GENOTYPIC CHARACTERISTICS OF HTLV-II ISOLATES FROM AMERINDIAN AND NON-INDIAN POPULATIONS

The Amerindian human T-cell lymphotropic virus type II isolate HTLV-II G12 has been demonstrated to be an HTLV-IIb with several unique featur es, including several restriction enzyme site changes, a distinctive p re-gag region, a stop codon within the pol gene, and an extended Tax p rotein, In this study, HTLV-II isolates from Amerindian and non-Indian populations were characterized by restriction enzyme site analysis to determine the prevalent HTLV-II subtype. In addition, DNA amplificati on by the polymerase chain reaction and Southern blot analyses were us ed to probe for the HTLV-IIG12 pre-gag region. Our results showed that of 13 Guaymi Indian isolates subtyped, all were HTLV-IIb, and that ap proximately one third of 17 isolates had the unique pre-gag region. Wh ile other HTLV-II-infected groups contained both HTLV-IIa and HTLV-IIb isolates, none of these isolates showed evidence of the distinctive H TLV-IIG12 pre-gag region. Lastly, DNA sequence analysis was used to de termine the prevalence of the stop codon within the pol gene open read ing frame. These analyses revealed that the occurrence of a stop codon within this sequence appeared to be characteristic of most HTLV-IIb s ubtypes. These results further our understanding of the genetic variat ions and evolution of the HTLV-II viruses within the endemically infec ted Amerindian populations, as well as U.S. intravenous drug users and other non-Indian populations.