Viral Protein Kinetics of Piscine Orthoreovirus Infection in Atlantic Salmon Blood Cells.
Piscine orthoreovirus(PRV) is ubiquitous in farmed Atlantic salmon (Salmo salar) and the cause of heart and skeletal muscle inflammation. Erythrocytes are important target cells for PRV. We have investigated the kinetics of PRV infection in salmon blood cells. The findings indicate that PRV causes an acute infection of blood cells lasting 1-2 weeks, before it subsides into persistence. A high production of viral proteins occurred initially in the acute phase which significantly correlated with antiviral gene transcription. Globular viral factories organized by the non-structural protein µNS were also observed initially, but were not evident at later stages. Interactions between µNS and the PRV structural proteins λ1, µ1, σ1 and σ3 were demonstrated. Different size variants of µNS and the outer capsid protein µ1 appeared at specific time points during infection. Maximal viral protein load was observed five weeks post cohabitant challenge and was undetectable from seven weeks post challenge. In contrast, viral RNA at a high level could be detected throughout the eight-week trial. A proteolytic cleavage fragment of the µ1 protein was the only viral protein detectable after seven weeks post challenge, indicating that this µ1 fragment may be involved in the mechanisms of persistent infection.
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. hanne.merethe.haatveit@nmbu.no.
Hanne Merethe
HM
Haatveit
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. oystein.wessel@nmbu.no.
Øystein
Ø
Wessel
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. turhan.markussen@nmbu.no.
Turhan
T
Markussen
Department of Immunology, Norwegian Veterinary Institute, 0454 Oslo, Norway. morten.lund@vetinst.no.
Morten
M
Lund
Department of Biosciences, University of Oslo, 0316 Oslo, Norway. bernd.thiede@ibv.uio.no.
Bernd
B
Thiede
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. ingvild.nyman@nmbu.no.
Ingvild Berg
IB
Nyman
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. stine.braaen@nmbu.no.
Stine
S
Braaen
Department of Immunology, Norwegian Veterinary Institute, 0454 Oslo, Norway. maria.dahle@vetinst.no.
Maria Krudtaa
MK
Dahle
Department of Food Safety and Infectious Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0454 Oslo, Norway. espen.rimstad@nmbu.no.
Espen
E
Rimstad
D000818:Animals; D004912:Erythrocytes / Q000648:ultrastructure / Q000821:virology*; D005393:Fish Diseases / Q000097:blood / Q000821:virology*; D015870:Gene Expression; D005814:Genes, Viral; D009135:Muscular Diseases / Q000097:blood / Q000662:veterinary / Q000821:virology; D018165:Orthoreovirus / Q000235:genetics / Q000648:ultrastructure; D059748:Proteolysis; D012367:RNA, Viral / Q000378:metabolism; D012088:Reoviridae Infections / Q000097:blood / Q000662:veterinary* / Q000821:virology; D020317:Salmo salar / Q000097:blood / Q000821:virology*; D019562:Viral Load / Q000662:veterinary; D014764:Viral Proteins / Q000378:metabolism*
D012367:RNA, Viral; D014764:Viral Proteins
Atlantic Salmon; PRV; Piscine orthoreovirus; blood cells; expression kinetics; non-structural protein; pathogenesis; proteolytic cleavage; µ1; µNS