Human T-Lymphocyte Virus (HTLV)-1 Envelope contains the C- terminus of gp46 and most of p21E of HTLV-I. This non-fusion, E. coli-derived protein starts from HIV-1 env. amino acid 165, and ends in amino acid 440. Human T-cell Leukaemia Virus Type I (HTLV-I) is a retrovirus that causes adult T-cell leukaemia (ATL).Synonyms: rHTLV-I, HTLVI envelope, HTLV-1 envelope, HTLV1 envelope