TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Immunohistochemical Detection Of Target Antigens In The Skin Of The Channel Catfish, Ictalurus punctatus Joanne L.Maki1, C. C. Brown2 and H. W. Dickerson1 1Department of Medical Microbiology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602; 2Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 The parasitic ciliate, Ichthyophthirius multifiliis, infects many species of fresh water fish and is of economic importance to the aquaculture industry world-wide. Fish exposed to sublethal numbers of parasites develop resistance to subsequent infection. This non-sterile, protective immunity appears to be antibody mediated in that parasite-specific antibodies are present in the sera and surface mucus of immune fish. In this study, immunohistochemical techniques were used to detect parasite antigen in the skin of naïve and immune catfish in situ. Parasites were detected in the skin of naïve fish throughout infection (Day 1 to Day 10). Immune fish were infected for only a short time post-exposure (5 hr and 24 hr) and did not have detectable parasite antigen in their skin after 5 days. In a second study, immunoglobulin containing cells were identified in situ using a purified polyclonal antibody made against affinity purified catfish immunoglobulin. Positive staining cells were demonstrated within the epidermis. These reagents and procedures will facilitate future studies designed towards understanding how fish acquire protective mucosal surface immunity against I. multifiliis. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page