Distribution and Pathogenicity of Two Cutthroat Trout Virus (CTV) Genotypes in Canada

The sole member of the Piscihepevirus genus (family Hepeviridae ) is cutthroat trout virus (CTV) but recent metatranscriptomic studies have identified numerous fish hepevirus sequences including CTV-2. In the current study, viruses with sequences resembling both CTV and CTV-2 were isolated from salm...

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Bibliographic Details
Published in:Viruses
Main Authors: Amy Long, Francis LeBlanc, Jean-René Arseneau, Nellie Gagne, Katja Einer-Jensen, Jan Lovy, Mark Polinski, Simon Jones, Kyle A Garver
Format: Article in Journal/Newspaper
Language:English
Published: MDPI AG 2021
Subjects:
Hepeviridae
Piscihepevirus
cutthroat trout virus
CTV-2
Atlantic salmon
Pacific salmon
Microbiology
QR1-502
Canada
Pacific
Sockeye
Salmo salar
Online Access:https://doi.org/10.3390/v13091730
https://doaj.org/article/48d71fa60ba448fea46851f78aa4ce98
Description
Summary:The sole member of the Piscihepevirus genus (family Hepeviridae ) is cutthroat trout virus (CTV) but recent metatranscriptomic studies have identified numerous fish hepevirus sequences including CTV-2. In the current study, viruses with sequences resembling both CTV and CTV-2 were isolated from salmonids in eastern and western Canada. Phylogenetic analysis of eight full genomes delineated the Canadian CTV isolates into two genotypes (CTV-1 and CTV-2) within the Piscihepevirus genus. Hepevirus genomes typically have three open reading frames but an ORF3 counterpart was not predicted in the Canadian CTV isolates. In vitro replication of a CTV-2 isolate produced cytopathic effects in the CHSE-214 cell line with similar amplification efficiency as CTV. Likewise, the morphology of the CTV-2 isolate resembled CTV, yet viral replication caused dilation of the endoplasmic reticulum lumen which was not previously observed. Controlled laboratory studies exposing sockeye ( Oncorhynchus nerka) , pink ( O. gorbuscha ), and chinook salmon ( O. tshawytscha ) to CTV-2 resulted in persistent infections without disease and mortality. Infected Atlantic salmon ( Salmo salar ) and chinook salmon served as hosts and potential reservoirs of CTV-2. The data presented herein provides the first in vitro and in vivo characterization of CTV-2 and reveals greater diversity of piscihepeviruses extending the known host range and geographic distribution of CTV viruses.

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