All viruses mutate over time, this is a common occurrence in nature. It is no different for SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 has had thousands of mutations since the original sequence of the virus was identified more than a year ago. These mutations usually do not change the behavior of the virus, and are considered ‘passenger’ mutations that carry the virus as it continues to spread.
However, some of the mutations are occasionally beneficial to the virus. Depending on where it occurs, it can help the virus become more contagious and spread faster, or it can help the virus better evade the immune system by making it less detectable. Several new variants of SARS-CoV-2 have been recently described, and many have raised alarm bells due to the fact that the virus has started behaving differently from the original variants, which is apparently more transmissible and / or less perceptible.
Now, new research from the University of Pittsburgh School of Medicine has shown that SARS-CoV-2 may be fragments of the genetic sequence that encodes an important part of the virus, the vein protein on its surface. The ear protein is used by the virus to cling to cells to infect it, and it is also the part of the virus that is targeted by antibodies.
“You can not fix what is not there,” senior author Paul Duprex, PhD, director of the Center for Vaccine Research at the University of Pittsburgh, said in a statement. “Once it’s gone, it’s gone, and if it’s gone in an important part of the virus that the antibody ‘sees’, it’s gone forever.”
The study, published in the journal Science, shows how the small deletion of fragments in the genetic code responsible for the structure of the peak protein makes it more resistant to neutralizing antibodies. This results in a form of adaptive evolution, as the proofreading mechanism in the virus that should normally detect and correct these errors during replication does not capture the fragment scrapings, resulting in a permanent change in the SARS-CoV-2 sequence to as a result, it alters virus evolution and behavior.
Multiple antibodies (green and red) bind SARS-CoV-2 vein protein within cells (blue) if there are no removals (LEFT). Removal of vein proteins stops the neutralization of antibody from binding (absence of green), but other antibodies (red) still attach very well (RIGHT). Repetitive deletion generates variants that escape neutralization. Image Credit: Kevin McCarthy and Paul Duprex