Gary R. Carlson, MD, College of Veterinary Medicine

Two new cell lines developed from chinook salmon with plasmacytoid leukaemia have been found to be producing a virus. The virus has been identified as a retrovirus based on: type of c.p.e. induced in culture; morphology and density of the particle; presence of Mn(2+)-dependent, poly(rA)-directed reverse transcriptase activity which was associated with a density of 1.16 to 1.18 g/ml in sucrose; electrophoretic pattern of the polypeptides from purified virions; elevated [3H]UTP labelling of RNA in the cell cultures occurring at a density of 1.16 to 1.18 g/ml in sucrose. This report describes the first isolation of a retrovirus from a salmonid cell line.