Level 1 — Absolute Beginner

Bats are amazing animals. Scientists found something new about bats. Bats called vesper bats have a special body part. This part helps them fight sickness.

Every animal has genes for antibodies. Antibodies are small helpers in the body. They find germs and stop them. Most mammals, like humans, have only one set of these genes.

But vesper bats have two sets. Scientists never saw this in any other mammal before. Scientists at Tulane University, Stanford University, and the CDC did this study. They looked at 26 kinds of bats.

This might explain why bats can carry viruses without getting sick. Bats are famous for this. Now scientists want to study bat antibodies more.

bat

A small flying mammal that is active at night.

antibody

A small protein in the body that helps fight germs.

gene

A piece of information inside the body that controls how it grows and works.

immune system

The part of the body that fights sickness.

scientist

A person who studies and learns about the world.

study

Careful research done to learn new facts.

virus

A tiny germ that can make people or animals sick.

mammal

An animal with fur that feeds milk to its babies.

Level 2 — Elementary

A new study has found something surprising about vesper bats. These bats have two separate sets of genes that build antibodies, the proteins the immune system uses to fight infections. No other mammal, including humans, has ever been found with two sets like this.

Vesper bats belong to a large family called Vespertilionidae. It is the biggest bat family, with more than 500 species living on every continent except Antarctica. One example is the parti coloured bat, which has dark brown fur tipped with silver white, giving it a frosted look.

The research was led by scientists at Tulane University, Stanford University, and the Centers for Disease Control and Prevention. They studied genomes and immune cells from 26 bat species and found two antibody gene regions. One region, called Locus A, is compact with 33 genes. The other, Locus B, is much larger, with 99 genes.

Scientists believe this extra set of genes may help explain why bats can carry viruses that are deadly to humans, such as relatives of Ebola and coronaviruses, without becoming sick themselves. Most bat immune research has focused on a different part of the immune system, so this discovery shows there is much more to learn.

genome

The complete set of genetic information in a living thing.

immune cell

A cell in the body whose job is to fight infection.

locus

A specific location on a strand of genetic material where a gene is found.

antibody

A protein made by the immune system to recognize and fight germs.

infection

The invasion of the body by harmful germs such as viruses.

species

A group of living things that share the same basic features.

adaptive immune system

The part of the immune system that learns to fight specific germs.

innate immune system

The body's fast, general first defense against germs.

Level 3 — Intermediate

Immunologists have long assumed that all mammals share a single antibody heavy chain locus, the genetic region responsible for generating the vast diversity of antibodies that recognize invading pathogens. A study published in 2026 in Science Advances overturns that assumption, revealing that vesper bats possess two entirely separate loci, an arrangement never before documented in any mammal.

Led by researchers at Tulane University, Stanford University, and the Centers for Disease Control and Prevention, the team analyzed genomes and immune cells across 26 species within Vespertilionidae, the largest bat family, which comprises more than 500 species distributed across every continent except Antarctica. The two loci differ dramatically in scale: Locus A is relatively compact, containing 33 variable genes, while Locus B is far more expansive, with 99 variable genes.

This genetic duplication effectively doubles the raw material vesper bats can draw on to generate antibody diversity, giving them a broader toolkit for recognizing and neutralizing pathogens than any other mammal studied to date. Researchers suspect this expanded capacity may help account for one of the most puzzling features of bat biology, namely their well documented tolerance for viruses, including relatives of Ebola and coronaviruses, that prove lethal to humans.

For years, bat immunology has centered on the innate immune system, the body's rapid, nonspecific first line of defense, while the adaptive immune system, which manufactures pathogen specific antibodies, has received comparatively little scrutiny. This discovery suggests that assumption deserves reconsideration, and that a fuller understanding of how bats coexist with dangerous viruses may depend on studying antibody genetics as closely as innate immunity.

heavy chain locus

The genetic region that provides the building blocks for antibody proteins.

pathogen

A germ, such as a virus or bacterium, that can cause disease.

tolerance

The ability of a body to coexist with something, such as a virus, without becoming harmed.

duplication

The process of a piece of genetic material being copied so that two versions exist.

immunologist

A scientist who studies the immune system.

neutralize

To make something harmless, such as a germ.

nonspecific

Not aimed at any one particular target.

scrutiny

Close and careful examination.

Level 4 — Advanced

For decades, a foundational tenet of mammalian immunogenetics held that every species, from mice to humans, inherits a single antibody heavy chain locus, the genomic architecture from which the adaptive immune system assembles its vast repertoire of pathogen specific antibodies. That tenet has now been upended. A study published in 2026 in Science Advances reports that vesper bats carry two wholly distinct heavy chain loci, a genomic duplication with no known precedent among mammals.

The finding emerged from a collaboration among researchers at Tulane University, Stanford University, and the Centers for Disease Control and Prevention, who sequenced genomes and profiled immune cells across 26 species within Vespertilionidae, the largest and most geographically dispersed bat family, encompassing more than 500 species across every continent save Antarctica. The two loci are markedly asymmetric in scale, the researchers found: Locus A is relatively modest, comprising 33 variable genes, whereas Locus B dwarfs it with 99, together conferring a combinatorial capacity for antibody generation unmatched elsewhere in the mammalian lineage.

The implications extend well beyond taxonomy. Bats have long confounded virologists for their apparent capacity to harbor pathogens, including relatives of Ebola and coronaviruses, that prove catastrophic in human hosts, and the prevailing explanatory framework has emphasized innate immune adaptations, the body's rapid, nonspecific defenses. This discovery reorients that framework, suggesting that an expanded adaptive repertoire, the genetic machinery generating tailored, pathogen specific antibodies, may be doing more of the explanatory work than previously credited.

Bat immunology has, until now, devoted disproportionate attention to innate defenses at the expense of adaptive mechanisms, a gap the study's authors argue is no longer tenable. Whether this duplicated locus arose from an ancient recombination event unique to Vespertilionidae, and whether related bat families harbor comparable architecture, remain open questions, but the discovery reframes a species long defined by its viral tolerance as, at the genetic level, exceptionally well equipped to fight infection on its own terms.

immunogenetics

The branch of science studying the genetic basis of the immune system.

repertoire

The full range of items or forms available, such as the antibodies a body can produce.

precedent

An earlier example or case that establishes a pattern for later ones.

asymmetric

Not equal or balanced on both sides.

combinatorial

Relating to the combination of different elements to produce many possible outcomes.

taxonomy

The scientific practice of classifying living things into groups.

virologist

A scientist who studies viruses.