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Different binding site: illustration of the coronavirus with the prominent spike proteins
Photo: KTS Design / Science Photo Library/ Getty Images
Since the beginning of the pandemic, virus variants have emerged that can bypass the protection against infection after vaccination or infection.
A specialist team led by Natalia Freund from Tel Aviv University has now identified antibodies that very reliably neutralize all known variants of the corona virus.
According to the study in the journal "Communications Biology", some of the first patients infected with Sars-CoV-2 in spring 2020 are still immune to the pathogen, and with a high degree of certainty also to the variants of the coronavirus that have mutated since then.
It is hoped that those who carry the same antibodies as them need to worry less about the risk of reinfection.
The experts isolated nine antibodies created by natural infection and tested them in the laboratory on different virus variants.
The antibodies came from the blood of patients who had contracted the wild type of the virus (Wuhan strain), which was still dominant at the time, in Israel in spring 2020.
An antibody with the abbreviation TAU-1109 neutralized 90 percent of the cultured coronaviruses of the delta variant and 92 percent of the currently predominant omicron variant in the laboratory.
A second antibody called TAU-2310 destroyed 97 percent of delta viruses and 84 percent of omicron viruses in the tests.
Vulnerability in the evolution of the virus
Immunologist Natalia Freund is convinced that she has found a weakness in the evolution of the virus.
This involves mutations in the characteristic spike protein, which forms the docking point of the virus on body cells.
Freund reports that the spike protein mutates predominantly at the same receptor binding site called ACE2.
The disadvantage of this: Most antibodies dock to ACE2 to render the corona virus harmless.
They are less able to recognize new virus variants with significantly altered ACE2 and can no longer fight them as reliably.
As a result, protection against infection decreases after vaccination with the new virus variants.
For this reason, adapted vaccines such as those now available against omicron have been developed.
The antibodies TAU-1109 and TAU-2310 bind to a different site on the spike protein, which "for some reason hardly ever mutates," says Freund.
Therefore, they could help in the defense against numerous virus variants.
The results from Tel Aviv were confirmed in laboratories at Israel's Bar Ilan University and the University of California in San Diego.
The molecular biologist Ye Xiang from China's Tsinghua University was also involved in the study.
The pandemic is so stubborn because of declining immunity, says Freund.
"People who were vaccinated against smallpox at birth and are 50 years old today still have antibodies and are therefore probably at least partially protected against monkeypox." In contrast, the number of antibodies effective against Covid-19 decreases noticeably after three months, "why we see people getting infected over and over again, even if they're triple vaccinated."
However, vaccination after three doses still offers good protection against a severe or even fatal course of the disease.
According to Freund, the antibodies that have now been identified could be given as medication in the first few days after infection and thus stop the spread of the virus in the body.
This could help people with a weakened immune system in particular who do not build up reliable protection against disease after vaccination.
It would also be conceivable to design novel vaccines that are intended to provide mucosal immunity and thus longer-lasting protection against infection in such a way that vaccinated people produce the newly discovered antibodies.
However, the products are not yet ready for the market.
And it is still unclear how reliably the antibodies protect against infections with different variants in practice.
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