Researchers are trying to figure out how Omicron defied the normal rules of evolution.
https://www.nytimes.com/live/2...
SARS-CoV-2's evolution took an unexpected turn in late 2020, when new variants began emerging.
As nurses and doctors struggle with a record-breaking wave of Omicron cases, evolutionary biologists are engaged in a struggle of their own: figuring out how this world-dominating variant came to be.
When the Omicron variant took off in southern Africa in November, scientists were taken aback by its genetic makeup. Whereas earlier variants had differed from the original Wuhan version of the coronavirus by a dozen or two mutations, Omicron had 53 — a shockingly large jump in viral evolution.
In a study posted online last week, an international team of scientists further deepened the mystery. They found that 13 of those mutations were rarely, if ever, found in other coronaviruses, suggesting they should have been harmful to Omicron. Instead, when acting in concert, these mutations appear to be key to some of Omicron's most essential functions.
Now the researchers are trying to figure out how Omicron defied the normal rules of evolution and used these mutations to become such a successful vector of disease.
"There's a mystery here that someone has to figure out," said Darren Martin, a virologist at the University of Cape Town who worked on the new study.
Mutations are a regular part of a coronavirus's existence. Every time a virus replicates inside of a cell, there's a small chance that the cell will create a flawed copy of its genes. Many of those mutations would make new viruses defective and unable to compete with other viruses.
But a mutation can also improve a virus. It could make the virus stick more tightly to cells, for example, or make it replicate faster. Viruses that inherit a beneficial mutation may outcompete others.
Over most of 2020, scientists found that different lineages of the coronavirus around the world gradually picked up a handful of mutations. The evolutionary process was slow and steady, until the end of the year.
In December 2020, British researchers were jolted to discover a new variant in England carrying 23 mutations not found in the original coronavirus isolated in Wuhan a year before.
— Carl Zimmer
If you want to read more about how Omicron mutated, there's a good article here:
https://www.nytimes.com/2022/0...
