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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03572

    Filtration, concentration and detection of salmonid alphavirus in seawater during a post-smolt salmon (Salmo salar) cohabitant challenge

    Lisa-Victoria Bernhardt, Mette Myrmel, Atle Lillehaug, Lars Qviller, Simon Chioma Weli

    *Corresponding author:

    ABSTRACT: Currently, the prevalence of salmonid alphavirus (SAV) in Norwegian Atlantic salmon farms is largely surveyed via sacrificing fish and sampling of organ tissue on a monthly basis. However, a more cost-efficient, straightforward, rapid, reliable, reproducible and animal welfare friendly method based on the detection of SAV in water could be considered as an alternative method. In the present study, such a method was developed and optimized through a six-week cohabitant challenge trial, using post-smolt Atlantic salmon Salmo salar L, challenged with high or low doses of SAV subtype 3 (SAV3). Tank water and tissue samples from cohabitant fish were collected at 16 time points. SAV3 was concentrated from the water by filtration, using either an electronegative or an electropositive membrane filter, which were subsequently rinsed with one of four different buffer solutions. SAV3 was first detected in tank water (7 days post-challenge, DPC), and later in cohabitant fish organ tissue samples (12 DPC). The electronegative filter (MF-Millipore™) and rinsing with NucliSENS® easyMAG® Lysis Buffer presented the best SAV3-recovery. A significant positive correlation was found between SAV3 in the tank water concentrates and the mid-kidney samples. Based on these results, detection of SAV3 in filtrated seawater is believed to have the potential to serve as an alternative method for surveillance of SAV in Atlantic salmon farms.