Current research suggests that viral polymerase may provide a new therapeutic target for host-adapted avian influenza. The related report by Gabriel et al, "Spread of Infection and Lymphocyte Depletion in Mice Depends on Polymerase of Influenza Virus" appears in the September 2009 issue of the American Journal of Pathology. Highly pathogenic avian influenza, commonly known as bird flu, is a strain of the influenza virus that has adapted to infect birds.