A recent paper tackled a mystery that has puzzled scientists for years; how the world’s only winged mammals carry viruses that cause severe disease while rarely becoming seriously ill themselves?
One prominent lab that studied them was in Wuhan, China, but they took their database of coronavirus samples offline in late 2019 so scientists in the rest of the world are stuck redoing a lot to try and figure out how it happens. Researchers from the U.S. Centers for Disease Control and academia found that the world’s largest family of bats carry two copies of the genes that produce antibodies that help the immune system recognize and fight infections. Their model was vesper bats, because that family includes over 500 species found on every continent where bats can survive. Antibodies are Y-shaped proteins consisting of two heavy protein chains and two light protein chains. In every other mammal, those heavy chains are built from a single set of gene. Vesper bats instead possess two separate heavy-chain gene systems, which makes it possible for them to generate enhanced antibody diversity.
The discovery of two distinct copies of proteins that prevent infection opens new avenues for understanding the evolution of immunity and how we respond to disease. Preventing human disease is a key reason why the Obama administration helped fund gain-of-function research in Wuhan back in 2014. They had bat and other animal samples from all across Asia and the world. They were looking closely at adaptive immune systems.
(A) Schematic of Ig gene annotations for A-IGH locus. (B) Pie chart of functionality and (C) gene family distribution for functional variable (V) genes for A-IGH locus. (D) Density plot of AID hotspots per kilobase in the constant gene encoding regions for A-IGH locus. (E) Schematic of Ig gene annotations for B-IGH locus. (F) Pie chart of functionality and (G) gene family distribution for functional variable genes for B-IGH locus. (H) Density plot of AID hotspots per kilobase in the constant gene encoding regions for B-IGH locus. (I) Nearest neighbor-joining tree of functional and ORF V genes for A-IGH and B-IGH with human V genes collapsed by V-gene family for reference. Created in BioRender. Pursell, T. (2026) https://BioRender.com/rru8vm2.
Genes along can't explain why they are effective viral reservoirs that give disease without catching it but because bats are pollinators and pest controllers their ability to serve as natural hosts for many viruses leads to worry about disease spillover. But bats aren't like Aedes Egyptii mosquitoes, disease vectors that could be wiped out and their ecological value taken up by a million other species, they are important enough we would benefit from coexisting with viruses the way they do.