Rapid Evolution of COVID-19 Virus Detected in White-Tailed Deer Population

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Rapid Evolution of COVID-19 Virus Detected in White-Tailed Deer Population

Rapid Evolution of COVID-19 Virus Detected in White-Tailed Deer Population. Research Reveals Deer as a Viral Reservoir, Facilitating Ongoing Mutations.

White-tailed deer in Ohio are carrying the COVID-19 virus, and the virus is evolving three times faster within deer than in humans.

This raises uncertainties regarding the potential for future inter-species transmission.

Between November 2021 and March 2022, scientists collected nasal swabs from 1,522 free-ranging deer in 83 out of 88 counties in Ohio.

Over 10% of the samples tested positive for the SARS-CoV-2 virus, with at least one positive case found in 59% of the tested counties.

Rapid Evolution of COVID-19 Virus Detected in White-Tailed Deer Population

Genomic Analysis and Findings:

Genomic analysis indicated that at least 30 cases of deer infections originated from humans—a surprising revelation for the research team.

“We usually consider inter-species transmission to be rare, but this sampling wasn’t extensive, and we recorded 30 spillover events. It seems remarkably easy for this virus to jump between humans and animals,” said Dr. Andrew Bowman, co-first author of the study and Associate Professor of Veterinary Preventive Medicine at Ohio State University. “There’s growing evidence that humans can become infected from deer—this is not entirely surprising. It might not be a one-way street.”

Collectively, the findings suggest that white-tailed deer serve as reservoirs for SARS-CoV-2, enabling the virus to continually mutate. The circulation of the virus within deer may lead to its spread to other wildlife and livestock.

This research was published in the August 28, 2023, edition of *Nature Communications*.

Previous Observations and Expansions:

Dr. Bowman and colleagues previously reported white-tailed deer infections with SARS-CoV-2 in nine locations in Ohio in December 2021. They continue to monitor whether deer have been infected with newer variants.

“We expanded our surveillance across Ohio to determine if this was a localized issue—it’s not, as we found this issue in many places, not just in urban deer, which have closer contact with humans. We found a significant number of positive deer in rural areas of the state as well,” noted Dr. Bowman.

In addition to active infection testing, researchers estimated that approximately 23.5% of Ohio’s deer had previously been infected with the virus based on blood samples containing antibodies.

Variation Analysis:

Out of the collected samples, 80 complete genome sequences represented various viral mutation groups. The highly transmissible Delta variant accounted for almost 90% of the sequences and was the dominant human virus strain in the United States in early autumn 2021. The Alpha variant, the first concerning mutation in humans during the spring of 2021, was also detected.

Analysis indicated that the genomic composition of the Delta variant in deer matched the predominant strain found in humans at the end of the peak human Delta variant infection period. This suggests spillover events, with deer-to-deer transmission occurring in clusters spanning multiple counties.

Dr. Bowman remarked, “Our findings might be related to timing—we were nearing the end of the peak human Delta variant infections when we found a significant number of Delta strains in deer. But we haven’t detected Alpha in humans for a long time. So, the idea that deer are harboring lineages that humans have already extinguished is concerning.”

This study indeed suggests that getting vaccinated against COVID-19 is likely to help protect humans from severe illness. An analysis of the impact of deer variants on Siberian hamsters, an animal model for SARS-CoV-2 research, showed that vaccinated hamsters did not become ill as their unvaccinated counterparts did when infected.

Rapid Evolution in Deer:

Concerningly, variants circulating within deer populations are expected to continue evolving. Investigations into the detected mutations in the samples revealed that the Alpha and Delta variants evolve more rapidly within deer compared to humans.

Dr. Bowman stated, “Deer not only become infected with and sustain SARS-CoV-2, but the rate of mutations within deer is accelerating, possibly differing from the viruses infecting humans.”

The question of how the virus transmits from humans to white-tailed deer remains a mystery. Thus far, despite approximately 30 million free-ranging deer in the United States, there haven’t been large-scale outbreaks of deer-originated strains in humans.

However, the possibility of transmission among animals remains significant. Dr. Bowman pointed out that approximately 70% of Ohio’s free-ranging deer have not been infected or exposed to the virus, saying, “So, this is a large pool of naïve animals, and the virus can spread with abandon through them, and that’s where having this animal host in play becomes something we need to pay attention to.”