Suppressed Induction of 2‐5AS in Cells with HTLV‐I Is Not Associated with the Fluctuation of IFN‐Receptor, IFN‐Regulatory Factors (IRF‐1 and IRF‐2) or STAT‐1α

Some viruses seem to be capable of suppressing interferon (IFN)-induced 2',5'-oligoadenylate synthetase (2-5AS) induction. Cells infected with human T-lymphotropic virus type-I (HTLV-I) show different natures for the constitutive production of IFN-gamma or sensitivity to IFN. Poor induction of 2-5AS was found in IFN-gamma producer cells carrying HTLV-I (MT-1, MT-2 and SMT-1). On the other hand, in non- or low-producing cell lines of IFN-gamma such as HUT102 and OKM-2, significant activity of 2-5AS was induced by treatment with IFN-alpha. A satisfactory level of IFN receptor was detectable in SMT-1 cells in spite of the poor induction of 2-5AS. There were no differences in either the interferon regulatory factor-2 (IRF-2) mRNA transcript or the level of STAT-1 alpha between SMT-1 and HUT102 cells. However, the transcription of IRF-1 mRNA was slightly reduced in SMT-1 cells as compared with that of HUT102 cells.