TWENTY-SECOND ANNUAL EASTERN FISH HEALTH WORKSHOP ROYAL PAVILLION RESORT, ATLANTIC BEACH, NC MARCH 18 - 20, 1997 Species Specific Targeting of Oyster Hemolymph Proteins by Perkinsus marinus Extracellular Proteases. Teresa D. Lewis, J. L. Oliver, and S. K. Kaattari Department of Environmental Sciences, School of Marine Science, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 Extracellular proteases (ECP) have been identified as contributing to the virulence of many pathogenic organisms. The oyster pathogen, Perkinsus marinus, has been shown to produce potent serine proteases in vitro which are capable of digesting oyster hemolymph. ECP was coupled to CNBr-Sepharose and co-incubated with hemolymph from the eastern oyster, Crassostrea virginica, and from the Pacific oyster, Crassostrea gigas, to investigate putative species related differences in resistance to infection. ECP was shown to specifically digest C. virginica hemolymph proteins, as was evidenced by the degradation of proteins in column eluants visualized by 10% SDS-PAGE. Crassostrea gigas hemolymph was resistant to proteolysis in all instances in a range of 17oC to room temperatures, for periods up to 48 h co-incubation. Although all C. virginica samples were sensitive to ECP, culture-derived proteases target varying hemolymph component proteins. Contributing to the variability observed in our studies may be the role various protein sources play in inducing protease production/activity in vitro. Additional investigations into the composition of hemolymph proteins and the determination of specific protease targets will provide insight into factors responsible for the susceptibility or resistance of oysters to P. marinus. Identification of such traits may be manipulated in future studies in a variety of applications, to include the eventual development of resistant strains of oysters. Return to 22nd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page