Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

11-1992

Journal

Biological Bulletin

Volume

183

Issue

3

First Page

476

Last Page

481

Abstract

Perkinsus marinus is a protozoan parasite responsible for a major infectious disease of the Eastern oyster, Crassostrea virginica. Nonspecific immunity was assayed in oysters with known intensities of infection so that the physiological responses of the host elicited by the parasite could be better understood. This report describes the capacity of hemocytes to generate reactive oxygen intermediates during the progression of the disease. The hemocytes constitute the major internal defense effector system of oysters, and cytotoxic oxygen species are thought to play central roles in antimicrobial activities of hemocytes and other phagocytic cells. Production of oxyradicals by both resting and phagocytically stimulated hemocytes was quantified by luminol-augmented chemiluminescence. Hemocytes from oysters with heavy Perkinsus infections produced significantly higher levels of chemiluminescence than their counterparts withdrawn from lightly or moderately infected individuals. Furthermore, in addition to a higher chemiluminescent activity per cell, the total circulating hemocyte count was elevated in the heavily infected animals. Therefore, advanced cases of this disease seem to be characterized by hemocyte activation and recruitment, with concomitant exuberant production of hemocyte-derived reactive oxygen intermediates. The resultant oxidant load may participate in the pathogenesis of the disease.

DOI

10.2307/1542024

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