The spontaneous production and release of morphologically typical, 85 to 90 nm diameter C-type retrovirus particles from four cell lines derived from three species of warmwater fish have been identified. Virus pellets from cell culture supernatants showed high levels of Mn<sup>2+</sup>-dependent reverse transcriptase activity at 24 °C. Peak enzyme activity was associated with a 1-16 g/ml sucrose gradient fraction. All four isolates induced a cytolytic infection of a bluegill fry cell line within 6 to 10 days.
Ferichs, G.N.; Morgan, D.; Skerrow, C.; Roberts, R.J.; Onions, D.E. Spontaneously productive C-type retrovirus infection of fish cell lines. Journal of General Virology (1991) 72: 2537-2539.