In-Depth: Molecular 'smokescreen' could explain omicron's rapid spread

A mutation allows the coronavirus to send out a cloud of proteins, acting like a smokescreen
Posted at 7:31 PM, Dec 27, 2021
and last updated 2021-12-28 02:15:33-05

SAN DIEGO (KGTV) – Scientists at UC San Francisco have identified a set of mutations in the coronavirus that help the pathogen temporarily deactivate the body’s immune defenses, a finding that may explain the omicron variant’s rapid spread across the globe and offer a new way to combat it.

Omicron and delta have similar mutations to the alpha variant in a little-studied region called ORF9B, according to UCSF molecular biologist Dr. Nevan Krogan.

In a new paper published in Nature, Krogan and his collaborators show the mutations in alpha’s ORF9B region allow it to send out waves of proteins that cloud the body’s innate immune system. The move temporarily disables the body’s initial alarm system and gives the virus free rein to multiply.

“This is like a smokescreen. The cells don’t know they’re infected. And that gives the virus a chance to ultimately replicate within the cells,” he said.

The paper in Nature only features experiments on alpha, but based on omicron’s genetic signature, Krogan suspects the variant should have an equally strong smokescreen – if not stronger.

Other scientists, like UC San Diego’s Dr. Robert Schooley, agree that ORF9B appears to be the driving force behind omicron’s rapid spread.

“I think from the standpoint of its ability to get around the world as fast as it has, that is the key protein,” Dr. Schooley said. “It’s a really important insight.”

This smokescreen effect is significant, Schooley said, because it delays the molecules that cause someone to experience coughing, sneezing and other symptoms.

“And so it allows the virus to grow extremely rapidly while we’re out playing beach volleyball and don’t even know we’re sick,” he said.

In lab experiments, alpha’s smokescreen lasted about 12 to 24 hours, but scientists say that’s plenty of time for an infected person to unknowingly spread the virus to others.

“If we could come up with a drug that would stop this smokescreen from happening, it could have a very profound effect here,” Dr. Krogan said.

A drug that could block ORF9B could not only disable omicron, it could treat whatever variant comes next, Krogan said. His lab is already trying to find such a substance.