Silencing of HIV-1 Subtype C Primary Isolates by Expressed Small Hairpin RNAs Targeted togag

Abstract

Discovery of sequence-specific silencing by activating the RNA interference (RNAi) pathway has led to exciting new strategies for treating infection with human immunodeficiency virus type 1 (HIV-1). Of the HIV-1 subtypes, C is especially common in areas of the world that are worst affected. Although prone to mutation, genome plasticity of this subtype is limited in functionally important regions. We identified conserved sequences within the HIV-1 subtype C gag open reading frame and assessed whether they are suitable targets for inhibition of viral replication by RNA Pol III-driven small hairpin RNAs (shRNAs). Initially, the efficacy of each of a panel of 10 shRNAs against HIV-1 was determined using a reporter assay. shRNAs A and B, which targeted the 5 end of gag, were most effective and were used to assess inhibition of replication in cultured cells of two R5 isolates (Du151 and Du422) and one X4 virus (SW7). These shRNAs diminished intracellular HIV-1 gag RNA and HIV-1 protein concentrations as well as p24 secretion by up to 80% without inducing an interferon response. However, shRNA-mediated knockdown efficacy against each of these viral isolates varied slightly. These data show successful activation of RNAi to inhibit the replication of biologically distinct HIV-1 subtype C isolates. The effector shRNAs described here are potential candidates for gene therapy applications against the most common global subtype of HIV-1.

Combined antiviral activity of interferon-α and RNA interference directed against hepatitis C without affecting vector delivery and gene silencing

“…2 d). Also, previous studies by others [ 33 , 34 ] and our group [ 13 ] showed no in vitro evidence of endogenous type I interferon responses after transduction with lentiviral vectors. The fact that exogenous IFN-α does not have an apparent impact on LV transductions makes a combined approach feasible.…”

RNA interference approaches for treatment of HIV-1 infection

“…Alterations in the RNA folding and structure of these regions can, however, lead to RNAi-resistance [ 92 , 93 ]. Alternatively, the targeting of genes that encode the structural and enzymatic proteins required for viral assembly and infection (including gag , pol , vif , and env ) is effective, despite the fact that these genes are not found in all transcripts [ 94 – 97 ]. While the integrase and reverse transcriptase proteins are targeted by different classes of antiretroviral drugs, the coding regions of these proteins can also be targeted by RNAi.…”

Role of siRNAs and miRNAs in the processes of RNA-mediated gene silencing during viral infections

“…Jacque et al showed siRNA-based inhibition of early and late stages in replication of HIV that made synthesis of DNA from RNA impossible. By now exist several viral sequencestargets that are attacked by specific to them siRNAs: Gag [99] and Env [100], gene of reverse transcriptase Pol [99], genes coding for regulatory proteins-Tat, Rev, Nef and Vif [101].…”