There is growing concern that the outbreak of monkeypox in humans will spread the virus in animals outside Africa.Chemistry

Eleven days after being bitten by a pet prairie dog, a 3-year-old girl in Wisconsin became the first person to be diagnosed with monkeypox outside of Africa on May 24, 2003. Two months later, her parents and 69 other people in the United States suspected or confirmed a case of the disease caused by a much more deadly relative of the smallpox virus. The monkeypox virus is endemic in parts of Africa, and rodents imported from Ghana appear to have infected prairie dogs in captivity in North America when they were bred together by a Texas animal dealer.

The ongoing outbreaks are affecting people outside Africa more than ever. As of June 7, there are nearly 1300 cases on multiple continents, many of which have sex with men. But, like the 2003 episode, today’s surge can make researchers crazy. The monkeypox virus can permanently inhabit non-African wildlife and form reservoirs that can cause repeated human outbreaks.

Currently, there are no animal reservoirs outside of Africa, but the 2003 outbreak in the United States was a close call. Nearly 300 animals No prairie dogs exposed from Ghana were found. In North America, “monkeypox has finally escaped from becoming a wildlife population,” said Anne Limoan, an epidemiologist at the University of California, Los Angeles, who has long studied the disease in the Democratic Republic of Congo (DRC). Suggests. But in the end, wildlife studies in Wisconsin and Illinois found no monkeypox virus, no infected humans transmitted the disease to others, and there was no concern about this exotic outbreak. I did.

Are the Americas, Europe, Asia, and Australia, where cases of monkeypox have been reported in this outbreak, similarly lucky this time?

Viruses frequently ping pong between humans and other species. COVID-19 is widely believed to be the result of SARS-CoV-2 jumping into humans from bats and other hosts, but humans are “zoonoses”, white-tailed deer, mink, cats, I also infected a dog. virus. One study In Ohio, antibodies to SARS-CoV-2 were found in more than one-third of the 360 ​​wild deer sampled. And in the last few centuries, when humans carried plague and yellow fever to new continents, their pathogens created reservoirs in rodents and monkeys, respectively-which later infects humans again.

As the outbreak of this monkeypox spreads, the virus has an unprecedented opportunity to settle in species outside Africa, infecting humans and increasing the chances of the evolution of more dangerous variants. “The monkeypox reservoir in non-African wildlife is a horrifying scenario,” says Bertram Jacobs of Tempe, a virologist at Arizona State University (ASU). human.

Public health officials in some countries advise people with monkeypox lesions to avoid contact with their pets until they have healed.A few 80% of cases Occurred in Europe, and European Food Safety Authority As of May 24, he said pets and wildlife were not infected. However, he added, “close cooperation between human and veterinary public health authorities is needed to manage exposed pets and prevent the disease from being transmitted to wildlife.”

The potential for humans infected with the monkeypox virus to spread it to wildlife outside Africa “justifies serious concerns,” said William Calesh, a veterinarian at the Ecohealth Alliance. last week We talked about this possibility in a discussion on monkeypox research hosted by the World Health Organization. So far, he says, the odds are lower due to the limited number of human cases. But pet rodents are especially worrisome. Wild rodents make up 40% of all mammals and can frequently attack debris and infect contaminated waste. “It’s a lot of opportunities,” he says.

There are no studies yet to identify the African reservoir of monkeypox virus.nevertheless Lab in Copenhagen, Denmark, First identified in 1958 by Asian research monkeys, scientists now believe that primates have captured it from African sources. Since the first case was reported in the DRC (then Zaire) in 1970, all human cases may be associated with a virus spilled from African animals.

However, so far 6 wild animals The virus trapped in Africa gave birth to three rope squirrels, a Gambian rat, a shrews, and a Sooty mangabey monkey. Antibodies to the monkeypox virus are most abundant in African squirrels. “We’re still not sure about the current reservoirs other than rodents,” said Grant McFadden, a poxvirus researcher also based at ASU.

However, it is clear that monkeypox can infect wild and many other types of animals in captivity. Giant anteaters, orangutans, gorillas, chimpanzees, gibbons and marmosets became ill at the 1964 zoo in Rotterdam, the Netherlands. Researchers have deliberately infected many laboratory animals, including rabbits, hamsters, guinea pigs, and chickens, but the virus does not reliably cause disease in some of them.

For many viruses, the key relationship between the viral surface protein and the receptor on the host cell determines which animal can be infected. For example, the SARS-CoV-2 spike protein latches on angiotensin converting enzyme 2. This enzyme is studded in various cells of humans, mink, cats, and many other species. However, poxviruses do not appear to require specific host receptors, allowing many to infect a wide range of mammalian cells. Waxinia, a smallpox vaccine virus, can infect fruit flies in addition to cattle and humans, said David Evans, a poxvirus researcher at the University of Alberta at Edmonton. Bernard Moss, a virologist at the National Institute of Allergy and Infectious Diseases (NIAID), found that some poxviruses have proteins on their surface. “Hydrophobic face” A water-repellent region that can non-specifically bind to hydrophilic cell membranes and initiate the infectious process.

However, the ability of the poxvirus to copy itself and ultimately stay in the seed to create a reservoir depends on how well it prevents the host’s immune attack. Poxviruses have a relatively large complement of genes, about 200, and about half weaken the host’s immune response. “Some viruses avoid direct contact with elements of the immune system and are executed to hide or stealth,” says McFadden. “Poxviruses generally stand up and fight.”

Their defense against host immunity appears to be heavily dependent on gene families scattered around the genome. Ankyrin repeat.. Evans says that the poxvirus protein containing these repeats acts as a “molecular flypaper” and sheds light on host proteins involved in the regulation of the immune response. “The orthopoxvirus has sequences of these ankyrin repeats, and most of them really don’t know what they’re targeting,” says Evans. “But the bottom line is that some of these viruses may hold the key to trying to understand why they have a host range to do.”

Smallpox virus, a smallpox virus, appears to have lost many of these antigenic genes. It survives only in humans and has no animal storage. That is why the global vaccination campaign was able to eradicate it. Monkeypox is clearly more indiscriminate. But many remaining questions about it mean that we don’t know if it will create a reservoir in non-African wildlife. “One of the challenges was lack of interest,” says Lisa Hensley, a microbiologist at the US Department of Agriculture, who began studying monkeypox as part of the US Army Institute in 2001.

Hensley, who has been working with monkeypox for nearly a decade at NIAID and has worked with Limoin, encourages people to be open about how the virus behaves and what to do next. “We realize that this is a disease we need to worry about and we don’t really know as much as we think we know.”