Abstract
Ouabain markedly inhibited the growth of the mouse cell lines K3b and JLS-V9 and the production of murine leukaemia virus (MuLV) in them. The inhibition of MuLV production was abolished by exposing the cells to normal medium or by adding a high concentration (43 mM) of K+ ions to the ouabain-containing medium. MuLV production was reduced by ouabain more rapidly than host cell directed protein synthesis. After treatment of cells with ouabain (0.5 mM) for 7 h, extracellular reverse transcriptase activities were reduced by 87 to 92%. However, the intracellular level of polymerase activities remained almost unchanged (77 to 98% relative to the control). Mouse interferon inhibited the production of MuLV in K3b cells and this antiviral action was not blocked by 0.5 mM-ouabain.