HTLV-II and human lymphoproliferative disorders.

HTLV-II is a rarely encountered human retrovirus that has been linked to atypical presentations of hairy-cell leukemia, as well as a variety of T-cell malignancies. Recently, HTLV-II prevalence has increased in the United States, particularly in populations of intravenous drug abusers. Comparative study of HTLV-I and HTLV-II has allowed for important insights into the mechanisms of retroviral replication and T-cell transformation.