Oligo‐2′,5′‐Adenylate Synthetase Activity in Cells Persistently Infected with Human T‐Lymphotropic Virus Type I (HTLV‐I)

Abstract

Spontaneous production of interferon-gamma (IFN-gamma) was shown in several T-lymphoblastoid cell lines persistently infected with human T-lymphotropic virus (HTLV-1). However, the produced IFN-gamma was not always associated with the induction of the antivirus state. The induction of oligo-2',5'-adenylate synthetase (2-5AS) by IFN was studied in five human T-cell lines persistently infected with HTLV-I (MT-1, MT-2, SMT-1, HUT 102 and OKM-2). Four cell lines are able to produce IFN-gamma spontaneously, while the OKM-2 cell line is not. Poor induction of 2-5AS was recognized in three (MT-1, MT-2 and SMT-1) of the four cell lines producing IFN-gamma, though the poor induction was improved after long-term cultivation of cells with IFN-alpha. On the contrary, in the OKM-2 cell line, significant activity of the enzyme was induced by IFN-alpha. Induction of 2-5AS was not correlated with cell growth inhibition, but with the antivirus state. Furthermore, an inverse relationship between IFN-gamma production and 2-5AS induction was demonstrated in these cell lines with the exception of HUT 102 cells.

The 2–5 A system: Modulation of viral and cellular processes through acceleration of RNA degradation

“…Other investigators have not found a correlation between growth inhibition and 2-5A system activity. Induction of 2-5A synthetase in human immunodeficiency virus (HIV)-infected T-cells was not correlated with growth inhibition, but was correlated with the antiviral state (Fujii et al, 1992). Although IFN-p resulted in a large increase in human prostatic JCA-1 cell 2-5A synthetase activity, neither increased p68 dsRNA-dependent protein kinase (PKR) levels nor RNase L activation could be demonstrated (Nakajima et al, 1994).…”

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

“…The failure of 2-5AS induction has been demonstrated in cells persistently infected with HTLV-I (MT-1, MT-2 and SMT-1), which exhibits the constitutive production of IFN-y. Among cells infected with HTLV-I, the non-or low-producing IFN-y (HUT102 and OKM-2) showed the normal induction of 2-5AS (6). An inverse relationship between IFNy production and 2-5AS induction was found in the cell lines infected with HTLV-I.…”

Imiquimod Suppresses Propagation of Herpes Simplex Virus 1 by Upregulation of Cystatin A via the Adenosine Receptor A1Pathway

“…The quantitative nature of the PCR was validated by the linearity of the determination curve at various concentrations of RNA. In accordance with previous papers, the primer sets used were as follows: cystatin A (37), cystatin C (40); TLRs 1,5,6,7,8,9, and 10 (13); TLR2, TLR4, and glyceraldehyde-3=-phosphate dehydrogenase (GAPDH) (33); and TLR3 (28). Primer sets for adenosine receptors A 1 , A 2A , A 2B , and A 3 were as described by Schön et al (31), except for the reverse primer of A 2A (5=-CTGCTTCAGCTGTCGTCGC G-3=).…”

“…FL cells were seeded at 10 5 cells/ml in a 6-cm dish and cultured for 24 h. For analyses of the effects of imiquimod on the cell viability and virus replication, the cells were cultured in a medium containing imiquimod for 12 or 24 h before virus infection. The cells were then inoculated with HSV-1 at a multiplicity of infection (MOI) of 0.1 or 1, incubated for 1 h for absorption, and then cultured for a further 24 h. Virus titers in the supernatants were determined by plaque assay using Vero cells as described previously (8). Cell viability was determined with a modified 3-(4,5-dimethylthoazol-2-yl)-2,5-diphenyltetrazolium bromide assay using Cell Counting Kit 8 (Dojin Chemical, Kumamoto, Japan).…”