Effects Of Triclosan On The Oyster Parasite, Perkinsus Marinus And Its Host, The Eastern Oyster, Crassostrea Virginica

FLE Chu, Virginia Institute of Marine Science
ED Lund, Virginia Institute of Marine Science
JA Podbesek

Abstract

Because temperature plays an important role on progression and transmission of disease caused by Perkinsus marinus in the field. the effects of triclosan on the viability of P. marinus meronts (trophozoites) and oyster hemocytes were tested at a range of environmental relevant temperatures. Additionally, we examined the triclosan effect on reactive oxidative intermediate production (ROI) by oyster hemocytes and tested the efficacy of treating infected oysters with triclosan in eliminating/ reducing P. marinus infection in a pilot experiment. When P. marinus cultivated at 13 degrees C, 20 degrees C, and 28 degrees C was exposed to triclosan at corresponding temperatures, 2-10 mu m triclosan killed 10-30% at 20 degrees C and > = 40% at 28 degrees C, but < = 10% at 13 degrees C. When exposure of P. marimus cultivated at 28 degrees C to triclosan at 26 degrees C similar mortality was noted as those recorded at 28 degrees C. Treating hemocytes from oysters maintained at 13 degrees C, 20 degrees C, or 26 degrees C with 2, 5, 10 mu M triclosan at corresponding temperatures. killed 2% to 13% at 13 degrees C and 6 to 16% at 20 degrees C. No mortality occurred in hemocytes exposed to 2-10 mu M triclosan at 26 degrees C. However, at the highest temperature and triclosan concentration tested (28 degrees C, 10 mu M triclosan), hemocyte mortality exceed 30%. Exposure of hemocytes to triclosan concentrations of 2-10 mu M for 4h at 4 degrees C significantly reduced the ROI production in hemocytes in a dose-dependent response. Treating P. marimus infected oysters with 300 and 600 mu g triclosan/oyster daily for 8 wk, significantly slowed the disease progression.