TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Interactions Between The Protozoan Perkinsus marinus And Its Host The Eastern Oyster (Crassostrea virginica) Mohamed Faisal and E.A. MacIntyre Department of Environmental Sciences, School of Marine Science, Virginia Institute of Marine Science, The College of William and Mary, Gloucester Point, VA 23062. Perkinsus marinus, the causative agent of Dermo, causes devastating losses in populations of the eastern oyster (Crassostrea virginica). In order to develop therapeutics for this disease our laboratories have been engaged in determining the molecular basis of Dermo pathogenesis. Of particular importance to the invasiveness of protozoan parasites is their elaboration of a spectrum of tissue-disruptive proteases. In this vein, our previous studies have demonstrated that P. marinus secretes extracellular serine proteases which are believed to be the cause of extensive necrosis and tissue disruption in infected oysters and have been found to enhance parasite propagation and compromise host defenses. Crassostrea virginica, however, has been found to possess several inhibitors of these proteases. The Pacific oyster (C. gigas) also possesses protease inhibitors with higher specific activities. Interestingly, Crassostrea spp. themselves, elaborate metalloprotease activities which can be detected in their plasma, and are increased during P. marinus infections. Together our work suggest that their may be a broad spectrum of humoral host defenses that is brought to bear on P. marinus infections by these two Crassostrea species. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page