Since the appearance of the Omicron, scientists have been trying to find out where this new variant of the Corona virus came from, how it infects the body, and a number of other things. Some scientists have an alternative theory that the Omicron may have evolved in animals.
The theory is that certain types of animals, particularly rodents, became infected with the SARS-CoV-2 virus around mid-2020. In this new species, the virus evolved, accumulating about 50 mutations in the spike protein before spreading back to humans.
Kristian Andersen, an immunologist at the Scripps Research Institute, was among those who put forward the idea that the Omicron might have emerged from a reverse zoonotic event.
To note, a zoonotic event is when an animal pathogen begins to infect and spread between humans. Reverse zoonoses are when the virus reenters an animal species.
"I know that most people think that this (coming from) immunocompromised individuals, and I think that makes sense. But to be honest, I really think this reverse zoonosis followed by a new zoonosis seems more likely given the available evidence and mutations themselves, because some of them are very unusual," Andersen said as quoted by Stat News.
A number of other scientists who study the evolution of viruses say that the conjecture could be true. Some other scientists place more emphasis on the theory that the variant develops in people with compromised immune systems, while the rest feel there isn't enough evidence at this point to support this possibility.
"Personally, I think it's more likely to circulate undetected, in immunocompromised individuals," said Emma Hodcroft, a molecular epidemiologist at the Institute of Social and Preventive Medicine in Bern, Switzerland. Nonetheless, Hodcroft insisted that it was important to explore hypotheses.
"I would definitely consider it a plausible alternative hypothesis for evolution during persistent infection in humans," said Andrew Rambaut, a professor of molecular evolution at the Institute of Evolutionary Biology in Edinburgh. He warned that the answers to all these questions would not appear any time soon.
One of the characteristics of SARS-2 underlies this thinking, it is able to infect a number of species, domestic dogs and cats, big cats, minks, to white-tailed deer. Given how easily the virus jumps from one species to another, people who study it think this list will grow.
The original virus that emerged from Wuhan, China, in early 2020 did not infect rodents. But when the Alpha, Beta, Delta variants started appearing, the viruses were known to infect rodents.
Robert Garry, a professor of microbiology and immunology at Tulane Medical School, has been tracking the emerging SARS-2 mutation. Seven of these, related to rodent adaptation, changes that appear to allow the virus to infect mice, and similar species.
The seven mutations, are in the Omicron. He believes it is a matter of whether the variant develops in an animal or human host. But if the evidence is in animals, the most likely place of evolution is rodents.
"Regardless of whether this variant appears in other species or not, given the ability of SARS-2 to jump species, there is a possibility that the world will face animal-derived variants in the future. The consequences of that? We must continue to tinker with vaccines," Garry warned. .
