DAO 57:109-116 (2003)  -  doi:10.3354/dao057109

ABSTRACT: Vibrio tapetis is the causative agent of brown ring disease (BRD), which affects a species of clam, Ruditapes philippinarum. After incubation with V. tapetis, hemocytes lose filopods and become rounded, indicating cytotoxic activity of the bacterium. To rapidly quantify this cytotoxicity, a flow-cytometry test was developed based on the capacity of V. tapetis to inhibit adhesion of clam hemocytes to plastic. Several bacteria:hemocyte ratios, the cytotoxicity of other Vibrio spp. pathogenic to bivalves, and that of various V. tapetis isolates were tested. Inhibition of adherence is detectable with as few as 5 bacteria per hemocyte. The greater cytotoxic activity of V. tapetis compared to that of V. splendidus and V. pectenicida suggests a specific pathogenicity of V. tapetis to R. philippinarum hemocytes. Although all V. tapetis isolates inhibited adhesion, significant variations in cytotoxicity among isolates was demonstrated.

KEY WORDS: Cytotoxicity · Flow cytometry · Vibrio tapetis · Ruditapes philippinarum · Bivalve hemocytes · Pathogenicity