A highly similar viral sequence was also discovered in one person in the vicinity who had had close contact with deer, providing the first indication of probable deer-to-human transmission of the virus, the researchers said.
According to the researchers, the discovery has not yet been published in a peer-reviewed publication, and there is no proof that the deer lineage is spreading among humans or that it presents a significant danger to them. According to preliminary laboratory testing, the lineage is unlikely to be able to elude detection by human antibodies.
However, the article was published only a few days after another team discovered that the Alpha version of the deer may have continued to spread and mutate in Pennsylvania deer populations even after it was eradicated from human populations, according to the paper.
The findings of the two research together show that the virus may have been circulating among deer for lengthy periods of time, increasing the possibility that the animals might serve as a long-term reservoir for the virus and a source of future variations.
According to Arinjay Banerjee, a virologist at the University of Saskatchewan who was not involved in either research, “there is absolutely no reason to be alarmed.”
Nevertheless, he said, “the more hosts there are, the more possibilities there are for the virus to adapt.”
It has already been discovered that the virus is common in white-tailed deer, according to previous research. According to research, humans have given the virus to deer on a number of occasions, and the deer subsequently spread the infection to one another. It is still unclear how people are transmitting the virus to deer, and there has been no proof to yet that the animals are transmitting it back to humans in the same way.
Over two dozen academics from various universities throughout Ontario participated in the Canada study as part of a larger collaborative effort. The scientists collected nasal swabs and lymph node tissue samples from 300 white-tailed deer killed by hunters in Ontario between November 1, 2020, and December 31, 2021, and analysed them. Only six percent of the animals, all of them were from southern Ontario, tested positive for the virus, indicating that they were still infected at the time of their deaths.
The researchers analysed the whole viral genomes from five infected deer and discovered a hitherto undocumented constellation of mutations that had not been previously seen. Overall, 76 changes — some of which had previously been discovered in deer, mink, and other afflicted animals — distinguished the lineage from the virus’s initial form.
They were most closely linked to viruses seen in human patients in Michigan, which is not far from southern Ontario, in November and December 2020. They were also identical to samples obtained from people and mink in Michigan earlier in the autumn, which was also confirmed.
According to these results, together with the pace at which the virus is accumulating mutations, the new lineage of the virus may have separated from previously known variants of the virus and been developing unnoticed since the late 2020s.
However, the exact route it will take remains unknown. One idea is that humans directly transmitted the virus to deer, and that the virus subsequently mutated as it spread through the cervids as a result of this transmission. Alternatively, the lineage may have originated at least partially in another, intermediary species — maybe farmed or wild mink — which subsequently passed it on to deer via some unknown mechanism.
Veterinary microbiologist Dr. Suresh Kuchipudi of Penn State, who was not involved in the study, said in an email that “we don’t have all the pieces in the jigsaw.” “We cannot rule out the possibility of an intermediary host being involved.”
In the autumn of 2021, a virus sample taken from a single human patient in southern Ontario was found to be quite similar to the deer samples. According to the researchers, the individual was known to have had “close contact” with deer.
In the second research, experts from the University of Pennsylvania’s veterinary and medical schools examined nasal swabs taken from 93 deer that died in Pennsylvania during the autumn and winter of 2021, and their findings were published in the journal Veterinary Research. Nineteen percent of those who tested positive for the virus were infected. Upon sequencing seven samples, the researchers discovered that five of the deer were infected with the Delta variation, whereas just two were infected with the Alpha version.
Furthermore, experts cautioned that individuals continue to abide by public health rules, which include refraining from feeding deer or other wildlife and using hands while cutting meat from wild animals.