scholarly journals Probabilistic control of HIV latency and transactivation by the Tat gene circuit

2018 ◽  
Vol 115 (49) ◽  
pp. 12453-12458 ◽  
Author(s):  
Youfang Cao ◽  
Xue Lei ◽  
Ruy M. Ribeiro ◽  
Alan S. Perelson ◽  
Jie Liang
Keyword(s):  
Cell Phenotype ◽  
Control Mechanisms ◽  
Viral Production ◽  
Gene Circuit ◽  
Hiv Tat ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Cell Phenotypes ◽  
Druggable Targets

The reservoir of HIV latently infected cells is the major obstacle for eradication of HIV infection. The “shock-and-kill” strategy proposed earlier aims to reduce the reservoir by activating cells out of latency. While the intracellular HIV Tat gene circuit is known to play important roles in controlling latency and its transactivation in HIV-infected cells, the detailed control mechanisms are not well understood. Here we study the mechanism of probabilistic control of the latent and the transactivated cell phenotypes of HIV-infected cells. We reconstructed the probability landscape, which is the probability distribution of the Tat gene circuit states, by directly computing the exact solution of the underlying chemical master equation. Results show that the Tat circuit exhibits a clear bimodal probability landscape (i.e., there are two distinct probability peaks, one associated with the latent cell phenotype and the other with the transactivated cell phenotype). We explore potential modifications to reactions in the Tat gene circuit for more effective transactivation of latent cells (i.e., the shock-and-kill strategy). Our results suggest that enhancing Tat acetylation can dramatically increase Tat and viral production, while increasing the Tat–transactivation response binding affinity can transactivate latent cells more rapidly than other manipulations. Our results further explored the “block and lock” strategy toward a functional cure for HIV. Overall, our study demonstrates a general approach toward discovery of effective therapeutic strategies and druggable targets by examining control mechanisms of cell phenotype switching via exactly computed probability landscapes of reaction networks.

scholarly journals Reactivation Kinetics of HIV-1 and Susceptibility of Reactivated Latently Infected CD4+T Cells to HIV-1-Specific CD8+T Cells

2015 ◽  
Vol 89 (18) ◽  
pp. 9631-9638 ◽  
Author(s):  
Victoria E. K. Walker-Sperling ◽  
Valerie J. Cohen ◽  
Patrick M. Tarwater ◽  
Joel N. Blankson
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antiretroviral Therapy ◽  
Time Frame ◽  
Virus Release ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Kinetics Of ◽  
Hiv 1

ABSTRACTThe “shock and kill” model of human immunodeficiency virus type 1 (HIV-1) eradication involves the induction of transcription of HIV-1 genes in latently infected CD4+T cells, followed by the elimination of these infected CD4+T cells by CD8+T cells or other effector cells. CD8+T cells may also be needed to control the spread of new infection if residual infected cells are present at the time combination antiretroviral therapy (cART) is discontinued. In order to determine the time frame needed for CD8+T cells to effectively prevent the spread of HIV-1 infection, we examined the kinetics of HIV transcription and virus release in latently infected cells reactivatedex vivo. Isolated resting, primary CD4+T cells from HIV-positive (HIV+) subjects on suppressive regimens were found to upregulate cell-associated HIV-1 mRNA within 1 h of stimulation and produce extracellular virus as early as 6 h poststimulation. In spite of the rapid kinetics of virus production, we show that CD8+T cells from 2 out of 4 viremic controllers were capable of effectively eliminating reactivated autologous CD4+cells that upregulate cell-associated HIV-1 mRNA. The results have implications for devising strategies to prevent rebound viremia due to reactivation of rare latently infected cells that persist after potentially curative therapy.IMPORTANCEA prominent HIV-1 cure strategy termed “shock and kill” involves the induction of HIV-1 transcription in latently infected CD4+T cells with the goal of elimination of these cells by either the cytotoxic T lymphocyte response or other immune cell subsets. However, the cytotoxic T cell response may also be required after curative treatment if residual latently infected cells remain. The kinetics of HIV-1 reactivation indicate rapid upregulation of cell-associated HIV-1 mRNA and a 5-h window between transcription and virus release. Thus, HIV-specific CD8+T cell responses likely have a very short time frame to eliminate residual latently infected CD4+T cells that become reactivated after discontinuation of antiretroviral therapy following potentially curative treatment strategies.

scholarly journals A Therapeutic Strategy to Combat HIV-1 Latently Infected Cells With a Combination of Latency-Reversing Agents Containing DAG-Lactone PKC Activators

2021 ◽  
Vol 12 ◽  
Author(s):  
Kouki Matsuda ◽  
Takuya Kobayakawa ◽  
Ryusho Kariya ◽  
Kiyoto Tsuchiya ◽  
Shoraku Ryu ◽  
...  
Keyword(s):  
Whole Body ◽  
Therapeutic Effects ◽  
Combined Antiretroviral Therapy ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Hiv 1 ◽  
Reversing Agents

Advances in antiviral therapy have dramatically improved the therapeutic effects on HIV type 1 (HIV-1) infection. However, even with potent combined antiretroviral therapy, HIV-1 latently infected cells cannot be fully eradicated. Latency-reversing agents (LRAs) are considered a potential tool for eliminating such cells; however, recent in vitro and in vivo studies have raised serious concerns regarding the efficacy and safety of the “shock and kill” strategy using LRAs. In the present study, we examined the activity and safety of a panel of protein kinase C (PKC) activators with a diacylglycerol (DAG)-lactone structure that mimics DAG, an endogenous ligand for PKC isozymes. YSE028, a DAG-lactone derivative, reversed HIV-1 latency in vitro when tested using HIV-1 latently infected cells (e.g., ACH2 and J-Lat cells) and primary cells from HIV-1-infected individuals. The activity of YSE028 in reversing HIV-1 latency was synergistically enhanced when combined with JQ1, a bromodomain and extra-terminal inhibitor LRA. DAG-lactone PKC activators also induced caspase-mediated apoptosis, specifically in HIV-1 latently infected cells. In addition, these DAG-lactone PKC activators showed minimal toxicity in vitro and in vivo. These data suggest that DAG-lactone PKC activators may serve as potential candidates for combination therapy against HIV-1 latently infected cells, especially when combined with other LRAs with a different mechanism, to minimize side effects and achieve maximum efficacy in various reservoir cells of the whole body.

scholarly journals Brain HIV-1 latently-infected reservoirs targeted by the suicide gene strategy

2020 ◽  
Author(s):  
Sepideh Saeb ◽  
Mehrdad Ravanshad ◽  
Mahmoud Reza Pourkarim ◽  
Fadoua Daouad ◽  
Kazem Baesi ◽  
...  
Keyword(s):  
Suicide Gene ◽  
Microglial Cells ◽  
Peripheral Tissues ◽  
Latently Infected ◽  
Shock And Kill ◽  
The Central Nervous System ◽  
Infected Cells ◽  
Set Up ◽  
The Brain ◽  
Hiv 1

Abstract Several strategies are currently investigated to reduce the pool of all HIV-1 reservoirs in infected patients in order to achieve functional cure. The most prominent HIV-1 cell reservoirs in the brain are microglial cells. Virus infection maybe lifelong. Infected microglial cells are believed to be the source of peripheral tissues reseeding and responsible for the emergence of drug resistance. Clearing infected cells from the brain is therefore crucial. However, many characteristics of microglial cells and the central nervous system prevent the eradication of brain reservoirs. Current trials, such as “shock and kill”, the “deep and lock” and the gene editing strategies do not respond to these difficulties. Therefore, new strategies have to be designed when considering brain reservoirs such as microglial cells. We set up an original gene suicide strategy using a latently infected microglial model. In this paper we provide proof of concept of this strategy. Our results demonstrate that this strategy enables the eradication of latently-infected microglial cells.

scholarly journals HIV Provirus Stably Reproduces Parental Latent and Induced Transcription Phenotypes Regardless of the Chromosomal Integration Site

2016 ◽  
Vol 90 (11) ◽  
pp. 5302-5314 ◽  
Author(s):  
Farhad B. Hashemi ◽  
Kris Barreto ◽  
Wendy Bernhard ◽  
Pargol Hashemi ◽  
Adam Lomness ◽  
...  
Keyword(s):  
T Cell ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Chromosomal Integration ◽  
Reporter Virus ◽  
Infected Population ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Latent Provirus

ABSTRACTUnderstanding the mechanisms of HIV proviral latency is essential for development of a means to eradicate infection and achieve a cure. We have previously described anin vitrolatency model that reliably identifies HIV expression phenotypes of infected cells using a dual-fluorescence reporter virus. Our results have demonstrated that ∼50% of infected cells establish latency immediately upon integration of provirus, a phenomenon termed early latency, which appears to occur by mechanisms that are distinct from epigenetic silencing observed with HIV provirus that establishes productive infections. In this study, we have used a mini-dual HIV reporter virus (mdHIV) to compare the long-term stability of provirus produced as early latent or productive infections using Jurkat-Tat T cell clones. Cloned lines bearing mdHIV provirus integrated at different chromosomal locations display unique differences in responsiveness to signaling agonists and chromatin-modifying compounds, and they also produce characteristic expression patterns from the 5′ long terminal repeat (LTR) dsRed and internal EIF1α-enhanced green fluorescent protein (EIF1α-eGFP) reporters. Furthermore, reporter expression profiles of single cell sorted subcultures faithfully reproduce expression profiles identical to that of their original parental population, following prolonged growth in culture, without shifting toward expression patterns resembling that of cell subclones at the time of sorting. Comparison of population dispersion coefficient (CV) and mean fluorescence intensity (MFI) of the subcloned lines showed that both untreated and phorbol myristate acetate (PMA)-ionomycin-stimulated cultures produce expression patterns identical to those of their parental lines. These results indicate that HIV provirus expression characteristics are strongly influenced by the epigenetic landscape at the site of chromosomal integration.IMPORTANCEThere is currently considerable interest in development of therapies to eliminate latently infected cells from HIV-infected patients on antiretroviral therapy. One proposed strategy, known as “shock and kill,” would involve treatment with therapies capable of inducing expression of latent provirus, with the expectation that the latently infected cells could be killed by a host immune response or virus-induced apoptosis. In clinical trials, histone deacetylase (HDAC) inhibitors were shown to cause reactivation of latent provirus but did not produce a significant effect toward eliminating the latently infected population. Results shown here indicate that integration of HIV provirus at different chromosomal locations produces significant effects on the responsiveness of virus expression to T cell signaling agonists and chromatin-modifying compounds. Given the variety of phenotypes produced by integrated provirus, it is unlikely that any single potential shock-and-kill therapy will be effective toward purging the latently infected population.

scholarly journals Block-And-Lock Strategies to Cure HIV Infection

Viruses ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 84 ◽  
Author(s):  
Gerlinde Vansant ◽  
Anne Bruggemans ◽  
Julie Janssens ◽  
Zeger Debyser
Keyword(s):  
Hiv Infection ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Hiv Cure ◽  
Major Barrier ◽  
Hiv Transcription ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Underlying Mechanisms

Today HIV infection cannot be cured due to the presence of a reservoir of latently infected cells inducing a viral rebound upon treatment interruption. Hence, the latent reservoir is considered as the major barrier for an HIV cure. So far, efforts to completely eradicate the reservoir via a shock-and-kill approach have proven difficult and unsuccessful. Therefore, more research has been done recently on an alternative block-and-lock functional cure strategy. In contrast to the shock-and-kill strategy that aims to eradicate the entire reservoir, block-and-lock aims to permanently silence all proviruses, even after treatment interruption. HIV silencing can be achieved by targeting different factors of the transcription machinery. In this review, we first describe the underlying mechanisms of HIV transcription and silencing. Next, we give an overview of the different block-and-lock strategies under investigation.

scholarly journals A Critical Review of the Evidence Concerning the HIV Latency Reversing Effect of Disulfiram, the Possible Explanations for Its Inability to Reduce the Size of the Latent Reservoir In Vivo, and the Caveats Associated with Its Use in Practice

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Harry D. J. Knights
Keyword(s):  
Immune Deficiency Syndrome ◽  
Deficiency Syndrome ◽  
Latent Reservoir ◽  
Major Barrier ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Hiv 1

Combination antiretroviral therapy (cART) effectively suppresses the replication of human immunodeficiency virus type 1 (HIV-1), improves immune function, and decreases the morbidity of acquired immune deficiency syndrome (AIDS). However, it is unable to eradicate the virus because it does not eliminate latently infected cells. The latent reservoir poses the major barrier to an HIV-1 cure. The “shock and kill” strategy aims to reactivate the virus and destroy latently infected cells. Many latency reversing agents (LRAs) reactivate HIV in vitro, but the absence of damaging side-effects and efficacy in vivo make disulfiram particularly promising. However, in clinical trials to date, disulfiram treatment has not resulted in a reduction in the size of the latent reservoir. In this article I will therefore discuss the evidence for the latency reversing effect of disulfiram, the possible explanations for its inability to reduce the size of the latent reservoir in vivo, and the caveats associated with its use in practice. These considerations will help to inform judgements about the prospect of an HIV cure from disulfiram based treatments.

scholarly journals The differential short- and long-term effects of HIV-1 latency-reversing agents on T cell function

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
G. Clutton ◽  
Y. Xu ◽  
P. L. Baldoni ◽  
K. R. Mollan ◽  
J. Kirchherr ◽  
...  
Keyword(s):  
T Cell ◽  
Histone Deacetylase Inhibitors ◽  
Cell Function ◽  
Cd8 T Cell ◽  
Cell Phenotype ◽  
T Cell Function ◽  
Latently Infected ◽  
Infected Cells ◽  
Hiv 1 ◽  
Reversing Agents

Abstract Despite the extraordinary success of HIV-1 antiretroviral therapy in prolonging life, infected individuals face lifelong therapy because of a reservoir of latently-infected cells that harbor replication competent virus. Recently, compounds have been identified that can reverse HIV-1 latency in vivo. These latency- reversing agents (LRAs) could make latently-infected cells vulnerable to clearance by immune cells, including cytolytic CD8+ T cells. We investigated the effects of two leading LRA classes on CD8+ T cell phenotype and function: the histone deacetylase inhibitors (HDACis) and protein kinase C modulators (PKCms). We observed that relative to HDACis, the PKCms induced much stronger T cell activation coupled with non-specific cytokine production and T cell proliferation. When examining antigen-specific CD8+ T cell function, all the LRAs except the HDACi Vorinostat reduced, but did not abolish, one or more measurements of CD8+ T cell function. Importantly, the extent and timing of these effects differed between LRAs. Panobinostat had detrimental effects within 10 hours of drug treatment, whereas the effects of the other LRAs were observed between 48 hours and 5 days. These observations suggest that scheduling of LRA and CD8+ T cell immunotherapy regimens may be critical for optimal clearance of the HIV-1 reservoir.

scholarly journals Low-Level Ionizing Radiation Induces Selective Killing of HIV-1-Infected Cells with Reversal of Cytokine Induction Using mTOR Inhibitors

Viruses ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 885
Author(s):  
Daniel O. Pinto ◽  
Catherine DeMarino ◽  
Thy T. Vo ◽  
Maria Cowen ◽  
Yuriy Kim ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Mtor Inhibitors ◽  
Viral Reservoirs ◽  
Viral Loads ◽  
Viral Spread ◽  
Novel Approach ◽  
Latently Infected ◽  
Shock And Kill ◽  
Infected Cells ◽  
Hiv 1

HIV-1 infects 39.5 million people worldwide, and cART is effective in preventing viral spread by reducing HIV-1 plasma viral loads to undetectable levels. However, viral reservoirs persist by mechanisms, including the inhibition of autophagy by HIV-1 proteins (i.e., Nef and Tat). HIV-1 reservoirs can be targeted by the “shock and kill” strategy, which utilizes latency-reversing agents (LRAs) to activate latent proviruses and immunotarget the virus-producing cells. Yet, limitations include reduced LRA permeability across anatomical barriers and immune hyper-activation. Ionizing radiation (IR) induces effective viral activation across anatomical barriers. Like other LRAs, IR may cause inflammation and modulate the secretion of extracellular vesicles (EVs). We and others have shown that cells may secrete cytokines and viral proteins in EVs and, therefore, LRAs may contribute to inflammatory EVs. In the present study, we mitigated the effects of IR-induced inflammatory EVs (i.e., TNF-α), through the use of mTOR inhibitors (mTORi; Rapamycin and INK128). Further, mTORi were found to enhance the selective killing of HIV-1-infected myeloid and T-cell reservoirs at the exclusion of uninfected cells, potentially via inhibition of viral transcription/translation and induction of autophagy. Collectively, the proposed regimen using cART, IR, and mTORi presents a novel approach allowing for the targeting of viral reservoirs, prevention of immune hyper-activation, and selectively killing latently infected HIV-1 cells.

scholarly journals Brain HIV-1 latently-infected reservoirs targeted by the suicide gene strategy

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Sepideh Saeb ◽  
Mehrdad Ravanshad ◽  
Mahmoud Reza Pourkarim ◽  
Fadoua Daouad ◽  
Kazem Baesi ◽  
...  
Keyword(s):  
Suicide Gene ◽  
Microglial Cells ◽  
Peripheral Tissues ◽  
Latently Infected ◽  
Shock And Kill ◽  
The Central Nervous System ◽  
Infected Cells ◽  
Set Up ◽  
Hiv 1 ◽  
New Strategies

AbstractReducing the pool of HIV-1 reservoirs in patients is a must to achieve functional cure. The most prominent HIV-1 cell reservoirs are resting CD4 + T cells and brain derived microglial cells. Infected microglial cells are believed to be the source of peripheral tissues reseedings and the emergence of drug resistance. Clearing infected cells from the brain is therefore crucial. However, many characteristics of microglial cells and the central nervous system make extremely difficult their eradication from brain reservoirs. Current methods, such as the “shock and kill”, the “block and lock” and gene editing strategies cannot override these difficulties. Therefore, new strategies have to be designed when considering the elimination of brain reservoirs. We set up an original gene suicide strategy using latently infected microglial cells as model cells. In this paper we provide proof of concept of this strategy.

scholarly journals Chromatin Functional States Correlate with HIV Latency Reversal in Infected Primary CD4+T cells

2018 ◽  
Author(s):  
Emilie Battivelli ◽  
Matthew S. Dahabieh ◽  
Mohamed Abdel-Mohsen ◽  
J. Peter Svensson ◽  
Israel Tojal Da Silva ◽  
...  
Keyword(s):  
T Cells ◽  
Viral Reactivation ◽  
Viral Reservoir ◽  
Immunodeficiency Virus ◽  
Latently Infected ◽  
Integration Sites ◽  
Shock And Kill ◽  
Infected Cells ◽  
Functional States ◽  
Hiv Integration

ABSTRACTHuman immunodeficiency virus (HIV) infection cannot be cured due to a small reservoir of latently infected CD4+T cells in treated patients. The “shock and kill” approach proposes to eliminate the reservoir by inducing its activation and the direct or indirect killing of infected cells. Current latency reversing agents (LRAs) do not reduce the viral reservoir in treated patients.We use a novel dual-fluorescent HIV reporter to identify and purify latent cells, and to determine the fraction of latent cells that undergo viral reactivation after infection of primary CD4+T cells. Unexpectedly, LRAs reactivate less than 5% of latent proviruses. Analysis of HIV integration sites from induced and non-induced latent populations reveals distinct provirus integration sites between these two populations in terms of chromatin functional states.These findings challenge “shock and kill”, and suggest the need of more potent LRAs in combination with immunomodulatory approaches to eradicate HIV reservoir.

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