title: Piscine Orthoreovirus from Western North America Is Transmissible to Atlantic Salmon and Sockeye Salmon but Fails to Cause Heart and Skeletal Muscle Inflammation.
abstract: Heart and skeletal muscle inflammation (HSMI) is a significant and often fatal disease of cultured Atlantic salmon in Norway. The consistent presence of Piscine orthoreovirus (PRV) in HSMI diseased fish along with the correlation of viral load and antigen with development of lesions has supported the supposition that PRV is the etiologic agent of this condition; yet the absence of an in vitro culture system to demonstrate disease causation and the widespread prevalence of this virus in the absence of disease continues to obfuscate the etiological role of PRV with regard to HSMI. In this study, we explore the infectivity and disease causing potential of PRV from western North America-a region now considered endemic for PRV but without manifestation of HSMI-in challenge experiments modeled upon previous reports associating PRV with HSMI. We identified that western North American PRV is highly infective by intraperitoneal injection in Atlantic salmon as well as through cohabitation of both Atlantic and Sockeye salmon. High prevalence of viral RNA in peripheral blood of infected fish persisted for as long as 59 weeks post-challenge. Nevertheless, no microscopic lesions, disease, or mortality could be attributed to the presence of PRV, and only a minor transcriptional induction of the antiviral Mx gene occurred in blood and kidney samples during log-linear replication of viral RNA. Comparative analysis of the S1 segment of PRV identified high similarity between this North American sequence and previous sequences associated with HSMI, suggesting that factors such as viral co-infection, alternate PRV strains, host condition, or specific environmental circumstances may be required to cause this disease.
authors.affiliation: Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada.
authors.forename: Kyle A
authors.initials: KA
authors.lastname: Garver
authors.affiliation: Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada.
authors.forename: Stewart C
authors.initials: SC
authors.lastname: Johnson
authors.affiliation: Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Polinski
authors.affiliation: Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada.
authors.forename: Julia C
authors.initials: JC
authors.lastname: Bradshaw
authors.affiliation: Animal Health Centre, Ministry of Agriculture, Abbotsford, British Columbia, Canada.
authors.forename: Gary D
authors.initials: GD
authors.lastname: Marty
authors.affiliation: Animal Health Centre, Ministry of Agriculture, Abbotsford, British Columbia, Canada.
authors.forename: Heindrich N
authors.initials: HN
authors.lastname: Snyman
authors.affiliation: Marine Harvest Canada, Campbell River, British Columbia, Canada.
authors.forename: Diane B
authors.initials: DB
authors.lastname: Morrison
authors.affiliation: Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada.
authors.forename: Jon
authors.initials: J
authors.lastname: Richard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D009202:Cardiomyopathies / Q000821:virology; D019353:Endemic Diseases; D005393:Fish Diseases / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000473:pathology / Q000821:virology; D009220:Myositis / Q000821:virology; D009656:North America / Q000453:epidemiology; D018165:Orthoreovirus / Q000145:classification / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D015995:Prevalence; D012367:RNA, Viral / Q000097:blood / Q000235:genetics / Q000378:metabolism; D012088:Reoviridae Infections / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D020317:Salmo salar / Q000097:blood / Q000821:virology*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
chemical_list: D012367:RNA, Viral