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MODULATION OF EASTERN OYSTER HEMOCYTE ACTIVITIES BY PERKINSUS MARINUS EXTRACELLULAR PROTEINS
Citation:
La Peyre, J. F. AND A. K. Volety. MODULATION OF EASTERN OYSTER HEMOCYTE ACTIVITIES BY PERKINSUS MARINUS EXTRACELLULAR PROTEINS. Presented at 91st Annual Meeting of the National Shellfisheries Association, Halifax, Nova Scotia, April 18-22, 1999.
Description:
The oyster pathogen Perkinsus marinusproduces many extracellular proteins (ECP) in vitro. Analysis of this ECP revealed a battery of hydrolytic enzymes. Some of these enzymes are known to modulate the activity of host defense cells. Although information on the effects of P. marinusECP on oyster hemocytes is limited, it has been shown that ECP can inhibit hemocyte motility and hemocyte chemiluminescence response. Moreover, ECP effects on Gulf coast oyster hemocytes are of special concern since these oysters harbor human pathogens such as Vibrio vulnificusand Vibrio parahaemolyticus. Perkinsus marinus infections may thus be associated with higher numbers of Vibriobacteria in oyster tissues. The objective of this initial study was to better characterize the effects of P. marinusECP on oyster hemocyte activities in vitro. Increasing concentrations of ECP caused increase degranulation and vacuolization of granulocytes (granular hemocytes). The normal spreading of the granulocytes and large hyalinocytes (agranular hemocytes) was also reduced and hemocyte clumping was increased. Phagocytosis of zymosan particles was significantly decreased at the highest concentration of ECP tested. More important, the capacity of hemocytes to kill Vibrio parahaemolyticuswas decreased in a dose dependent manner within 30 min of exposure to ECP. P. marinuscan clearly be detrimental to oyster hemocytes in vitro. The potential effect of ECP on oyster hemocytes in vivoand the possible relationship between P. marinusinfection intensities and oyster tissue Vibrioload in Gulf coast oysters remain to be investigated.