Our data indicate that swine-adapted influenza viruses spread readily among pigs and from pigs to other susceptible mammalians and support the notion that AIVs undergo genetic adaptation to efficiently cross the species barrier. Our transmission models hold potential to study the factors that lead to the generation of pandemic influenza viruses.

There is a need for a standard in vitro procedure to infect larval fish with bacteria. Such a procedure could be used as a tool to evaluate fish quality, verify fish sensitivity to a certain bacterial strain or evaluate the pathogenicity of a bacterium towards a given fish species. The availability of a challenge test is a prerequisite in studies dealing with the effect of different medicinal treatments on diseased fish. An oral challenge test would offer the possibility to investigate the routes of infection via the digestive tract, i.e. after feeding contaminated feeds. Different authors have suggested that infection of marine fish was established through the food chain (Sera and Kumata, 1972;Campbell and Buswell, 1983;Muroga et al., 1987). The present study aims to verify this hypothesis and proposes a standard challenge procedure for turbot (Scophthalmus maximus) larvae with a pathogenic Vibrio anguillarum strain.Turbot (32 days old) originating from a commercial hatchery (France Turbot SA, Noirmoutiers, France) were acclimated for 1 week in a holding tank maintained at 19 °C. The water was continuously aerated and circulated over a biofilter. Daily, 10% of the water was replaced with new aerated seawater of the same temperature. The animals were fed twice daily with Artemia at a density of 300 nauplii fish -1. No mortalities were noticed after 3 days acclimation. The fish were then distributed in ten 5 1 aquaria at a density of 20 individuals per aquarium. Each aquarium was continuously aerated with an airstone and maintained at 19 °C. Daily, dead fish and faeces were siphoned off, one-third of the water was changed, salinity and nitrogen levels were checked, and fish behaviour was observed. The experiment involved two groups of fish, challenged and non-treated controls, with five replicates for each.

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ObjectivesSwine have been regarded as intermediate hosts in the spread of influenza from birds to humans but studies of the sialylated glycans that comprise their respiratory tract have not been extensively studied in the past. This study analyzed the sialylated N‐glycan and O‐glycan profile of swine trachea and lung and correlated this with ex‐vivo infection of swine explants with avian influenza viruses.SampleLungs and tracheal samples were obtained from normal farm and laboratory raised swine and used for ex vivo infection as well as mass spectrometric analysis. Infection of the ex vivo tissues used high pathogenic and low pathogenic avian viruses including the novel H7N9 virus that emerged in China in early 2013.Main outcome measuresAssessment of successful replication was determined by TCID50 as well as virus immunohistochemistry. The N‐glycan and O‐glycan profiles were measured by MALDI‐TOF and sialylated linkages were determined by sialidase treatment. Lectin binding histochemistry was also performed on formalin fixed tissue samples with positive binding detected by chromogen staining.ResultsThe swine respiratory tract glycans differed from the human respiratory tact glycans in two main areas. There was a greater abundance of Gal‐α‐Gal linkages resulting in a relative decrease in sialylated glycans. The swine respiratory tract also had a greater proportion of glycans containing Neu5Gc and Siaα2‐6 glycans than the human respiratory tract. Infection with avian viruses was confined primarily to lung bronchioles rather than trachea and parenchyma.ConclusionsIn contrast to previous studies we found that there was not as much expression of Siaα2‐3 glycans on the surface of the trachea. Infection of Siaα2‐3 binding avian viruses was restricted to the lower respiratory tract bronchioles. This finding may diminish the ability of the swine to act as an intermediary in the transmission of avian viruses to humans.

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