Vesper Bats Carry a Second Antibody Gene System Never Seen in Any Other Mammal

Bats can harbor viruses capable of causing severe disease without usually becoming seriously ill themselves, a puzzle that has challenged scientists for years. Researchers at Tulane University, working with collaborators at Stanford University and the Centers for Disease Control, say they may have found part of the explanation. A study in the journal Science Advances found that vesper bats carry two distinct copies of the genes used to produce antibodies, the disease-fighting proteins of the immune system. Every other known mammal has only one such set.

Vesper bats are the world's largest bat family, with more than 500 species found on every continent except Antarctica. "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..."

Antibodies are Y-shaped proteins built from two heavy and two light protein chains. In humans and every other known mammal, the heavy chains come from a single set of genes. Frank and her collaborators found that vesper bats instead have two separate heavy-chain gene systems, potentially giving them another route for generating antibody diversity.

Much previous research into bat disease resistance has focused on innate immunity, the body's immediate defense against infection. Frank said the findings point to adaptive immunity, the antibody-producing part of the immune system, as an area deserving closer attention. "We think this discovery is an important piece of the puzzle," she 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..."

Bats play important ecological roles as pollinators, seed dispersers and natural pest controllers, while also serving as natural hosts for many viruses, Frank said.