Covid: Omicron comes from mice, say Chinese scientists

The Omicron variant of Covid was first identified in Africa last November. Since then, it has attracted the attention of the international medical community for its large number of mutations, some that had not been observed in previous variants. Thus, Chinese scientists point out that Omicron comes from mice, where it hatched, stabilized, and then leapt towards the humans.

Researchers at the Chinese Academy of Sciences in Beijing analyzed the molecular spectrum of mutations of the Omicron variant and found that the patient in whom this transformation evolved may not have been human, but a rodent, as it was adapted to infect the cells of these animals.

“Our results suggest that the Ómicron progenitor jumped from humans to mice, rapidly accumulated mutations conducive to infecting that host, and then jumped back to humans, indicating an evolutionary path between species for the Ómicron outbreak,” write the Chinese experts in genetics and biology.

The authors also note the three hypotheses about the origin of Ómicron highlighted by the scientific community so far: that it developed in a human population of the world with little viral surveillance; that evolved in a patient with an immunosuppressive disease infected with Covid; or that it may have accumulated its numerous mutations in a non-human host and then jumped to humans. And we know that rodents are a species in close contact with people, and that essentially Covid-19 is one of many coronaviruses that inhabit humans and animals.

“The molecular spectrum of Omicron mutations prior to the outbreak does not agree with the evolutionary history of humans,” but it does with an evolutionary history in mice, the scientists write in their study published today. Journal of Genetics and Genomics.

“We found that the molecular spectrum of Omicron mutations before the outbreak was inconsistent with the rapid accumulation of mutations in humans, and that it suggested a trajectory in which Omicron’s parent experienced a human-to-mouse reverse zoonotic event at some point during the pandemic (most likely mid-2020) and accumulated mutations in a host mouse for more than a year before returning to humans in late 2021, “the Chinese scientists note.

In other words, according to these findings, Ómicron first jumped from humans to mice sometime in 2020. In rodents it evolved and adapted to jump back to humans in late 2021 … and here we are in the middle of a global wave contagions that have reached all-time highs.

Humans represent the largest known reservoir of SARS-CoV-2 and frequently come into contact with other animals, including livestock animals, pets or wild animals that invade homes in search of food and shelter, ”the investigation reads.

“Given the ability of SARS-CoV-2 to jump through various species, Global populations appear likely to face additional animal-derived variants until the pandemic is well controlled. Therefore, our study emphasizes the need for viral surveillance and sequencing in animals, especially those in close contact with humans ”, they conclude.

Read more:

+ IHU: They discover a new variant of Covid-19 with more mutations than Ómicron

+ Ómicron vs Delta: What these COVID variants have in common

+ How effective are COVID vaccines against the Omicron variant

+ Flurone: Symptoms of the combination of Covid with influenza

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