TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Swim Bladder Sarcoma In Atlantic Salmon: Epizootiology And Current State Of Knowledge Paul R.Bowser1, J.W.Casey1, S.L.Quackenbush1, R.N.Casey1, J.A.Coll2, L.Lofton3, H.M.Opitz4, D. Bouchard5, and R.C.Cipriano6 1Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401; 2Northeast Fisheries Center, USFWS, Lamar, PA 16848; 3USFWS, North Attleboro, MA 02760; 4Maine Cooperative Extension, University of Maine, Orono, ME 0469; 5Micro Technologies, Inc., Richmond, ME 04357; 6 USGS/BRD, National Fish Health Research Laboratory, 1700 Leetown Road, Kearneysville, WV 25430. Swim Bladder Sarcoma was diagnosed in adult Atlantic salmon (Salmo salar) held in a quarantine facility at the North Attleboro National Fish Hatchery (NANFH), MA. The fish had been collected as 1+ and 2+ year-old fish from the Pleasant River, ME, and were to be used as brood fish in a fish population augmentation program for that river. Signs of disease were observed at the NANFH in older (4+ yr-old) fish first, followed by 3+ yr-old fish. Disease was not observed in 2+ yr-old fish. The mortality pattern was chronic in nature. PCR cloning and gene-sequencing techniques were used to identify the presence of a retrovirus in the tumor. Preliminary analysis of the virus genome indicated that, within the Family Retroviridae, the Salmon Swim Bladder Sarcoma virus (SSSV) is distinct from the other known fish retroviruses : Walleye Dermal Sarcoma Virus (WDSV), Walleye Discrete Epidermal Hyperplasia Virus-1 and -2 (WEH1, WEH2), and Perch Epidermal Hyperplasia Virus (PEHV). A PCR diagnostic test was developed to detect proviral DNA (POL region) of SSSV in blood samples. In addition to fish held at NANFH, a separate group of Pleasant River Atlantic salmon were being held for the USFWS at a quarantine facility at a private hatchery in Maine. In November, 1998, 10 NANFH Atlantic salmon were examined. Five fish were considered moribund (external hemorrhage, white skin patches) while the other five fish were considered "normal." PCR testing identified 3/5 moribund fish as positive for proviral DNA while 0/5 of the normal fish were positive. December, 1998, sampling of NANFH included the identification of virus-positive fish for use in further studies following transport to quarantine facilities at the National Fish Health Research Laboratory. An attempt was made to select and bleed 40 fish that showed early signs of disease. These fish were identified by numbered jaw tags. PCR testing indicated that 24/40 fish in this group were PCR-positive for proviral DNA. All of the remaining Pleasant River Atlantic Salmon at NANFH were bled (for later testing) and euthanized. None of these untagged fish showed any signs of disease. The quarantine facility in which the fish were held was then disinfected. At the private hatchery, 36/76 fish were bled for testing; PCR testing indicated that 2/36 fish were PCR-positive for proviral DNA. No tumors were observed upon gross examination of these fish (n=76) during necropsy. No swim bladder sarcomas have been reported in any other population of Atlantic salmon in either public or private facilities in the region. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page