Differences in gene expression in Atlantic salmon parr and smolt after challenge with Piscine orthoreovirus (PRV).
Heart and skeletal muscle inflammation (HSMI) are a disease of farmed Atlantic salmon (Salmo salar) associated with Piscine orthoreovirus (PRV). The disease appears mainly during the marine production phase. This study examined if smoltification and transfer to seawater could compromise immune responses to PRV. Parr and smolts of the same origin were challenged by cohabitation with intraperitoneally injected salmon. Peak levels of PRV in spleen of cohabitants were reached after 8 weeks, but at a lower level in parr compared to smolts. Thereafter the virus levels declined, but remained significantly lower in parr than in smolts. Both groups developed typical HSMI histopathological heart lesions, which were most prominent after 10 weeks. Microarray and qPCR analyses revealed slightly lower expression of immune genes in spleen and head kidney of smolts before challenge. Infected parr showed earlier induction of genes involved in innate antiviral immunity, as well as for genes related to B and T cell responses. Gene expression profiles also indicated stimulation of heme and iron metabolism and erythropoiesis in smolts, which may indicate replacement of PRV-infected erythrocytes.
Nofima AS, Norwegian Institute of Food, Fisheries & Aquaculture Research, Ås, Norway. Electronic address: Lill-Heidi.Johansen@Nofima.no.
Lill-Heidi
LH
Johansen
Section of Immunology, Norwegian Veterinary Institute, Oslo, Norway.
Maria Krudtaa
MK
Dahle
Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.
Øystein
Ø
Wessel
Nofima AS, Norwegian Institute of Food, Fisheries & Aquaculture Research, Ås, Norway.
Gerrit
G
Timmerhaus
VESO Vikan, Namsos, Norway.
Marie
M
Løvoll
Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway; SalMar ASA, Kverva, Norway.
Magnus
M
Røsæg
Nofima AS, Norwegian Institute of Food, Fisheries & Aquaculture Research, Ås, Norway.
Sven Martin
SM
Jørgensen
Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.
Espen
E
Rimstad
Nofima AS, Norwegian Institute of Food, Fisheries & Aquaculture Research, Ås, Norway. Electronic address: Aleksei.Krasnov@nofima.no.
Aleksei
A
Krasnov
D000818:Animals; D017756:Aquaculture / Q000379:methods; D005393:Fish Diseases / Q000276:immunology* / Q000821:virology; D015870:Gene Expression / Q000276:immunology*; D020411:Oligonucleotide Array Sequence Analysis; D018165:Orthoreovirus; D016133:Polymerase Chain Reaction; D012088:Reoviridae Infections / Q000662:veterinary*; D020317:Salmo salar / Q000276:immunology* / Q000821:virology*
Atlantic salmon; HSMI; Microarray; Parr; Piscine reovirus; Smolt