Monkeypox could open up a new reservoir in the animal kingdom: health

In May 2003, eleven days after being bitten by one of her prairie dogs, a three-year-old girl from Wisconsin became the first person outside Africa to contract monkeypox. Two months later, her parents and 69 other people in the United States had suspected or confirmed cases of the infection. The monkeypox virus is endemic to parts of Africa, and rodents imported from Ghana had apparently infected captive prairie dogs from North America when a pet trader in Texas housed them together.

At that time, the pathogen was quickly stopped. The situation is different in the current outbreak. It is affecting more people outside Africa than ever: more than 2,600 cases across multiple continents, many of them men having sex with men. The scale of the outbreak has also opened up an opportunity that makes researchers shiver: the monkeypox virus could permanently settle in wildlife outside of Africa, creating a reservoir that could lead to repeated outbreaks among humans.

There is currently no known animal reservoir outside of Africa. But the 2003 outbreak was already a tight deal, mainly because nearly 300 Ghanaian animals and abandoned prairie dogs were never found. “We narrowly missed out on monkeypox that has settled in a North American wildlife population,” said Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who studied the disease in the Democratic Republic of the Congo. DRC).

However, wild animal investigations in Wisconsin and Illinois never found the monkeypox virus, none of the infected people passed the disease on to other people, and worries about this exotic outbreak have long since disappeared. Will the world be just as lucky this time around?

Giant anteaters, orangutans and chimpanzees fell ill in a 1964 outbreak in a Rotterdam zoo

Viruses often jump back and forth between humans and other species. Although it is widely believed that Sars-CoV-2 passed from a bat to humans via another host, humans have also infected deer, mink, cats and white-tailed dogs with the coronavirus in “reverse zonoses”. In a study in Ohio, antibodies against Sars-CoV-2 were found in more than a third of the 360 ​​wild animals examined. And in past centuries, when humans carried plague and yellow fever to new continents, these pathogens formed reservoirs in native rodents or monkeys, which later infect humans again.

Colored electron micrograph of monkeypox virus.

(Photo: Andrea Mannel / dpa)

As the monkeypox epidemic spreads around the world, the virus has an unprecedented opportunity to establish itself in non-African animal species. From there, the pathogen could return to humans and would have more and more opportunities to develop new, perhaps more dangerous, variants. “Monkeypox reservoirs in wildlife outside of Africa are a frightening scenario,” said Bertram Jacobs, a virologist at Arizona State University in Tempe.

Health authorities in several countries have recommended people with monkeypox injuries to avoid contact with their pets. So far, around 80% of cases have occurred in Europe, and the European Food Safety Authority said no domestic or wild animals had been infected until 24 May. However, the agency added that “close collaboration between human and veterinary professionals is needed to treat exposed pets and prevent transmission of the disease to wild animals.”

The possibility that humans infected with the monkeypox virus could transmit it to wildlife outside of Africa “raises serious concern,” said William Karesh, veterinarian of the EcoHealth Alliance. For now, Karesh said the chances are still low due to the limited number of human cases. Of particular concern, however, have been the rodents kept as pets, as well as the large numbers of wild rodents, which often collect litter and could become infected with the contaminated litter.

The African reservoir for the monkeypox virus has yet to be precisely determined. So far, the virus has only been detected in six wild animals captured in Africa: three rope squirrels, a Gambian mouse, a shrew, and a sooty mangabey monkey. Antibodies to monkeypox virus are most commonly found in African squirrels. “We still don’t know much about the current reservoir other than rodents,” says Grant McFadden, a researcher on the smallpox virus also at Arizona State University.

“Smallpox viruses, in general, rise and fight.”

However, it is clear that monkeypox can also infect many other animal species in the wild and in captivity. A 1964 outbreak in a Rotterdam zoo killed giant anteaters, orangutans, gorillas, chimpanzees, a gibbon and a marmoset. The researchers intentionally infected laboratory animals such as rabbits, hamsters, guinea pigs and chickens.

In many viruses, the surface proteins that can couple to receptors on host cells determine which animals the pathogen can infect; the spike protein of Sars-CoV-2, for example, binds to the ACE2 protein, which is found on a variety of cells in humans, mink, cats, and many other species. However, poxviruses do not appear to require specific host receptors, allowing many of them to infect a wide range of mammalian cells. David Evans, a smallpox virus researcher at the University of Alberta at Edmonton, notes that vaccinia, the smallpox vaccine virus, can infect fruit flies as well as cows and humans.

However, whether a poxvirus can thrive in an infected cell and eventually survive in a species to form a reservoir depends on how well it can repel host immune attacks. Compared to other pathogens, smallpox has many genes – around 200 – and about half of these subvert the host’s immune response. “Some viruses hide and avoid direct contact with the immune system,” says McFadden. “Smallpox viruses, in general, rise and fight.”

Variola, the smallpox virus, appears to have lost many of these genes that affect the immune system. It only survives in humans and has no reserves in animals, which is why the global vaccination campaign has eradicated it. Monkeypox is clearly more promiscuous. But it is not yet known whether it is capable of creating reservoirs in non-African fauna. “One of the problems is the lack of interest,” says Lisa Hensley, a microbiologist with the US Department of Agriculture who began researching monkeypox in a US Army laboratory in 2001.

Hensley, who has spent nearly a decade researching monkeypox at the US National Institute of Allergy and Infectious Diseases (NIAID) and has partnered with Anne Rimoin, urges people to stay alert and monitor how the virus behaves and what it might do. do next. “We realize that this is a troubling disease and that we don’t know as much as we think we know.”

This post it is in the original in the scientific journal Science appeared, published by the AAAS. German montage: cvei

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