Nucleotide sequence analysis of a full‐length human T‐cell leukemia virus type I from adult T‐cell leukemia cells: A prematurely terminated PX open reading frame II

Abstract
Human T‐cell leukemia virus type 1 (HTLV‐I) is etiologically associated with adult T‐cell leukemia/lymphoma (ATL). The prototypic HTLV‐I, ATK, is the only full‐length provirus cloned from uncultured leukemic cells and completely sequenced prior to this study. We have determined the complete nucleotide sequence of another full‐length HTLV‐I provirus cloned directly from leukemic cells. A premature termination codon was found in the second open reading frame (orf II) of the pX region. Our finding indicates that open reading frame II of the HTLV‐I pX region is not required for outgrowth of ATL leukemic clones in vivo.