Researchers at Tulane University, along with collaborators at Stanford University and the Centers for Disease Control, announced on July 29 that they have discovered a potential reason why bats can carry viruses that cause severe disease in other species while rarely becoming seriously ill themselves.
In a study published in Science Advances, the team found that vesper bats—the world's largest family of bats—have two distinct copies of the genes responsible for producing antibodies. In contrast, every other known mammal has only one such set. The researchers say this discovery opens new avenues for understanding how immunity evolves and how animals respond to disease.
The discovery was made in vesper bats, which include more than 500 species distributed across every continent except Antarctica. Their evolutionary success has long intrigued scientists, and this newly identified antibody system may help explain their resilience.
Antibodies are Y-shaped proteins composed of two heavy protein chains and two light protein chains. In humans and all other known mammals, these heavy chains are built from a single set of genes. The research team found that vesper bats possess two separate heavy-chain gene systems, providing them with an entirely new way to generate antibody diversity.
"We think this discovery is an important piece of the puzzle," said Frank, one of the lead researchers. "It doesn't fully explain why bats are such effective viral reservoirs, but it reveals a level of immune variety we didn't know existed and gives us an entirely new direction to explore." Frank also noted that while past research focused on innate immunity in bats, this study highlights the importance of their adaptive immune system—the part responsible for producing antibodies.
Frank said understanding how bats coexist with viruses without becoming ill could eventually help scientists better understand immune responses across species and improve strategies for preventing disease spillover. "We've learned an enormous amount about immunity by studying humans and laboratory mice," Frank said. "But the natural world is far more varied than that. Every time we study a species that has evolved differently, we have the opportunity to discover something entirely new."
