Complete nucleotide sequence of HTLV-II isolate RNA: comparison of envelope sequence variation of HTLV-II isolates from U.S. blood donors and U.S. and Italian IV drug users

The entire nucleotide sequence of human T-cell lymphotropic virus type II (HTLV-II) from a previously described isolate of patient NRA (HTLV-IINRA) was determined. Clones encoding the 5′ LTR and gag, pol, env and tax/rex open reading frames were subcloned and sequenced on both strands. The provirus consisted of 8957 nucleotides and showed 95.2% homology with the HTLV-IIMo prototype at the nucleotide level. Less than 5% amino acid variation between HTLV-IINRA and HTLV-IIMo was observed for coding regions. Although isolate HTLV-IINRA had an additional 25 amino acids at the 3′ end of the tax/rex, this region was 96% homologous with the 5′ end of HTLV-IIMo 3′ LTR. To further investigate HTLV-II variability, a portion of the env gp46 gene derived from 9 HTLV-II infected persons was amplified by polymerase chain reaction and sequenced. Sequenced was obtained for 320 nucleotides corresponding to HTLV-IIMo position 5291 to 5610. Isolates similar to the HTLV-IIMo and HTLV-IINRA prototypes were identified, and sequences were highly conserved.