TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Transforming Growth Factor-beta In Teleost Fish: Quantitative PCR Applied To A Field Study Of Fish Health Craig Harms,1 Chris Ottinger,2 Christine Densmore,2 Vicki Blazer,2 Suzanne Kennedy-Stoskopf1 1Department of Microbiology, Pathology and Parasitology, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough St., Raleigh, NC 27606; 2U.S. Geological Survey/BRD, National Fish Health Research Laboratory, 1700 Leetown Road, Kearneysville, WV 25430 Transforming growth factor (TGF)-b is a cytokine with diverse functions affecting immune function. Increased levels of TGF-b have been found in several disease states associated with immunosuppression in mammals. The ability to measure differences in TGF-b production in fish could provide a valuable tool for evaluating the impact of environmental contaminants and infectious agents on fish immunity. A TGF-b was isolated and cloned from hybrid striped bass (Morone saxatilis x M. chrysops). Consensus primers were designed which specifically amplify by polymerase chain reaction (PCR) a TGF-b segment from at least 11 species of teleost fish comprising 8 taxonomic families in 5 orders. A quantitative PCR (RT-qcPCR) assay was devised to measure TGF-b mRNA expression in teleost fish. During summer of 1998, the RT-qcPCR assay for TGF-b was incorporated into a larger study of fish health from 4 tributaries of Chesapeake Bay. White perch (Morone americana) were sampled from the Pocomoke, Wicomico, Choptank and Back Rivers in June, August and October. Splenic mononuclear cell TGF-b transcription levels were initially highest in perch from the Back River, which flows through an industrial area of Baltimore, than from the 3 eastern shore rivers. However, levels from Back River fish remained steady throughout the sampling period, while significant increases to values greater than those from the Back River were noted from the other 3 rivers in August and October, coincident with the appearance of cutaneous ulcerative lesions in menhaden (Brevoortia tyrannus) from those waters. Anterior kidney macrophage bacteriocidal activity declined on a population basis inversely to the rise in TGF-b expression. While elevated TGF-b expression and depressed macrophage bacteriocidal activity did not correlate on an individual fish basis, these findings together suggest seasonal immune system modulation of white perch from Chesapeake Bay eastern shore tributaries. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page