Project number:
2018-102
Project Status:
Completed
Budget expenditure:
$59,327.00
Principal Investigator:
Peter Speck
Organisation:
Flinders University
Project start/end date:
15 Nov 2018
-
29 Jun 2019
Contact:
FRDC
To understand the risk of OsHV-1 spreading to commercial Pacific oyster growing regions, vectors need to be understood. A major gap is to understand the importance of non-OsHV-1 hosts and their role as reservoirs and in transmission of the virus. This project will provide information to better understand this risk, and to inform the status of PIRSA's ban on take of shellfish from the Port River.
1. Implement and validate OsHV-1 in situ hybridisation assay
2. Assess OsHV-1 infection in PCR positive non-C. gigas hosts using ISH
Final report
ISBN:
978-1-925562-33-0
Authors:
Peter Speck
Jim Mitchell
Jane Yeadon and Marty Deveney
Final Report
•
2019-09-01
•
863.76 KB
2018-102-DLD.pdf
South Australia (SA) has a large edible oyster industry primarily growing Pacific oysters
(Crassostrea gigas). The industry is regionally-based, an important employer and a substantial contributor
to regional economies. Pacific oyster mortality syndrome (POMS) is a serious infectious disease of
C. gigas caused by ostreid herpesvirus-1 microvariant (OsHV-1 microvariant). The first outbreak of
OsHV-1 in Australia occurred in 2010, in the Georges River-Botany Bay and Port Hacking-Sydney
Harbor estuaries in NSW. OsHV-1 was subsequently detected in the Hawkesbury River system (2013) and
eastern Tasmania (2016). The production and economic impacts of these outbreaks have been substantial.
OsHV-1 infection was confirmed in the Port River, SA, in February 2018 in association with high
mortality (50-90+%) of feral Pacific oysters. POMS was not identified in SA outside the control area, and
surveillance has shown commercial growing areas in SA to be free of OsHV-1. Surveillance has shown
that C. gigas in the Port River system has high prevalence of OsHV-1 infection.
Mussels (Mytilus spp.) share similar habitats to Pacific oysters and are common in the Port River estuary
(1). Mussels are demonstrated as hosts for OsHV-1 in Ireland (2), and show some histopathological signs
of disease but outbreaks in mussels are not described. We aimed to implement an OsHV-1 in situ
hybridization (ISH) assay and assess OsHV-1 infection in PCR positive non-C. gigas hosts using ISH.
An in situ hybridization (ISH) test for OsHV-1 was implemented at Flinders University based on
published primers for detection of the virus. ISH showed a strong signal in sections from infected C. gigas
and none in uninfected C. gigas. Bivalves were collected in the Port River by SARDI, sampled and tested
for OsHV-1 using PCR. Three PCR positive samples of Mytilus spp. were also positive by ISH, showing
infection with OsHV-1.
Confirmation that mussels are a host of OsHV-1 has a range of important management implications.
Movement of mussels likely poses a risk for transmission of OsHV-1, so control activities designed to
decrease host populations that target only Pacific oysters are unlikely to be successful; biofouling
management should be general rather than targeting only Pacific oysters. Containment measures should
target all bivalve species. Mussels for translocation to OsHV-1 free areas should be sourced from
biosecure hatcheries and tested to provide evidence of OsHV-1 freedom.
