Interferon induction in mouse fibroblast L-A9 cells

Mouse L-A9 cell interferon was induced by infection with Newcastle disease virus. Interferon production was 1.5 X 10(5) IU/10(7) cells. Interferon was partially purified by precipitation with ammonium sulphate, chromatography on CM-Sephadex and hydrophobic chromatography on octyl-agarose. The specific activity of the final preparation was 1.7 X 10(7) IU/mg protein. Treatment of L-A9 cells with 20 IU/ml interferon prior to viral infection inhibited the intracellular accumulation of reovirus-specific double-stranded RNA. Dose-response studies of the cells to interferon indicated that L-A9 cells require 10, 13 and 15 IU/ml to obtain 50% viral plaque reduction for Marituba virus, vesicular stomatitis virus and reovirus, respectively. The present results demonstrate the potential of mouse L-A9 cells as an interferon-producing system and also as a model for the study of the effect of cellular response to exogenous interferon treatment on the replication of RNA viruses.