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Scientists have determined a new, highly mutated version The coronavirus that may have evolved in animals since late 2020 in white-tailed deer in southwestern Ontario.

They also found a very similar viral sequence in a person in the area who had close contact with deer, the first evidence of possible deer-to-human transmission of the virus.

“The virus is evolving in deer and moving away from what we clearly see in humans,” said Samira Mubareka, a virologist at the Sunnybrook Research Institute and the University of Toronto and author of the new paper.

The report has yet to be published in a peer-reviewed journal, and there is no evidence that the deer lineage spreads or poses a high risk to humans. Preliminary laboratory experiments suggest that the strain is unlikely to escape human antibodies.

However, the newspaper was published on the Internet a few days later. another team reported That the alpha variant may have continued to spread and evolve in Pennsylvania elk even after it disappeared from human populations.

Together, the two studies suggest that the virus can circulate among deer for a long time, increasing their risk. animals can become a long-term reservoir a source of the virus and future variants.

“There is absolutely no need to panic,” said Arinjay Banerjee, a virologist at the University of Saskatchewan who was not involved in either study.

However, he added, “The more hosts you have, the more opportunities there are for the virus to evolve.”

Previous studies found that virus common in white-tailed deer. Studies show that humans repeatedly transmit the virus to deer and then pass it on to one another. How humans spread the virus to deer remained a mystery, and until now there was no evidence that animals gave it back to humans.

The Canadian study was a collaboration involving more than two dozen researchers at institutions in Ontario. Scientists collected nasal swabs and lymph node tissue samples from 300 white-tailed deer killed by hunters in Ontario between November 1 and December 31, 2021. Six percent of animals from southwestern Ontario tested positive for the virus, suggesting they were actively infected when they died.

The researchers sequenced the entire viral genomes of five infected deer and found a unique previously undocumented constellation of mutations. Overall, 76 mutations, some previously found in deer, mink, and other infected animals, separated the lineage from the original version of the virus.

The deer samples were most closely related to viral samples from human patients in Michigan, not far from southwestern Ontario, in November and December 2020. They also resembled specimens taken from humans and mink in Michigan earlier that fall.

These findings, and the rate at which the virus has accumulated mutations, suggest that the next generation may have differentiated from known versions of the virus and have evolved undetected since late 2020.

But the exact path is unclear. One possibility is that humans passed the virus directly to the deer, and the virus then accumulated mutations as it spread between the cells of the uterus. Alternatively, the lineage may have evolved, at least in part, from another intermediate species (perhaps the farmed or wild mink) that later somehow passed it on to deer.

D., a veterinary microbiologist at Penn State who was not involved in the research. “We don’t have all the pieces of the puzzle,” Suresh Kuchipudi said in an email. “We cannot rule out the involvement of an intermediate host.”

A viral sample collected in the fall of 2021 from a human patient in southwestern Ontario closely matched the deer samples. This person is known to have “close contact” with the deer. the researchers said.

(Though Dr. Mubareka noted that people should not worry about accidental, indirect encounters, such as having a deer roaming in their backyard, they were unable to reveal further details about the nature of this contact for privacy reasons.)

The sample size is small, the scientists warned, and there is no conclusive evidence that the person contracted the virus from deer. “We don’t have enough information yet to confirm that this transition is back to humans,” said Roderick Gagne, a wildlife disease ecologist at the University of Pennsylvania’s School of Veterinary Medicine.

But at the time the human sample was collected, Ontario was sorting virus samples from anyone in the area who tested positive in a PCR test. The researchers found no other humans infected with similar versions of the virus, making it less likely to evolve independently in humans.

Dr. “If it was circulating widely in humans, or even narrowly circulating in humans, we would have caught it,” Mubareka said.

There is also no evidence that the person infected with soy has transmitted the virus to anyone else.

And early data suggest that current vaccines should still be able to protect against strains. The scientists found that antibodies from vaccinated humans were able to neutralize pseudoviruses — harmless, non-replicating viruses — designed to resemble deer strains.

In the second study, scientists from the University of Pennsylvania’s veterinary and medical schools analyzed nasal swabs from 93 deer that died in Pennsylvania during the fall and winter of 2021. 19 percent were actively infected with the virus. When the researchers sequenced seven of the samples, they found that five of the deer were infected with the Delta variant, while two were infected with Alpha.

At the time the samples were collected, Delta was common among human residents of the United States, but the Alpha wave that hit Americans in the spring of 2021 had long since subsided.

“Alpha seems to persist in white-tailed deer even when it’s not roaming in humans,” said Eman Anis, a microbiologist at the University of Pennsylvania School of Veterinary Medicine and author of the study.

Indeed, Delta samples in deer were genetically similar to those from humans, suggesting that they crossed species lines relatively recently. But the two Alpha sequences were more distinctly separated from the human lineage. (They also differed significantly from each other, suggesting that the variant was introduced to the deer population at least twice.)

The author of the Pennsylvania study, Dr. “The main outcome would be that deer continue transmission and infections within their populations,” Gagne said. “So it’s not just, you know, a spread from humans, the deer get infected and then gush.”

It is unknown whether these lineages will continue to circulate and thrive in deer, as is the risk they may pose to humans and other animals.

“Based on the available information, I would say that the risk of transmitting the virus to humans is low to wildlife, including deer,” said Jeff Bowman, a research scientist at the Ontario Northern Department of Development, Mines, Natural Resources and Forestry. Canadian newspaper writer.

But the scientists said continued surveillance is critical. Dr. Mubareka suggested that authorities improve wastewater dredging in Ontario and other nearby areas, specifically to look for deer lineage and ensure it doesn’t become more common.

Experts also urged people to continue to follow guidelines set forth by public health agencies, including not feeding deer or other wildlife and wearing gloves when butchering.

Dr. “We also need to reduce the largest reservoir of this virus,” Mubareka said.