Scientists identify antibodies that block Omicron Covid variant. How?

Research on  antibodies that neutralize omicron  has been published in the journal Nature which may  further help to design vaccines and antibody treatments. These may potentially be effective no only against Omicron, but other variants that may emerge in the future.

These finding tells us that by focusing on antibodies that target these highly conserved sites on the spike protein, there is a way to overcome the virus' continual evolution

The Omicron variant has an unusually high number of 37 mutations in the spike protein, which the virus uses to enter and infect the human cells.

It is thought that these changes explain in part why the variant has been able to spread so rapidly, to infect people who have been vaccinated and to reinfect those who have previously been infected.

The main questions we were trying to answer is how has this constellation of mutations in the spike protein of the Omicron variant affected its ability to bind to cells and to evade the immune system's antibody responses.

To assess the effect of these mutations, the researchers engineered a disabled, non replicating virus, called a pseudovirus, to produce spike proteins on its surface, as coronaviruses do.

They then created pseudoviruses that had spike proteins with the Omicron mutations and those found on the earliest variants identified in the pandemic.

The researchers first looked to see how well the different versions of the spike protein were able to bind to protein on the surface of cells, that the virus uses to latch onto and enter the cell. This protein is called as angiotensin converting enzyme-2 (ACE2) receptor.

It was stated that the Omicron variant spike protein was able to bind 2.4 times more than spike protein found in the virus isolated at the very beginning of the pandemic.

That is not a huge increase, but in the SARS outbreak in 2002-2003, mutations in the spike protein that increased affinity were associated with higher transmissibility and infectivity

They also found that the Omicron version was able to bind to mouse ACE2 receptors efficiently, suggesting Omicron might be able to "ping-pong" between humans and other mammals.

The researchers then looked at how well antibodies against earlier isolates of the virus protected against the Omicron variant.

They did this by using antibodies from patients who had previously been infected with earlier versions of the virus, vaccinated against earlier strains of the virus, or had been infected and then vaccinated.

The team found that antibodies from people who had been infected by earlier strains and from those who had received one of the six most-used vaccines currently available all had reduced ability to block infection.

Antibodies from people who had been infected, recovered, and then had two doses of vaccine also had reduced activity, but the reduction was less, about fivefold, clearly demonstrating that vaccination after infection is useful.

Antibodies from people, in this case a group of renal dialysis patients, who had received a booster with a third dose of the mRNA vaccines produced by Moderna and Pfizer showed only a 4-fold reduction in neutralizing activity.

This shows that a third dose is really, really helpful against Omicron.