2010 Annual Report 1a.Objectives (from AD-416) 1) Pathogenesis of avian inluenza virus isolates in swine;. 2)Role of avian polymerases in adaptation of swine influenza viruses to swine;. 3)Genetic characterization of swine and avian influenza viruses to swine; and. 4)Preparation of reagents. 1b.Approach (from AD-416) 1) Pathogenesis of avian influenza virus isolates in swine will be evaluated after inoculation into a group of four week old pigs. Microscopic and macroscopic lung lesions and viral replication in lungs and nasal cavities will be determined.. 2)Various reassortant viruses containing avian and/or swine polymerase genes will be established using reverse genetics approaches. These reassortant viruses will be tested for their pathogenic potential in swine.. 3)Swine and avian influenza isolates will be genetically characterized using conventional sequencing approaches.. 4)Hyperimmune sera and various viruses will be made available as reagents. 3.Progress Report This is the fourth year of a 7-year-project that is part of a multi-institutional grant. The National Animal Disease Center's role is to conduct studies testing the susceptibility of swine to infection with low pathogenic avian influenza viruses. Pigs were shown to be susceptible to infection with H9 influenza A subtype viruses similar to when swine are inoculated with the H5 and H7 influenza subtype viruses. Although the pigs can become infected, there appears to be little shedding of the virus to contact pigs. Collectively, these studies support the assumption that pigs can be infected with many different types of influenza.