A Caribbean Echinoderm Pathogen: Identification And Host Range     Kimberly B. Ritchie   MicroGenomics, Inc., Carlsbad CA.            In January of 1997, a massive die-off of the heart urchin Meoma ventricosa was observed in Curacao, Netherlands Antilles. Necropsies of affected individuals were performed and compared with unaffected individuals. Comparative microbiological analysis revealed a unique bacterium associated with catch connective tissue in affected individuals. It was hypothesized that this may be the cause of spine loss in affected urchins. The bacterial isolate was used to inoculate a test urchin, Lytechinus variegates. Of ten urchins inoculated during two experiments, all died within five days of inoculation. None of the ten control inoculations produced any sign of disease. 16S rDNA analysis showed the bacterium to be closely related to Pseudoalteromonas haloplanktis subsp. tetraodonis. Monoclonal antibody testing revealed that the isolate produced tetrodotoxin. Host range studies performed in Bocas del Toro, Panama showed a number of urchins, as well as sea stars were susceptible to infection by the bacterium, and that a range of susceptibly patterns exist among echinoderms.