Deer carry SARS-CoV-2 variants that are extinct

ITHACA, NY – Cornell University researchers have found that white-tailed deer – the most abundant large mammal in North America – are harboring SARS-CoV-2 variants that were once widespread, but are no longer found in humans.

Whether or not deer can serve as a long-term reservoir for these obsolete variants is still unknown, as scientists continue to collect and analyze new data.

The study, published Jan. 31 in the journal Proceedings of the National Academy of SciencesThis represents one of the most comprehensive studies to date to assess the prevalence, genetic diversity and evolution of SARS-CoV-2 in white-tailed deer.

“One of the most striking findings of this study was the discovery of the co-communication of the three types of anxiety – alpha, gamma and delta – in this wild animal population,” said Diego Diehl, associate professor of population medicine and diagnostic sciences at Cornell. .

During the epidemic, deer have been infected with SARS-CoV-2 through continuous contact with humans, possibly through hunting, wildlife rehabilitation, eating wild animals or contaminated water or water sources.

“A virus that appeared in humans in Asia, possibly after an event that spread from an animal reservoir to humans, has apparently, or possibly, now found a new wildlife reservoir in North America,” Diehl said.

The 5,700 samples used in the study were collected in New York over two years, 2020-22.

When the researchers compared the genomic sequences of the variants found in the deer with the sequences of similar variants taken from humans in New York, they found that the viruses had mutated in the deer, suggesting that the variants had been circulating in the deer for several months. Until the alpha and gamma variants were discovered in deer, for example, there was no evidence that these viral strains had yet spread to humans. In fact, when they were found in deer, none of the strains were found in humans for four to six months in New York.

“When we compared the sequences between those viruses recovered from white-tailed deer with the human sequences, we observed a significant number of mutations in the genome of the virus,” Dill said, noting that some viruses had up to 80 mutations. The human sequences provide further evidence that the virus may have been circulating in deer for some time. The mutations suggest that the virus has adapted to deer, possibly making it more transmissible among them.

Further study is needed to confirm whether these variants will disappear in deer over time or whether SARS-CoV-2 risks spreading to other wildlife, including predators.

“Because of the evidence obtained in our study, it is very important to continue to really understand and track the virus in these animal populations to see if it can support or spread to humans and other wildlife,” Diehl said.

There are an estimated 30 million white-tailed deer in the United States. A 2022 study by Diel et al found that SARS-CoV-2 was found in 40% of white-tailed deer in five states surveyed in 2021.

For more information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews.


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