Bats serve as hosts for deadly viruses, such as rabies, Ebola, Marburg, and the novel coronavirus. However, bats that carry such lethal viruses actually do not fall ill because they have a strong immune system.
Recent research has revealed how bats develop this powerful immune system. The key to the secret of the bat immune system was its 'ability to fly.'
An international research team, including the Senckenberg Research Institute in Germany and the Zheshang University-Edinburgh University Research Institute in China, announced the results of their analysis of the genomes of 20 species of bats on Jan. 29 (local time). This research was published in the international journal Nature.
Bats are known to be major hosts for more than 200 viruses, including rabies, Ebola, and Marburg. However, even if bats are infected with these viruses, they rarely become ill. When humans are infected with a virus, serious immune reactions can occur, but bats manage this well to maintain their health.
Aaron Irving, a researcher at the Zheshang University-Edinburgh University Research Institute, noted, "Bats have a unique immune system that allows them to maintain their health even when infected. This ability to regulate their immune response may be the key to the survival of bats."
To gain a deeper understanding of bat immune systems, the research team decoded the genes of 20 species of bats. As a result, bats had far more immune-related genes than other mammals. Although bats had various genetic variations across species, the variations related to immunity were common across all bat species. This indicates that bats have developed a strong immune system since their ancestral stages.
In particular, the Greater Horseshoe Bat and Hipposideridae bats carried variations of the ISG15 gene. This gene plays a crucial role in regulating viral infections and may effectively suppress infections such as coronaviruses.
The research team explained that the development of the bat immune system occurred around the same time as the evolution of their ability to fly. Research Institute Irving stated, "Bats have a very active metabolism, with their hearts beating more than 1,000 times per minute while flying. This process generates harmful substances that can induce inflammation in the body, but bats may have evolved a strong immune system to regulate these substances."
The research team believes that studying the unique immune systems of bats could lead to new therapies for regulating human immune responses. Michael Hiller, a researcher at the Senckenberg Research Institute, emphasized, "Studying the immune capabilities that nature has bestowed upon bats could help in developing drugs to regulate human immune hypersensitivity responses."
However, there are also opposing opinions regarding this hypothesis. Some scientists argue that "data proving a direct link between flight and immunity is insufficient" and that "although other animals also have high metabolisms, they do not possess immune systems as strong as those of bats, indicating that further research is needed."
Reference
Nature (2025), DOI: https://doi.org/10.1038/s41586-024-08471-0