Scientists have discovered natural compounds in the human body, which, binding to coronavirus, make it immune to antibodies. According to the authors, it explains why the COVID-19 suffered, even if they had a high level of antibodies, they can become re-infected. The results of the study are published in the journal Science Advances.
British researchers from the Francis Creek Institute, Imperial College of London, Royal College of London and University College of London in collaboration with colleagues from Italy and the Netherlands found that natural compounds that are part of hemoproteins – biliverdin and bilirubin – suppress the binding of antibodies with spike protein Coronavirus.
It all started with the fact that the biologists from the Francis Creek Institute, who participated in the development of tests for antibodies, found that SARS-COV-2 spacing protein firmly binds to the biliverdin – a substance that gives these proteins an unusual green color.
Then, using the serum of the blood of people previously overwhelmed COVID-19, the authors found that biliverdine by 30-50 percent suppresses the combination of human antibodies with a spike protein, making them ineffective when neutralizing the virus. Considering the fact that biliverdin uses only a small plot on the surface of the virus to bind, such a strong decrease in antibody efficiency has become a surprise for researchers.
To find out the acting molecular mechanism, the authors studied in detail the interaction between spike protein, antibodies and biliverdin using methods of cryo-electron microscopy and X-ray crystallography.
They found that biliverdine is attached to the N-terminal spike domain and stabilizes it so that the spike cannot be revealed. According to scientists, this means that some antibodies will not be able to access their target sites, contact the virus and neutralize it.
Interestingly, the levels of biliver and the other, which has the same action of the compound, bilirubin, in the blood and tissues increases as the immune response to infection with the SARS-COV-2 virus.
“And the more these molecules, the greater the virus of the opportunity to hide from the antibodies. This is a really striking process, since the virus benefits from the side effect of the damage already caused by them,” says the first author of Annakiaar Rosa (Annachiara Rosa), scientific Petra Cherepanova’s laboratory officer.