Altered response of oyster hemocytes to Haplosporidium nelsoni (MSX) plasmodia treated with enzymes or metabolic inhibitors

To avoid phagocytosis, parasites may mask themselves with host-like molecules that prevent recognition as nonself or they may produce substances that interfere with host cellular defenses. The protozoan parasite Haplosporidium nelsoni, which causes MSX disease in the eastern oyster Crassostrea virgi...

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Bibliographic Details
Published in:Journal of invertebrate pathology 1998-09, Vol.72 (2), p.160-166
Main Authors: FORD, S. E, ASHTON-ALCOX, K. A
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
carbohydrase
Crassostrea virginica
Enzyme Inhibitors
Eukaryota - immunology
Fundamental and applied biological sciences. Psychology
Haplosporidium nelsoni
Hemocytes - immunology
Hemocytes - parasitology
Hydrolases
Invertebrates
Iodoacetates
Mollusca
MSX disease
Ostreidae - immunology
Pathology
Phagocytosis - immunology
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Summary:To avoid phagocytosis, parasites may mask themselves with host-like molecules that prevent recognition as nonself or they may produce substances that interfere with host cellular defenses. The protozoan parasite Haplosporidium nelsoni, which causes MSX disease in the eastern oyster Crassostrea virginica, is not ingested by host hemocytes. To assess potential avoidance mechanisms, oyster hemocytes were incubated with plasmodial stages of the parasite that had been pretreated with one of a variety of enzymes (proteases and carbohydrases) to alter surface molecules or with metabolic inhibitors to prevent the synthesis or active uptake of "masking" molecules, as well as the production and discharge of inhibitory substances. The maximum increase in phagocytosis resulting from treatment with carbohydrases was 12.5% (beta-galactosidase) and with proteases was 18% (Proteinase K). Inhibitors of aerobic metabolism resulted in a similar level of enhancement. In contrast, treatment of parasites with the glycolysis inhibitor iodoacetate enhanced phagocytosis by up to 66%. Thus, the process that obstructs phagocytosis involves aerobic and, especially, anaerobic pathways. The greater effect of a metabolic inhibitor compared to enzymes suggests that the mechanism involves more than just surface modification and may include the production of interference molecules.
ISSN:0022-2011
1096-0805
DOI:10.1006/jipa.1998.4775