Co-expression of sialic acid receptors compatible with avian and human influenza virus binding in emus (Dromaius novaehollandiae)

Influenza A viruses (IAVs) continue to threaten animal and human health with constant emergence of novel variants. While aquatic birds are a major reservoir of most IAVs, the role of other terrestrial birds in the evolution of IAVs is becoming increasingly evident. Since 2006, several reports of IAV isolations from emus have surfaced and avian influenza infection of emus can lead to the selection of mammalian like PB2-E627K and PB2-D701N mutants. However, the potential of emus to be co-infected with avian and mammalian IAVs is not yet understood. As a first step, we investigated sialic acid (SA) receptor distribution across major organs and body systems of emu and found a widespread co-expression of both SA alpha 2,3Gal and SA alpha 2,6Gal receptors in various tissues that are compatible with avian and human IAV binding. Our results suggest that emus could allow genetic recombination and hence play an important role in the evolution of IAVs.