Activation of infected lymphocytes is required for HIV replication to be detected. The goal of this proposal is elucidation of cis-acting HIV long terminal repeat (LTR) elements and trans-acting cellular factors that contribute to the conversion of latent HIV infection. This information will allow the development of therapeutic agents that inhibit steps in the activation of HIV, have minimal effects on normal T cell physiology, and prolong the latent state in infected patients. Identification of cis-acting elements in the HIV-1LTR that respond to physiologic T cell activation agonists will be achieved with the use of a reporter gene in transient transfection assays in a human CD4+ T cell line, Jurkat, and in peripheral blood T lymphocytes (PBLs). In addition, the sequences in the HIV-1LTR that respond to proliferation or """"""""late activation"""""""" events will be examined in mononuclear cell lines that proliferate after exposure to well-characterized growth factors. Transacting factor(s) that act on these cis-acting elements in the HIV-1LTR will be characterized for binding specificity and similarity to known DNA binding proteins in protein gel retardation assays. With the use of radioactively labeled oligonucleotides and a bacteriophage expression library, the cDNA for a specific trans-acting factor(s) will be cloned. The protein products will be used in cell-free transcription systems. Determination of the viral sequences and cellular factors that increase viral gene expression in activated lymphocytes will aid in understanding mechanisms that lead to the clinical onset of AIDS. HIV-2 is an etiologic agent of AIDS in West Africa but is associated with a longer asymptomatic period than that of HIV-1. Divergence of sequences in the HIV-2LTR from the HIV-1LTR may account for a differential response of HIV-2 to T cell activation. The target sequences in the HIV-2LTR for T cell activation signals will be identified in transient transfection assays in the Jurkat cell line. Further comparison of HIV-1 and 2 will be achieved through the construction of chimeric LTRs. Initial observations suggest that the HIV-2 enhancer in the LTR differs functionally from the HIV-1 enhancer and influences trans-activation of the HIV-2LTR by its viral gene product, tat-2. Comparison of processes in HIV-1 and 2LTR directed gene expression may reveal selective steps in T cell activation or cellular factors that contribute to viral latency and thus prolong the asymptomatic state. A long term objective, which will be the subject of future work based on the results of the current proposal, is the study of the response of virus with wildtype LTR, virus with mutated LTRs, and virus with chimeric HIV-1 and 2LTRs to T cell activation in human PBLs.
| Sepp, T; Tong-Starksen, S E (1997) STAT1 pathway is involved in activation of caprine arthritis-encephalitis virus long terminal repeat in monocytes. J Virol 71:771-7 |
| Tong-Starksen, S E; Sepp, T; Pagtakhan, A S (1996) Activation of caprine arthritis-encephalitis virus long terminal repeat by gamma interferon. J Virol 70:595-9 |
| Pagtakhan, A S; Tong-Starksen, S E (1995) Function of exon 2 in optimal trans-activation by Tat of HIV type 2. AIDS Res Hum Retroviruses 11:1367-72 |
| Tong-Starksen, S E; Baur, A; Lu, X B et al. (1993) Second exon of Tat of HIV-2 is required for optimal trans-activation of HIV-1 and HIV-2 LTRs. Virology 195:826-30 |
| Tong-Starksen, S E; Welsh, T M; Peterlin, B M (1990) Differences in transcriptional enhancers of HIV-1 and HIV-2. Response to T cell activation signals. J Immunol 145:4348-54 |
