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Abstracts
Workgroup: Frontiers in Disease Research
Oyster Herpes Virus Threat to U.S. Oyster Producers
Principal Investigator(s):
Dr. Ralph Elston, Pacific Shellfish Institute Mailing address: PO Box 687, Carlsborg, WA 98324 USA. Phone: 360-681-3122
Co-Investigator(s):
Dr. Bruce Barber, University of Maine
Dr. Eugene Burreson, Virginia Institute of Marine Science
Dr. Carolyn S. Friedman, University of Washington
Dr. Kimberly Reece, Virginia Institute of Marine Science
Dr. Eugene Burreson, Virginia Institute of Marine Science
Dr. Carolyn S. Friedman, University of Washington
Dr. Kimberly Reece, Virginia Institute of Marine Science
Funding Period: 10-1-01 to 9-30-03
We have tested Eastern oyster (Crassostrea virginica) larvae and spat from Virginia, Louisiana and Maine using the polymerase chain reaction procedure for oyster herpes virus and all groups have tested negative. The procedure was first validated by K. Reece and N. Stokes of VIMS. Similarly, tests of Pacific oyster (C. gigas) spat from Washington state were negative for the herpes virus. Oysters from Tomales Bay, California tested PCR+ for the herpes virus (Fig. 1) using the first set of PCR primers ("A" primers) when examined by team member C. Friedman of the U.W. Our recent results indicate an infection prevalence ranging between 3.3% and 43% at a single site in Tomales Bay, California. Historical examinations suggest that herpes virus may not be widespread in the U.S. because we have not observed the degree of mortality or lesions described by European researchers where the disease occurs in both larval and juvenile oysters.
IMPACTS and/or BENEFITS:
The recent (October 2002) PCR+ results from Tomales Bay, California indicate that it is of critical time importance to establish the nature and magnitude of this threat to U.S. producers. As a precautionary measure, it should be assumed that this virus is not widespread in cultured stocks of Eastern or Pacific oysters in the United States and further, that U.S. oyster stocks that are not infected may be at risk should they become infected. Therefore, the continuation of the study is all the more critical in order to define its geographic distribution, evaluate its significance to U.S. fishery resources and recommend appropriate management steps which could include actions to prevent further spread of the virus. Government representatives from French and New Zealand fishery agencies have opposed the designation of this virus disease as being Notifiable by the international animal health advisory organization, the Office Internationale des Epizooties (O.I.E.). The presence or absence and relative impact of the virus variant form we have found in California that apparently is highly significant to hatcheries in France and New Zealand remains largely uncharacterized. Our results to date using the polymerase chain reaction method have failed to detect the virus from samples of both east (C. virginca) and most west coast (C. gigas) oyster larvae and juveniles, suggesting a localized distribution of this virus. Until a scientific study more thoroughly documents the absence or presence of the herpes virus in both hatchery and nursery produced stocks and adult stocks, measures cannot be taken to preclude its introduction, or its spread. Conversely, appropriate management procedures cannot be formulated until its presence and distribution are established in locations where the virus is identified.
PROJECT PUBLICATIONS:
Herpes virus in Pacific oysters from Tomales Bay, California (in preparation, C. Friedman, lead author)
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