Experimental Reproduction of a Disease Causing Mass Mortality of Japanese Pearl Oyster Pinctada fucata martensii by Injection of Diseased Oyster Hemolymph

Abstract

To elucidate the causative agent of the mass mortality of cultured pearl oyster Pinctada fucata martensii, with a reddish brown adductor muscle and histopathological changes in the loose connective tissue, experimental challenges on healthy oysters were undertaken using hemolymph from diseased oysters as an inoculum under a feeding or a non-feeding condition. The oysters inoculated with the supernatant, the precipitated hemocytes or the filtrate of the diseased oyster hemolymph died within 2 to 3 months, showing signs similar to those of spontaneously affected oysters. These results indicate that a filterable agent in both the supernatant and the pellet of hemolymph of diseased oysters causes the disease.