2011 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 fifth 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 selected non-swine influenza viruses. Previously, pigs were shown to be susceptible to infection with H9, H7, and H5 influenza A subtype viruses. The studies demonstrated that pigs are susceptible to a number of isolates in these subtypes. As part of the response to the emergence of the pandemic 2009 H1N1 virus, the susceptibility of pigs to recent H1N1 seasonal human influenza viruses was tested. Similar to the avian studies, pigs could be infected with the viruses, but developed little if any clinical disease following infection. Collectively, the studies support the assumption that pigs can be infected with many different types of influenza. This observation supports the hypothesis that swine can serve as a potential mixing vessel for avian and human influenza viruses leading to the production of novel influenza viruses. Progress was monitored via email and conference calls.