Experts hope North American mouse can help on vaccine
Deer mice, the most abundant mammal native to North America, can catch the coronavirus and pass it to other mice in laboratory settings, raising a remote possibility that they could become a reservoir for the pathogen in nature and transmit it to humans, according to two new studies not yet peer-reviewed.
The findings also mean that deer mice may be useful to study coronavirus vaccines, antiviral therapies and infections in the laboratory.
Experts played down the probability that deer mice are harboring the infection in nature, although Tony Schountz, an expert in bat-borne viruses at Colorado State University and a study author, said it is conceivable that a person could give the coronavirus to a wild mouse and begin the chain of transmission.
The mice, belonging to the genus Peromyscus, are often studied in biology fieldwork because they are so abundant; in such cases, captured animals may come in close contact with scientists.
“It’s a statistically unlikely event, but I don’t think it’s zero,”
Schountz said.
The authors of the second study, by the Public Health Agency of Canada, were circumspect, writing that “the potential for the establishment of Peromyscus rodents as a North American reservoir for SARS-CoV-2 is unknown.”
In the Colorado State University study, researchers infected mice with large amounts of the virus delivered through their noses. Those mice passed the virus to other animals, which in turn passed it to a third group. The second study also showed that infected deer mice passed the virus to one another in experiments performed at the Public Health Agency of Canada’s National Microbiology Laboratory.
“The deer mouse work is actually a really nice example of the type of infectivity studies that are used to experimentally test susceptibility,” said Elinor Karlsson, a professor at the University of Massachusetts Medical School and director of the Vertebrate Genomics Group at the Broad Institute, who was not a member of the research teams.
Early studies in lab conditions should not cause panic about viral spread in the woodlands. “In nature, there’s no evidence today that deer mice are carrying this virus,” Klein said.
Scientists know that the coronavirus spilled over into people from an animal host. It most likely originated in bats and possibly infected other creatures on its path from the wilderness to the first human patient zero.
Coronaviruses also have jumped hosts in the opposite direction — from humans to animals — as when people infected camels with MERS. More recently, big cats at a New York zoo tested positive for SARS-CoV-2, which probably was transmitted from an infected zoo worker.