Human Immunodeficiency Virus Type 1 Provirus Research Articles

HIV-1 RNA in extracellular vesicles is associated with neurocognitive outcomes

Human immunodeficiency virus type-1 (HIV-1) is responsible for significant mortality and morbidity worldwide. Despite complete control of viral replication with antiretrovirals, cells with integrated HIV-1 provirus can produce viral transcripts. In a cross-sectional study of 84 HIV+ individuals of whom 43 were followed longitudinally, we found that HIV-1 RNAs are present in extracellular vesicles (EVs) derived from cerebrospinal fluid and serum of all individuals. We used seven digital droplet polymerase chain reaction assays to evaluate the transcriptional status of the latent reservoir. EV-associated viral RNA was more abundant in the CSF and correlated with neurocognitive dysfunction in both, the cross-sectional and longitudinal studies. Sequencing studies suggested compartmentalization of defective viral transcripts in the serum and CSF. These findings suggest previous studies have underestimated the viral burden and there is a significant relationship between latent viral transcription and CNS complications of long-term disease despite the adequate use of antiretrovirals.

Magnitude of Type I Interferon Responses by Plasmacytoid Dendritic Cells After TLR7 Stimulation Is Associated With Human Immunodeficiency Virus Type 1 (HIV-1) Reservoir Sizes in Cisgender Women With HIV-1 on Antiretroviral Therapy.

Human immunodeficiency virus type 1 (HIV-1) disease manifestations differ between cisgender women and men, including better control of viral replication during primary infection and less frequent residual HIV-1 replication on antiretroviral therapy (ART) in cisgender women with HIV-1 (WWH). Investigating plasmacytoid dendritic cell (pDC) functions and HIV-1 reservoir sizes in 20 WWH on stable ART, we observed inverse correlations between interferon-α and tumor necrosis factor responses of pDCs to Toll-like receptor 7/8 stimulation and intact/total proviral HIV-1 DNA levels. Additionally, ISG15 mRNA levels in peripheral blood mononuclear cells correlated with cytokine responses of pDCs. These findings demonstrate an association between higher type I interferon responses and lower HIV-1 reservoir sizes in WWH on ART, warranting studies to identify the underlying mechanisms.

Novel role of host protein SLC25A42 in the HIV-1 reactivation of latent HIV-1 provirus.

Despite the effectiveness of combination antiretroviral therapy, human immunodeficiency virus (HIV)infection remains incurable. To seek new strategies to overcome HIV type 1 (HIV-1) latency, one of the major barriers to HIV elimination, it is crucial to better understand how this state is maintained. Here, by means of an RNA interference screen employing an HIV-1 latency model using monocytic cell lines, we identified solute carrier family 25 member 42 (SLC25A42) as a potential host factor not previously known to affect HIV-1 latency. SLC25A42 knockdown resulted in increased HIV-1 expression, whereas forced expression of exogenous SLC25A42 suppressed it in SLC25A42-depleted cells. SLC25A42 depletion increased HIV-1 proviral transcriptional elongation but did not cause HIV-1 activation in an HIV-1 Tat-depleted latency model. This suggests that the role of SLC25A42 in HIV-1 transcription depends on HIV-1 Tat. Chromatin immunoprecipitation-qPCR analysis further revealed that SLC25A42 accumulated on or near the HIV-1 5' long terminal repeat promoter region of the HIV-1 provirus, suggesting a possible role in regulating HIV-1 Tat near this promoter region. These results indicate that SLC25A42 plays a novel role in HIV-1 latency maintenance in monocytic HIV-1 reservoirs.

Targeted shock-and-kill HIV-1 gene therapy approach combining CRISPR activation, suicide gene tBid and retargeted adenovirus delivery

Infections with the human immunodeficiency virus type 1 (HIV-1) are incurable due the long-lasting, latent viral reservoir. The shock-and-kill cure approach aims to activate latent proviruses in HIV-1 infected cells and subsequently kill these cells with strategies such as therapeutic vaccines or immune enhancement. Here, we combined the dCas9-VPR CRISPR activation (CRISPRa) system with gRNA-V, the truncated Bid (tBid)-based suicide gene strategy and CD3-retargeted adenovirus (Ad) delivery vectors, in an all-in-one targeted shock-and-kill gene therapy approach to achieve specific elimination of latently HIV-1 infected cells. Simultaneous transduction of latently HIV-1 infected J-Lat 10.6 cells with a CD3-retargeted Ad-CRISPRa-V and Ad-tBid led to a 57.7 ± 17.0% reduction of productively HIV-1 infected cells and 2.4-fold ± 0.25 increase in cell death. The effective activation of latent HIV-1 provirus by Ad-CRISPRa-V was similar to the activation control TNF-α. The strictly HIV-1 dependent and non-leaky killing by tBid could be demonstrated. Furthermore, the high transduction efficiencies of up to 70.8 ± 0.4% by the CD3-retargeting technology in HIV-1 latently infected cell lines was the basis of successful shock-and-kill. This novel targeted shock-and-kill all-in-one gene therapy approach has the potential to safely and effectively eliminate HIV-1 infected cells in a highly HIV-1 and T cell specific manner.

Wogonin inhibits latent HIV-1 reactivation by downregulating histone crotonylation

BackgroundWogonin, a flavone isolated from Scutellaria baicalensis Georgi, is a commonly used phytochemical with anti-inflammatory and antitumor properties. However, the antiviral activity of wogonin against human immunodeficiency virus type 1 (HIV-1) has not been reported. PurposeThe current study aimed to explore whether wogonin can suppress latent HIV-1 reactivation and the mechanism of wogonin in inhibiting proviral HIV-1 transcription. MethodsWe assessed the effects of wogonin on HIV-1 reactivation using flow cytometry, cytotoxicity assay, quantitative PCR (qPCR), viral quality assurance (VQA), and western blot analysis. ResultsWogonin, a flavone isolated from S. baicalensis, significantly inhibited the reactivation of latent HIV-1 in cellular models and in primary CD4+ T cells from antiretroviral therapy (ART)-suppressed individuals ex vivo. Wogonin exhibited low cytotoxicity and long-lasting inhibition of HIV-1 transcription. Triptolide is a latency-promoting agent (LPA) that inhibits HIV-1 transcription and replication; wogonin had a stronger ability to inhibit HIV-1 latent reactivation than triptolide. Mechanistically, wogonin inhibited the reactivation of latent HIV-1 by inhibiting the expression of p300, a histone acetyltransferase, and decreasing the crotonylation of histone H3/H4 in the HIV-1 promoter region. ConclusionOur study found that wogonin is a novel LPA that can inhibit HIV-1 transcription by HIV-1 epigenetic silencing, which could bear promising significance for future applications of HIV-1 functional cure.

Role of inflammasomes in HIV-1 infection and treatment.

Although combined antiretroviral therapy (cART) is effective in inhibiting human immunodeficiency virus type 1 (HIV-1) replication, it does not eradicate the virus because small amounts of latent HIV-1 provirus persist in quiescent memory CD4+ T cells. Therefore, strategies for eradicating latent HIV-1 are urgently needed. Recently, several studies have reported that the inflammatory response and lymphocyte death induced by HIV-1 depend on inflammasomes and pyroptosis, suggesting that inflammasomes and pyroptosis have a vital role in HIV-1 infection and contribute to the eradication of latent HIV-1. In this review, we summarize current knowledge of the role of inflammasomes, including NLR family pyrin domain-containing protein 3 (NLRP3), caspase recruitment domain-containing protein 8 (CARD8), interferon-inducible protein 16 (IFI16), NLRP1, NLR family CARD domain-containing 4 (NLRC4), and absent in melanoma 2 (AIM2), in HIV-1 infection and discuss promising therapeutic strategies for HIV-1-associated diseases by targeting inflammasomes.

CRISPR/Cas9 Ablation of Integrated HIV-1 Accumulates Proviral DNA Circles with Reformed Long Terminal Repeats.

ABSTRACTGene editing may be used to excise the human immunodeficiency virus type 1 (HIV-1) provirus from the host cell genome, possibly eradicating the infection. Here, using cells acutely or latently infected by HIV-1 and treated with long terminal repeat (LTR)-targeting CRISPR/Cas9, we show that the excised HIV-1 provirus persists for a few weeks and may rearrange in circular molecules. Although circular proviral DNA is naturally formed during HIV-1 replication, we observed that gene editing might increase proviral DNA circles with restored LTRs. These extrachromosomal elements were recovered and probed for residual activity through their transfection in uninfected cells. We discovered that they can be transcriptionally active in the presence of Tat and Rev. Although confirming that gene editing is a powerful tool to eradicate HIV-1 infection, this work highlights that, to achieve this goal, the LTRs must be cleaved in several pieces to avoid residual activity and minimize the risk of reintegration in the context of genomic instability, possibly caused by the off-target activity of Cas9.IMPORTANCE The excision of HIV-1 provirus from the host cell genome has proven feasible in vitro and, to some extent, in vivo. Among the different approaches, CRISPR/Cas9 is the most promising tool for gene editing. The present study underlines the remarkable effectiveness of CRISPR/Cas9 in removing the HIV-1 provirus from infected cells and investigates the fate of the excised HIV-1 genome. This study demonstrates that the free provirus may persist in the cell after editing and in appropriate circumstances may reactivate. As an episome, it might be transcriptionally active, especially in the presence of Tat and Rev. The persistence of the HIV-1 episome was strongly decreased by gene editing with multiple targets. Although gene editing has the potential to eradicate HIV-1 infection, this work highlights a potential issue that warrants further investigation.

Targeting Epigenetics to Cure HIV-1: Lessons From (and for) Cancer Treatment.

The Human Immunodeficiency Virus type 1 (HIV-1) integrates in the host genome as a provirus resulting in a long-lived reservoir of infected CD4 cells. As a provirus, HIV-1 has several aspects in common with an oncogene. Both the HIV-1 provirus and oncogenes only cause disease when expressed. A successful cure of both cancer and HIV-1 includes elimination of all cells with potential to regenerate the disease. For over two decades, epigenetic drugs developed against cancer have been used in the HIV-1 field to modulate the state of the proviral chromatin. Cells with an intact HIV-1 provirus exist in three states of infection: productive, inducible latent, and non-inducible latent. Here focus is on HIV-1, transcription control and chromatin structure; how the inducible proviruses are maintained in a chromatin structure that allows reactivation of transcription; and how transcription switches between different stages to allow for an abundance of different transcripts from a single promoter. Recently it was shown that a functional cure of HIV can be achieved by encapsulating all intact HIV-1 proviruses in heterochromatin, giving hope that epigenetic interventions may be used to end the HIV-1 epidemic.

CRISPR-Cas9 as a curative drug for chronic viral infection

The innovation of CRISPR-Cas9 has single-handedly revolutionized biotechnology by enabling efficient and specific cutting of DNA. CRISPR-Cas9 approaches are promising not only to targetthe human genome but also DNA of pathogenic viruses, which coincidentally is the canonical function in its bacterial origin. Since 2014, a myriad of studies has proven the efficacy of CRISPR-Cas9 treatment to cleave viral DNA intermediates in vitro. One of the most widely targeted is theproviral genome of human immunodeficiency virus type-1 (HIV-1). The disease burden of HIV-1 is massive—the infection is incurable and has remained a pandemic for over four decades. Integrated HIV-1 provirus inside the human genome causes viral persistence inside latent cellular reservoirs, eluding antiretroviral therapy (ART) and sterilizing cure. Specific targeting anddisruption of HIV-1 proviral genome is necessary to achieve viral clearance, which can be achieved with CRISPR-Cas9. Here, we review the features and up to date evidence of CRISPRCas9 to target the HIV-1 proviral genome and suppress viral replication. We will also discuss potential CRISPR/Cas9 delivery methods in vivo, combination with other gene editing modalities and other therapeutic approaches, to bring gene editing-based HIV-1 cure closer into clinical use.

The HIV-1 Provirus Excised by a Single CRISPR/Cas9 RNA Guide Persists in the Host Cell and May Be Reactivated

Gene editing may be used to cut out the human immunodeficiency virus type-1 (HIV-1) provirus from the host cell genome and eradicate infection. Here, using cells acutely or latently infected by HIV and treated with long terminal repeat-targeting CRISPR/Cas9, we show that the excised HIV provirus persists for a few weeks and, by means of HIV Integrase, rearranges in circular molecules. Circularization and integration restore proviral transcriptional activity that is enhanced in the presence of exogenous Tat and Rev or tumor necrosis factor-α, respectively, in acutely or latently infected cells. Although confirming that gene editing is a powerful tool to eradicate HIV infection, this work highlights that, to achieve this goal, the provirus has to be cleaved in several pieces and the infected cells treated with antiviral therapy before and after editing.

Broadly active zinc finger protein-guided transcriptional activation of HIV-1

Human immunodeficiency virus type 1 (HIV-1) causes a persistent viral infection resulting in the demise of immune regulatory cells. Clearance of HIV-1 infection results in integration of proviral DNA into the genome of host cells, which provides a means for evasion and long-term persistence. A therapeutic compound that specifically targets and sustainably activates a latent HIV-1 provirus could be transformative and is the goal for the “shock-and-kill” approach to a functional cure for HIV-1. Substantial progress has been made toward the development of recombinant proteins that target specific genomic loci for gene activation, repression, or inactivation by directed mutations. However, most of these modalities are too large or too complex for efficient therapeutic application. We describe here the development and testing of a novel recombinant zinc finger protein transactivator, ZFP-362-VPR, which specifically and potently enhances proviral HIV-1 transcription both in established latency models and activity across different viral clades. Additionally, ZFP-362-VPR-activated HIV-1 reporter gene expression in a well-established primary human CD4+ T cell latency model and off-target pathways were determined by transcriptome analyses. This study provides clear proof of concept for the application of a novel, therapeutically relevant, protein transactivator to purge cellular reservoirs of HIV-1.

Safe CRISPR-Cas9 Inhibition of HIV-1 with High Specificity and Broad-Spectrum Activity by Targeting LTR NF-κB Binding Sites

Viral latency of human immunodeficiency virus type 1 (HIV-1) has become a major hurdle to a cure in the highly effective antiretroviral therapy (ART) era. The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system has successfully been demonstrated to excise or inactivate integrated HIV-1 provirus from infected cells by targeting the long terminal repeat (LTR) region. However, the guide RNAs (gRNAs) have classically avoided transcription factor binding sites (TFBSs) that are readily observed and known to be important in human promoters. Although conventionally thought unfavorable due to potential impact on human promoters, our computational pipeline identified gRNA sequences that were predicted to inactivate HIV-1 transcription by targeting the nuclear factor κB (NF-κB) binding sites (gNFKB0, gNFKB1) with a high safety profile (lack of predicted or observed human edits) and broad-spectrum activity (predicted coverage of known viral sequences). Genome-wide, unbiased identification of double strand breaks (DSBs) enabled by sequencing (GUIDE-seq) showed that the gRNAs targeting NF-κB binding sites had no detectable CRISPR-induced off-target edits in HeLa cells. 5′ LTR-driven HIV-1 transcription was significantly reduced in three HIV-1 reporter cell lines. These results demonstrate a working model to specifically target well-known TFBSs in the HIV-1 LTR that are readily observed in human promoters to reduce HIV-1 transcription with a high-level safety profile and broad-spectrum activity.

The Use of Toll-Like Receptor Agonists in HIV-1 Cure Strategies.

Toll-like receptors (TLRs) are a family of pattern recognition receptors and part of the first line of defense against invading microbes. In humans, we know of 10 different TLRs, which are expressed to varying degrees in immune cell subsets. Engaging TLRs through their specific ligands leads to activation of the innate immune system and secondarily priming of the adaptive immune system. Because of these unique properties, TLR agonists have been investigated as immunotherapy in cancer treatment for many years, but in recent years there has also been growing interest in the use of TLR agonists in the context of human immunodeficiency virus type 1 (HIV-1) cure research. The primary obstacle to curing HIV-1 is the presence of a latent viral reservoir in transcriptionally silent immune cells. Due to the very limited transcription of the integrated HIV-1 proviruses, latently infected cells cannot be targeted and cleared by immune effector mechanisms. TLR agonists are very interesting in this context because of their potential dual effects as latency reverting agents (LRAs) and immune modulatory compounds. Here, we review preclinical and clinical data on the impact of TLR stimulation on HIV-1 latency as well as antiviral and HIV-1-specific immunity. We also focus on the promising role of TLR agonists in combination strategies in HIV-1 cure research. Different combinations of TLR agonists and broadly neutralizing antibodies or TLRs agonists as adjuvants in HIV-1 vaccines have shown very encouraging results in non-human primate experiments and these concepts are now moving into clinical testing.

Chromatin maturation of the HIV-1 provirus in primary resting CD4+T cells.

Human immunodeficiency virus type 1 (HIV-1) infection is a chronic condition, where viral DNA integrates into the genome. Latently infected cells form a persistent, heterogeneous reservoir that at any time can reactivate the integrated HIV-1. Here we confirmed that latently infected cells from HIV-1 positive study participants exhibited active HIV-1 transcription but without production of mature spliced mRNAs. To elucidate the mechanisms behind this we employed primary HIV-1 latency models to study latency establishment and maintenance. We characterized proviral transcription and chromatin development in cultures of resting primary CD4+ T-cells for four months after ex vivo HIV-1 infection. As heterochromatin (marked with H3K9me3 or H3K27me3) gradually stabilized, the provirus became less accessible with reduced activation potential. In a subset of infected cells, active marks (e.g. H3K27ac) and elongating RNAPII remained detectable at the latent provirus, despite prolonged proviral silencing. In many aspects, latent HIV-1 resembled an active enhancer in a subset of resting cells. The enhancer chromatin actively promoted latency and the enhancer-specific CBP/P300-inhibitor GNE049 was identified as a new latency reversal agent. The division of the latent reservoir according to distinct chromatin compositions with different reactivation potential enforces the notion that even though a relatively large set of cells contains the HIV-1 provirus, only a discrete subset is readily able to reactivate the provirus and spread the infection.

The Role of Macrophages in HIV-1 Persistence and Pathogenesis.

Current antiretroviral therapy (ART) effectively suppresses Human Immunodeficiency Virus type 1 (HIV-1) in infected individuals. However, even long term ART does not eradicate HIV-1 infected cells and the virus persists in cellular reservoirs. Beside memory CD4+ T cells, cells of the myeloid lineage, especially macrophages, are believed to be an important sanctuary for HIV-1. Monocytes and macrophages are key players in the innate immune response to pathogens and are recruited to sites of infection and inflammation. Due to their long life span and ability to reside in virtually every tissue, macrophages have been proposed to play a critical role in the establishment and persistence of the HIV-1 reservoir. Current HIV-1 cure strategies mainly focus on the concept of “shock and kill” to purge the viral reservoir. This approach aims to reactivate viral protein production in latently infected cells, which subsequently are eliminated as a consequence of viral replication, or recognized and killed by the immune system. Macrophage susceptibility to HIV-1 infection is dependent on the local microenvironment, suggesting that molecular pathways directing differentiation and polarization are involved. Current latency reversing agents (LRA) are mainly designed to reactivate the HIV-1 provirus in CD4+ T cells, while their ability to abolish viral latency in macrophages is largely unknown. Moreover, the resistance of macrophages to HIV-1 mediated kill and the presence of infected macrophages in immune privileged regions including the central nervous system (CNS), may pose a barrier to elimination of infected cells by current “shock and kill” strategies. This review focusses on the role of monocytes/macrophages in HIV-1 persistence. We will discuss mechanisms of viral latency and persistence in monocytes/macrophages. Furthermore, the role of these cells in HIV-1 tissue distribution and pathogenesis will be discussed.

N4BP1 restricts HIV-1 and its inactivation by MALT1 promotes viral reactivation.

RNA-modulating factors not only regulate multiple steps of cellular RNA metabolism, but also emerge as key effectors of the immune response against invading viral pathogens including human immunodeficiency virus type-1 (HIV-1). However, the cellular RNA-binding proteins involved in the establishment and maintenance of latent HIV-1 reservoirs have not been extensively studied. Here, we screened a panel of 62 cellular RNA-binding proteins and identified NEDD4-binding protein 1 (N4BP1) as a potent interferon-inducible inhibitor of HIV-1 in primary T cells and macrophages. N4BP1 harbours a prototypical PilT N terminus-like RNase domain and inhibits HIV-1 replication by interacting with and degrading viral mRNA species. Following activation of CD4+ T cells, however, N4BP1 undergoes rapid cleavage at Arg 509 by the paracaspase named mucosa-associated lymphoid tissue lymphoma translocation 1 (MALT1). Mutational analyses and knockout studies revealed that MALT1-mediated inactivation of N4BP1 facilitates the reactivation of latent HIV-1 proviruses. Taken together, our findings demonstrate that the RNase N4BP1 is an efficient restriction factor of HIV-1 and suggest that inactivation of N4BP1 by induction of MALT1 activation might facilitate elimination of latent HIV-1 reservoirs.

PR-957, a selective immunoproteasome inhibitor, reactivates latent HIV-1 through p-TEFb activation mediated by HSF-1

The existence of latent reservoirs of Human Immunodeficiency Virus type-1 (HIV-1) is a major obstacle in eliminating the virus. Thus, an urgent need exists for effective latency reversing agents (LRAs) based on the “shock and kill” strategy. Proteasome inhibitors were recently studied as LRAs, but were considered too toxic for clinical use. Here, we demonstrated that PR-957, a selective immunoproteasome inhibitor, effectively reactivated latent HIV-1 provirus in vitro and ex vivo. Our data also suggests that PR-957 has relatively low cytotoxicity. Furthermore, it does not influence global T cell activation and decreases the expression levels of HIV-1 receptors/co-receptors. We demonstrated synergistic activation of latent HIV-1 with PR-957 and Prostratin (a protein kinase C activator) that alleviated the extent of T cell activation induced by Prostratin. In addition, PR-957 exhibited latency reversing efficacy through activating p-TEFb mediated by HSF-1 pathway. Moreover, PR-957 did not affect the activity of combination antiretroviral therapy (cART) drugs and the PR-957-reactivated virus was effectively inhibited with cART drugs. In conclusion, the immunoproteasome inhibitor PR-957 is a promising candidate LRA for future HIV-1 eradication strategies.

Chidamide, a histone deacetylase inhibitor-based anticancer drug, effectively reactivates latent HIV-1 provirus

Although combination antiretroviral therapy (cART) is highly effective in suppressing human immunodeficiency virus type 1 (HIV-1) replication, it fails to eradicate the virus from HIV-1-infected individuals because HIV-1 integrates into the resting CD4+ T cells, establishing latently infected reservoirs. Histone deacetylation is a key element in regulating HIV-1 latent infection. Chidamide, a new anticancer drug, is a novel type of selective histone deacetylase inhibitor. Here we showed that chidamide effectively reactivated HIV-1 latent provirus in different latently infected cell lines in a dose- and time-dependent manner. Chidamide had relatively low cytotoxicity to peripheral blood mononuclear cells (PBMCs) and other latent cell lines. We have demonstrated that chidamide reactivated HIV-1 latent provirus through the NF-κB signaling pathway. The replication of the newly reactivated HIV-1 could then be effectively inhibited by the anti-HIV-1 drugs Zidovudine, Nevirapine, and Indinavir. Therefore, chidamide might be used in combination with cART for functional HIV-1 cure.

Mycobacterium tuberculosis reactivates latent HIV-1 in T cells in vitro.

Following proviral integration into the host cell genome and establishment of a latent state, the human immunodeficiency virus type 1 (HIV-1) can reenter a productive life cycle in response to various stimuli. HIV-1 reactivation occurs when transcription factors, such as nuclear factor-κB (NF-κB), nuclear factor of activated T cells (NFAT), and activator protein -1 (AP-1), bind cognate sites within the long terminal repeat (LTR) region of the HIV-1 provirus to promote transcription. Interestingly, pattern recognition receptors (PRRs) that recognize pathogen-associated molecular patterns (PAMPs) can reactivate latent HIV-1 through activation of the transcription factor NF-κB. Some PRRs are expressed on central memory CD4+ T cells (TCM), which in HIV-1 patients constitute the main reservoir of latent HIV-1. Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), interacts with PRRs through membrane components. However, the ability of Mtb to reactivate latent HIV-1 has not been extensively studied. Here we show that phosphatidylinositol mannoside 6 (PIM6), a component of the Mtb membrane, in addition to whole bacteria in co-culture, can reactivate HIV-1 in a primary TCM cell model of latency. Using a JLAT model of HIV-1 latency, we found this interaction to be mediated through Toll-like receptor-2 (TLR-2). Thus, we describe a mechanism by which Mtb can exacerbate HIV-1 infection. We hypothesize that chronic Mtb infection can drive HIV-1 reactivation. The phenomenon described here could explain, in part, the poor prognosis that characterizes HIV-1/Mtb co-infection.

Screening of an FDA-approved compound library identifies levosimendan as a novel anti-HIV-1 agent that inhibits viral transcription

Combination antiretroviral therapy (cART) has been proven to efficiently inhibit ongoing replication of human immunodeficiency virus type 1 (HIV-1), and significantly improve the health outcome in patients of acquired immune deficiency syndrome (AIDS). However, cART is unable to cure HIV-1/AIDS. Even in presence of cART there exists a residual viremia, contributed from the viral reservoirs of latently infected HIV-1 proviruses; this constitutes a major hurdle. Currently, there are multiple strategies aimed at eliminating or permanently silence these HIV-1 latent reservoirs being intensely explored. One such strategy, a recently emerged “block and lock” approach is appealing. For this approach, so-called HIV-1 latency-promoting agents (LPAs) are used to reinforce viral latency and to prevent the low-level or sporadic transcription of integrated HIV-1 proviruses. Although several LPAs have been reported, there is still a question of their suitability to be further developed as a safe and valid therapeutic agent for the clinical use. In this study, we aimed to identify new potential LPAs through the screening an FDA-approved compound library. A new and promising anti-HIV-1 inhibitor, levosimendan, was identified from these screens. Levosimendan is currently used to treat heart failure in clinics, but it demonstrates strong inhibition of TNFα-induced HIV-1 reactivation in multiple cell lines of HIV-1 latency through affecting the HIV-1 Tat-LTR transcriptional axis. Furthermore, we confirmed that in primary CD4+ T cells levosimendan inhibits both the acute HIV-1 replication and the reactivation of latent HIV-1 proviruses. As a summary, our studies successfully identify levosimendan as a novel and promising anti-HIV-1 inhibitor, which should be immediately investigated in vivo given that it is already an FDA-approved drug.