Human T-Cell Lymphotropic Virus Types 1 and 2

Human T-cell lymphotropic virus type 1 (HTLV-1) was the first pathogenic human retrovirus to be discovered. It was isolated in 1979 from the peripheral blood lymphocytes of a patient with adult T-cell leukemia/lymphoma (ATLL) (1). Following years of research to find a retroviral agent involved in ATLL, Yoshida and Yamamato isolated a retrovirus from an ATLL patient in 1986 that they named adult T-cell leukemia virus. Soon, the similarities between HTLV-1 and adult T-cell leukemia virus were confirmed, and the name HTLV-1 was chosen. Shortly thereafter, the closely related virus HTLV-2 was isolated from the splenic cells of an individual with hairy cell T-cell leukemia (2).