Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis in small subsets of HTLV-1 carriers. HTLV-1-specific T-cell responses play critical roles in anti-viral and anti-tumor host defense during HTLV-1 infections. Some HTLV-1 carriers exhibit selective loss or anergy of HTLV-1-specific T-cells at an asymptomati...

Human T-lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia (ATL). In Japan, the number of HTLV-1 carriers is estimated to be 1.2 million and more than 700 cases of ATL have been diagnosed every year. Considering the poor prognosis and lack of curative therapy of ATL, it seems mandatory to establish an effective strategy for the treatment of ATL. In this study, we...

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis, and other inflammatory diseases. Despite such severe outcomes of HTLV-1 infection, the level of HTLV-1 expression in vivo is very low and rapidly increases after transfer of cells to culture conditions. The mechanisms of this phenomenon have remained obscure...

Human T-cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T-cell leukemia (ATL). This study examined the status of the oncogenic transcription factor AP-1 in leukemic cells freshly isolated from patients with ATL. Leukemic cells from peripheral blood of all patients with ATL exhibited constitutive AP-1 DNA binding activity, whereas mononuclear cells from normal individuals did...

The genome of human T-cell leukemia virus (HTLV) was surveyed in fresh tumor cells of 163 patients with lymphoma and leukemia from the southwest part of Japan where adult T-cell leukemia (ATL) is endemic. Leukemic cells of all 88 cases of ATL tested so far were found to contain the provirus genome and also found to be monoclonal with respect to the integration site of provirus genome. In most c...

Human T-lymphotropic virus type I (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 viral transactivator/oncoprotein, Tax, activates viral transcription and usurps regulatory mechanisms that are critical for cell growth and division to facilitate viral replication. The effects that Tax exerts...

    The study of tumor viruses paves the way for understanding the mechanisms of virus pathogenesis, including those involved in establishing infection and dissemination in the host tumor affecting immune-compromised patients. The processes ranging from viral infection to progressing malignancy are slow and usually insufficient for establishment of transformed cells that develop cancer in only ...

Human T-cell leukemia virus type 1 (HTLV-1) is causally associated with adult T-cell leukemia (ATL), an aggressive T-cell malignancy with a poor prognosis. To elucidate ATL pathogenesis in vivo, a variety of animal models have been established; however, the mechanisms driving this disorder remain poorly understood due to deficiencies in each of these animal models. Here, we report a novel HTLV-...

Human T-cell leukemia virus type 1 (HTLV-1)-associated adult T-cell leukemia and T-cell lymphoma (ATL) are aggressive diseases with poor prognoses, limited therapeutic options, and no curative treatment. In this study, we used a mouse model of ATL and restored expression of the microRNA, miR-124a, to identify in vivo downstream effectors responsible for its tumor-suppressive functions in ATL ce...

Human T‑cell leukemia virus type 1 (HTLV‑1), the first retrovirus to be identified, is the etiological agent of an aggressive clonal malignancy of mature CD4+ T lymphocytes known as adult T‑cell leukemia (ATL). The prognosis of ATL patients remains poor despite the availability of a number of clinical chemotherapy drugs. In addition, HTLV‑1‑infected and ATL cells possess an intrinsic resistance...