Dec 03, 2021 12:00:00

Researchers claim that the Omicron strain of the new coronavirus may have evolved among 'rodents'

Known as a new variant of the new coronavirus, '

B.1.1.529 (Omicron strain) ' is unusual, with more than 30 mutations in the spike protein on the virus surface, which is important for infecting human cells. We are very cautious because of the large number of mutations that can be said. Some researchers argue that the place where such an Omicron strain acquired the mutation 'may have evolved among other animal species such as rodents rather than humans.'

Where did'weird' Omicron come from? | Science | AAAS
https://www.science.org/content/article/where-did-weird-omicron-come

Some experts believe Omicron variant may have evolved in an animal host
https://www.statnews.com/2021/12/02/some-experts-suggest-omicron-variant-may-have-evolved-in-an-animal-host/

Omicron variant may have evolved in rats, one theory says | Live Science
https://www.livescience.com/omicron-origin-theory-rodents

The Omicron strain, which is attracting attention as a new mutant strain of the new coronavirus, was reported to WHO from South Africa in November 2021, but this does not mean that the mutation occurred in South Africa. In fact, Omicron strains have been detected in samples collected before the report by South Africa in the Netherlands and Nigeria, and it has been pointed out that the Omicron strain may have spread to each country before the report.

Since there are so many mutations contained in the Omicron strain and it is difficult to identify the closest mutant strain, it seems that it has evolved in parallel with the previous alpha strain and delta strain. 'I think (the time when the Omicron strain diverged from other mutants) dates back to mid-2020,' said Emma Hodcroft, a virologist at the University of Bern, Switzerland.

The question here is, 'Where did the Omicron strain evolve?' The fact that it was not detected by humans until so many mutations were acquired suggests that the Omicron strain may have evolved in a special environment rather than the general population in which the virus is frequently analyzed. I am.

One possible explanation is the hypothesis that 'repeated infections evolved within a population with little virus analysis.' 'I think this evolved somewhere in southern Africa during the winter epidemic, not in South Africa, where there is a lot of sequencing,' said Christian Drosten, a virologist at the Berlin Medical College in Germany. Claim. Meanwhile, Andrew Rambaut, a professor of molecular evolutionary chemistry at the University of Edinburgh in the United Kingdom, said that this type of virus has not been found elsewhere, and that there are places on the earth where infections are repeated in isolation for a long period of time. He said it was hard to think of.

Another explanation is the hypothesis that 'it evolved in the body of immunosuppressed COVID-19 patients who are chronically present with the new coronavirus.' From past

cases , it is known that the new coronavirus exists in the body of patients whose immunity is suppressed by cancer treatment for a long period of time and undergoes mutation in the body. However, viral mutations found in immunosuppressed patients with influenza and other infectious diseases are accompanied by 'mutations that reduce human-to-human infectivity,' and mutations that increase infectivity, such as the Omicron strain. Is hard to get up.

A hypothesis different from 'mutation in isolated human populations' and 'mutation in immunosuppressed patients' is that 'Omicron strain has evolved among non-human animal species such as rodents. Isn't it? ' Kristian Andersen, an infectious disease researcher at the Scripps Research Institute in the United States, said that 'Omicron strains had diverged from other mutant strains as of 2020', which is the evolution of Omicron strains in non-human animal species. It is said that it can be explained by the hypothesis that it has achieved.

The new coronavirus is known to be a virus that infects animal species other than humans, and it is known that it actually infects dogs, cats , gorillas, etc. Cases of human infection have also been reported.

A mutant of the new coronavirus infects humans from mink, killing 17 million minks-GIGAZINE

Robert Garry, a professor of microbiology at Tulane University School of Medicine, points out that seven of the mutations in the Omicron strain appear to allow infection of rodents such as mice and rats. It is unclear whether the Omicron strain really evolved among the rodents, but it is possible that the original virus found in Wuhan, China, was mutated and the infection and mutation were repeated among the rodents. There is.

Many researchers studying the evolution of the virus should rule out the possibility at the time of writing, saying that Anderson's hypothesis that 'Omicron strains have evolved among rodents' is not impossible. I don't think so. 'The interesting thing (about the Omicron strain) is how crazy it is (from the traditional mutant strain),' said Mike Worobey, an evolutionary biologist at the University of Arizona. Worobey supported the hypothesis that the Omicron strain had evolved in immunosuppressed patients, but there were cases of a new coronavirus epidemic in wild white-tailed deer from November 2020 to January 2021. He seems to be reconsidering Anderson's hypothesis.

Angela Rasmussen, a coronavirus researcher at the University of Saskatchewan, Canada, supports the hypothesis that the Omicron strain has evolved among rodents. 'It's obvious to everyone that this virus has been on an independent evolutionary path for a long time, and I think it's very surprising. For me, (Omicron strain evolved in rodents). It gives us the idea that this idea is possible, 'Rasmussen said.