humans, is said to have played only the role of an intermediate host.
- Researchers argue that future coronavirus pandemics could occur.
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Laboratory, pangolins, bat or a combination of both… The question of the origin of the coronavirus continues to arouse the curiosity of researchers around the world. An enigma all the more difficult to solve as the coronaviruses have the ability to recombine, making the identification of its origin complicated. The researchers had to reconstruct the history of these recombinations to understand the path of the virus and its evolutions. They published their results on Tuesday July 28 in the journal Nature Microbiology.
The pangolin, a simple intermediate host
This work of reconstructing the virus and its metamorphoses allowed researchers to conclude that the lineage to which this coronavirus belongs differentiated from others around 40 to 70 years ago. While SARS-CoV-2 is genetically similar to 96% of RaTG13, a betacoronavirus from bats Rhinolophus affinis, originally from the Chinese province of Yunana and identified in 2013, it has deviated from it since 1969. Researchers also found that SARS-CoV-2 shares a characteristic with its parents that allows it to bind to receptors at surface of human cells. This finding suggests that other viruses that can infect humans have long been circulating in Chinese bats.
In this story, the pangolin is missing, which is said to be the direct transmitter of the virus to humans. The latter would in reality only be an intermediate host. The study also suggests that the role of the pangolin is not essential for SARS-CoV-2 to be transmitted to humans and that the virus could very well have passed from bats to humans. Thanks to its properties, the new coronavirus has the ability to replicate in the upper respiratory tract of humans and pangolins.
Anticipate future pandemics
Researchers believe that the current health crisis will not be isolated and that potential future pandemics must be anticipated. “It won’t be our last coronavirus pandemic, warns Macej Boni, biologist at Penn State University (United States), in a communicated.A much more comprehensive and real-time surveillance system must be put in place to bring this type of virus under control before the number of cases reaches 100.”The latter, as well as others, are campaigning for better sampling of wild bats in order to better identify the future risks of contamination.
The potential new pandemics are linked to our lifestyles. As noted The Conversation, the increase in breeding activities not far from areas dedicated to nature protection increases contact between wild and domestic animals. The boom in human demography, which leads to the reduction of natural environments, and the intensification of animal husbandry near urban areas has increased the risks of inter-species transmission. A recent example concerns Japanese encephalitis in Southeast Asia which is due to the combination of increased irrigation of rice fields, animal husbandry and human demography.
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