Lack of hemocyte chemiluminescence stimulation by Perkinsus marinas in eastern oysters Crassostrea virginica with dermo disease

Phagocytosis of zymosan A particles by hemocytes of eastern oyster Crassost rea virginica stimulates the production of reactive oxygen species (ROS), w hich are easily quantified by luminol-augmented chemiluminescence (CL). Ant imicrobial defense mechanisms of hemocytes may involve the activity of cyto toxic ROS. The CL response to phagocytosis of zymosar. by hemocytes from C. virginica with advanced Perkinsus marinus infections is more elevated than that produced by zymosan in cells from uninfected oysters. This effect is perhaps akin to macrophage activation. Phagocytosis of P. marinus cells by hemocytes withdrawn from uninfected oysters produced no detectable CL respo nse. Hemocytes withdrawn from oysters with P marinus infections ranging fro m light to heavy were evaluated for CL responses after phagocytosis of zymo san or P. marinus. Increases in CL stimulation by zymosan were seen as the intensity of infection increased. Despite avid phagocytosis of P. marinus, CL activity of the hemocytes was not seen, regardless of the level of infec tion of the host. Lack of hemocytic ROS stimulation by ingestion of P. mari nus cells may contribute to in vivo survival of this parasite.