SHANDONG, China — The global debate surrounding the origin of the coronavirus continues on endlessly. Many believe SARS-CoV-2, and consequently COVID-19 (the illness it causes), was created artificially in a lab. Others argue it is of natural origin, like any other coronavirus strain. Just like everything else with this awful virus, politics and personal beliefs have played a major role in the ongoing narrative surrounding SARS-CoV-2’s origin.
Now, however, a new study has documented a recently discovered bat coronavirus (RmYN02) that is very similar to SARS-CoV-2. It is believed to be SARS-CoV-2’s closest viral relative, specifically regarding the insertion of amino acids within the two viruses’ spike proteins. The close similarities between the two strains suggests there is nothing artificial about SARS-CoV-2.
“Since the discovery of SARS-CoV-2 there have been a number of unfounded suggestions that the virus has a laboratory origin,” says senior author Weifeng Shi, director and professor at the Institute of Pathogen Biology at Shandong First Medical University in China, in a release. “In particular, it has been proposed the S1/S2 insertion is highly unusual and perhaps indicative of laboratory manipulation. Our paper shows very clearly that these events occur naturally in wildlife. This provides strong evidence against SARS-CoV-2 being a laboratory escape.”
RmYN02 was discovered after a careful examination of 227 bat samples taken from the Yunnan province in China between May and October 2019.
“Since the discovery that bats were the reservoir of SARS coronavirus in 2005, there has been great interest in bats as reservoir species for infectious diseases, particularly as they carry a very high diversity of RNA viruses, including coronaviruses,” Shi explains.
RNA samples of RmYN02 were sent in for analysis shortly after COVID-19 first appeared in January of this year.
RmYN02 and SARS-CoV-2 share 97.2% of the same RNA in the longest encoding section of their genomes, referred to as 1ab. The two strains differ, though, when it comes to SARS-CoV-2’s ability to infect humans.
So, the main connecting factor between the two viral strains is that both contain amino acid insertions in their spike proteins. While the insertions themselves aren’t the same, just the fact that other insertions in general already existed in another coronavirus strain indicates SARS-CoV-2 is of a natural origin.
“Our findings suggest that these insertion events that initially appeared to be very unusual can, in fact, occur naturally in animal betacoronaviruses,” Shi notes.
“Our work sheds more light on the evolutionary ancestry of SARS-CoV-2,” he concludes. “Neither RaTG13 nor RmYN02 is the direct ancestor of SARS-CoV-2, because there is still an evolutionary gap between these viruses. But our study strongly suggests that sampling of more wildlife species will reveal viruses that are even more closely related to SARS-CoV-2 and perhaps even its direct ancestors, which will tell us a great deal about how this virus emerged in humans.”
The study is published in Current Biology.