Coronavirus: Scientists Identify Evolutionary Origins of SARS-CoV-2
Where did it come from?
An international research team of Chinese, European, and U.S. scientists has reconstructed the evolutionary history of SARS-CoV-2, the virus that causes the coronavirus, according to a study published in Nature Microbiology.
The researchers now know that particular viral lineage has been circulating in bats for decades—diverging from other bat viruses about forty to seventy years ago—and likely includes other contagions that have the potential to infect humans.
“Collectively our analyses point to bats being the primary reservoir for the SARS-CoV-2 lineage,” the study’s authors wrote.
“While it is possible that pangolins, or another hitherto undiscovered species, may have acted as an intermediate host facilitating transmission to humans, current evidence is consistent with the virus having evolved in bats resulting in bat sarbecoviruses that can replicate in the upper respiratory tract of both humans and pangolins.”
The researchers noted that in concluding their findings, they had to engage in rigorous detective work to identify the full makeup of the virus.
“Coronaviruses have genetic material that is highly recombinant, meaning different regions of the virus’ genome can be derived from multiple sources,” Maciej Boni, associate professor of biology at Penn State, said in a news release.
“This has made it difficult to reconstruct SARS-CoV-2’s origins. You have to identify all the regions that have been recombining and trace their histories. To do that, we put together a diverse team with expertise in recombination, phylogenetic dating, virus sampling, and molecular and viral evolution.”
SARS-CoV-2 was found to be 96 percent genetically similar to the RaTG13 coronavirus that was discovered in 2013 in a sample of the Rhinolophus affinis horseshoe bat in Yunnan Province, China.
SARS-CoV-2 is believed to have diverged from RaTG13 in 1969.
“The ability to estimate divergence times after disentangling recombination histories, which is something we developed in this collaboration, may lead to insights into the origins of many different viral pathogens,” Philippe Lemey, of the Department of Evolutionary and Computational Virology, KE Leuven, said in a release.
Like the older members of the lineage, the coronavirus also has the ability to bind with human receptor cells.
“This means that other viruses that are capable of infecting humans are circulating in horseshoe bats in China,” David Robertson, professor of computational virology at MRC-University of Glasgow Centre for Virus Research, said in a release.
He added that preventing future pandemics will require better samplings of wild bats and utilizing human-disease surveillance systems that can identify novel pathogens in real-time.
“The key to successful surveillance,” Robertson said, “is knowing which viruses to look for and prioritizing those that can readily infect humans. We should have been better prepared for a second SARS virus.”
Now more than eight months into the pandemic, there are roughly 30.2 million confirmed cases of coronavirus worldwide, including at least 947,000 related deaths, according to the latest data from Johns Hopkins University.
Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. Follow or contact him on LinkedIn.