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Tracing the origin of COVID-19


On June 5 Nature published "The Biggest Mystery: What It Will Take to Trace The Coronavirus Source", summarizing The views of The novel Coronavirus source.


The origin of novel Coronavirus has been one of the biggest problems since the beginning of the pompous epidemic. While bats are now almost certainly the source, there is still no clear answer as to how they spread to humans. One explanation is that bats passed the virus to intermediate hosts, which then spread to humans.


In mid-May, WHO called on international organizations to work together to trace the origin of novel Coronavirus. Some scientists said, it is difficult to find the animal origin, and it is difficult to completely exclude the Wuhan Virus research institute as the source.


The Wuhan Virus Research Institute, a laboratory that studies bat coronaviruses, happens to be in the city where the outbreak first occurred. And, unfortunately, some of the institute's work has attracted attention. An independent investigation of the Wuhan Virus Research Institute could provide convincing evidence to rule out the lab as the source, but given the complex geopolitics, such an investigation is impossible.


Animal origin



A new study in China analyzed partial sequences of about 1,240 coronavirus species in bats and found that the novel CoronavirusSARs-CoV-2 was most closely related to a group of viruses found in horseshoe-bats. Novel Coronavirus appears to have originated in Yunnan, but the team only collected virus samples from Sites in China, so they cannot rule out the possibility that SARS-COV-2 may have come from neighboring Myanmar and Laos, where horseshoe-bats are also found.


Shi Zhengli, a researcher at the Wuhan Virus Research Institute, attracted special attention during the pandemic for her work on coronavirus. Shi says she has long warned of the risk of another SARS-like disease in animals. Volker Thiel, a virologist at the University of Bern, says she has actually warned us that bat viruses can exist in nature and that they can spread to humans.


If a virus almost identical to SARS-COV-2 could be found in animals, it would explain how the virus spread to humans. But that would require extensive sampling of coronaviruses in Chinese wildlife. China has reportedly started such investigations, but there is little information about them. Identifying the animal source of SARS-COV-2 may take a long time. A similar investigation was conducted after the SARS outbreak that year. The first case appeared in November 2002 and was not identified as coronavirus until April 2003. It took nearly 15 years and extensive animal sampling to determine the source of the virus was bats.


The virus has been studied around the world using computational models, cellular biology and animal experiments, but has so far remained elusive.


Laboratory conjecture


Wuhan Virus Research Institute is one of dozens of biosafety Level 4 (P4) laboratories in the world. Although there is no evidence that the virus came from there, completely ruling it out would be tricky and time-consuming. Coronaviruses associated with SARS-COV-2 do exist in laboratories, and if workers are accidentally infected with virus samples and then spread them to outsiders, the virus could spread. But that's a myth, no evidence. In April, the institute's director said the virus was definitely not laboratory produced and that researchers knew how to manage virus samples. In 2017, Nature visited the Wuhan P4 laboratory, where the President showed off new equipment, high-security test rooms and a well-designed ventilation system, all of which ensure that pathogens are safely controlled. The director said his team had established the world's most advanced biosafety research laboratory in collaboration with French biosafety scientists. The agency also has no records of accidents.


Scientists say forensic investigations are needed to determine whether the lab is linked to the virus. You need to sample the lab, interview the staff, review lab books and safety incident records, and see what kind of experiments the researchers are conducting.


Frank Hamill, a former manager of the P4 laboratory in the United States, said such an investigation might not yield any conclusive results. Even biosafety laboratories in the United States are not fully open and transparent about what they do, and it is hypocritical to ask the Wuhan Virus Research Institute to open up to public investigation.


Products of nature


Some scientists outside China have studied the genome in detail and concluded that the virus is a natural product, not a laboratory one.


An analysis published March 17 in Nature Medicine discusses several unusual features of the virus and suggests they may be caused by natural processes. First, the researchers had to use existing coronavirus RNA as a skeleton in an attempt to genetically modify the virus. If scientists study the new coronavirus, they are likely to use known skeletons.


To enter cells, coronaviruses use the receptor binding domain (RDB) to lock onto receptors on the cell surface. The RBD of SARS-COV-2 has parts that are different from any other coronavirus. Although experimental evidence suggests that the virus binds successfully to human cells, it does not do so well. In the authors' opinion, no attempt has been made to design a virus to design RBD, so it is likely to be the result of natural selection.


The authors also point out that another unusual feature of SARS-COV-2, which is part of a mechanism that helps the virus enter human cells, is the Flynn protease cleavage site. The authors suggest that natural processes may explain how this feature arose. Indeed, similar loci have been found in coronaviruses, supporting the authors' view that sarS-COV-2 components may all be derived from natural processes.


The paper's lead author says SARS-COV-2 is unlikely to be produced or operated in a laboratory, and that they have plenty of data to suggest it is natural, with no data or evidence to suggest any link to the laboratory.


Jack Nunberg, a virologist at the University of Montana in Missoula, said there was unlikely to be a signature signal of genome manipulation, and he did not believe the virus came from a laboratory. For example, if scientists add a description of the Flynn protease cleavage site to a virus's genome, there is no way to know whether humans or nature inserted it, he said.


It will be very difficult, if not impossible, to prove or disprove the theory that the virus was released by laboratories, and hopefully governments will be better prepared for the next pandemic.


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