Coronavirus Laboratory Created Or Not – Scientists Provide Evidence
According to findings published today in Nature Medicine, the novel coronavirus pandemic that emerged in the Chinese city of Wuhan in December 2019 and later spread to more than 70 countries originated due to natural evolution.
The genome sequence data analysis of the novel coronavirus and other related viruses found no evidence that the virus is engineered or created in a laboratory.
Kristian Andersen, Ph.D., the corresponding author of the paper and an associate professor of immunology and microbiology at Scripps Research, said that SARS-CoV-2 originated through natural processes, and is confirmed by comparing the genome sequence data of known coronavirus strains.
The authors of the paper “The proximal origin of SARS-CoV-2,” include Edward Holmes, of the University of Sydney; W. Ian Lipkin, of Columbia University; Andrew Rambaut, of the University of Edinburgh and Robert F. Garry, of Tulane University, along with Andersen.
Various strains of coronavirus cause illness, ranging widely in severity. Two such severe illnesses that emerged in the last two decades were the Severe Acute Respiratory Syndrome (SARS) epidemic in 2003 in China, and the Middle East Respiratory Syndrome (MERS) originated in Saudi Arabia in 2012.
The novel coronavirus outbreak that began in December 2019, subsequently named as SARS-CoV-2, has killed more than 7,900 people around the world until today. 198,152 confirmed cases are reported, although many more with mild symptoms have gone undiagnosed.
The genome sequence data of SARS-CoV-2 was made available by Chinese scientists, shortly after the epidemic. Chinese authorities recognized the epidemic soon and identified that the COVID-19 is transmitting from humans to humans after the first introduction onto the human population. The sequencing data provided by the Chinese authorities was used by Anderson and collaborators at various research institutions to study the origin and evolution of the novel coronavirus.
The researchers analyzed the genetic template for armatures on the outside of the virus used to grab and invade the outer walls of animal and human cells and the genome sequence of spike proteins. Two major features of the spike protein were studied; the cleavage site that helps the virus to crack open and enter host cells and the receptor-binding domain(RBD) that acts as a grappling hook to hold on to host cells.
Genome sequencing of spike proteins revealed that the RBD portion has evolved to target ACE2 on the outside of human cells that are involved in regulating blood pressure. The spike protein of novel coronavirus binds to human cells very effectively that the scientists said it is because of natural selection, not due to genetic engineering. This rules out the possibility of a laboratory-created coronavirus.
The data on the overall molecular structure of SARS-CoV-2 supported the evidence for natural selection. If someone had to create a new coronavirus as a pathogen, they would have engineered it from the molecular structure of a known virus. But researchers found that the molecular structure or backbone of the SARS-CoV-2 is significantly different from other known coronaviruses, but showed resemblance to viruses found in pangolins and bats.
Thus the possibility of a laboratory manipulation behind the origin of new coronavirus was ruled out by its distinct backbone and mutations in the RBD portion.
This new discovery was crucial and necessary as many rumors are being circulated about the origin of the SARS-CoV-2 virus, said Josie Golding, Ph.D., epidemics lead at UK-based Wellcome Trust.
The scientists concluded the paper by ending speculations about genetic engineering, claiming that the virus is the product of natural evolution.
Origin of the virus
The scientists also provided information on most likely sources of the novel coronavirus as well as two possible scenarios.
In the first scenario, the scientists suggested that the virus might have undergone natural selection in a non-human host animal and then transmitted to humans. In this scenario, the cleavage site that opens up the virus and the RBD portion that binds to host cells would have evolved before transmitting to humans. This is how the previous SARS and MERS outbreaks happened. The virus jumped to humans from civets and camels, respectively, and then contracted between humans.
As the new coronavirus is similar to a coronavirus seen in bats, scientists suspect bats as the most likely reservoir of SARS-CoV-2. But cases of direct bat-human transmission was not documented, suggesting the possibility of an intermediate host between them. The epidemic would have begun as soon as the virus infected the first person, as it had already acquired features to infect and transmit between humans.
The second scenario could be that the virus evolved to become pathogenic within the human population. The non-pathogenic virus might have transmitted from animals to humans, and later evolved to its current stage inside humans. The RBD structure of coronavirus found in armadillo-like animals and pangolins in Asia and Africa is similar to that of the novel coronavirus. This scenario suggests that the virus might have jumped from a pangolin to humans either directly or through some intermediate hosts like ferrets or civets. Later the two distinct features of spike protein; the RBD and cleavage site would have evolved within a human possibly during the undetected circulation of the virus in the human population, way before the epidemic began.
The scientists also identified that the cleavage site of SARS-CoV-2 is similar to that of bird flu viruses that easily transmit between humans. Such a virulent cleavage site might have evolved inside humans, which kick-started the epidemic.
It is difficult to say which scenario is most likely to happen, said co-author Andrew Rambaut. But the current evidence proves that the novel coronavirus is not laboratory created. Among the two scenarios, if the first one is true and if the virus enters humans in its current pathogenic form, this raises the possibility of future outbreaks as the virus could still be circulating in the animal population and could jump to humans once again. The chances for the second scenario to happen are lower.
The Pew Charitable Trusts, the US National Institutes of Health, the European Research Council, the Wellcome Trust, and an ARC Australian Laureate Fellowship funded the project.