Pigs’ anatomical similarities to humans led Radiah Minor, Ph.D. to wonder if they could also be affected by the virus that causes COVID-19. She is currently testing pigs and other food animals.
Research team investigates SARS CoV-2’s potential to infect food animals
Consider the pig.
A source of tasty meat. The inspiration for countless puns. Responsible for $10 billion in yearly revenue and 44,000 jobs statewide, according to a recent economic impact survey. It also is a source of identity for North Carolina towns from Lexington in the west to Greenville in the east.
In addition to their economic impact and contribution to the food supply, pigs are connected to humans through a host of anatomical similarities known to every biology student. Pig skin, for example, is a go-to treatment for burn victims. Pig heart valves have successfully replaced human heart valves, being of the same approximate size and shape. Fetal pigs’ muscles are almost identical to those of humans.
Radiah Minor, Ph.D.
As SARS-CoV-2, the novel coronavirus currently responsible for a global pandemic, swept across North Carolina in early 2020, animal sciences professor Radiah Minor, Ph.D. – an immunologist whose research has included swine – began to wonder whether those anatomical similarities could mean that pigs and, to a lesser degree, chickens and cattle could be infected by SARS-CoV-2. A respiratory virus, SARS-CoV-2 causes the disease COVID-19, which had caused more than 25 million confirmed infections and contributed to more than 400,000 deaths nationwide by late January, according to the Centers for Disease Control and Prevention.
This fall, Minor and a team of colleagues from the College of Agriculture and Environmental Sciences will put that question to the test, thanks to a grant of more than $240,000 from the N.C. Policy Collaboratory, the University of North Carolina system’s research collaboration agency. The team includes Leonard Williams, Ph.D., director of N.C. A&T’s Center for Excellence in Post-Harvest Technologies; Andrea Gentry-Apple, DVM, Uchenna Anele, Ph.D., and poultry specialist Yewande Fasina, Ph.D., all from the Department of Animal Sciences; and Jenora Waterman, Ph.D., and Vinaya Kelkar, Ph.D., from the Department of Biology.
Their goal is twofold: first, to ascertain whether the SARS-CoV-2 virus can infect pigs, chickens and cattle; and, if so, to establish safety protocols to protect the thousands of workers across the state who come into contact with each species.
“There seems to be a prevailing assumption that animals, particularly livestock, couldn’t be infected by people with the virus, but that aspect really has not been studied,” Minor said. “There are still so many unknowns. We became curious about food animals, particularly swine, which have a high percentage of genetic similarity to humans.” Minor pointed out that pig and human lungs and hearts are similar in size and structure.
“Chickens and cattle are less anatomically similar, but we don’t know if they can be affected. We really should.”
As the virus raged through the spring and summer, Minor was intrigued by news reports of animals testing positive for COVID-19: a tiger in the Bronx, a dog in Hong Kong and another in Chapel Hill, and several domestic cats. One commonality in these cases, she noticed, was that all the animals had been in proximity to people who also had tested positive. The virus itself is thought to be of animal origin and is believed to have originated in Wuhan, China.
In addition to this anecdotal evidence, Minor said, there’s scientific evidence as well: Recent studies have shown that the virus uses angiotensin-converting enzyme 2, or ACE2, receptors in respiratory, cardiovascular, intestinal and nervous-system cells to infect humans and some animals, including pigs. Then, there’s precedent: Two previous epidemic-causing coronaviruses – Middle East Respiratory Syndrome, or MERS, which became known in 2012, and Severe Acute Respiratory Syndrome, or SARS, first identified in 2003 – both were detected in agricultural animals.
“This summer, I overlaid a map of the less-populated hot-spot counties in North Carolina, where cases of the virus were doubling every two or three days, with a map of the counties significantly involved in pig, poultry and cattle production. They matched,” she said.
“Given their proximity to humans, it seemed that food animals should be included in community testing initiatives, especially swine, poultry and cattle. It may be that animals can be reservoirs for the virus. Maybe they’re not spreading the disease, but if it’s in them, and people work with those animals, they may be exposing themselves.”
The results of Minor’s study could have a significant impact on how agricultural animals are handled by their human ranchers and processors nationwide, but particularly in North Carolina, where pigs and poultry are the top agricultural commodities. The state is the country’s second-largest swine producer, with 9.7 million hogs on nearly 2,300 operations, and its fourth-largest producer of broilers, with nearly 515.3 million chickens on 5,700 operations, according to the Council for Agricultural Science and Technology. Together, swine and poultry accounted for nearly $39 billion in revenue and nearly 200,000 jobs in the state in 2019, according to industry sources.
Risk to the food supply is generally low, Minor said. Humans can’t get the virus by eating it because it can’t survive the high temperatures of cooking or the rigors of stomach acid. Picking up a package with virus on the outside poses a fairly low risk also, Minor said; a “critical mass” of virus must be present to bring about infection.
Instead, the main risk to people is the potential for exposure where they didn’t expect it.
“Knowing for sure that animals could harbor the virus would lead to protocols for people who work with food animals,” Minor said. “We could take steps to safeguard the health of those workers.”
Those steps might include changes such as farm workers wearing masks, face shields and coveralls that are changed daily, like those of hospital workers.
Using tissues of swine, poultry and cattle collected from the state’s slaughterhouses, Minor and her team will test for the presence of SARS-CoV2 virus and its specific antibodies, using guidelines and protocols established by the Centers for Disease Control. If the virus is found to be present, the team will develop animal-specific standard operating procedures for sampling, testing and herd-management practices, aimed at mitigating the spread of the virus. The guidelines would be shared with public health officers, state veterinary officials and farmers.
Although she doesn’t know what the group will find, Minor’s primary goal is to know all that can be known about how the virus spreads.
“COVID-19 is the most significant health crisis of the modern era. We need to determine all the places the virus can live, and if there’s a potential for exposure, eliminate that exposure,” she said. “Right now, there’s a lot that we still don’t know. If we’re going to quell this pandemic, we have to do what we can.”
