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 This genetic sequence does not appear in any earlier versions of the
coronavirus, called SARS-CoV-2, but is ubiquitous in many other
viruses including those that cause the common cold, and also in the
human genome, researchers said.
By inserting this particular snippet into itself, Omicron might be
making itself look "more human," which would help it evade attack by
the human immune system, said Venky Soundararajan of Cambridge,
Massachusetts-based data analytics firm nference, who led the study
https://osf.io/f7txy posted on Thursday on the website OSF
Preprints.
This could mean the virus transmits more easily, while only causing
mild or asymptomatic disease. Scientists do not yet know whether
Omicron is more infectious than other variants, whether it causes
more severe disease or whether it will overtake Delta as the most
prevalent variant. It may take several weeks to get answers to these
questions.
Cells in the lungs and in the gastrointestinal system can harbor
SARS-CoV-2 and common-cold coronaviruses simultaneously, according
to earlier studies. Such co-infection sets the scene for viral
recombination, a process in which two different viruses in the same
host cell interact while making copies of themselves, generating new
copies that have some genetic material from both "parents."
This new mutation could have first occurred in a person infected
with both pathogens when a version of SARS-CoV-2 picked up the
genetic sequence from the other virus, Soundararajan and colleagues
said in the study, which has not yet been peer-reviewed.
The same genetic sequence appears many times in one of the
coronaviruses that causes colds in people - known as HCoV-229E - and
in the human immunodeficiency virus (HIV) that causes AIDS,
Soundararajan said.
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 South Africa, where Omicron was
first identified, has the world's highest rate
of HIV, which weakens the immune system and
increases a person's vulnerability to infections
with common-cold viruses and other pathogens. In
that part of the world, there are many people in
whom the recombination that added this
ubiquitous set of genes to Omicron might have
occurred, Soundararajan said.
"We probably missed many generations of
recombinations" that occurred over time and that
led to the emergence of Omicron, Soundararajan
added.
More research is needed to confirm the origins
of Omicron's mutations and their effects on
function and transmissibility. There are
competing hypotheses that the latest variant
might have spent some time evolving in an animal
host.
In the meantime, Soundararajan said, the new
findings underscore the importance of people
getting the currently available COVID-19
vaccines.
"You have to vaccinate to reduce the odds that
other people, who are immunocompromised, will
encounter the SARS-CoV-2 virus," Soundararajan
said.
(Reporting by Nancy Lapid; Editing by Will
Dunham)
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