Boston University researchers say they may have discovered why the omicron variant of the coronavirus resulted in less severe illness than the original virus.
Their work, published in the journal Nature on Wednesday, suggests that a protein mutation — in addition to changes in the virus's spike protein — played an important role in omicron's ability to bypass immunity and cause milder symptoms than the original coronavirus.
Ron Corley, who chairs the Department of Microbiology at BU's Chobanian & Avedisian School of Medicine, said it was differences in the omicron variant, as well as vaccines, that made many people less sick when omicron dominated infections last year.
"This just simply shows that it's not only the vaccines, but it's also the virus itself that has changed, and that we did not know before this study," Corley said.
The research, conducted at BU's National Emerging Infectious Disease Laboratories (NEIDL), and with a team of international scientists, shows mutations in a protein known as NSP6 appear to be a key factor in the less severe illness experienced by many people infected by omicron. The study's authors said their findings suggest the spike protein mutations had a more limited impact on the severity of COVID. Their discovery, they said, could eventually lead to new treatments that might hamper the effects of the virus.
"This is an important piece of work," said virologist Mohsan Saeed, the study's senior author, in an interview with BU's The Brink. "This provides us with an exciting new concept for future vaccines and therapeutics — if we know how to weaken the virus, we can better fight it."
The scientists also disputed previous media reports that suggested they created a potentially dangerous version of the coronavirus as part of of their research. The university has denied these claims.
In a draft of their early work published online last year, the researchers reported that the original virus used in their experiments killed 100% of the mice tested. When they created a hybrid virus by adding omicron's mutations to the spike protein, the virus killed 80%. (After the researchers also added the mutations to the NSP6 protein, all of the mice survived exposure to the virus.)
But Saeed pointed out that the mice in the experiment were engineered to be sensitive to the virus, so the scientists could more quickly see the potential to cause disease.
“There’s a huge difference in disease presentation and outcome between these artificially engineered mice and human beings,” Saeed said.
Because of the controversy, the National Institutes of Health examined the research. The agency provided funding for some of the laboratory instruments used in the work but determined that no federal standards were violated. The agency found that because the research was privately funded, the researchers did not have to disclose that their work involved creating a hybrid version of the virus.
"After careful review, the National Institutes of Health can confirm that the Boston University experiments described in a pre-print article on SARS-CoV-2 research were funded with private funds and were not subject to NIH review," the agency said through a spokesperson.
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