An experimental investigation on aspects of infectious salmon anaemia virus (ISAV) infection dynamics in seawater Atlantic salmon, Salmo salar L. |
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| Authors: | A Gregory L A Munro M Snow K L Urquhart A G Murray R S Raynard |
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| Institution: | Fisheries Research Services, Aberdeen, UK |
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| Abstract: | This study investigated infection dynamics of infectious salmon anaemia virus (ISAV) by conducting two experiments to examine minimum infective dose and viral shedding of ISAV. In terms of minimum infective dose, the high variability between replicate tanks and the relatively slow spread of infection through the population at 1 × 101 TCID50 mL?1 indicated this dose is approaching the minimum infective dose for ISAV in seawater salmon populations. A novel qPCR assay incorporating an influenza virus control standard with each seawater sample was developed that enabled the quantity of ISAV shed from infected populations to be estimated in values equivalent to viral titres. Viral shedding was first detected at 7 days post-challenge (5.8 × 10?2 TCID50 mL?1 kg?1) and rose to levels above the minimum infective dose (4.2 × 101 TCID50 mL?1 kg?1) on day 11 post-challenge, 2 days before mortalities in ISAV inoculated fish started. These results clearly demonstrate that a large viral shedding event occurs before death. Viral titres peaked at 7.0 × 101 TCID50 mL?1 kg?1 15 days post-infection. These data provide important information relevant to the management of ISA. |
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| Keywords: | Atlantic salmon dose ISAV viral shedding |
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