Bats have been blamed as a possible source of the new coronavirus pandemic ravaging the globe. But they might also point to possible ways out of it.
Scientists say the winged mammals' immune systems may offer clues on how to fight the new coronavirus and other dangerous viruses in humans.
"Humans have two possible strategies if we want to prevent inflammation, live longer and avoid the deadly effects of diseases like COVID-19," explained study lead author Vera Gorbunova, a professor of biology at the University of Rochester in New York. "One would be to not be exposed to any viruses, but that's not practical. The second would be to regulate our immune system more like a bat."
Many deadly viruses that affect people are believed to have originated in bats, including rabies, Ebola and SARS-CoV-2, the strain that causes COVID-19. But bats have evolved a secret weapon: They're better able to tolerate viruses than humans and other mammals.
"We've been interested in longevity and disease resistance in bats for a while, but we didn't have the time to sit and think about it," Gorbunova said in a university news release.
"Being in quarantine gave us time to discuss this, and we realized there may be a very strong connection between bats' resistance to infectious diseases and their longevity. We also realized that bats can provide clues to human therapies used to fight diseases," she explained.
Typically, a species' lifespan is associated with its body size. The smaller a species, the shorter its lifespan. But many bat species have lifespans of 30 to 40 years, which is impressive for their size, the authors noted in a review article published recently in Cell Metabolism.
Bats' longevity and tolerance to viruses may be due to their ability to control inflammation, which is involved in both aging and disease. Viruses, including COVID-19, can trigger inflammation.
With COVID-19, this inflammatory response goes "haywire," Gorbunova said. In fact, in many cases it is the inflammatory response that kills the patient, more so than the virus itself.
"The human immune system works like that: Once we get infected, our body sounds an alarm and we develop a fever and inflammation. The goal is to kill the virus and fight infection, but it can also be a detrimental response as our bodies overreact to the threat," Gorbunova said.
In contrast, bats' immune systems control viruses without mounting a strong inflammatory response.
There are several possible reasons why bats evolved to fight viruses and live long lives. Flight may be one of them, the researchers noted.
Bats are the only mammals that can fly, which required them to adapt to rapid increases in body temperature, sudden surges in metabolism and molecular damage. These adaptations may also assist in disease resistance, the study authors suggested.
Another factor is that many species of bats live in large, dense colonies, and hang close together on cave ceilings or in trees. Those conditions are ideal for transmitting viruses and other pathogens.
According to Andrei Seluanov, a biology professor at the University of Rochester, "Bats are constantly exposed to viruses. They are always flying out and bringing back something new to the cave or nest, and they transfer the virus because they live in such close proximity to each other."
This means that bats' immune systems are continuously adapting to deal with new viruses. Studying bats' immune systems could lead to new ways to fight aging and diseases in humans, the researchers said.
The U.S. Centers for Disease Control and Prevention has more on COVID-19.