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

Colleen A. Burge, Kimberly S. Reece, Arun K. Dhar, Peter Kirkland, Benjamin Morga, Lionel Dégremont, Nicole Faury, Bryanda J.T. Wippel, Alanna MacIntyre, Carolyn S. Friedman

Research output: Contribution to journalArticle


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.

Original languageEnglish (US)
Pages (from-to)137-144
Number of pages8
JournalDiseases of aquatic organisms
StatePublished - Mar 12 2020


  • Alkalinity
  • Crassostrea gigas
  • Emerging infectious diseases
  • Microvariant
  • OsHV-1 µvars
  • Ostreid herpesvirus 1
  • POMS
  • Pacific oyster
  • Viral disease
  • qPCR

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

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  • Cite this

    Burge, C. A., Reece, K. S., Dhar, A. K., Kirkland, P., Morga, B., Dégremont, L., Faury, N., Wippel, B. J. T., MacIntyre, A., & Friedman, C. S. (2020). First comparison of French and Australian OsHV-1 µvars by bath exposure. Diseases of aquatic organisms, 138, 137-144.