White-tailed deer SARS-CoV-2 infection

An interesting new study of wild deer populations in northeastern Ohio has shown repeated spillover of various strains of Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). This may facilitate the emergence of new variants of the virus and provide a natural reservoir for non-humans in which the virus can re-enter the human population.

study: SARS-CoV-2 infection in free-range white-tailed deer (Odocoileus virginianus).. Image Credit: Jim Cumming / Shutterstock

Background

SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) in 2019, has killed about 5 million people worldwide so far. This virus is thought to be a zoonotic disease. Spilled from animal species to humans, the latter has not been identified so far.

Natural SARS-CoV-2 infections have been recorded in livestock and wildlife, the latter under human control. These include many large cats, gorillas, minks, and some otters. Under laboratory conditions, more and more animals can carry the virus, such as skunks, hamsters, fruit bats, and white-tailed deer.

Many species known to occur in white-tailed deer, such as ferrets, cats, and dogs, were also able to infect each other with the virus. Computational models show how the virus binds to angiotensin converting enzyme 2 (ACE2), a receptor for host cells of various species.

In some parts of the United States, such as Utah, reverse transcription-polymerase chain reaction (RT-PCR) has shown that free-range mink is COVID-19-positive. These were thought to be minks that escaped the mink farm. In Spain, a couple of minks were also COVID-19 positive.

However, about 40% of white-tailed deer sampled in Michigan, Pennsylvania, Illinois, and New York indicate the presence of antibodies to this virus. This is a concern as the virus can settle in such new reservoirs and spill from it to other animals or return to humanity.

Not only does this species have an ACE2 receptor that predicts high binding affinity for the virus, but it has also been ly shown to be susceptible and capable of infection.

What did the study show?

Available as a preprint in current research bioRxiv* The server, SARS-CoV-2 antibody, was identified in more than one-third of free-range deer in northeastern Ohio. The species studied here are numerous in many parts of the United States, ranging from rural to urban areas, with more than 45 per square mile in some areas. Both are free-range and farmed, providing ample opportunity for deer and human transmission.

This kind, Odocoileus virginianusWas sampled from nine locations in the region via RT-PCR between January and March 2021, a few weeks after the winter waves. This person-to-deer spread seems to have occurred at least six times during the pandemic winter waves.

The estimated prevalence of the virus was high near human settlements and near urban areas. During this period, a large amount of virus circulates in humans and, by extension, in the environment, giving the highest probability of human-to-deer transmission.

Whole-genome sequences were available in 6 of 9 locations in 10 days. These reflected the same stocks that were then dominant in Ohio’s population. B.1.2 was found on 4 sites, B.1.596 was found on 1 site on 2 dates, and B..582 was found on 1 site. No alpha and delta variants of the virus were found. In humans, these became widespread after February 2021.

Phylogenetic analysis Human-to-deer transmission occurs separately at each site, indicating that different variants of the B.1.2 virus are involved. Unlike other sites, the multiple samples were successfully sequenced, so the deer may have spread the virus to each other at the three sites.

There were 7 deer sequences over 2 dates at 23 day intervals at one site, and there was a B.1.596 sequence. These contained four unique mutations that have been identified in other viruses around the world but not found in the closest human-derived viral sequence.

What is the impact?

The findings show how the virus spreads, the rate of transmission between and within deer species, viral mutations that adapt the virus to these animals, and the potential for deer to function as non-human reservoirs. We are seeking further investigation. Scientists have concluded that the virus has already infected the deer population several times, although the route is unknown.

This type of pattern was seen during the highest viral circulation in humans and was observed during the 2009 H1N1 influenza pandemic. Depending on the presence of suppressors in the sample, the number of transmissions is even higher and can lead to their destruction in some cases.

A systematic and detailed surveillance program needs to answer such questions, especially given the recent surge in human delta mutation cases. This helps to understand if the subspecies transmitted last winter is still circulating among these animals.

Given the different settings in which human-deer interactions occur, possible transmission routes may include wastewater, trash cans, backyard feeding bins, or feeding stations. In multiple studies, waterway pollution is a recurring suggestion and is enhanced by the isolation of the virus from tap water and wastewater. The spread path between deer can be aerosol, environment, or direct.

The outbreak of clinical disease among deer is also an important question to be answered. Men were found to be more susceptible to infection, probably due to different behaviors, such as home range expansion, migration, and contact with other deer during the fall / winter.

Researchers said that monitoring the evolution of SARS-CoV-2 in wildlife populations, including white-tailed deer, weasels, rodents, and other susceptible species, could help manage and mitigate future COVID-19. It will be important for the effort. “

*Important Notices

bioRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.