The National Institutes of Health said this week that it would put an end to research on chimpanzees, years after its European counterparts did the same. Ethical concerns, peer pressure on scientists, tight regulations, and the rise of other research models all lessened the demand for chimps in the lab — but there are a handful of research areas where our closest primate cousins were once invaluable.

Chimps helped in the fight against hepatitis and HIV

At the Chimp Haven sanctuary in rural Louisiana — home to 186 chimps formerly used for biomedical research, entertainment, or as pets — around half of the residents were previously injected with HIV or hepatitis viruses. Chimps were used at the beginning of the AIDS epidemic when researchers were still trying to understand what they were facing. That work was phased out fairly early, however, because chimp symptoms of infection are different than those of people, and they take so long to develop that it wasn’t practical to study them, said Welkin Johnson, an HIV researcher at Boston College.

Chimps have been more useful for studying hepatitis C and similar viruses, as only apes are vulnerable to chronic infections. So, when a panel convened two years ago to advise the NIH on its chimp research, it decided to leave 50 animals available for such research. But thanks to the recent development of mouse models that are susceptible to hepatitis, it’s now clear that those chimpanzees aren’t needed for hepatitis research, said Stephen Ross, an animal behavior specialist at the Lincoln Park Zoo in Chicago and a member of that 2013 panel.

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It’s not just about human health. Virus research helps the chimps, too.

Scientists first discovered respiratory syncytial virus when lab chimps caught it from their handlers. The virus is the most common cause of lung and airway infections among young children in the United States and kills more than 160,000 people worldwide. Chimps were used in early vaccine development against the virus, but vaccine candidates that were effective in chimps proved useless in people, and so research was stopped. New rodent and sheep models also obviated the need to study RSV in the great apes.

Now, unfortunately, wild chimps are dying from the virus, caught from tourists in Africa. Stopping chimp research into RSV might protect individual animals from experimentation, but it may hurt the health of the species, which would benefit from effective medicines against the virus, noted Peter Walsh, a biological anthropologist at the University of Cambridge in the United Kingdom. The same is also true of Ebola and other deadly viral pathogens that threaten to obliterate wild chimp populations — and could potentially jump to humans.

Like us, chimps are social beings — and behavioral studies will continue

The NIH’s decision won’t affect most of the behavioral and cognitive research going on in chimps because that research doesn’t cause harm to the animals. Ross’s research, for example, focuses on how to better care for chimpanzees, and the animal’s use of tools — both of which he can continue to investigate at the zoo.

Ross is less sure about the future of neuroimaging in chimps, which may be considered “invasive” if the animals undergo anesthesia only for the purpose of a study — a “no-no” under the NIH’s new rules. Researchers are now trying to train chimps to go willfully into an MRI scanner and lie still through all the banging that human subjects endure.

Wild populations could suffer from the NIH ban

Walsh is worried that without research on captive chimps, it will be much harder to protect their wild counterparts. He argued that the NIH has a moral responsibility to help safeguard them, because decades ago the agency killed hundreds of wild chimps to stock its research labs. Now, in retiring the last of its research chimps, NIH officials “have abdicated their moral and ethical responsibility for political reasons,” he said, “and that’s just wrong.”

Regardless of the rationale, Cathy Willis Spraetz, president of Chimp Haven, believes there are now more ethical ways to get the same information on chimps without harming their well-being. “I believe that perhaps there were a lot of things accomplished with chimpanzees in research,” she said, “but now with advanced technology and other means of looking for curative disease, it’s only fitting that we give them back some of their freedoms.”

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