CEIRR Researchers Investigate the Evolution of the SARS-CoV-2 Virus in White-Tailed Deer and Implications for Human Spread

Publication CommentaryOctober 20, 2023

In conjunction with the National Institutes of Health (NIH), researchers from St. Jude Children's Research Hospital Center for Excellence in Influenza Research and Response (SJCEIRR) characterized the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from humans into white-tailed deer in Ohio. Dillon McBride, a graduate student and lead author, along with Dr. Andrew Bowman, SJCEIRR PI Dr. Richard Webby, and others recently published their work in Nature Communications. In July 2021, free-ranging white-tailed deer were identified as a host for SARS-CoV-2 after at least 6 cases of human-to-deer transmissions were reported. Current consensus suggests that the SARS-CoV-2 virus that caused the COVID-19 pandemic originated in animals. As such, there is a need to fill our gaps in knowledge related to the evolution of the virus in non-human hosts and what interplay exists with humans.

Herd of white-tailed deer grazing.

The SARS-CoV-2 virus continues to produce variants that have unpredictable characteristics. As the number of non-human hosts for SARS-CoV-2 increases, future mutations that occur within these populations may have implications for the health of humans and livestock. Culling livestock can slow the spread of an outbreak to limit devastation. However, wildlife populations that are free-ranging – such as white-tailed deer – present an even greater risk, as controlling viral spread is almost impossible.  

To investigate the status of SARS-CoV-2 in white-tailed deer, the authors conducted statewide surveillance in Ohio from November 2021 to March 2022. Ohio is the seventh most populous state in the United States and had the eighth highest recorded number of COVID-19 cases. 1522 nasal swabs were collected from 83 of 88 counties in a large-scale effort to understand the infection rate, spread, evolution, and persistence of the disease.  

The authors found that SARS-CoV-2 evolved around three times faster in white-tailed deer than in humans, with deer-to-deer transmission persisting for up to eight months and dispersing across hundreds of kilometers. Although evidence of SARS-CoV-2 transmission from white-tailed deer into humans exists, there have been no substantial outbreaks of deer-origin SARS-CoV-2 in humans. The results of this study are consistent with this – generally, the white-tailed deer origin virus had not undergone enough change to be a risk for infection in humans. This is important as there are approximately 30 million white-tailed deer in the United States, a population that is increasingly in contact with humans and livestock. Furthermore, the authors found that the overall rate of SARS-CoV-2 evolution in deer will likely decline over time, selecting for specific changes that are able to evade the immune system – similar to what has happened in humans.  

The findings from McBride et al. (2023) highlight the importance of continued surveillance of SARS-CoV-2 in non-human hosts to understand new pathways for viral evolution. The authors propose that future studies should focus on integrating movement data with pathogen tracking to better understand animal-to-animal transmission in wild free-ranging populations. McBride et al. adds to the growing body of influenza and SARS-CoV-2 surveillance efforts led by SJCEIRR on transmission, evolution, and immunogenicity of these viruses that will aid in preventing future pandemics.

McBride DS et al. (2023) Accelerated evolution of SARS-CoV-2 in free-ranging white-tailed deer. Nature Communications. 14: 5105.