TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Protease Inhibitory Activity In The Eastern Oyster, Crassostrea virginica, And Its Relationship To Disease Resistance Jacques L. Oliver1, M. Faisal1, P. M. Gaffney2, S. K. Allen1, and S. L. Kaattari1 1Dept. of Environmental Sciences, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062, USA; 2College of Marine Studies, University of Delaware, Lewes, DE 19958, USA Selected stocks of eastern oysters, Crassostrea virginica, were interbred to produce ten families with high inter- and intrafamily genetic variability. This underlying genetic variability is believed to be related to physiological variability and, in turn, variation in capability to resist disease. In an effort to identify potential biochemical markers for resistance to Dermo, a disease afflicting eastern oysters, each family was assessed for protease inhibitory activity to Perkinsus marinus protease. Subsamples were procured at two time points during the summer, and after exposure to the pathogen. Concurrently, individual oysters were diagnosed for the presence and intensity of the pathogen via Ray's Thioglycollate Medium (RFTM) test. Family survival, disease intensity, and protease inhibitory activity were compared to assess family performance. Families PG-2 and Pg-14 had the highest survival, lowest average disease intensity, and highest average protease inhibitory activity. In field challenges, the same two families exhibited the highest survival and growth rates. Among all families, disease intensity correlated with protease inhibitory activity. Results indicate a positive inverse relationship between disease intensity and protease inhibitory activity. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page