A leading poxvirus expert says he envisages a new line of attack for biologists studying the monkeypox virus in the current outbreak in the midwestern United States.
Mark Buller of Saint Louis University in Missouri says he will try to develop a laboratory model for monkeypox infection using prairie dogs, common rodents that seem to be capable of transmitting the virus.
Until this month, monkeypox — a milder cousin of smallpox — had been seen only in parts of west Africa, where it is endemic in wild rodent populations that are sometimes hunted for food. Now 33 people in Wisconsin, Illinois and Indiana have contracted the disease from pet prairie dogs. The virus is thought to have arrived in a Gambian giant rat, which was imported as part of the growing trade in exotic pets.
“We know nothing about the natural biology of monkeypox at all,” Buller says. Research has been limited in part because the disease is rare in humans, but also because there is no good animal model.
Among the animals infected experimentally with monkeypox is the cotton rat, a shoe-sized rodent found in Mexico and the southern United States. These animals succumb quickly to an injection of virus and are useful for testing antiviral drugs and for studying the virus's lethal effects.
But Buller says that a natural host would be much better for studying basic questions about monkeypox, such as how it is transmitted, what cells it infects, what genes control its virulence, and how the host responds. “You could get a natural profile of the disease,” he says.
Buller hasn't ruled out trying the Gambian giant rat, but many animals fare poorly in captivity, and setting up a new laboratory colony of an untried rodent species is fraught with complications. “Some animals turn out to be more trouble than they are worth,” he says. Prairie dogs, on the other hand, handle captivity quite well, and are already being used in a number of laboratories studying infectious disease.
Other poxvirus researchers are eager to see Buller's efforts succeed. Donald Smee, a virologist at Utah State University in Logan, would like to test his hypothesis that drug-resistant monkeypox viruses are also less deadly, but has not yet found an animal model in which to do this. Prairie dogs may work if the virus proves lethal to them in the first place, he says.
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Knight, J. Prairie-dog model offers hope of tackling monkeypox virus. Nature 423, 674 (2003). https://doi.org/10.1038/423674b