How ‘washing’ wild apes for science could undermine research

How ‘washing’ wild apes for science could undermine research

Long-tailed macaque laboratory at the Breeding Center of the National Primate Research Center in Thailand.

Since the COVID-19 pandemic in 2020, the supply of research monkeys has been low.Photograph: Mladen Antonov/AFP via Getty

In 2019, immunologist Jonah Sascha received a shipment of monkeys for his research into infectious diseases. But while taking initial chest X-rays, Sasha found one monkey that stood out for all the wrong reasons: It was carrying the bacteria that causes tuberculosis (TB).

The infected animal rendered the entire shipment of 20 monkeys unfit for use in research due to the risk of spreading infection. “We lost all those animals,” says Sasha, who studies stem cell transplants as a treatment for HIV at Oregon Health & Science University’s National Primate Research Center in Beaverton. “This cost hundreds of thousands of dollars in damage and delayed our research for many years.”

In many ways, Sasha was lucky to have discovered the sick monkey: If it had forced its way into a medical trial, it could have confounded the results, says Ricardo Carrión, a microbiologist at the Texas Biomedical Research Institute’s Southwest National Primate Research Institute. . Center in San Antonio.

Sasha does not know how the monkeys contracted tuberculosis, as they are usually raised in captivity, which ensures that they are free of diseases. But the risk of disease is a growing concern among scientists who work with monkeys; News reports indicate that some laboratory monkeys are illegally captured from the wild, mislabeled as captive-bred and sold as research animals, a practice known as monkey washing.

Suspicious actions

Long-tailed macaques (Macaca fascicle), or cynomolgus macaques, make good models for infectious disease research and vaccine development because they resemble humans genetically and physically. Biomedical researchers use captive-bred primates that are free of certain types of viruses, bacteria, and parasites.

Over the past two decades, China has been the largest exporter of research macaques, with the United States in particular relying heavily on its supply. But at the beginning of the COVID-19 pandemic in 2020, China halted the export of macaques and other wildlife to limit the potential spread of the disease. “It really impacts the availability of these animals,” Carreon says.

In the wake of the pandemic, the global supply of high-quality research monkeys remains at an all-time low. In May, a report from the US National Academies of Sciences, Engineering, and Medicine found that more than half of researchers surveyed had problems obtaining primates for their research in 2021. The report also found that researchers are now waiting longer than they were before COVID-19. 19 struck out to buy research macaques, and the cost per animal has risen dramatically. Before the pandemic, a single long-tailed macaque cost between $7,500 and $8,500, Carreon says. But now, it can cost up to $55,000.

The high demand and high costs for research monkeys has created a market for monkey traffickers, says Anne-Lise Chapper, a veterinarian who has researched the illegal wildlife trade at the University of Adelaide in Australia.

Evidence of this trade is slowly emerging. In November 2022, eight people – including two wildlife officials from Cambodia – were charged with smuggling hundreds of wild long-tailed macaques from Cambodia to the United States for use in research; The animals were allegedly labeled captive. It is not clear whether any of them ended up being used in research.

Since China’s export ban, Cambodia has risen as a major exporter of research monkeys, says Chaber. She and her colleagues published a study in June1 It is estimated that exports of macaques from Cambodia increased from approximately 10,000 in 2018 to a total of 30,000 in 2019 and 2020. Such a leap would be impossible without resorting to poaching, smuggling, or relying on unapproved breeding farms, because the current number of registered breeding females says they have not been able to produce many offspring.

A macaque breastfeeds from its mother while its father watches the footsteps of Angkor Wat, Cambodia.

There has been a sharp increase in research monkeys being trafficked illegally.Credit: Sean Ray Harris/Getty

Confusing results

Aside from the ethical and legal problems associated with smuggling wild monkeys into medical experiments, this practice can also invalidate study results. Carreon says wild apes are already exposed to a range of diseases. This means that in vaccine studies, they will produce a very different immune response than animals raised for this purpose in sterile facilities.

In some cases, viral infections suppress the monkeys’ immune systems, which can hamper their response to experimental vaccines, says Malcolm France, an independent veterinary consultant who specializes in the care of animals used in medical research, based in Sydney, Australia.

Some retroviruses — a group that includes HIV — can alter the immune system even when they don’t cause obvious disease. For example, the common, but often asymptomatic, T-lymphotropic simian virus stimulates cells to release high levels of cytokines, which are proteins that regulate the immune response. Such changes make it nearly impossible for researchers to distinguish between the effects of a drug they might be testing and those caused by a viral infection.

Another retrovirus, simian foamy virus, can damage cell membranes, making it difficult to maintain cell line cultures from infected monkeys. This would hinder research into the mechanisms of infectious diseases, such as those in which viruses replicate inside cells.

Viruses are not the only pathogens that can cause problems in the laboratory. Lung mites (Simicola pneumonia(), small parasites that infect wild monkeys, causing rash-like lesions in the respiratory tract, which can be confused with those caused by other diseases.

France says that keeping smuggled wild monkeys in captivity would cause them a lot of stress. This can cause an infection that was dormant to turn into a full-blown disease. “Apart from the obvious impact on well-being, this also introduces uncontrolled variables that can significantly affect the validity of the experimental data,” says France.

Global supply

Putting an end to monkey washing is not easy, says Astrid Andersson, a conservation biologist who specializes in the wildlife trade at the University of Hong Kong. Every year, thousands of macaques are legally traded for research purposes. Such trade makes it easy for smugglers to slip through the cracks. When there are large numbers of animals being traded legally, “it can easily provide cover for the laundering of illegally purchased wildlife,” Anderson says.

Chapper says research institutions should inspect the facilities from which they obtain research monkeys, to ensure that animal husbandry complies with regulations. Facilities also need to be audited regularly to detect any suspicious activity, she adds.

Genotyping research monkeys would help facilities track where they came from, Carrión says. Working with captive-bred animals that are well understood and properly managed is best of all. “We know (from) conducting experiments that healthy, happy animals lead to the most consistent data.”

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