Virologists have discovered two new mutations in the genome of a new type of coronavirus, thanks to which SARS-CoV-2 can better fight antibodies. The researchers published the results of the study on bioRxiv.
“When studying the evolution of the coronavirus, the researchers paid all their attention to small substitutions in the structure of its genome, while large and small insertions were practically not studied. We filled this gap by finding that such changes can greatly alter the antigenic profile of SARS-CoV-2 envelope proteins. In particular, the ins246DSWG and ins15ATLRI inserts, discovered in January 2021, can make the virus resistant to the action of antibodies,” the researchers write.
During the year of the pandemic, many small mutations appeared in the genome of the new type of coronavirus. Some of them increased the contagion of SARS-CoV-2, which caused the virus to spread throughout the planet quickly. The vast majority of these changes occurred in the part of the coronavirus RNA that controls the production of its envelope proteins.
American and Russian virologists, led by a leading researcher at the US National Center for Biotechnological Information, Yevgeny Kunin, were interested in how the evolution of the coronavirus can be influenced by other types of mutations that cause new inserts to appear in its genome. To do this, the researchers analyzed almost half a million SARS-CoV-2 genomes that scientists from around the world have deciphered over the entire time of the pandemic.
Comparing these genomes with the original version of the virus from Wuhan, the scientists found in the RNA of about a thousand samples of SARS-CoV-2 one and a half hundred unique inserts of different configurations. After analyzing them, biologists concluded that the vast majority of such inserts were very short — no more than three or four nucleotides.
These inserts were distributed very unevenly across the genome: many were concentrated in those parts of the RNA of the virus that controls the production of a certain part of the S-protein — a key part of the SARS-CoV-2 envelope, which is responsible for the penetration of the coronavirus into infected cells.
Two such inserts, ins246DSWG and ins15ATLRI, significantly change the structure of the part of the virus envelope to which many antibodies from the blood of patients are bound. Therefore, scientists suggest that the appearance of such inserts will help the coronavirus become more resistant to antibodies and cellular immunity. Further observations of the evolution of SARS-CoV-2 will show how likely, such a scenario is, summed up Kunin and his colleagues.