Virological and immunological mechanisms in the pathogenesis of human T-cell leukemia virus type 1.

Human T-cell leukemia virus type 1 (HTLV-1) was the first retrovirus shown to cause human disease, such as adult T-cell leukemia and HTLV-1 associated myelopathy/tropic spastic paraparesis. HTLV-1 mainly infects CD4 T cells and deregulates their differentiation, function and homeostasis, which should contribute to the pathogenesis of HTLV-1, for example, inducing transformation of infected CD4 T cells and chronic inflammatory diseases. Therefore, not only virological approach but also immunological approach regarding CD4 T cells are required to understand how HTLV-1 causes related human diseases. This review focuses on recent advances in our understanding of the interaction between HTLV-1 and the main host cell, CD4 T cells, which should provide us some clue to the mechanisms of HTLV-1 mediated pathogenesis.