Induction of unique mRNAs by human interferons.

Treatment of human fibroblast cells with human interferon (INF-alpha, IFN-beta, or IFN-gamma) resulted in the accumulation of at least four newly synthesized mRNAs. The mRNAs code for proteins having molecular weights of 56,000, 57,000, 62,000, and 68,000 when characterized in a wheat germ cell-free translation system. A direct relationship was observed between the amount of IFN used and the degree of both the accumulation of the induced mRNAs and the development of an antiviral state. In the case of IFN-alpha or IFN-beta, time course studies indicated that the induced mRNAs appeared as early as 40 min, accumulated for 2 h, then remained ribosome bound for up to 16 h. The ability of fibroblast cells to develop an antiviral state always coincided directly with both the appearance and the level of accumulation of the induced mRNAs. Further mRNA synthesis beyond 2 h had a minimal effect on the development of an antiviral state. Human IFN-gamma also induced the synthesis of the same four mRNAs but required higher interferon titers and a longer incubation time. In addition, IFN-gamma induced a disproportionate amount of the mRNA coding for the 68,000 molecular weight protein and three new mRNAs not detected in cells treated with IFN-alpha or IFN-beta. Mouse interferon induces the original four mRNAs in human cells but to a far lesser extent. This correlated with the inability of these cells to develop much resistance to viral infection.