Preliminary Report On A Pathogenic Virus From The Spiny Lobster, Panulirus argus       Jeffrey D. Shields1, D. Behringer2, and M. Butler2   1Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, VA 23062; 2Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529.       During an investigation of social denning behavior in juvenile spiny lobster, Panulirus argus, in the Florida Keys, USA, several lethargic or moribund individuals were observed. Affected lobsters frequently died during handling, and exhibited lethargy or weakness and milky hemolymph. Wet smears, Giemsa-stained prepared smears, and histological samples indicated hemocytopenia, and significant debris in the hemolymph presumably resulting from hemocyte or tissue degradation. Gram stains for bacterial infections were negative in several infected individuals. Histological examination indicated alterations in the hemocytes indicative of a viral infection. These alterations were observed in hyalinocytes and semigranulocytes, but not granulocytes. Infected hemocytes exhibited hypertrophy, with hypertrophied nuclei, nuclear inclusions, and an apparently altered nuclear membrane. Challenge trials using inoculated hemolymph from infected donors were successful in transmitting the disease with signs of infection occurring in most lobsters after 50-80 d. In 1999, the overall prevalence of infection was 12.2%, but infections were patchily distributed over certain locations. Adult lobsters have not been observed with the infection. Additional infection trials, impacts on the social behavior of juveniles, and a TEM study to identify the agent are currently underway.