A virus resembling Covid-19 has existed in Cambodia since 2010

 The origin of the source of the Covid-19 corona virus is still a mystery. Researchers thought that bats were the first to spread it.

In November and December 2010, the United Nations Educational, Scientific and Cultural Organization (UNESCO) and Cambodian authorities invited researchers from the Muséum National d'Histoire Naturelle in Paris to explore several sites in northern Cambodia.

The aim was to study the biodiversity of bats at Preah Vihear Temple, and the large number of bat species caught during the survey, including eight types of horseshoe bats (genus Rhinolophus). These bats are of great interest to virologists, because they are the reservoir for all Sarbecoviruses, a group of coronaviruses that include SARS-CoV and SARS-CoV-2, which led to the SARS epidemic in 2002-2004 and the current COVID-19 pandemic, respectively.

In 2020, 10 years after the expedition, samples stored in a refrigerator with a temperature of -80 ° C were removed and tested by the Pasteur Institute of Cambodia (IPC) for Sarbecoviruses. A PCR test showed two positive results and complete genome sequencing was initiated. Two variants of the virus close to SARS-CoV-2 were found in two bats of the Rhinolophus shameli species that we caught in 2010 in a cave in Steung Treng Province.

The results of this study are freely available on the bioRxiv website and await peer review. (This practice is now being widely used to quickly share new knowledge regarding the COVID-19 pandemic.)

Viruses such as SARS-Cov-2 are found in bats in China's Yunnan Province and mainland Southeast Asia

This discovery is important because this virus is the first to be discovered outside of China that is close to SARS-CoV-2 - of the 29,913 bases aligned in the genomes of the two viruses, 93% are identical. All previously described were found in animals captured in China, including two viruses found in two species of rhinolophus bat in southern China, and two different viruses (90% and 85%) found in pangolins seized by Chinese customs. in Guangdong and Guangxi Provinces.

The new virus from Cambodia found in a bat species endemic to Southeast Asia is not that different from Yunnan, where two bats with viruses such as SARS-CoV-2 were found.

The immediate implication is that viruses similar to SARS-Cov-2 have been circulating for decades, as molecular dating reveals, through Southeast Asia and Yunnan, and different bat species may have spread these viruses to the caves they inhabit.

Chinese researchers have been looking for Sarbecoviruses in their country for about 15 years. They found more than 100 viruses that resemble SARS-CoV but only two are related to SARS-Cov-2. Therefore, this new data confirms the hypothesis that most viruses like SARS-CoV-2 are present in Southeast Asia, while viruses like SARS-CoV are predominantly present in China.

The data in the image above indirectly supports the hypothesis that the SARS-CoV-2 group actually originated from mainland Southeast Asia. And yes, the human populations in Cambodia, Laos, Thailand and Vietnam appear to be less affected by the COVID-19 pandemic pandemic than other countries in the region, such as Bangladesh, Myanmar, Malaysia, the Philippines and Indonesia. This suggests that the populations of the four mainland countries may be favorably affected by the herd immunity levels of Sarbecoviruses.

Pangolins are infected by bats in Southeast Asia

Apart from bats, the Sunda Pangolin (Manis javanica) is the only wild animal that has a virus similar to SARS-CoV-2. The problem is that these finds were found in a rather unique context, namely the pangolin sale. Several sick animals were confiscated by Chinese customs in Guangxi Province in 2017-2018 and Guangdong Province in 2019.

Although the viruses sequenced in pangolins are not very close to SARS-CoV-2 (one virus is 85% identical and the other is 90% identical), this virus indicates that at least two Sarbecoviruses may have been imported to China quite long before the COVID-19 epidemic. . And indeed, it has been found that pangolins from Southeast Asian countries have infected each other while imprisoned in Chinese territory.

The question that remains is how pangolins were originally infected. Could they have been infected in their natural Southeast Asian environment, prior to being captured? The discovery of a new virus close to SARS-CoV-2 in bats in Cambodia supports this hypothesis, because Rhinolophus bats and pangolins can make contact, at least occasionally in caves in Southeast Asia. This reinforces the hypothesis that the pangolin trade is responsible for the export of a large number of SARS-CoV-2-like viruses to China.

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