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A U.S. finding gives researchers hope for a universal vaccine against Omicron and future variants.
Since its first appearance just over two and a half years ago in Wuhan, China, the SARS-CoV-2 coronavirus has developed new mutations. More infectious viral variants have become prevalent. However, vaccines and therapeutic antibodies predominantly target earlier strains of the coronavirus. The currently circulating variant BA.5, for example, seems to be able to evade immune protection particularly well.
Experts are therefore hoping for a vaccine that is effective against all previous – and especially future – variants of the coronavirus. Such a universal vaccine would elicit an antibody response in the body so broad that it protects against any mutations.
With mice
Researchers at Harvard Medical School in Boston may be significantly closer to such a vaccine. Using mice, they have identified an antibody that can neutralize all known variants of Sars-CoV-2.
The rodents, which formed human immune cells after genetic manipulation, were injected twice at intervals of four weeks with the spike protein of the Wuhan strain or nanoparticles containing its binding site. Through this contact with viral material, the humanized immune system of the mice produced nine different strains of antibodies against SARS-CoV-2.
To determine how well these defense proteins worked against the different viral variants, the researchers performed neutralization tests with one monoclonal antibody from each line. One of these antibodies – SP1-77 – proved to be extra effective.
“New mechanism”
This is because SP1-77 binds the spike protein at a site that is hardly affected by the coronavirus mutations. Instead of docking at the coronavirus receptor-binding site like most other antibodies, the antibody binds at the ACE2-binding site opposite.
Through a “novel mechanism,” it neutralizes the current variants, says study co-author Thomas Kirchhausen. SP1-77 allows the virus to dock with the ACE2 receptor on the cell surface but blocks the fusion of the outer viral membrane with the cell membrane.
As a result, the coronavirus can bind to human cells but cannot infect them.
- source: kurier.at/picture: pixabay.com
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