It is one of the The puzzling mysteries of the Covid pandemic: Where is it? Omicron appeared from, almost a year ago? The fast-moving, extremely contagious variant arrived shortly after Thanksgiving 2021, rife with strange mutations. When the scientists untangled this array, they discovered that Omicron is not related to Delta or Alpha, the two waves before it. Instead, its difference from its closest common ancestor back in the day more than a yearduring the first few months of the pandemic — a geological epoch in the time of viral replication.
That is a tough question. How can something be so conveyable that it rips more 120 countries in two months, and yet evaded detection for so long? Within the puzzle lies a riddle: If Omicron evolved not from previous variants but parallels them, where has it been hiding all this time?
Competing hypotheses jostled for consideration: It took refuge in a group of people with little exposure to the outside world and no participation in sequence programs. It has found a home for someone who is so immunocompromised that they cannot overcome the infection, leaving the virus territory to replicate and change. Or, a third thought: It falls back into the animal kingdom — not into the bats it first found a host in, but into some new species that can mutate in novel ways.
That possibility, officially known as reverse zoster and informally as overflow reaction, is already a known risk. In April 2020, just a few months after the virus began to spread internationally, it migrated to the mink farm in the Netherlands, causing death or preventive slaughter millions of animals—And a few months later it went on a trip back to human.
No one can say exactly which of the three theories exactly explains Omicron’s appearance — and with Omicron itself rotating variations so quickly, the discussion has not been out of the question. Researchers. Now, a new study from a research team at the University of Minnesota is giving that debate new energy. Their analysis showed that Omicron adapted to the mousewhere it grows its array of mutations before passing it on to humans.
“These Omicron mutations are an evolutionary imprint left by the virus during transmission from one animal to another,” said senior author Fang Li, professor of pharmacology and director of the Research Center The university’s coronavirus, said in a statement. (Li declined an interview.)
In the study, published last week in Proceedings of the National Academy of Sciences, the researchers took a structural biology approach – studying the shape of molecules inside the virus – to check for mutations in Omicron’s mutant protein, which allows it to enter cells. They found certain mutations cause the virus to bind more effectively to a specific receptor, ACE2, because it exists in mouse cells, than the human version of that receptor. They confirmed that worked by assembling non-infectious pseudoviruses that express the Omicron spike protein and observing their binding to cells engineered to include mouse or human receptors. They found that Omicron had more of a relationship with the mouse version.
