A SARS-Cavi-2 related coronavirus has been found in a Shemal horse bat captured in Cambodia in 2010.Credit: Merlin de Tuttle / SPL
Two lab freezers in Asia have made surprising discoveries. The researchers said Nature They have found a coronavirus associated with SARS-CV-2, the virus responsible for the epidemic, in horse bats stored in a freezer in Cambodia. Meanwhile, a team from Japan has reported the discovery of another closely related coronavirus – also found in stable bat droppings.
The virus is the first known relative of SARS-Cavi-2 to be found outside China, supporting the World Health Organization’s discovery in Asia for the origin of the epidemic animal. Strong evidence suggests that the origin of SARS-Cavi-2 comes from horse bats, but that it passes directly from bats to humans, or through an intermediate host, remains a mystery.
The virus was found in two horse bats in Cambodia (Rhinolofus shy) Occupied the north of the country in 2010. The genome of the virus has not yet been fully sequenced – or its discovery has not been published – it is of absolute importance for a difficult epidemic to be sure.
Even if the virus is very closely related – or the ancestor of the epidemic virus – it could provide crucial information about how SARS-COV-2 passed from bats to humans, and the discovery of the origin of the epidemic, says Veasna Duong. Virologist at the Institute Pasteur in Penh, who led the search for old specimens in Cambodia and warned Nature Their discovery in early November. To provide such insights, the researchers say, the virus must share more than 97% of its genome with SARS-CV-2, which is more than its closest known relative, the researchers say.
The new virus may be more remotely related, said Etienne Simone-Laurier, a virologist at the Pasteur Institute in Paris, and studying it would help scientists learn more about the diversity in the virus family. The virus, after which it will be shared publicly.
The same is true of another virus, called RC-o319, known in Japanese horse bats (Rhinolofus cornutus) Captured in 2013. The virus shares 81% of its genome with SARS-CoV-2, according to one paper. Published on November 2 – which is very far from giving an understanding of the origin of the epidemic, says Edward Holmes, a virologist at the University of Sydney in Australia.
No matter what the Cambodian team finds, both findings are exciting as they confirm that viruses closely related to SARS-Cove-2 are relatively common. Rhinolofus Alice Latin, an evolutionary biologist at the Wildlife Conservation Society Vietnam in Hanoi, says she saw some of the Cambodian team’s analysis, but was not involved in the investigation.
“This is what we were looking for, and we found it,” says Duong. “It was amazing and surprising at the same time.”
Epidemic origin
There are also plans to test bats and other stored specimens, says Aaron Irving, an infectious-diseases researcher at Zhejiang University in Hangzhou, China. Mammals for antibodies against SARS-Cavi-2.
“I didn’t expect to find a relative of SARS-CV-2,” says Shin Murkami, a virologist at the University of Tokyo, who was part of a team that decided to re-examine animal samples for the virus following the epidemic.
A handful of well-known coronaviruses, including RATG-13, are closely related to SARS-CV-2. It was found in an intermediate horse bat (Rhinolofus affinis) And published in 2013 in Yunnan, China2 Only earlier this year. Many other coronaviruses are also found there Rhinolofus Bats and pangolins were captured between 2015 and 2019, which scientists now associate closely with SARS-Cavi-2.
“SARS-COV-2 was not a new virus that suddenly popped up. The group’s viruses existed before we became aware of them in 2019, “said Tracy Goldstein, associate director of the Forest Health Institute at the University of California, Davis, who is involved with the California Mbodian team.
Latin says the discovery confirms that Rhinolofus Bats are reservoirs of this virus.
The virus in Cambodia
Duong’s team captured Shemal’s horse belt in Cambodia as part of a US-government-funded predict project that surveyed the worldwide wildlife epidemic for potential viruses and ended earlier this year. In April, the U.S. Department of International Development The agency gave the program an additional 3 million and a 6-month extension to find evidence of stork-cov-2 in animal samples – mostly bats, as well as pangolins and other animals – in Laos, Malaysia, Nepal, Thailand, Vietnam and Cambodia. Sitting in the laboratory freezer. A full report on the investigation is expected next week.
Duong says the initial genome sequencing of the new bat virus short – 324 base pairs long – shows that it was similar in the same field as SARS-Covey-2 and RATG-13, suggesting that the three are closely related. The region is highly protected from coronaviruses, Latin says, and is used to quickly identify whether the virus is new or known. But it is not yet clear whether RATG-13 or the new virus is more closely related to SARS-CoV-2.
It’s hard to say with such a small piece, says Vibol Hule, a virologist at the Cambodian Institute of Pasteur, who in 2010 trapped Shamel’s horse bed at the entrance to a cave. Pairs.
In a separate analysis, the Cambodian team, which helped analyze the bats, sequenced about 70% of the genomes of the new virus using locally available technology, says Eric Carlson, a virologist at the Pasteur Institute in Cambodia. Missing from that sequence were instructions for critical parts of the virus, such as encoding a gene or spike protein that the coronavirus normally uses to enter cells. Duong says sequencing this section indicates whether the virus can infect human cells.
Irving says the new virus must be at least 99% like SARS-CO-2 to become the immediate ancestor of the current epidemic virus. The genomes of Ratji 13 and SARS-Covi-2 differ by only 4%, but that diversion represents an evolution of 40 to 70 years as they share a common ancestor. Although different for many decades, the virus is similar enough to enter cells to use the same receptor. Cell studies suggest that RaTG13 may infect people.
Another close relative
Of the known coronaviruses associated with SARS-CoV-2, the newly discovered RC-o319 seems to be the most remotely related, Duong says.
In a cell study, a Japanese team found that the virus could not bind to a receptor used by SARS-CV-2 to enter human cells, suggesting that it could not easily infect humans.
Shin says his teammates caught more bats in Japan earlier this year, and plans to test them for coronavirus. And in October, Hull returned to a cave in northern Cambodia to catch more bats.
More SARS-Cavi-2-related coronaviruses probably exist Rhinolofus Holmes says the bat population throughout the region. “Hopefully, one or more of these will be so closely related to SARS-Cove-2 that we can count them as true ancestors.”
