Bats carry viruses like coronaviruses, Ebola, and Nipah yet rarely fall ill. Tulane University researchers discovered why: over 500 species of vesper bats possess two distinct copies of antibody heavy-chain genes, an immune arrangement never before seen in any mammal. Published in Science Advances with Stanford and CDC collaborators, the finding reveals a diversified immune arsenal that may explain bats remarkable viral tolerance. While most bat immunity research focused on innate defenses, this study shows the adaptive immune system holds surprises too. The next step is understanding how this duplicated system functions and interacts with viruses.