PLoS Biology (2019)

Bats are important natural reservoirs for detrimental human zoonotic viruses but are themselves generally asymptomatic carriers. In PLoS Biology, Liu and colleagues investigate the contribution that adaptive immunity might provide to the resistance of bats to viruses that are usually highly pathogenic in most other mammals. Looking at the presentation of peptides from four different viruses, including MERS and Ebola viruses, by bat major histocompatibility complex class I, they observe several unusual structural features. Bats have a three– or five–amino acid addition that leads to extension of the α1 helix of major histocompatibility complex class I and tighter insertion of the peptide into the binding groove. The five–amino acid insertion is unique to bats, whereas the three–amino acid insertion is also seen in some marsupials. There is also unusual use of a proline in the terminal amino acids of the bound peptide. Collectively, these features may underpin more-effective adaptive antiviral immunity.