Drug targets in human T-lymphotropic virus type 1 (HTLV-1) infection

Human T-lymphotropic virus type 1 (HTLV-1), the first known human retrovirus, induces various human diseases with a long latency period. The mechanism by which the virus causes diseases is still unknown. Studies indicate that viral replication is important at least for the development of HTLV-1 associated myelopathy, and therefore treatments based on our knowledge of human immunodeficiency virus type-1 (HIV-1) can be utilized to develop potent antiretroviral therapies targeting the replication enzymes reverse transcriptase, protease and integrase as well as the envelope glycoproteins. Furthermore, accessory gene products such as Tax and HBZ may also provide targets for chemotherapy. Treatment targeting these viral proteins may prevent the development of other HTLV-1-related diseases including adult T-cell leukemia, although such treatment may not be useful during the progression of the disease. This review describes the characteristics of HTLV-1 replication enzymes, envelope glycoproteins, and accessory proteins Tax and HBZ, and discusses the status of drug development strategies.