Masao Matsuoka, MD, Ph.D. Professor?? Human T-Cell Leukemia Virus type 1 (HTLV-1), and human immunodeficiency Virus (HIV) Are Two major human retroviruses. HTLV-1 Induces clonal Proliferation of Infected CD4 + T cells. After a long latent period, HTLV-1 causes adult T-cell leukemia (ATL) and inflammatory diseases in a part of carriers. On the other hand, HIV destroys CD4 + T-cells, and ruins the immune system of infected individuals, resulting in the onset of acquired immunodeficiency syndrome (AIDS). In our laboratory, we pursue the molecular mechanisms of caner, virus induced diseases through research of these human.