Scientists at the Institute of Biomolecular Sciences and Technologies of the University of Louvain (UCLouvain), Belgium investigated the interaction between sialic acids (SAs), which are sorts of sugar residues present on the surface of cells, and the spike (S) protein of SARS-CoV-2 (using atomic force microscopy). The findings of the study were published in Nature Communications on Tuesday.
The team of scientists led by David Alsteens identified a variant of the sugar (9-O-acetylated) residue that decorates the cells and found that it interacted more strongly with the S protein than other sugars.
According to the researchers, these sugar help in promoting cell recognition and allows viruses to identify their targets more easily. However, it also facilitate their point of attachment to allow them to enter their host cell and thus initiate their infection.
The scientists also made another discovery: they decided to catch the virus in its own trap, by preventing it from binding to its host cell. The team found that this can be done by blocking S protein’s points of attachment and thus suppressing any interaction with the cell surface.
However, one of the conditions for this is that the interaction between the virus and the agent blocking it is stronger than the one between the virus and the cell. The scientists demonstrated that multivalent structures (or glycoclusters) with multiple 9-O-acetylated sialic acids on their surface are able to block both binding and infection by SARS-CoV-2.
If the virus doesn’t attach to the cells, it can’t enter and therefore dies (lifetime 1 to 5 hours). This blocking action prevents infection, the scientists claimed.
At present, various anti-covid vaccines primarily address the SARS-CoV-2 mutations but not the virus as a whole. However, this discovery has the advantage of acting on the virus, independently of the mutations, as per the scientists.
Now the scientists will carry out tests on mice in order to apply this blocking of virus binding sites and observe whether this works on the organism. The outcomes will help in the development of an antiviral based on these sugars, administered by aerosol, in case of infection or high-risk contact. According to the scientists, this discovery is also interesting for the future, to counter other viruses with similar attachment factors.