Modulation of Crassostrea virginica hemocyte reactive oxygen species production by Listonella anguillarum.

Luminol- and lucigenin-augmented chemiluminescence (CL) were used to evaluate the ability of Listonella (formerly Vibrio) anguillarum to stimulate the production of reactive oxygen species (ROS) by Crassostrea virginica hemocytes. Whereas heat-killed L. anguillarum stimulated hemocyte CL in the lucigenin system, viable L. anguillarum did not. Neither viable nor heat-killed bacteria stimulated hemocyte production of luminol CL. Metabolically active L. anguillarum generated ROS, as indicated by luminol and lucigenin CL. It is proposed that bacterial catalase suppressed hemocyte-derived luminol CL. L. anguillarum, which possesses the antioxidant enzyme catalase, suppressed luminol CL generated by zymosan-stimulated hemocytes. Conversely, the catalase negative bacterium Carnobacterium piscicola had no effect on hemocyte-derived luminol CL elicited by zymosan. The inability of viable L. anguillarum to stimulate hemocyte ROS production, as measured by CL, does not support the proposed role for ROS in hemocyte-mediated bactericidal activity.