© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey “Bird flu”  Caused by avian influenza virus (AIV)  Endemic in wild and domestic birds  16 H and 9 N subtypes  Only H5 and H7 are highly pathogenic  Though many H5 & H7 varieties are not  “Bird flu” caused by H5N1  Symptoms  Severe respiratory infection  Organ failure  High mortality rate

© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey Outbreak timeline I  1996  H5N1 isolated from farm goose in China  1997  18 human cases reported in Hong Kong with 6 fatalities  2003  Thailand reports outbreak among zoo animals  Poultry farm infections in South Korea  2004  Vietnam, Japan, Thailand, Cambodia, Laos, Indonesia, and Malaysia report poultry infections  Vietnam and Thailand report human cases and fatalities

© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey Outbreak timeline II  2005  First published account of human-to-human transmission  Cambodia and Indonesia report human cases  6,345 migratory birds found dead in China  H5N1 found among poultry and wild birds in Russia, Kazakhstan, Mongolia, Turkey, Romania, and Croatia  January 2006  Human cases and deaths reported in Turkey

© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey The genomics of the Avian Influenza Virus  Avian influenza virus (AIV) genome  8 RNA segments  Each ~900 to ~2300 bp  11 proteins  Large scale sequencing of avian influenza viruses  Analyzed 336 avian influenza viruses  Collected between 1976 and 2004  Global sample including wild birds and poultry

© 2005 Prentice Hall Inc. / A Pearson Education Company / Upper Saddle River, New Jersey A potential virulence determinant  The NS gene  Highly variable  NS1 only produced in infected cell  Ligand identified that binds to many receptors and proteins in intracellular pathways  Ligand sequence not found in mild human viruses  Could NS1 identify highly pathogenic avian influenza strains?