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Diseases of Aquatic Organisms

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DAO 138:137-144 (2020)  -  DOI:

First comparison of French and Australian OsHV-1 µvars by bath exposure

Colleen A. Burge1,*, Kimberly S. Reece2,, Arun K. Dhar3, Peter Kirkland4, Benjamin Morga5, Lionel Dégremont5, Nicole Faury5, Bryanda J. T. Wippel6, Alanna MacIntyre2, Carolyn S. Friedman6

1Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, Maryland 21202, USA
2Virginia Institute of Marine Sciences, William & Mary, PO Box 1346, Gloucester Point, Virginia 23062, USA
3Aquaculture Pathology Laboratory, School of Animal and Comparative Biomedical Sciences, The University of Arizona, 1117 E Lowell Road, Tucson, AZ 85721, USA
4Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Menangle, NSW 2568, Australia
5Ifremer, RBE-SG2M-LGPMM, Station La Tremblade, 17390 La Tremblade, France
6School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195, USA
*Corresponding author:

ABSTRACT: Economically devastating mortality events of farmed and wild shellfish due to infectious disease have been reported globally. Currently, one of the most significant disease threats to Pacific oyster Crassostrea gigas culture is the ostreid herpesvirus 1 (OsHV-1), in particular the emerging OsHV-1 microvariant genotypes. OsHV-1 microvariants (OsHV-1 µvars) are spreading globally, and concern is high among growers in areas unaffected by OsHV-1. No study to date has compared the relative virulence among variants. We provide the first challenge study comparing survival of naïve juvenile Pacific oysters exposed to OsHV-1 µvars from Australia (AUS µvar) and France (FRA µvar). Oysters challenged with OsHV-1 µvars had low survival (2.5% exposed to AUS µvar and 10% to FRA µvar), and high viral copy number as compared to control oysters (100% survival and no virus detected). As our study was conducted in a quarantine facility located ~320 km from the ocean, we also compared the virulence of OsHV-1 µvars using artificial seawater made from either facility tap water (3782 µmol kg-1 seawater total alkalinity) or purchased distilled water (2003 µmol kg-1). Although no differences in survival or viral copy number were detected in oysters exposed to seawater made using tap or distilled water, more OsHV-1 was detected in tanks containing the lower-alkalinity seawater, indicating that water quality may be important for virus transmission, as it may influence the duration of viral viability outside of the host.

KEY WORDS: Ostreid herpesvirus 1 · Microvariant · OsHV-1 µvars · POMS · Pacific oyster · Crassostrea gigas · Viral disease · qPCR · Alkalinity · Emerging infectious diseases

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Cite this article as: Burge CA, Reece KS, Dhar AK, Kirkland P and others (2020) First comparison of French and Australian OsHV-1 µvars by bath exposure. Dis Aquat Org 138:137-144.

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