Understanding Salmon gill poxvirus disease; an emerging threat for Atlantic salmon farming

Forskere ved Veterinærinstituttet og National Institute of Health (NIH) USA har gjort et banebrytende arbeid på det første poxvirus genomet fra fisk. Viruset er i samme familie som det beryktede koppevirus og ser ut til å øke i forekomst i norsk oppdrettsnæring. Vi har nå etablert analysemetoder som gjør at vi lettere kan ha oversikt over utbredelsen av viruset, salmon gill poxvirus (SGPV) og sykdommen det assosieres med. I 2021 så gjorde vi flere forsøk på å dyrke laksepoxviruset. Fra felt vet vi at stress er en viktig faktor for at viruset gir sykdom og vi forsøkte å dyrke viruset i ASG-10 cellelinjen sammen med cortisol. Ingen tegn til virusreplikasjon ble påvist. Videre mistenker vi at sonikering og fryse tine prosedyrer av smittematerialet påvirker virusets evne til å binde og infisere celler og ASG-10 cellelinjen ble eksponert for denne typen materiale, men uten at vi kunne påvise replikasjon. Vi har også forsøkt å inokulere insektcellelinjen SF9 med SGPV uten tegn til virusreplikasjon.

SALPOX has clearly demonstrated that cortisol injection of salmon infected with SGPV lead to clinical disease. This confirms experiences from the field, where stress is suspected as a risk factor for development of SGPVD in SGPV infected animals and handling and other types of stressful interventions should be avoided. Further, SALPOX has shown that the host gill transcriptome during an outbreak reflects the pathological observations and indicates immunosuppression. This can help explain the high levels of coinfections in gills after an SGPVD outbreak, and suggest that transcriptional biomarkers can be used alongside pathological evaluations, and in the short term, help to understand SGPVD and ultimately prevent the disease and complex gill diseases. The new NRC financed projects IMMUNOPOX and TRACEPOX benefit highly from the knowledge generated in SALPOX and the research on SGPV and the disease in may cause will continue in the next years in these projects

Researchers at The Norwegian Veterinary Institute (NVI) and National Institute of Health (NIH) USA, have just published a ground breaking paper on the first poxvirus genome from a fish, associated with an emerging disease of Atlantic salmon. Previous lack of diagnostic tools has hampered the control of this disease. Our new tools open new possibilities, but funding is needed. This project, SALPOX, will develop models needed to achieve fundamental characterization of SGPVD. Western Fisheries research center, USA, will contribute in establishment of a culture system for SGPV and National Institutes of Health, USA will provide pox expertise advice. Nofima will contribute on infection mechanisms and transcriptome analysis and Norwegian University of Life Sciences and VESO Vikan will provide facilities for infection trials. Overall this project will provide basic tools and models that ultimately is the fundament for making good decisions regarding health management, especially during the smolitification period, to reduce losses related to the emerging SGPVD.