Evidence for an oncovirus in swimbladder fibrosarcoma of Atlantic salmon Salmo salar L.

Abstract

several cases of swimbladder neoplasia were found in pen-reared Atlantic salmon i^almo salar L. on a commercial marine fish farm in Scotland, in the summer and autumn of 1976. A histological examination showed the condition to be a fibrosarcoma (McKnight, 1978). The multiple incidence of tumours prompted an electron microscopic survey, in an attempt to discover if the condition had been caused by an infectious agent; this communication reports preliminary evidence in support of such an aetiology.Suspect fish were brought back alive to the laboratory, where they were killed and tbeir swimbladders removed. Pieces of tissue were fixed with 2-5% phosphatebuffered glutaraldehyde, postfixed with 1% buffered osmic acid, then alcoholdehydrated and embedded in Epon 812 epoxy resin. Sections were cut on an LKB Ultrotome III, then stained with a saturated solution of uranyl acetate in methanol, followed by alkaline lead citrate (Reynolds 1963), and examined in a Siemens Elmiskop 1 electron microscope.

Spontaneously productive C-type retrovirus infection of fish cell lines

“…Similar viruses have not hitherto been reported in fish cell cultures, but C-type particles have been observed in lesions from epidermal hyperplasia of northern pike (Esox lucius) (Winqvist et al, 1968;Yamamoto et al, 1983), epidermal hyperplasia and dermal sarcoma of walleye perch (Stizostedion vitreum) (Walker, 1969;Yamamoto et al, 1985), swimbladder fibrosarcoma of Atlantic salmon (Salmo salar) (Duncan, 1978) and fin papillomatosis of European smelt (Osmerus eperlanus) (Anders, 1989). C-type particles and reverse transcriptase activity associated with 1.15 to 1.16 g/ml sucrose gradient fractions have also been identified in tissue from northern pike lymphosarcoma (Papas et al, 1976) and white sucker (Catostomus commersoni) papillomatosis (Sonstegard, 1977).…”

Further evidence for a viral etiology in plasmacytoid leukemia of Chinook salmon Oncorhynchus tshawytscha

“…Our experiments also indicate that 1979, Gross 1983), dermal sarcoma of walleye Renibacterium salmoninarum and Enterocytozoon salStizostedion vitreum (Martineau et al 1990), and neumonis are not the cause of the disease. This concurs rofibromatosis of damsel fish Pomacentrus partitus Retroviruses have been associated with these lesions and other neoplasms of fishes (Papas et al 1976, Duncan 1978, Yamamoto et al 1985, Martineau et al 1990, Anders et al 1991. Retroviruses, including those that cause leukemias, are well recognized causes of immunosuppression.…”

A New Virus Isolated from Salmonid Fish.

“…The virion density is between 1.16 and 1.18 g/ml in sucrose, and they have RT activity (White and Fenner, 1986;Doane and Andersen, 1987;Coffin, 1990). Recently some retroviruses have been reported to induce proliferative consitions in salmonid fish (Duncan, 1978;McKnight, 1978;Kent et al, 1990). Eaton and Kent (1992) reported a retrovirus infection in chinook salmon with plas macytoid leukemia (PL).…”