[Regulation of HTLV-1 gene expression and its relevance to proliferation of the infected cells].

Proliferation of HTLV-1 after infection is one of the crucial steps that affects development of adult T cell leukemia. In addition, one of the regulatory factors, tax protein, activates not only viral transcription from the LTR but also transcription of genes coding IL-2 and IL-2 receptor and eventually supposed to induce proliferation of infected T cells. However, expression of tax protein is regulated negatively by another viral regulatory factor, rex protein, in a novel fashion. The process of ATL development is discussed in relation to the regulation of viral gene expression.