By Dr. Becker
Bats happen to be one of my very favorite mammals, but I’m in the minority. Often these guys are thought of as disease riddled, blood sucking flying rodents. In fact, their reputation is such that they are one of the least researched animals in history. But all that could be changing.
An increasing number of scientists and researchers have become interested not only in the ability of bats to fly for prolonged periods of time, but also in how they are able to survive deadly viruses like SARS and Ebola. A recent genetic analysis of two bat species, the Black flying fox and David’s Myotis (Myotis davidii), provides new information about how bats are able to dodge disease and enjoy remarkably long lives. The study was published in the January issue of Science Magazine1.
While bats are able to quickly spread infectious agents that affect humans, they don’t suffer themselves from some of the most dangerous, deadly pathogens known to man. The new genetic analysis of two very different bat species shows how they do it, and the research points to a connection between the health and longevity of bats and their ability to fly.
'Bat Pack' Discovers Missing Gene
The researchers who performed the genetic analysis are known as the “Bat Pack.” They are a group of scientists from the Australian Animal Health Laboratory and the Beijing Genome Institute.
The Bat Pack investigated the genes of a large fruit bat (the black flying fox) and a tiny insect-eating bat (David’s Myotis) and discovered both species are missing a gene segment that triggers an overwhelming immune response to infection known as a cytokine storm. This inflammatory response is actually what kills the host, not the virus itself. As it turns out, the immune system of bats doesn’t produce this devastating cytokine response in the presence of infection.
Researchers want to understand how bats manage to suppress this response, with an eye toward developing new drugs for humans that minimize inflammation. These drugs might be anti-inflammatories, or they might be in the form of genetic therapy that targets certain gene segments.
Bats Aren’t Immune to Every Infection
Interestingly, bats aren’t immune to certain fungal infections. In fact, millions of bats across North America have died from a fungal infection called white-nose syndrome. The infection wakes the bats from hibernation during winter months and they subsequently starve to death. During hibernation, a bat’s immune system is suppressed, which makes him more susceptible to white-nose syndrome. When he wakes up, his immune system overreacts, creating immune reconstitution inflammatory syndrome (IRIS).
Hopefully, future research will unravel the mystery of why bats are so resistant to viruses but so susceptible to fungi.
Ability to Fly Tied to the Health and Longevity of Bats
In addition to avoiding viral infections, bats also don’t suffer from age-related diseases or cancer. Compared to a similar-sized animal like a rat that lives only two or three years, bats live between 20 and 40 years. Researchers theorize this has to do with the ability of bats to fly.
Flying is an extreme form of physical activity that burns enormous stores of energy. This generates free radicals that cause tissue damage and diseases like cancer. The scientists discovered that both species of bat in the study possess a large number of DNA repair genes, including a gene called P53, which is involved in the repair of damaged DNA. The researchers believe the extra repair genes increase the metabolism of bats, allowing them to fly.
According to Dr. Chris Cowled, a researcher at the Australian Animal Health Laboratory and one of the study authors:
"What we found intriguing was that some of these genes also have secondary roles in the immune system.
"We're proposing that the evolution of flight led to a sort of spill over effect, influencing not only the immune system, but also things like ageing and cancer."