How Bats Outsmart the World’s Deadliest Viruses
Researchers identified two antibody-producing gene loci in 26 bat species.
Ever since the pandemic, bats have been left with a pretty bad reputation—but while COVID turned human society upside down, the bats didn't even notice.
To figure out how they flew away unharmed, researchers at Tulane and Stanford Universities focused on the animals' immune cells.
The team found that bats defy biology textbooks by operating two distinct antibody factories on separate chromosomes to neutralize threats.
“We've never seen anything like this in a mammal before,” said corresponding author Dr. Hannah Frank, an associate professor of ecology and evolutionary biology at Tulane University School of Science and Engineering.
Why bats harbor deadly viruses without getting sick
Bats possess a seemingly biological superpower: they can harbor some of the world's most terrifying viruses without getting sick.
While pathogens such as Ebola and SARS-CoV-2 (the virus behind COVID-19) can cripple human populations, bats act like a first-class flight for these deadly germs. They carry them around with zero symptoms, spreading them globally while flying away completely unscathed.
So, how do they pull this off, and what are we missing?
For years, scientists trying to solve this have focused almost entirely on the bat's frontline innate immune response, largely ignoring their adaptive defense—the system that creates antibodies to handle specific infections. Very little is known about how bats make specific B cell receptors and custom antibodies to handle infections.
This knowledge gap came down to a dogmatic rule in biology textbooks: every known mammal on Earth has just one genetic starting point—a single heavy chain locus—to build its antibody arsenal.
Scientists naturally assumed bats followed the same blueprint. Past research only looked at a handful of species, so this assumption completely blinded scientists to the true diversity hidden across the broader bat family tree.
A new study decided it was finally time to figure out how these flying luxury cabins for viruses were so lucky. Researchers performed a genetic sweep of Vespertilionidae, the largest family of bats. They wanted to answer a simple, exciting question: have these animals completely rewritten the mammalian rulebook to fight off deadly viruses?
Inside the double antibody factory that shields bats from viruses
The team started by analyzing high-quality genome maps across 34 bat species, before focusing on a single model species, the big brown bat, to see how these genes behaved.
They used single-cell RNA sequencing and B cell receptor sequencing on spleen cells to identify which genes the cells used, and tissue sequencing to check the final antibody collections.
The study turned up a genetic phenomenon never seen before in mammals. Instead of the standard single antibody factory found in humans and all other known mammals, the bats operated two entirely separate factories sitting on completely different chromosomes.
This dual-locus setup was identified across 26 bat species.
The results also showed a massive asymmetry between the two systems: Locus A was compact, carrying 33 variable genes, and Locus B was much larger, encoding 99 variable genes.
Cell and Gene Therapies: The Evolution of Advanced Biologics
This eBook takes a look at the challenges shaping advanced biologics, alongside practical strategies to improve consistency, scalability, and compliance across development and manufacturing.View eBook
To balance out this immunity upgrade, the bats made a genetic trade-off; they completely deleted one of their antibody helper systems—the kappa light chain—leaving behind an expanded lambda light chain.
Kappa light chain
One of two distinct classes of small protein subunits that form the outer arms of an antibody. It is encoded by the IGK gene locus and typically accounts for the majority of light chains found in human and mouse immune systems.
Lambda light chain
The alternative class of small protein subunits used in antibody assembly. It is encoded by a separate gene locus (IGL) and features a different structural composition, providing diversity to the immune system's antigen-binding sites.
The single-cell data revealed how bats coordinate this double layout without causing chaos. Individual immune cells still only choose one locus to express at a time, but young cells show a bias toward trying Locus A first, suggesting that bats build antibodies in a strict, sequential order.
Once active, the two systems handle entirely different jobs to tackle viruses.
Locus A mutates rapidly to sharpen its attack, easily switching forms to create specialized IgG and mucosal IgA antibodies for targeted protection. Meanwhile, Locus B focuses on variety over precision; it rarely switches forms, instead driving a broad, frontline IgM antibody response to catch a wide range of viruses.
How bats’ immune systems could change future virus research
This discovery could send many biology textbook writers back to the editing room.
Liquid Biopsies in Cancer: Technologies, Applications, and Emerging Advances
This infographic provides an overview of liquid biopsy workflows, applications, and innovations addressing current limitations.View Infographic
“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,” said Frank.
The findings also correct past errors in how we track bat infections; previous studies likely missed vital immune data by predominantly focusing on IgG antibodies, overlooking the IgM responses generated by Locus B.
“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.”
Some limitations do remain: the dataset had a low number of cells using Locus B, reducing the statistical power of the evolutionary analysis. Scientists also need to map the genetic differences between individual wild animals.
Future work will need to update common laboratory tools to ensure they can capture both antibody types.
“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: Pursell T, Reers A, Mikelov A, et al. Immunoglobulin heavy chain locus duplication in bats. Sci Adv. 2026;12(31):eaeb6714. doi: 10.1126/sciadv.aeb6714
This article is a rework of a press release issued by Tulane University. Material has been edited for length and content.
Add Technology Networks as a preferred Google source to see more of our trusted coverage.
