The study of highly pathogenic avian influenza (HPAI) seeks to understand the pathogenic nature of these viruses. Belonging to the H5 or H7 subtype, HPAI causes significant economic loss in poultry and in recent years has also led to die offs in wild birds. In addition, the zoonotic nature of H5N1 has caused human infection associated with high mortality, although these viruses have not yet evolved to cause a pandemic. Mechanisms of virulence by HPAI...