According to a study by American scientists, new strains of the SARS-CoV-2 coronavirus contain genetic mutations that allow it to evade the immune response. This makes the new variants of the virus resistant to neutralizing antibodies. The results of the study are published in the journal Science.
Researchers from the University Of Pittsburgh School Of Medicine examined a database of genetic sequences of the new coronavirus collected worldwide. When the project started in the summer of 2020, SARS-CoV-2 was considered relatively stable, but now the picture has changed.
The further the virus evolves, the more genetic mutations scientists discover in it. Most of all, experts are concerned about the ability of the coronavirus to evade immune responses by selectively removing small fragments of its genetic sequence. This process is called deletion by biologists.
The authors found that deletions as the SARS-CoV-2 virus evolves occur at the same sequence points — places where the virus can tolerate a change in shape without losing its ability to enter cells and make copies. In particular, deletions occur in the part of the sequence that encodes the form of the spike protein, which is targeted by the neutralizing effect of antibodies. As a result, the antibodies cannot capture the virus, and it continues to infect the cells unhindered.
For the first time, scientists encountered neutralization-resistant deletions when they observed an immune-compromised patient who was infected with SARS-CoV-2 for 74 days before eventually dying from COVID-19. During this long time for the virus and the immune system, SARS-CoV-2 went through a long evolutionary path in the patient’s body, which led to the accumulation of dangerous mutations in his genome.
New strains, first identified in the UK and South Africa, have similar deletions. The so-called “British variant,” which was later given the name B. 1.1.7, the authors found in the data sets back in October 2020, when nothing was known about its increased virulence.
Fortunately, the authors note, the new strains are still neutralized by the full range of antibodies present in the plasma of convalescents. Still, it is unclear how quickly they will learn to elude existing vaccines and therapeutics in the future and how long these vaccines and drugs will be effective.
“The extent to which these deletions undermine immune defenses remains to be determined. At some point, we will have to start developing new vaccines or discuss the idea. And this is important to understand when it comes to developing tools to fight the virus,” lead author Kevin McCarthy, associate professor of molecular biology and molecular genetics, said in a press release from the University of Pittsburgh.
So far, researchers see a way out in the development of the largest number of different approaches.
“Chasing the virus in different ways is the only way we can defeat the werewolf. A combination of different antibody combinations Manotel with antibodies, different types of vaccines. In the event of a crisis, we need backup options,” concluded another author, Dr. Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh.