Researchers from the Faculty of Medicine of the University of British Columbia have carried out the first structural analysis at the molecular level of the spike protein , spike or “spike” protein of the Omicron variant of the coronavirus SARS-CoV-2 responsible for the COVID-19 pandemic.
The analysis was carried out with a resolution of almost one atom using cryoelectron microscopy. The result is the complete structure of the spike protein, with which the coronavirus attaches itself to human cells and how it infects them. It is especially relevant because among the many mutations that the Omicron variant has undergone, the spike protein is the one that will allow the development of more effective treatments against this variant and those derived from it.
The spike protein , located on the outside of a coronavirus, allows SARS-CoV-2 to enter human cells. The Omicron variant has a total number of 37 mutations in this protein, between three and five times more than the previous variants.
Omicron has a greater ability to evade antibodies, and for this reason the vaccines have lost some of their effectiveness
Structural analysis revealed that several mutations (R493, S496 and R498) create new salt bridges and hydrogen bonds between the spike protein and the human cell receptor known as ACE2. The researchers concluded that these new linkages appear to increase binding affinity, that is, the strength with which the virus adheres to human cells, while other mutations (K417N) decrease the strength of this linkage.
Because of these changes, Omicron adheres more closely to human cells than the Delta variant that dominated before the pandemic. In addition, this protein in Omicron has a greater ability to evade antibodies, and for this reason the vaccines have lost some of their effectiveness, although they continue to be effective in preventing the most serious manifestations of the disease.
However, the Omicron variant was less effective in preventing antibodies created by vaccines, compared to immunity from natural infection in unvaccinated patients. This suggests that vaccination “remains our best defense,” said Dr. Subramaniam, an author of the review.