Optimizing Barrier Protection During a
Pandemic Event Caused by Influenza A

How Influenza A Can Become a New Virus Scientists have identified hemagglutinin (HA) virus mutations through samples taken from an Inuit female found buried in the Alaskan tundra who died during the 1918 pandemic. The finding was essential, as it was discovered that there were subtle modifications to the shape of the HA protein molecule on the virus that permits transmission from birds to humans. The HA molecule protrudes from the surface of the virus as a series of spikes, making it possible to lock onto receptors on the surface of cells in the human body.38 It then proceeds into the cell to infect it. The HA of human and bird viruses interact with different receptors, which means bird viruses are normally unable to be transmitted to humans. However, in the 1918 pandemic, an antigenic shift occurred in the HA protein, subtly changing shape, allowing it the capability to attach to receptors in human as well as bird cells.39 Furthermore, these extremely virulent recombinant viruses expressing HA could infect the entire lung and induce elevated levels of macrophage-derived chemokines and cytokines, resulting in infiltration of inflammatory cells and severe hemorrhage. Influenza subtypes that express hemagglutinins H1 to H15 and neuraminidases N1 to N9 are found in wild waterfowl, but only H1, H2, and H3 hemagglutinin subtypes had previously been known to cause human illness.40

Previous Page | Table of Contents | Next Page