Whole-genome analysis of piscine reovirus (PRV) shows PRV represents a new genus in family Reoviridae and its genome segment S1 sequences group it into two separate sub-genotypes.

Molly Jt Kibenge,Marcos G Godoy,Tokinori Iwamoto,Alexandra Morton,Yingwei Wang,Frederick Sb Kibenge

doi:10.1186/1743-422x-10-230

Abstract

BackgroundPiscine reovirus (PRV) is a newly discovered fish reovirus of anadromous and marine fish ubiquitous among fish in Norwegian salmon farms, and likely the causative agent of heart and skeletal muscle inflammation (HSMI). HSMI is an increasingly economically significant disease in Atlantic salmon (Salmo salar) farms. The nucleotide sequence data available for PRV are limited, and there is no genetic information on this virus outside of Norway and none from wild fish.MethodsRT-PCR amplification and sequencing were used to obtain the complete viral genome of PRV (10 segments) from western Canada and Chile. The genetic diversity among the PRV strains and their relationship to Norwegian PRV isolates were determined by phylogenetic analyses and sequence identity comparisons.ResultsPRV is distantly related to members of the genera Orthoreovirus and Aquareovirus and an unambiguous new genus within the family Reoviridae. The Canadian and Norwegian PRV strains are most divergent in the segment S1 and S4 encoded proteins. Phylogenetic analysis of PRV S1 sequences, for which the largest number of complete sequences from different “isolates” is available, grouped Norwegian PRV strains into a single genotype, Genotype I, with sub-genotypes, Ia and Ib. The Canadian PRV strains matched sub-genotype Ia and Chilean PRV strains matched sub-genotype Ib.ConclusionsPRV should be considered as a member of a new genus within the family Reoviridae with two major Norwegian sub-genotypes. The Canadian PRV diverged from Norwegian sub-genotype Ia around 2007 ± 1, whereas the Chilean PRV diverged from Norwegian sub-genotype Ib around 2008 ± 1.

Highlights

Piscine reovirus (PRV) is a newly discovered fish reovirus of anadromous and marine fish ubiquitous among fish in Norwegian salmon farms, and likely the causative agent of heart and skeletal muscle inflammation (HSMI)
The newly discovered piscine reovirus (PRV) belongs to the family Reoviridae, subfamily Spinareovirinae [1], probably in a new reovirus genus that is distant to the genera Orthoreovirus and Aquareovirus [2], with genome segments, PRV is like members of the genus Orthoreovirus and unlike the genus Aquareovirus with segments
Amplification and sequencing of cDNA of genomic segments of PRV from fish samples Piscine reovirus was readily detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) during testing at the Atlantic Veterinary College laboratory in fish tissue samples from western Canada, and at the ETECMA diagnostic laboratory in fish tissue samples from Chile

Summary

Introduction

Piscine reovirus (PRV) is a newly discovered fish reovirus of anadromous and marine fish ubiquitous among fish in Norwegian salmon farms, and likely the causative agent of heart and skeletal muscle inflammation (HSMI). PRV is associated with heart and skeletal muscle inflammation (HSMI) [2]; an emerging disease of marinefarmed Atlantic salmon [11], first recognized in 1999 in western Norway [12] and subsequently in Scotland [13]. The virus can be propagated in the GF-1 cell line [19], derived from the tissue of orange-spotted grouper, Epinephelus coioides [20], and cardiac and skeletal muscle pathology typical of HSMI can be reproduced in naïve Atlantic salmon by experimental inoculation with the supernatant from cell culture passaged PRV [19]. There is anecdotal evidence that it is present in farmed Atlantic salmon and wild Pacific salmon in British Columbia-Canada [27], where 75% of 300 farm salmon reportedly tested positive for PRV [27] but no sequence information was reported

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