| Flavobacterium columnare and Edwardsiella ictaluri are the leading causes for losses in the aquaculture industry. The losses from the diseases caused by these pathogens total {dollar}2.5 million for catfish and {dollar}100 million for total aquaculture. F. columnare's infection rates and stressors associated with outbreaks have been well-characterized, but the specific inflammatory responses of catfish neutrophils to the bacteria have not been studied. The objective, therefore, was to investigate the pro-inflammatory effects of the outer membrane proteins, extracellular products, and whole live bacteria, heat-killed (HK), and formalin-killed (FK) F. columnare and E. ictaluri to determine the effects on channel catfish phagocyte physiology. Phorbol myristate acetate-stimulated hydrogen peroxide production, inducible nitric oxide production, and phagocytosis of yeast particles, and the expression of CYP1A and lysozyme protein were measured in phagocytes after exposure to F. columnare and E. ictaluri bacteria or product. F. columnare-treated cells did not produce hydrogen peroxide or nitric oxide, nor was phagocytosis affected. E. ictaluri increased hydrogen peroxide production, nitric oxide production, and enhanced phagocytosis in phagocytes when given as ECPs, OMPs, HK bacteria, and FK bacteria. Both OMPs increased lysozyme protein expression, and ECPs and OMPs of both bacteria suppressed CYP1A expression. |
