Where did COVID-19 originate? Scientists have an explanation
Scientists have discovered where the COVID-19 pandemic began
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Researchers managed to “hunt down” new traces of the origin of the coronavirus. They confirmed that the pandemic began in an animal market in the city of Wuhan, located in central China.
Former FBI Director Christopher Wray declaredthat pthe COVID-19 pandemic likely spread through a leak from a laboratory in Wuhan. However, the World Health Organization named such a version is “extremely unlikely. Now scientists have new data, writes Nature.
What do previous studies say?
In earlier studies, scientists used genomic data collected by experts from the China Centers for Disease Control and Prevention (China CDC) shortly after the market was closed in January 2020.
Over several weeks, they visited the market repeatedly to take swabs from stalls, garbage cans, toilets, sewage drains, stray animals and abandoned frozen animal products. They contained large amounts of DNA and RNA from various sources that the researchers had to study and sequence.
When last April researchers published results in the journal Nature, they reported that samples from SARS-CoV-2 were taken from wild animals on the market, specifically raccoon-like dogs (Nyctereutes procyonoides)which can pick up SARS-CoV-2 and spread the virus to other animals.
However, the team notes that at the time it was not possible to establish that the animals were infected with SARS-CoV-2. Even if they were infected, they could have picked up the infection from the person who brought the virus to the market. Therefore, the role of the market was unclear here.
What was discovered in the course of the latest research?
Now the new conclusion of scientists is different.
In the latest study, scientists used more sophisticated genomic techniques to identify species they believe are possible “intermediate hosts” of SARS-Cov-2.
The most likely “hosts” are raccoon dogs and the palm civet (Paguma larvata), which may also be susceptible to the virus. Other possible “owners” include shrill bamboo rats (Rhizomys pruinosus)the Amur hedgehog (Erinaceus amurensis) and the Malayan porcupine (Hystrix brachyura).
But so far, scientists have not managed to find out whether they can catch SARS-CoV-2 and spread the infection. According to the team, Reeves’ muntjac (Muntiacus reevesi) and the Himalayan marmot (Marmota himalayana) can also be carriers of the virus, but with a lower probability.
The co-location of viral and genetic material from the animals “strongly suggests” that the animals were infected, says Gigi Gronval, a biosecurity specialist at Johns Hopkins University in Baltimore, Maryland (USA).
Bats, from which the “ancestor” of SARS-CoV-2 probably originated, was not detected in genetic data. The lack of bat DNA is not surprising, says Alice Hughes, a conservation biologist at the University of Hong Kong who studies bats. Although they are often eaten in southern China, they are not usually sold in local markets.
Authors of the study Cell also claim that the variety of viruses on the market indicates that this is where the pandemic originated. In particular, they say that the presence of two lineages of SARS-CoV-2 (known as A and B) circulating in the market proves that the virus passed from animals to humans twice.
The results of the study also suggest that the raccoon dogs at the Huanan market were probably closer “relatives” to the wild raccoon dogs collected at other markets in the same province, and not so closely related to the domesticated animals found in northern China .
This suggests that they may have come from the central or southern parts of the country. The closest known relatives of SARS-CoV-2 were isolated from bats in southern China, Laos, and other Southeast Asian countries.
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