Mobilization-competent Lentiviral Vector-mediated Sustained Transcriptional Modulation of HIV-1 Expression.

Current anti-HIV-1 strategies reduce replication through targeting of viral proteins and RNA; meanwhile, targeting at the level of the integrated provirus has been less explored. We show here that mobilization-competent vectors containing small noncoding RNAs targeted to transcriptionally active regions of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) can take advantage of integrated virus and modulate HIV-1 replication. Transcriptional silencing of HIV-1 correlates with an increase in silent-state epigenetic marks including histone and DNA methylation, a loss of nuclear factor-kappaB (NF-kappaB) recruitment, and requires Argonaute 1 (Ago-1), histone deacetylase 1 (HDAC-1), and DNA methyltransferase 3a (DNMT3a) localization to the LTR. Long-term suppression of the virus was observed for 1 month with no evidence of viral resistance. These data show that RNA-directed transcriptional silencing of HIV-1 can be delivered by a mobilization-competent vector, suggesting that this system could be used to target long-term selective pressures on conserved promoter elements to evolve less pathogenic variants of HIV-1.