366. Negative Feedback Inhibition of HIV-1: A Novel HIV-1 LTR-hsp70 Fusion Promoter Directs HIV-1 Inducible siRNA Expression

Abstract

Small interfering RNAs (siRNAs) can induce potent gene silencing by directing degradation of cognate mRNA. Controlled expression of siRNA would be highly attractive especially since reports indicate that even short double stranded RNA molecules can induce a non-specific interferon response. We have designed an HIV inducible short hairpin siRNA system in which part of the Drosophila hsp70 promoter (TATA box and surrounding sequences) is cloned downstream of the HIV-1 LTR and TAR region. We demonstrate shRNA expression only in presence of HIV-1 Tat. Cells infected with HIV-1 proviral DNA can efficiently induce shRNA expression from this construct, which in turn inhibits viral replication, thus establishing a negative feedback loop. These results demonstrate for the first time a functional HIV-1 inducible siRNA system.