Epigenetic compound screening uncovers small molecules for re-activation of latent HIV-1

Abstract

During infection with the human immunodeficiency virus type 1 (HIV-1), latent reservoirs are established, which circumvent full eradication of the virus by antiretroviral therapy (ART) and are the source for viral rebound after cessation of therapy. As these reservoirs are phenotypically undistinguishable from infected cells, current strategies aim to reactivate these reservoirs, followed by pharmaceutical and immunological destruction of the cells. Here, we employed a simple and convenient cell-based reporter system, which enables sample handling under biosafety level (BSL)-1 conditions, to screen for compounds that were able to reactivate latent HIV-1. The assay showed a high dynamic signal range and reproducibility with an average Z-factor of 0.77, classifying the system as robust. The assay was used for high-throughput screening (HTS) of an epigenetic compound library in combination with titration and cell-toxicity studies and revealed several potential new latency reversing agents (LRAs). Further validation in well-known latency model systems verified earlier studies and identified two novel compounds with very high reactivation efficiency and low toxicity. Both drugs, namely N-hydroxy-4-(2-[(2-hydroxyethyl)(phenyl)amino]-2-oxoethyl)benzamide (HPOB) and 2',3'-difluoro-[1,1'-biphenyl]-4-carboxylic acid, 2-butylhydrazide (SR-4370), showed comparable performances to other already known LRAs, did not activate CD4+ T-cells or caused changes in the composition of PBMCs as shown by flow cytometry analyses. Both compounds may represent an effective new treatment possibility for revocation of latency in HIV-1 infected individuals.