A team of scientists identified antibodies that could target unchanged parts of the new coronavirus as it continues to mutate and evolve. This is an advance that could lead to new therapies to neutralize Omicron and other variants of COVID-19.
David Veesler of the University of Washington School of Medicine in the US said identifying "broadly neutralizing" antibodies such as those in the coronavirus spike protein, which the virus uses to enter human cells, could help develop better vaccines and antibodies that would be effective not only against Omicron, but also against other variants that may appear in the future.
"These findings tell us that by focusing on antibodies that target a highly conserved area of the spike protein, there is a way to address the continued evolution of the virus," said Dr Veesler.
So far, studies have shown that Omicron has 37 mutations in the spike protein, which partly explains why this variant can spread so quickly, infecting vaccinated people and re-infecting those who have previously recovered.
In the new study published in the journal Nature, the researchers assessed the effect of this mutation by developing an inactivated non-replicating virus (called a pseudovirus) to produce spike proteins on its surface.
They engineered a pseudovirus that had a spike protein along with the Omicron mutation as well as that found in the earliest variants identified during the pandemic.
Along w/ Omicron's rapid spread is a flood of first-rate research papers. Today @nature 3 reports on its immune escape, including vs most monoclonal antibodies (Abs) and work around via broad neutralizing Abshttps://t.co/8OUgwh5qRrhttps://t.co/r6Cy54VgXwhttps://t.co/S0xAEhXUdm
— Eric Topol (@EricTopol) December 23, 2021
The researchers assessed how well different versions of this spike protein could bind to the ACE2 receptor, a protein on the surface of human cells that the virus uses as a gateway to and infecting tissues.
They found that the Omicron spike protein could bind 2.4 times better than the spike protein found in viruses isolated early in the pandemic.
"It wasn't a huge increase, but in the SARS outbreak in 2002-2003, mutations in the spike protein that increased affinity were associated with higher transmission and infectivity," said Dr Veesler.
When the scientists assessed how the immune system acted against previous viral isolates that protected against Omicron, they found that antibodies from people who had been infected by the previous strain, and from those who had received one of the six most widely used vaccines currently available, all experience a reduced ability to block infection.
We discovered that the #SARSCoV2 #Omicron RBD, but not Alpha or Beta RBDs, bound mouse ACE2, likely due to Q493R which is similar to Q493K isolated upon mouse adaptation by @Baric_Lab https://t.co/XISz9PglNR
These data *putatively* reflect #Omicron expanded tropism
4/8 pic.twitter.com/hdeyPwzvnh
— The Veesler Lab (@veeslerlab) December 14, 2021
The study also identified four classes of antibodies that retain their ability to neutralize Omicron. Antibodies in each of these classes target one of four specific areas of the spike protein present, not only in the Sars-CoV-2 variant but also in a group of related coronaviruses, called sarbecoviruses.
Scientists believe that specific areas of these viral spike proteins remain unchanged, and are "conserved", suggesting that they play an important function that the proteins could lose if they mutated.
Based on the findings, the researchers say that designing vaccines and antibody treatments that target this area could be effective against a broad spectrum of variants.
