title: Relationship between viral dose and outcome of infection in Atlantic salmon, Salmo salar L., post-smolts bath-challenged with salmonid alphavirus subtype 3.
abstract: Salmonid alphavirus subtype 3 (SAV3) causes pancreas disease (PD) and adversely affects salmonid aquaculture in Europe. A better understanding of disease transmission is currently needed in order to manage PD outbreaks. Here, we demonstrate the relationship between viral dose and the outcome of SAV3 infection in Atlantic salmon post-smolts using a bath challenge model. Fish were challenged at 12 °C with 3 different SAV3 doses; 139, 27 and 7 TCID50L-1of seawater. A dose of as little as 7 TCID50L-1of seawater was able to induce SAV3 infection in the challenged population with a substantial level of variation between replicate tanks and, therefore, likely represents a dose close to the minimum dose required to establish an infection in a population. These data also confirm the highly infectious nature of SAV through horizontal transmission. The outcome of SAV3 infection, evaluated by the prevalence of viraemic fish, SAV3-positive hearts, and the virus shedding rate, was positively correlated to the original SAV3 dose. A maximal shedding rate of 2.4 × 104TCID50L-1of seawater h-1kg-1was recorded 10 days post-exposure (dpe) from the highest dose group. The method reported here, for the quantification of infectious SAV3 in seawater, could be useful to monitor PD status or obtain data from SAV3 outbreaks at field locations. This information could be incorporated into pathogen dispersal models to improve risk assessment and to better understand how SAV3 spreads between farms during outbreaks. This information may also provide new insights into the control and mitigation of PD.
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.|Department of Biology, University of Bergen, P. O. Box 7803, 5020, Bergen, Norway.
authors.forename: Jiraporn
authors.initials: J
authors.lastname: Jarungsriapisit
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Lindsey J
authors.initials: LJ
authors.lastname: Moore
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Stig
authors.initials: S
authors.lastname: Mæhle
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Cecilie
authors.initials: C
authors.lastname: Skår
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Ann Cathrine
authors.initials: AC
authors.lastname: Einen
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Ingrid Uglenes
authors.initials: IU
authors.lastname: Fiksdal
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Hugh Craig
authors.initials: HC
authors.lastname: Morton
authors.affiliation: Department of Biology, University of Bergen, P. O. Box 7803, 5020, Bergen, Norway.
authors.forename: Sigurd O
authors.initials: SO
authors.lastname: Stefansson
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway.
authors.forename: Geir Lasse
authors.initials: GL
authors.lastname: Taranger
authors.affiliation: Institute of Marine Research, Nordnesgaten 50, 5005, Bergen, Norway. sonal.patel@imr.no.
authors.forename: Sonal
authors.initials: S
authors.lastname: Patel
mesh_terms: D000524:Alphavirus; D018354:Alphavirus Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D000818:Animals; D005393:Fish Diseases / Q000635:transmission / Q000821:virology*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D020317:Salmo salar / Q000821:virology*; D019562:Viral Load; D017201:Virus Shedding; D014871:Water Microbiology