New human and simian HIV-related retroviruses possess functional transactivator (tat) gene

Abstract

New human retroviruses antigenically related to HIV and even more closely to STLV-III have been recently isolated from individuals from some West African countries^1–4. One of these viruses, HTLV-IV_P, was reportedly isolated from lymphocytes of a healthy female prostitute^1,2. Another isolate, LAV-2_FG, was obtained from an AIDS patient and third, SBL-6669, from an individual with lymphadenopathy⁴. Current epidemiological studies indicate that some of these virus isolates cause immune deficiency whereas others may not or may be less efficient at inducing immune deficiency. Similarly, STLV-III apparently does not cause immune deficiency in its natural host, African green monkey⁵. A novel feature of HIV is the possession of a gene termed tat, which is implicated in its pathobiology^6–12. We report here that, like HIV, HTLV-IV_P, LAV-2_FG (HIV-2) and SBL-6669, as well as STLV-III_AGM possess the putative tat gene, irrespective of their pathogenic potential in vivo. Interestingly, HTLV-IV_P/L A V-2_FG long terminal repeat (LTR) is equally well transactivated by the HTLV-IV_P/LAV-2_FG and HTLV-III_B tat function, HTLV-III_B LTR responds better to its own tat function.