We previously reported that inflammatory arthropathy resembling rheumatoid arthritis (RA) develops among transgenic mice carrying the long terminal repeat (LTR)-env-pX-LTR region of human T cell leukemia virus type I (LTR-pX-Tg mice). Because four genes are encoded in this region, we produced transgenic mice that only express the tax gene to examine its role in the development of arthritis. Tra...

Human T-cell leukemia virus type 1 (HTLV-1), an etiological agent of adult T-cell leukemia, immortalizes and transforms primary human T cells in vitro in both an interleukin (IL)-2-dependent and IL-2-independent manner. Expression of the HTLV-1 oncoprotein Tax transforms the growth of the mouse T-cell line CTLL-2 from being IL-2-dependent to IL-2-independent. Withdrawal of IL-2 from normal acti...

To understand the mechanism of p56lck protein downregulation observed in human T cells infected by human T-cell leukemia virus type 1 (HTLV-1), we have investigated the ability of the 3' end of the HTLV-1 genome as well as that of the tax and rex genes to modulate p56lck protein expression and p56lck mRNA synthesis. By using Jurkat T cells stably transfected with constructs that expressed eithe...

Patients with human T-cell leukemia virus type-l (HTLV-1)associated myelopathy (HAM/TSP) generally harbor a much greater population of HTLV-l-infected T cells in peripheral blood mononuclear cells (PBMCs) than asymptomatic carriers. These cells are not malignant but frequently proliferate clonally. To investigate the possibility that higher expression of the viral activator Tax induces preferen...

Interleukin 15 (IL-15) mRNA is expressed in a wide variety of tissue types. However, with the exception of some T cell lines, IL-15 transcript expression has not been described in T cells. Herein we demonstrate that IL-15 mRNA can be detected in freshly isolated normal T cells and T cell lines. Furthermore, its expression is 3- to 4-fold higher in human T cell lymphotropic virus type I (HTLV-I)...

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T cell leukemia (ATL), which is an aggressive form of T-cell malignancy. HTLV-1 oncoproteins, Tax and HBZ, play crucial roles in the immortalization of T-cells and/or leukemogenesis by dysregulating the cellular functions in the host. Recent studies show that HTLV-1-infected T-cells have reduced expression of the BCL1...

Although the p21X protein of human T cell leukaemia virus type 1 (HTLV-1) is generally thought to be expressed from a doubly spliced mRNA transcript (tax/rex mRNA) that encodes the p40tax, p27rex and p21X proteins, we have shown previously that a novel, alternatively spliced mRNA transcript (p21X mRNA) is responsible for p21X production in HTLV-1-infected cell lines. In the present study, we an...

IL-15Ralpha mRNA and protein levels are increased in human T cell lymphotropic virus type-I (HTLV-I)-associated adult T cell leukemia. Previously, we demonstrated that IL-15Ralpha expression was activated by HTLV-I Tax, in part, through the action of NF-kappaB. However, there appeared to be additional motifs within the IL-15Ralpha promoter that were responsive to HTLV-I Tax. In this study, we d...

Objective(s):HTLV-1 is the first human retrovirus that has been recognized and is associated with HAM/TSP and ATLL. Studies have shown that less than five percent of HTLV-1 infected carriers develop HAM/TSP or ATLL and about ninety-five percent remain asymptomatic. Therefore, the proviral load with Tax may affect cellular genes such as cytokines and oncogenes, as well as involve in pathogenicit...