Bat-derived influenza-like viruses H17N10 and H18N11

• Bat-derived influenza-like virus hemagglutinin and neuraminidase lack canonical functions and structures.
• Putative functional modules/domains in other bat-derived influenza-like proteins are conserved.
• Potential genomic reassortments with canonical influenza virus cannot be ruled out and should be assessed.

Shorebirds and waterfowls are believed to be the reservoir hosts for influenza viruses, whereas swine putatively act as mixing vessels. The recent identification of two influenza-like virus genomes (designated H17N10 and H18N11) from bats has challenged this notion. A crucial question concerns the role bats might play in influenza virus ecology. Structural and functional studies of the two major surface envelope proteins, hemagglutinin (HA) and neuraminidase (NA), demonstrate that neither has canonical HA or NA functions found in influenza viruses. However, putative functional modules and domains in other encoded proteins are conserved, and the N-terminal domain of the H17N10 polymerase subunit PA has a classical structure and function. Therefore, potential genomic reassortments of such influenza-like viruses with canonical influenza viruses cannot be excluded at this point and should be assessed.