INHIBITION OF HIV REPLICATION BY SENSE AND ANTISENSE REV RESPONSE ELEMENTS IN HIV-BASED RETROVIRAL VECTORS

The life cycle of human immunodeficiency virus type 1 (HIV-I) is criti cally dependent on the transregulatory proteins Tat and Rev. Tat incre ases the production of HIV-specific mRNAs by direct binding to the tra nsactivation response (TAR) element located at the 5' end of all HIV t ranscripts. In contrast, Rev uses a complex RNA stem loop structure, t he Rev response element (RRE), which is found in full-length and singl y spliced HIV transcripts, Rev is required for the cytoplasmic express ion of full-length mRNAs encoding Gag, Pol, and Env structural protein s. The complex intracellular interactions between Tat, Rev, host cell factors, and their respective RNA response elements should be suscepti ble to interdiction by genetic therapies designed to introduce and exp ress novel genetic information. We show that the expression of antisen se RREs inhibited the cytoplasmic expression of RRE containing HIV-I t ranscripts. HIV-based retroviral vectors containing either the antisen se (-) or sense (+)RREs inhibited HIV replication in transient transfe ctions. The production of full-length HIV mRNA was also decreased sign ificantly by the expression of RREs in either orientation. Interesting ly, there was a paradoxic increase in HIV p24 gag production at low le vels of inhibitor; this effect may have been the result of encapsidati on of RRE-containing HIV-based retroviral vectors. The data suggest th at the introduction and inducible expression of RRE-containing, HIV-ba sed retroviral vectors may have therapeutic value in HIV infection.