Vesper bats possess a second antibody gene system unseen in other known mammals, revealing a new level of immune diversity.
Bats can harbor viruses capable of causing severe disease without usually becoming seriously ill themselves, a biological puzzle that has challenged scientists for years. Researchers at Tulane University, working with collaborators at Stanford University and the Centers for Disease Control, may now have uncovered part of the explanation.
A study published in Science Advances found that vesper bats, the world’s largest bat family, carry two distinct copies of the genes used to produce antibodies. Every other known mammal has only one such set. The finding reveals an unexpected way mammalian immunity can be organized and may help researchers understand how bats respond to infection.
“We’ve never seen anything like this in a mammal before,” said Hannah Frank, associate professor of ecology and evolutionary biology at Tulane University School of Science and Engineering and corresponding author of the study. “This completely changes our understanding of how mammalian immune systems can be organized and raises exciting new questions about why bats have been so evolutionarily successful and how they respond to viruses.”
The discovery came from vesper bats, a family containing more than 500 species distributed across every continent except Antarctica. Their evolutionary success has long drawn scientific interest, and the newly identified antibody system could provide one clue to that success.
A second gene system expands antibody diversity
Antibodies are Y-shaped proteins built from two heavy protein chains and two light protein chains. In humans and every other mammal known to science, the heavy chains are produced from a single set of genes.
Frank and her collaborators found that vesper bats have two separate heavy-chain gene systems instead, potentially giving them another route for generating antibody diversity.
Adaptive immunity may hold more clues
Much previous research into bat disease resistance has concentrated on innate immunity, the body’s immediate defense against infection. Frank said the new results point to another area that deserves closer attention: adaptive immunity— the part responsible for producing antibodies.
“We think this discovery is an important piece of the puzzle,” Frank said. “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.”
Bat immunity could inform spillover research
Bats play important ecological roles as pollinators, seed dispersers, and natural pest controllers, while also serving as natural hosts for many viruses, Frank said. Learning how they can coexist with those viruses without becoming sick could eventually deepen understanding of immune responses across species and contribute to strategies aimed at reducing 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.”
Reference: “Immunoglobulin heavy chain locus duplication in bats” by Taylor Pursell, Ashley Reers, Artem Mikelov, Prasanti Kotagiri, Brandon Lam, James A. Ellison, Scott D. Boyd and Hannah K. Frank, 29 July 2026, Science Advances.
DOI: 10.1126/sciadv.aeb6714
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