COVID Variants Detected in Animals, May Find Hosts in Mice
March 25, 2021 – New variants of the coronavirus aren’t just problems for humans.
New research shows they can infect animals as well, and for the first time, variants have been able to infect mice, a development that may complicate efforts to curb the global spread of the virus.
Plus, two new studies have implications for pets. Veterinarians from Texas and the UK have documented infections of B.1.1.7 – the rapidly spreading variant first found in the UK – in dogs and cats. The animals in the UK study also had heart damage, but it is not known whether the damage was caused by the virus or was already there and was discovered as a result of their infections.
Animal studies of the coronavirus and its emerging variants are urgent, says Sarah Hamer, DVM, veterinarian and epidemiologist at the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University at College Station.
She is part of a network of scientists who are swabbing the pets of people diagnosed with COVID-19 to find out how often the virus passes from people to animals.
The collaboration is part of the CDC’s One Health initiative. One Health aims to fight infectious diseases by recognizing that people can only be fully protected from pathogens if animals and the environment are also protected.
“More than 70% of emerging human diseases have their origin in animal populations,” Hamer said. “So if we just focus on studying the disease as it appears in humans and if we don’t know where these pathogens have been transmitted or circulate for years, then we might miss the ability to detect a disease. early emergence. We might miss the ability to control these diseases before they happen. become problems for human health.
Variants move to mice
In new work, researchers at the Institut Pasteur in Paris have shown that the worrying variants B.1.351 and P.1, which were first identified in South Africa and Brazil, respectively, can infect mice , giving the virus a potential new host.
Older versions of the virus couldn’t infect mice because they weren’t able to bind to receptors in their cells. These two variants can.
On the one hand, this is a good thing, because it will help scientists to conduct experiments on mice more easily. Previously, if they wanted to experiment with the coronavirus in mice, they had to use a special strain of mice that was bred to carry human ACE2 receptors on their lung cells. Now that mice can become naturally infected, any breed will do, making studying the virus in animals less expensive and time-consuming.
On the other hand, the idea that the virus could have several different ways of spreading is not good news.
“Since the start of the epidemic and since human coronaviruses have come from animals, it has been very important to establish in which species the virus can replicate, especially those species that live near humans,” said said Xavier Montagutelli, DVM, head of the Mouse Genetics Laboratory at the Institut Pasteur. His study was published as a pre-print ahead of peer review on BioRXIV.
Once a virus becomes established in a population of animals, it will continue to spread and change and may eventually be transmitted to humans. This is the reason why birds and pigs are closely monitored for influenza viruses.
So far, with this coronavirus, only one animal has been found to catch and spread the virus and transmit it to humans – farmed mink. Researchers have also documented antibodies to the coronavirus in escaped mink living near farms in Utah, suggesting that the virus has the potential to spread to wild populations.
And the passage of the virus in mice suggests that the virus could establish itself in a population of wild animals living near humans.
“At this point, we have no evidence that wild mice are infected, or can be infected by humans,” Montagutelli said. He added that his results underscore the need to regularly test animals for signs of infection. He said these surveys will need to be updated as new variants emerge.
“So far we’ve been fortunate that our species of cattle weren’t really susceptible to this,” said Scott Weese, DVM, professor at the Ontario Veterinary College at the University of Guelph in Canada, who studies emerging infectious diseases that are transmitted between animals and people.
While the outbreaks on the mink farms have been bad, imagine what would happen, Weese said, if the virus moved to pigs.
“If it infects a barn with a few thousand pigs – which is like the mink scenario – but we have a lot more pig farms than mink farms,” he said.
“With these variants, we have to reset,” he said. “We’ve figured out all of this about animals and how they spread or how they don’t, but now we have to repeat all of these studies to make sure it’s the same.”
Variants of pet capture, too
Pets living with people infected with SARS-CoV-2 can catch it from their owners, and cats are especially susceptible, Weese said.
Contact tracing studies, which also tested animals for signs of the virus, showed that between 20% and 50% of cats living with infected people showed signs of infection, while 20% to 30% dogs were infected.
“It’s pretty common” for pets to contract COVID, Weese said.
Now, two new studies have shown that furry babies can also be infected with the new variant B.1.1.7.
The first study, conducted by researchers at Texas A&M, documented the variant in a dog and cat in Brazos County, Texas. Neither the old black lab mix nor the older domestic cat showed symptoms of COVID-19. They were tested as part of a CDC funded project.
Weese said pets are threatened by those infected, but do not appear to play a significant role in spreading the disease to humans. So, if you have pets, there is no reason to worry that they will bring you the virus. You are more likely to be a risk to them.
The second study, carried out at a specialist animal hospital in the south-east of England, documented infection with the B.1.1.7 virus variant in 11 dogs and cats. Most of the pets exhibited unusual symptoms, including inflamed hearts and heart damage.
Weese called the study interesting and said its findings merited further investigation, but stressed that the study could not determine if the infection caused heart damage or if it was already there.
“It’s a human virus. There’s no doubt about it. It can affect other species, but it likes people much better,” he said.
“If you think about the big picture and what the potential role of animals is, pets pose a pretty low risk,” he said.
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