718. PTD-Fusion Peptide as a Delivery Vehicle for siRNA To Target HIV Reservoirs

Abstract

Viral reservoirs are established early during an HIV infection; remain unaffected by highly active antiretroviral therapy (HAART) for their whole life and virus reemerge after treatment failure or interruption in treatment. It is often proposed that the brain serves as an important HIV reservoir. While macrophages/microglia (MM) in the brain undergoes a productive infection following virus entry, HIV infection in astrocytes becomes dormant after a brief period of viral replication. Given their lifespan and low rate of turnover, astrocytes may harbor the viral genome for long periods of time. In the presence of HAART, viral transcription and translation proceeds normally in the infected cells, except that virus is not assembled into fully infectious particles. Moreover, HIV infected macrophages sustain viral replication for their whole life and may be responsible for rebound of the virus in antiviral treatment interruption or failures. To reduce the impact of viral proteins, viral replication and emergence of drug resistance, inhibition of HIV transcription is of the utmost importance. To inhibit HIV transcription and replication we used Tat siRNA to target HIV in latently infected monocytic, HIV infected primary macrophages and astrocytic (SVGA) LTR-GFP reporter cells. We used a peptide based approach to deliver siRNA. Peptide based transduction of siRNA was very efficient in macrophages and astrocytes without any toxicity as compared to Lipofectamine 2000 and PEI transfection reagents. Tat siRNA strongly inhibited Tat mediated LTR transactivation activity up to 120 hrs in SVGA-LTR-GFP reporter cells in a dose dependent manner (0.4 |[mu]|M|[ndash]|0.1 |[mu]|M). Further, Tat siRNA strongly inhibited TNF-|[alpha]| reactivated HIV in latently HIV infected monocytic cells (THP89) for 72 hrs. To verify further whether Tat siRNA can inhibit HIV infection in primary macrophages, therefore, we established HIV infection in macrophages and then Tat siRNA was transduced on 2nd day post infection. In different experiments, we observed strong inhibition of HIV replication from day 12 to day 21 post infection in macrophages using Tat-siRNA. Conclusion: HIV transcription and replication is strongly inhibited by Tat-siRNA in cells which acts as a long term reservoir of HIV in the human body.