Naoko Miyano-Kurosaki

Long-term, high dose interferon-alpha treatment in HTLV-I-associated myelopathy/tropical spastic paraparesis: a combined clinical, virological and immunological study.

The efficacy of long-term, high dose interferon-alpha (IFN-alpha) therapy was studied in seven patients with HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). IFN-alpha was administered at a dose of 6 x 10(6) international units daily for the initial 2 weeks and thereafter 3 times a week for the following 22 weeks. Five patients showed a sustained improvement in motor performance during and up to 6 months after the completion of IFN-alpha. The other patient who responded to IFN-alpha initially dropped out at 3 months because of depression, while another patient first deteriorated and thereafter dropped out. In the six responders, the absolute number of peripheral blood lymphocytes (PBL) harboring the HTLV-I genome as evaluated by the quantitative polymerase chain reaction method decreased significantly during the therapy period (28.6 +/- 16.6% reduction, P = 0.0083), whereas the one deteriorated patient showed a 2.5-fold increase in HTLV-I-infected cells. The autoproliferation of CD4+ T clone cells from a single cell culture was markedly depressed even after the cessation of IFN-alpha in the responders who completed long-term IFN-alpha therapy. In addition, the CD8+DR+ T cells in the peripheral blood and soluble IL-2 receptor levels in the sera increased significantly during the therapy in all patients (P = 0.0431 and P = 0.0041, respectively). Therefore, the results of our study suggested that both the reduction of HTLV-I proviral DNA load and immunomodulation by long-term IFN-alpha therapy contributed to its sustained clinical benefits.

Inhibition of HTLV-I Induction and Virus-Induced Syncytia Formation by Oligodeoxynucleotides

HTLV-I is an exogenous human retrovirus that is a causative agent of adult T cell leukemia (ATL). In addition to the structural genes (gag, pol and env), a gene termed pX is postulated to be associated with leukemogenesis in ATL. Since no effective chemotherapy is currently available, it is important to find suitable therapeutic means against ATL. Here, we tested the inhibitory effect of antisense oligodeoxynucleotides (ODNs) on HTLV-I infection in different systems. ODNs were synthesized with the phosphorothioate backbone targeted to either structural genes or transactivator genes. The phosphorothioate ODNs were found to have two distinct target sites to exert their effect on HTLV-I infection: 1) Several ODNs, including sense ODNs and random oligomers, blocked syncytium formation induced by HTLV-I at a concentration of 0.1 μM. Their inhibitory effect on syncytium formation seemed to be exerted in a nonantisense manner, most probably due to their interaction with the cell membrane. 2) Efficient suppression by ODNs of gag gene expression after chemical induction was observed in HTLV-I-transformed T cells in an antisense manner. In this suppression, tax-antisense ODN showed virtually complete inhibition of gag protein expression, but not RNA expression, at the concentration of 0.1 μM, whereas tax-sense ODN displayed a weak inhibitory effect. Our results suggest that the influence of the phosphorothioate compound should be considered from the aspect of two separated mechanisms of antiviral activity, the effects on early (viral adsorption) and late (translation) phase infection.

A novel assay system for anti-human immunodeficiency virus type 1 (HIV-1) activity using a subclone of a monocytic cell line, U937

A subclonal cl.1–14 cell was established from a monocytic cell line U937 by a limiting dilution method. The anti‐HIV‐1 activity of some antiviral compounds was evaluated in HIV‐1‐infected cl.1–14 cells. The results demonstrated that although AZT was a potent inhibitor of HIV‐1 replication in cl.1–14 cells, its 50% effective concentration (EC50) values was 80 times higher than that in HIV‐1 infected MT‐4 cells; the EC50 of AZT was 0.16 μM and 0.002 μM in cl.1–14 and MT‐4 cells, respectively. In contrast, the anti‐HIV‐1 activity of ddA, ddI and ddC in cl.1–14 cells was comparable to that in MT‐4 cells. The antiviral activity of nevirapine, dextran sulfate, curdlan sulfate and T22 did not differ significantly between the cl. 1–14 and MT‐4 cells. The antiviral activity of several compounds in the HIV‐1‐infected cl.1–14 cells was similar to that in the HIV‐1jr‐fl‐infected human peripheral macrophages. Our results suggest that cl.1–14 cell cultures are very useful for estimating antiviral activity and more advantageous than the use of peripheral blood macrophages.