FIG. 5.

Alignment of BLV and HTLV-1 Env precursors by amino acid sequences and the shared motifs indicated above the sequences. Residues predicted to span the membrane are in italics. Dark gray, residues identical in both proteins; light gray, conserved residues (D↔E, K↔R, S↔T, Y↔F, and I↔L↔V). Numbering begins with the first amino acid of each Env precursor protein. The BLV sequence is that of our WT BLV (GenBank accession no. AY078387), so H108 represents the strain-specific Y108H substitution. BLV residues altered in variants are underlined. The HTLV sequence shown is the consensus from accession no. J02029 (60), D13784 (38), M37747 (27), and M67514 (42).