Since it first appeared two and a half years ago in Wuhan, China, the SARS-CoV-2 coronavirus has constantly developed new mutations. more infectious Virus variants have prevailed. Vaccines and therapeutic antibodies mostly target earlier strains of the coronavirus. The currently circulating variant BA.5 seems to be able to circumvent the immune protection particularly well.
Experts are therefore hoping for a vaccine that is effective against all previous – and especially future – variants of the corona virus. Such a universal vaccine would need an antibody response in the body cause, which is so broad that it protects against any mutations.
With mice
researchers der Harvard Medical School in Boston could now be a significant step closer to such a vaccine. Using mice, they have an antibody identified, which can neutralize all known variants of Sars-CoV-2.
The rodents, the developed human immune cells after genetic manipulationthe spike protein of the Wuhan strain or nanoparticles with its binding site were injected twice with an interval of four weeks. Through this exposure to viral material, the mice’s humanized immune system produced nine different strains of antibodies against SARS-CoV-2.
In order to determine how well these defense proteins work against the different virus variants, the researchers then carried out neutralization tests with one monoclonal antibody from each line. One of these antibodies – SP1-77 – proved to be extra effective.
“New Mechanism”
The reason for this is that SP1-77 binds the spike protein at a site that is hardly affected by the mutations of the coronavirus. Instead of like most other antibodies at the To dock with the receptor binding site of the coronavirus, the antibody binds to the opposite side to the ACE2 binding site.
Through a “new mechanism” it neutralizes the current variants, says study co-author Thomas Kirchhausen. SP1-77 allows the virus to dock to the ACE2 receptor on the cell surface, but blocks the fusion of the outer virus membrane with the cell membrane.
The coronavirus can thus bind to human cells, but cannot infect the cell.