FIG. 2.

HTLV-I genomic organization and encoded proteins. The approximate sizes of HTLV-I proviral genes are shown for mRNAs encoding the structural Gag, protease (pr), reverse transcriptase (RT), envelope (Env), and regulatory proteins (open boxes). The protease is encoded by the 3′ end of gag mRNA in a different reading frame from the Gag proteins extending into the 5′ end of pol. The RNase H and integrase (not shown) are encoded by pol. The pX gene has four ORFs. ORF-I may encode p12^I; ORF-II may encode p13^II and p30^II; ORF-III encodes p21^rex and p27^rex; and ORF-IV encodes p40^tax. The LTR R region begins at the initiation of transcription site.