When Omicron began to emerge in southern Africa in November of last year, the scientific community was astonished by its genetic makeup.
Previous variants differed from the Wuhan strain by dozens of mutations, while Omicron boasts an astonishing 53 mutations, marking a significant leap in the virus’s evolutionary process.
In a study published last week, an international team of scientists emphasized the mystery surrounding this number of mutations.
The research team discovered that among the 53 mutations, there are 13 rare mutations, some of which had never been seen in other coronaviruses. This suggests that these mutations should have been detrimental to Omicron.
Omicron has mutations never seen in previous coronaviruses. (Photo: ST).
However, instead of being harmful, when combined, these mutations appear to be key to some of Omicron’s most important functions.
Researchers are now trying to determine how Omicron defies normal evolutionary rules and uses these mutations to become such a successful pathogen.
“There is a mystery here, and someone has to figure it out,” said Dr. Darren Martin, a virology expert at the University of Cape Town, South Africa, who is one of the contributors to the new research.
Defying Logic
Mutations are a common phenomenon in the existence of coronaviruses. Each time a virus replicates inside a cell, there is a chance that the cell will produce a faulty version of its genetic material.
Many of these mutations will result in new, defective viruses that cannot compete with other viruses.
However, mutations can also enhance a virus’s capabilities, helping it adhere more tightly to cells or replicate faster. Viruses that inherit beneficial mutations can outcompete others.
Throughout most of 2020, scientists discovered that different strains of coronaviruses around the world were gradually accumulating mutations. This evolutionary process was slow and steady until the end of that year.
In December 2020, British scientists were thrilled to discover a new strain of the virus in the UK that carried 23 mutations not found in the strain isolated in Wuhan, China, a year earlier.
The new strain, named Alpha, quickly became widespread worldwide. In 2021, faster-spreading variants emerged, including the Delta variant with 20 specific mutations, which overshadowed Alpha and became the dominant strain last summer.
Then, Omicron appeared, with more than double the number of mutations compared to previous variants.
Immediately after Omicron’s emergence, Dr. Martin and his colleagues set out to reconstruct the virus’s evolutionary process by comparing Omicron’s 53 mutations with those of other coronaviruses.
Omicron shares some mutations with Delta and other strains, suggesting that they have appeared multiple times and that natural selection has favored them.
However, scientists found a different pattern when they examined the spike protein on the surface of Omicron that allows it to attach to cells.
Omicron’s spike has 30 mutations. Researchers found that 13 of these mutations are extremely rare in other coronaviruses, even in related viruses found in bats.
These 13 mutations have never been seen in the millions of coronavirus gene sequences that scientists have assembled since the pandemic began.
If a mutation is beneficial to the virus, or even neutral, scientists believe it would appear more frequently in other variants.
But if these are rare mutations or completely absent, it could indicate that they are harmful to the virus, hindering its replication.
Dr. Martin suggests that such mutations would create errors, preventing the virus from surviving long and leading to its demise.
However, Omicron has defied that logic.
