Complete nucleotide sequence of an amerindian human T-cell lymphotropic virus type II (HTLV-II) isolate: Identification of a variant HTLV-II subtype b from a Guaymi Indian

The complete nucleotide sequence of a human T-cell lymphotropic virus type II (HTLV-II) isolate from a Panamanian Guaymi Indian was determined and analyzed. When this new viral isolate (HTLV-II(G12)) was compared with prototypic HTLV-II(MoT), the overall nucleotide sequence similarity was 95.4%, while the predicted amino acid sequence similarity was 97.5%. Although the overall percentage of nucleotide and amino acid identity with prototypic HTLV-II(MoT) (subtype a) was high, HTLV-II(G12) displayed several distinctive features that defined it as an HTLV-II subtype b. However, there were several characteristics unique to this isolate, which included a cluster of nucleotide substitutions in the pre-gag region and changes in restriction enzyme sites within the pre-gag region and the gag, pol, env, and pX genes. In addition, two nucleotide changes in the C terminus of the Tax protein coding sequence inserted an Arg residue for a stop codon and appeared to result in a larger tax gene product in HTLV-II(G12). Although the HTLV- II(G12) isolate appears to be a variant of the prototypic HTLV-IIb, this information represents the first complete nucleotide sequence of any HTLV-II subtype b. These data will allow further studies on the evolutionary relationships between the HTLV-II subtypes and between HTLV-I and HTLV-II.