Bats are the only mammals that can fly (though some can glide). They have excellent hearing, navigate by echolocation, and they can eat their body weight in insects in a single night. But bats’ most impressive superpower is a remarkable tolerance to viral infections.
Bats host many viruses, viruses that would sicken and even kill other mammals, without suffering serious consequences themselves (rabies is an exception). And that superpower may be related to the ability to fly, explains Cara Brook, a professor at the University of Chicago who studies the ecological and evolutionary dynamics of infections that jump from animals to humans, in particular infections that come from wild bats.
Long Lifespans Make For Better Viral Protection
Flying is metabolically expensive. A bat in flight increases its basal metabolic rate 15-fold compared with its resting rate, Brook says. Organisms that have high metabolic rates tend to be small-bodied and very short-lived. That’s probably because organisms with high metabolic rates accumulate oxidative stress in their cells, and so tissues and organs degrade more quickly, shortening their lifespans.
Bats, however, are unusually long-lived for their body size. Brook and other scientists who study bats think that bats evolved molecular pathways that mitigate the oxidative damage caused by the increased metabolism, thus increasing their lifespans. So what does this have to do with viruses?
Read More: Evidence of Origins of the COVID-19 Outbreak Disputes the Lab Leak Theory
Bat Immune Systems
Brook’s theory is that many of these molecular pathways, in addition to extending bats’ lifespans, made bats more tolerant of viruses. But how? The answer, according to Brook, is that the damage to a cell infected with a virus is similar to that caused by metabolic activity, and bats have evolved to dampen that response. The immune response to a virus is highly inflammatory.
“What we experience as disease is actually immunopathology,” Brook explains. When you have a fever from the flu, for example, that’s your immune system’s response to the flu virus. But bats don’t develop these intense immune responses to the viruses they harbor. “We think that’s really a byproduct of their adaptations for flight,” says Brook.
That’s super cool, but it also could be very useful. If researchers can understand how bats handle these infections without becoming sick, they might learn how to make humans more resilient to infections. A team of U.S. and Canadian researchers led by Michael Letko has developed a new set of tools to help researchers do just that.
Growing Bat Cells
Letko is a molecular virologist at Washington State University. He and his team have recently cultured two new lines of bat cells that can be grown and divided indefinitely in the lab. The work was described in a paper published in PLOS Biology. These cell lines will be useful for learning how bats co-exist with viruses that can kill humans in droves. This could be crucial when the next pandemic arises, of course, but the utility of these cells goes beyond that.
“Viruses oftentimes trigger all sorts of pathologies,” says Letko. “If we can understand how to control those pathologies, we can apply them to lots of other scenarios, not just infectious disease.”
Some private labs are already culturing these cell lines, but they’re not available for outside researchers. Work funded by the U.S. government, however, must be shared freely. Letko’s research was funded by the National Institutes of Health (NIH) and was a collaborative effort of scientists from the U.S. and Canada.
Letko and colleagues have arranged for these cell lines to be available to any researchers who need them for their work.
“We have lots of experts who probably would be able to say something about what’s going on in these animals if they had the ability to study it, but they don’t,” he says. “So we’re hoping that putting this resource out there will let people with a wide range of backgrounds really get into this.”
Humans didn’t develop the ability to fly. But we did develop the ability to study animals that do fly. And that’s turning out to be an even more useful skill.
Read More: Why Bats Are Breeding Grounds for Deadly Diseases Like Ebola and SARS
Article Sources
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Avery Hurt is a freelance science journalist. In addition to writing for Discover, she writes regularly for a variety of outlets, both print and online, including National Geographic, Science News Explores, Medscape, and WebMD. She’s the author of Bullet With Your Name on It: What You Will Probably Die From and What You Can Do About It, Clerisy Press 2007, as well as several books for young readers. Avery got her start in journalism while attending university, writing for the school newspaper and editing the student non-fiction magazine. Though she writes about all areas of science, she is particularly interested in neuroscience, the science of consciousness, and AI–interests she developed while earning a degree in philosophy.
