First Isolation of Vibrio tapetis, the Etiological Agent of Brown Ring Disease (BRD), in Manila Clam Ruditapes philippinarum in Japan

Abstract

Mass mortality occurred in Manila clam Ruditapes philippinarum under a hanging cultivation condition from April to July 2008 in Japan. A bacterium was isolated from the affected clams showing brown conchiolin deposits on the inner shell surface and identified as Vibrio tapetis, the causal agent of brown ring disease (BRD) in clams, by bacteriological characterization and genetic analysis. Experimental infection of clams confirmed pathogenicity of the isolated bacterium. These results indicate that the present mortality of cultured clams was caused by BRD. This is the first report on isolation of V. tapetis from diseased R. philippinarum in Japan.