The first comprehensive analysis of an animal’s immune response to the 1918 influenza virus provides new insights into the killer flu, report federally supported scientists in an article appearing online today in the journal Nature. Key among these insights, they found that the 1918 virus triggers a hyperactive immune response that may contribute to the lethality of the virus. Furthermore, their results suggest that it is the combination of all eight of the 1918 flu virus genes interacting synergistically that accounts for the exceptional virulence of this virus.