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Background H9 N2 avian influenza viruses continue to spread in poultry and wild birds throughout Eurasia. Objectives To characterize H9 N2 influenza viruses from pheasants, quail, and white-bellied bustards ( WBBs) used to train falcons in the United Arab Emirates ( UAE). Methods Four H9 N2 viruses were isolated from pheasants, quail, and WBB used for falconry in the UAE, and antigenic, molecular, phylogenetic analysis, and invivo characterization of H9 N2 viruses were performed. Results and conclusions The pheasant and WBB isolates were antigenically and molecularly clearly related and along with the quail isolates contained multiple 'avian-human' substitutions. The release of smuggled H9 N2-infected birds for falconry may contribute to the spread of these viruses to wild birds, domestic poultry, and humans. [ABSTRACT FROM AUTHOR]

North American triple reassortant swine (TRS) influenza A viruses have caused sporadic human infections since 2005, but human-to-human transmission has not been documented. These viruses have six gene segments (PB2, PB1, PA, HA, NP, and NS) closely related to those of the 2009 H1N1 pandemic viruses. Therefore, understanding of these viruses' pathogenicity and transmissibility may help to identify determinants of virulence of the 2009 H1N1 pandemic viruses and to elucidate potential human health threats posed by the TRS viruses. Here we evaluated in a ferret model the pathogenicity and transmissibility of three groups of North American TRS viruses containing swine-like and/or human-like HA and NA gene segments. The study was designed only to detect informative and significant patterns in the transmissibility and pathogenicity of these three groups of viruses. We observed that irrespective of their HA and NA lineages, the TRS viruses were moderately pathogenic in ferrets and grew efficiently in both the upper and lower respiratory tracts. All North American TRS viruses studied were transmitted between ferrets via direct contact. However, their transmissibility by respiratory droplets was related to their HA and NA lineages: TRS viruses with human-like HA and NA were transmitted most efficiently, those with swine-like HA and NA were transmitted minimally or not transmitted, and those with swine-like HA and human-like NA (N2) showed intermediate transmissibility. We conclude that the lineages of HA and NA may play a crucial role in the respiratory droplet transmissibility of these viruses. These findings have important implications for pandemic planning and warrant confirmation. [ABSTRACT FROM AUTHOR]