White-nose disease has killed millions of bats in North America over the past two decades. The disease is caused by a fungus whose infestation wakes bats from hibernation. As a result, the animals use up their energy reserves and starve to death. To ensure that the great die-off does not continue, biologists have now developed a new antidote.
White-nose disease is considered one of the most devastating wildlife diseases in North America. Since first appearing in New York state in 2006, it has spread rapidly, killing millions of bats in 40 U.S. states and nine Canadian provinces. The disease is caused by the cold-loving fungus Pseudogymnoascus destructans, which attacks bats during their hibernation and typically turns the nose and parts of the wings white.
The fungal infection awakens the bats from their hibernation, causing them to use up their valuable fat reserves and ultimately starve to death. Small species such as the North American mouse-eared bat (Myotis septentrionalis) and the Eastern pipistrelle bat (Perimyotis subflavus) are particularly affected. In areas where the fungus has raged, their populations have declined by up to 90 percent.
A Gallic bat village
In order to save more bats from death, scientists have been working on ways to cure white-nose disease or prevent infections for years. Previous approaches include, for example, the disinfection of bat caves using UV-C radiation and the development of an experimental vaccine. There are also great hopes for so-called probiotic cocktails. They are intended to change the microbiome of bats and make them more resistant to Pseudogymnoascus infection. But the microbiome of winged mammals is complex and so far poorly understood.
In order to close these knowledge gaps and develop a suitable antidote, researchers led by Chadabhorn Insuk from McMaster University in Canada have now sampled 76 very special bats. They come from the community of Lillooet in British Columbia, which, like the Gallic village in the Asterix comics, seems to be the only one in its region to hold its own against the plague raging there. While infections are rising in the rest of British Columbia, the deadly fungus appears to be having little impact on bats around Lillooet. But why? Insuk and her colleagues hoped to find the answers to this on the wings of the resident bats. Various bacteria and fungi live on these, which, like the microbiome in the human intestine, play an important role in the animal’s immune system.
A new antidote
The result: Insuk and her colleagues were able to detect almost 3,000 bacterial and over 11,000 fungal species on the wings of Lillooet bats, including Pseudomonas bacteria. They are considered a protective shield against the deadly fungus that causes white-nose disease and could therefore also explain the bats’ unusual immunity. “This type of information will allow us to manipulate the microbiome to ensure bat survival,” explains senior author Jianping Xu.
In fact, the researchers have already “copied” the microbiome of Lillooet bats and applied it as a probiotic cocktail to bat roosting sites in British Columbia and Washington state. As a result, mortality there fell. So there is new hope in the fight against white-nose disease.
Source: McMaster University; Specialist article: Microbiology Spectrum, doi: 10.1128/spectrum.00376-24