Understanding bat immune system may help establish new COVID-19 drug targets: Scientists

NEW YORK: Bats’ ability to tolerate viruses like the novel coronavirus may stem from their ability to regulate inflammation, according to a study review which says studying the flying mammals’ immune system may provide new targets for human therapies against COVID-19.

Researchers, including those from the US Rochester University, said that the bats can tolerate the pathogens without any ill effects as they are the ancestral hosts of many deadly viruses affecting humans such as Ebola, rabies, and the novel coronavirus, SARS-CoV-2. While humans experience adverse symptoms when suffering from these pathogens, bats are capable of tolerating viruses and, in fact, live much longer than land mammals of similar size.

In the review research, published in the journal Cell Metabolism, the scientists evaluated how bats’ natural ability to control inflammation can contribute to their longevity and tendency to combat diseases.

Vera Gorbunova, study co-author, University of Rochester said that the inflammation goes haywire with COVID-19, and it may be the inflammatory response that kills the patient rather than the virus itself. She explained that once we get infected, our body sounds an alarm and we develop a fever and inflammation and this is how our human immune system works. Gorbunova said the purpose of this immune system response in humans is to destroy the virus and combat infection but added that it can also be a negative response as the bodies of patients overreact to the threat.

According to the scientists, unlike humans, bats have different mechanisms that limit virus replication in their bodies, as well as dampen their immune response to the virus. As a result, there is a beneficial balance in bats with their immune systems suppressing viruses, while not staging a strong inflammatory response at the same time. They pointed out that one of the factors for this ability may be driven by their flight. And explained that bats, being the only mammals that can fly, need to adapt to rapid changes in body temperature, drastic changes in metabolism and molecular damage which may also assist in disease resistance.

Andrei Seluanov, another co-author of the study, said that the 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.

Since bats are continually exposed to viruses, scientists believe their immune systems are in a “perpetual arms race with pathogens”—a pathogen will invade the organism, the immune system will create a pathogen-fighting mechanism, the pathogen will grow again, and so on. Gorbunova said that dealing with all of these viruses may be shaping bats’ immunity and longevity.

The scientists noted that while humans may be developing social habits that parallel those of bats, they have not yet evolved bats’ sophisticated mechanisms to combat viruses as they emerge and swiftly spread.

COVID-19 has such a different pathogenesis in older people. Age is one of the most critical factors between living and dying, and we have to treat aging as a whole process instead of just treating individual symptoms, Gorbunova said. According to the researchers, studying bats’ immune systems can provide new targets for human therapies to fight diseases and aging. Scientists can develop drugs, after studying how bats have mutated or completely eliminated several genes involved in inflammation, to inhibit these genes in humans.

Gorbunova said that humans have two possible strategies if they want to prevent inflammation, live longer, and avoid the deadly effects of diseases like COVID-19. One of them would be to not be exposed to any viruses which is practically impossible, and the second would be to control our immune system more like a bat.