Spontaneously productive C-type retrovirus infection of fish cell lines.

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(2+)-dependent reverse transcriptase activity at 24 degrees C. Peak enzyme activity was associated with a 1 x 16 g/ml sucrose gradient fraction. All four isolates induced a cytolytic infection of a bluegill fry cell line within 6 to 10 days.