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-γ or sensitivity to IFN. Poor induction of 2-5AS was found in IFN-γ 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-γ such as HUT102 and OKM-2, significant activity of 2-5AS was induced by treatment with IFN-α. 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-1α 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.