scholarly journals Key Players in HIV-1 Transcriptional Regulation: Targets for a Functional Cure

Viruses ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 529 ◽  
Author(s):  
Luisa Mori ◽  
Susana T. Valente
Keyword(s):  
Integration Site ◽  
Great Part ◽  
Treatment Interruption ◽  
Host Genome ◽  
Viral Reservoir ◽  
Latent Reservoir ◽  
Functional Cure ◽  
Transcript Elongation ◽  
Rna Transcript ◽  
Hiv 1

HIV-1 establishes a life-long infection when proviral DNA integrates into the host genome. The provirus can then either actively transcribe RNA or enter a latent state, without viral production. The switch between these two states is governed in great part by the viral protein, Tat, which promotes RNA transcript elongation. Latency is also influenced by the availability of host transcription factors, integration site, and the surrounding chromatin environment. The latent reservoir is established in the first few days of infection and serves as the source of viral rebound upon treatment interruption. Despite effective suppression of HIV-1 replication by antiretroviral therapy (ART), to below the detection limit, ART is ineffective at reducing the latent reservoir size. Elimination of this reservoir has become a major goal of the HIV-1 cure field. However, aside from the ideal total HIV-1 eradication from the host genome, an HIV-1 remission or functional cure is probably more realistic. The “block-and-lock” approach aims at the transcriptional silencing of the viral reservoir, to render suppressed HIV-1 promoters extremely difficult to reactivate from latency. There are unfortunately no clinically available HIV-1 specific transcriptional inhibitors. Understanding the mechanisms that regulate latency is expected to provide novel targets to be explored in cure approaches.

scholarly journals The chromatin landscape at the HIV-1 provirus integration site determines viral expression

2020 ◽  
Vol 48 (14) ◽  
pp. 7801-7817 ◽  
Author(s):  
Gerlinde Vansant ◽  
Heng-Chang Chen ◽  
Eduard Zorita ◽  
Katerina Trejbalová ◽  
Dalibor Miklík ◽  
...  
Keyword(s):  
Integration Site ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Rna Expression ◽  
Direct Link ◽  
Viral Expression ◽  
Active Transcription ◽  
Provirus Integration Site ◽  
Provirus Integration ◽  
Hiv 1

Abstract HIV-1 persists lifelong in memory cells of the immune system as latent provirus that rebounds upon treatment interruption. Therefore, the latent reservoir is the main target for an HIV cure. Here, we studied the direct link between integration site and transcription using LEDGINs and Barcoded HIV-ensembles (B-HIVE). LEDGINs are antivirals that inhibit the interaction between HIV-1 integrase and the chromatin-tethering factor LEDGF/p75. They were used as a tool to retarget integration, while the effect on HIV expression was measured with B-HIVE. B-HIVE tracks insert-specific HIV expression by tagging a unique barcode in the HIV genome. We confirmed that LEDGINs retarget integration out of gene-dense and actively transcribed regions. The distance to H3K36me3, the marker recognized by LEDGF/p75, clearly increased. LEDGIN treatment reduced viral RNA expression and increased the proportion of silent provirus. Finally, silent proviruses obtained after LEDGIN treatment were located further away from epigenetic marks associated with active transcription. Interestingly, proximity to enhancers stimulated transcription irrespective of LEDGIN treatment, while the distance to H3K36me3 only changed after treatment with LEDGINs. The fact that proximity to these markers are associated with RNA expression support the direct link between provirus integration site and viral expression.

scholarly journals MAT2A-Mediated S-Adenosylmethionine Level in CD4+ T Cells Regulates HIV-1 Latent Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaofan Yang ◽  
Ting Huang ◽  
Tiantian Wang ◽  
Hongbo Gao ◽  
Haitao Zhang ◽  
...  
Keyword(s):  
T Cells ◽  
Molecular Mechanisms ◽  
Latent Infection ◽  
Cell Model ◽  
Antiretroviral Drugs ◽  
Viral Reservoir ◽  
Latent Reservoir ◽  
Functional Cure ◽  
Potential Biomarker ◽  
Hiv 1

Antiretroviral drugs effectively halt HIV-1 replication and disease progression, however, due to the presence of a stable viral latent reservoir, the infection cannot be cured by antiretroviral drugs alone. Elucidating the molecular mechanisms underlying HIV-1 latent infection remains a critical hurdle that precludes the development of novel therapeutic strategies aiming for a potential functional cure. Cellular metabolism has been reported to affect HIV-1 replication in CD4+ T cells, but it remains largely unclear whether it is involved in the regulation of HIV-1 latency. Here, we performed a sub-pooled CRISPR library knockout screen targeting 1773 metabolic-related genes in a cell model of HIV-1 latent infection and found that Methionine Adenosyltransferase 2A (MAT2A) contributes to HIV-1 latency. MAT2A knockout enhanced the reactivation of latent HIV-1 while MAT2A overexpression did the opposite. Mechanistically, MAT2A modulates HIV-1 latency through S-Adenosylmethionine (SAM)-mediated one-carbon flux. MAT2A knockout resulted in a significant downregulation of DNA and histone methylation at the HIV-1 5’-LTR. Importantly, we found that the plasma level of SAM is positively correlated with HIV-1 DNA in PBMCs from ART-treated infected individuals, suggesting SAM could serve as a potential biomarker for the latent viral reservoir. Overall, this study reveals an important role of MAT2A-mediated one-carbon metabolism in regulating HIV-1 latency and provides a promising target for the development of new strategies for a functional cure of HIV-1.

scholarly journals The XPB Subunit of the TFIIH Complex Plays a Critical Role in HIV-1 Transcription and XPB Inhibition by Spironolactone Prevents HIV-1 Reactivation from Latency

2020 ◽  
Author(s):  
Luisa Mori ◽  
Katharine Jenike ◽  
Yang-Hui Jimmy Yeh ◽  
Benoît Lacombe ◽  
Chuan Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Line ◽  
Treatment Interruption ◽  
Viral Reservoir ◽  
Functional Cure ◽  
Hiv Transcription ◽  
Long Term Treatment ◽  
Cellular Transcription ◽  
Hiv 1

HIV transcription requires assembly of cellular transcription factors at the HIV-1promoter. The TFIIH general transcription factor facilitates transcription initiation by opening the DNA strands around the transcription start site and phosphorylating the C-terminal domain for RNA polymerase II (RNAPII) for activation. Spironolactone (SP), an FDA approved aldosterone antagonist, triggers the proteasomal degradation of the XPB subunit of TFIIH, and concurrently suppresses acute HIV infection in vitro. Here we investigated SP as a possible block-and-lock agent for a functional cure aimed at the transcriptional silencing of the viral reservoir. The long-term activity of SP was investigated in primary and cell line models of HIV-1 latency and reactivation. We show that SP rapidly inhibits HIV-1 transcription by reducing RNAPII recruitment to the HIV-1 genome. shRNA knockdown of XPB confirmed XPB degradation as the mechanism of action. Unfortunately, long-term pre-treatment with SP does not result in epigenetic suppression of HIV upon SP treatment interruption, since virus rapidly rebounds when XPB reemerges; however, SP alone without ART maintains the transcriptional suppression. Importantly, SP inhibits HIV reactivation from latency in both cell line models and resting CD4+T cells isolated from aviremic infected individuals upon cell stimulation with latency reversing agents. Furthermore, long-term treatment with concentrations of SP that potently degrade XPB does not lead to global dysregulation of cellular mRNA expression. Overall, these results suggest that XPB plays a key role in HIV transcriptional regulation and XPB degradation by SP strengthens the potential of HIV transcriptional inhibitors in block-and-lock HIV cure approaches. IMPORTANCE Antiretroviral therapy (ART) effectively reduces an individual’s HIV loads to below the detection limit, nevertheless rapid viral rebound immediately ensues upon treatment interruption. Furthermore, virally suppressed individuals experience chronic immune activation from ongoing low-level virus expression. Thus, the importance of identifying novel therapeutics to explore in block-and-lock HIV functional cure approaches, aimed at the transcriptional and epigenetic silencing of the viral reservoir to block reactivation from latency. We investigated the potential of repurposing the FDA-approved spironolactone (SP), as one such drug. SP treatment rapidly degrades a host transcription factor subunit, XPB, inhibiting HIV transcription and blocking reactivation from latency. Long-term SP treatment does not affect cellular viability, cell cycle progression or global cellular transcription. SP alone blocks HIV transcription in the absence of ART but does not delay rebound upon drug removal as XPB rapidly reemerges. This study highlights XPB as a novel drug target in block-and-lock therapeutic approaches.

A new small-molecule compound, Q308, silences latent HIV-1 provirus by suppressing Tat- and FACT-mediated transcription

2021 ◽  
Author(s):  
Chen-liang Zhou ◽  
Yi-fan Huang ◽  
Yi-bin Li ◽  
Tai-zhen Liang ◽  
Teng-yi Zheng ◽  
...  
Keyword(s):  
Small Molecule ◽  
Difficult Problem ◽  
Viral Reservoir ◽  
Functional Cure ◽  
Latently Infected ◽  
Small Molecule Compound ◽  
Infected Cells ◽  
Latent Hiv ◽  
Anti Hiv ◽  
Hiv 1

Eliminating the latent HIV reservoir remains a difficult problem for creating an HIV functional cure or achieving remission. The “block-and-lock” strategy aims to steadily suppress transcription of the viral reservoir and lock the HIV promoter in deep latency using latency-promoting agents (LPAs). However, to date, most of the investigated LPA candidates are not available for clinical trials, and some of them exhibit immune-related adverse reactions. The discovery and development of new, active, and safe LPA candidates for an HIV cure are necessary to eliminate residual HIV-1 viremia through the “block-and-lock” strategy. In this study, we demonstrated that a new small-molecule compound, Q308, silenced the HIV-1 provirus by inhibiting Tat-mediated gene transcription and selectively downregulating the expression levels of the facilitated chromatin transcription (FACT) complex. Strikingly, Q308 induced the preferential apoptosis in HIV-1 latently infected cells, indicating that Q308 may reduce the size of the viral reservoir and thus further prevent viral rebound. These findings highlight that Q308 is a novel and safe anti-HIV-1 inhibitor candidate for a functional cure.

scholarly journals A minor population of macrophage-tropic HIV-1 variants is identified in recrudescing viremia following analytic treatment interruption

2020 ◽  
Vol 117 (18) ◽  
pp. 9981-9990 ◽  
Author(s):  
Viviane M. Andrade ◽  
Carla Mavian ◽  
Dunja Babic ◽  
Thaissa Cordeiro ◽  
Mark Sharkey ◽  
...  
Keyword(s):  
Treatment Interruption ◽  
Viral Reservoir ◽  
Analytic Treatment ◽  
Recombinant Viruses ◽  
Minor Population ◽  
Clock Analysis ◽  
A Minor ◽  
Molecular Clock Analysis ◽  
Insight Into ◽  
Hiv 1

HIV-1 persists in cellular reservoirs that can reignite viremia if antiretroviral therapy (ART) is interrupted. Therefore, insight into the nature of those reservoirs may be revealed from the composition of recrudescing viremia following treatment cessation. A minor population of macrophage-tropic (M-tropic) viruses was identified in a library of recombinant viruses constructed with individual envelope genes that were obtained from plasma of six individuals undergoing analytic treatment interruption (ATI). M-tropic viruses could also be enriched from post-ATI plasma using macrophage-specific (CD14) but not CD4+ T cell-specific (CD3) antibodies, suggesting that M-tropic viruses had a macrophage origin. Molecular clock analysis indicated that the establishment of M-tropic HIV-1 variants predated ATI. Collectively, these data suggest that macrophages are a viral reservoir in HIV-1–infected individuals on effective ART and that M-tropic variants can appear in rebounding viremia when treatment is interrupted. These findings have implications for the design of curative strategies for HIV-1.

scholarly journals Autologous IgG antibodies block outgrowth of a substantial but variable fraction of viruses in the latent reservoir for HIV-1

2020 ◽  
Vol 117 (50) ◽  
pp. 32066-32077
Author(s):  
Lynn N. Bertagnolli ◽  
Joseph Varriale ◽  
Sarah Sweet ◽  
Jacqueline Brockhurst ◽  
Francesco R. Simonetti ◽  
...  
Keyword(s):  
T Cell Activation ◽  
Neutralizing Antibodies ◽  
Cell Activation ◽  
Viral Evolution ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Env Protein ◽  
Autologous Antibodies ◽  
Hiv 1

In untreated HIV-1 infection, rapid viral evolution allows escape from immune responses. Viral replication can be blocked by antiretroviral therapy. However, HIV-1 persists in a latent reservoir in resting CD4+ T cells, and rebound viremia occurs following treatment interruption. The reservoir, which is maintained in part by clonal expansion, can be measured using quantitative viral outgrowth assays (QVOAs) in which latency is reversed with T cell activation to allow viral outgrowth. Recent studies have shown that viruses detected in QVOAs prior to treatment interruption often differ from rebound viruses. We hypothesized that autologous neutralizing antibodies directed at the HIV-1 envelope (Env) protein might block outgrowth of some reservoir viruses. We modified the QVOA to reflect pressure from low concentrations of autologous antibodies and showed that outgrowth of a substantial but variable fraction of reservoir viruses is blocked by autologous contemporaneous immunoglobulin G (IgG). A reduction in outgrowth of >80% was seen in 6 of 15 individuals. This effect was due to direct neutralization. We established a phylogenetic relationship between rebound viruses and viruses growing out in vitro in the presence of autologous antibodies. Some large infected cell clones detected by QVOA carried neutralization-sensitive viruses, providing a cogent explanation for differences between rebound virus and viruses detected in standard QVOAs. Measurement of the frequency of reservoir viruses capable of outgrowth in the presence of autologous IgG might allow more accurate prediction of time to viral rebound. Ultimately, therapeutic immunization targeting the subset of variants resistant to autologous IgG might contribute to a functional cure.

scholarly journals Characterization of Intact Proviruses in Blood and Lymph Node from HIV-Infected Individuals Undergoing Analytical Treatment Interruption

2019 ◽  
Vol 93 (8) ◽  
Author(s):  
Line K. Vibholm ◽  
Julio C. C. Lorenzi ◽  
Joy A. Pai ◽  
Yehuda Z. Cohen ◽  
Thiago Y. Oliveira ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Lymphoid Tissues ◽  
Viral Rebound ◽  
Analytical Treatment ◽  
Latent Hiv ◽  
Hiv 1

ABSTRACT The role of lymphoid tissue as a potential source of HIV-1 rebound following interruption of antiretroviral therapy (ART) is uncertain. To address this issue, we compared the latent viruses obtained from CD4+ T cells in peripheral blood and lymph nodes to viruses emerging during treatment interruption. Latent viruses were characterized by sequencing near-full-length (NFL) proviral DNA and env from viral outgrowth assays (VOAs). Five HIV-1-infected individuals on ART were studied, four of whom participated in a clinical trial of a TLR9 agonist that included an analytical treatment interruption. We found that 98% of intact or replication-competent clonal sequences overlapped between blood and lymph node. In contrast, there was no overlap between 205 latent reservoir and 125 rebound sequences in the four individuals who underwent treatment interruption. However, rebound viruses could be accounted for by recombination. The data suggest that CD4+ T cells carrying latent viruses circulate between blood and lymphoid tissues in individuals on ART and support the idea that recombination may play a role in the emergence of rebound viremia. IMPORTANCE HIV-1 persists as a latent infection in CD4+ T cells that can be found in lymphoid tissues in infected individuals during ART. However, the importance of this tissue reservoir and its contribution to viral rebound upon ART interruption are not clear. In this study, we sought to compare latent HIV-1 from blood and lymph node CD4+ T cells from five HIV-1-infected individuals. Further, we analyzed the contribution of lymph node viruses to viral rebound. We observed that the frequencies of intact proviruses were the same in blood and lymph node. Moreover, expanded clones of T cells bearing identical proviruses were found in blood and lymph node. These latent reservoir sequences did not appear to be the direct origin of rebound virus. Instead, latent proviruses were found to contribute to the rebound compartment by recombination.

scholarly journals Concurrent administration of IFNα14 and cART in TKO-BLT mice enhances suppression of HIV-1 viremia but does not eliminate the latent reservoir

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kathrin Sutter ◽  
Kerry J. Lavender ◽  
Ronald J. Messer ◽  
Marek Widera ◽  
Katie Williams ◽  
...  
Keyword(s):  
Infection Type ◽  
Treatment Interruption ◽  
Type I Interferons ◽  
Latent Reservoir ◽  
Type I ◽  
Concurrent Administration ◽  
Viral Dna ◽  
Therapy Interruption ◽  
Hiv 1

AbstractCombination antiretroviral therapy (cART) prevents HIV-1 replication but does not eliminate the latent reservoir and cure the infection. Type I interferons (IFN) mediate antiviral effects through different mechanisms than cART. We previously showed that IFNα14 is the most potent IFNα subtype against HIV-1 and that it can significantly reduce the HIV-1 proviral reservoir. This study sought to determine whether combining cART with IFNα14 therapy would produce greater reductions in HIV-1 viral and proviral loads than ART alone. Immunodeficient Rag2−/−γc−/−CD47−/− C57BL/6 mice were humanized by the BLT method, infected with HIV-1JR-CSF and the in vivo efficacy of cART was compared with combined cART/IFNα14 therapy. Infection was allowed to establish for 6 weeks prior to 4 weeks of treatment with oral cART either with or without IFNα14. Plasma viral RNA and splenic CD4+ T cell viral DNA levels were measured immediately after treatment and after 2 weeks of therapy interruption. Augmentation of cART with IFNα14 resulted in significantly enhanced suppression of HIV-1 plasma viremia. However, no significant reduction in total viral DNA was detectable. Furthermore, virus rebounded after treatment interruption to similar levels in both groups. Thus, augmentation of cART with IFNα14 resulted in a more pronounced reduction of HIV viremia levels over cART alone, but the effect was not potent enough to be detected at the viral DNA level or to prevent virus rebound following therapy interruption in immune system-humanized mice.

scholarly journals Sensing of HIV-1 Entry Triggers a Type I Interferon Response in Human Primary Macrophages

2017 ◽  
Vol 91 (15) ◽  
Author(s):  
Jérémie Decalf ◽  
Marion Desdouits ◽  
Vasco Rodrigues ◽  
François-Xavier Gobert ◽  
Matteo Gentili ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Viral Entry ◽  
Reverse Transcription ◽  
Great Part ◽  
Interferon Response ◽  
Viral Reservoir ◽  
Type I ◽  
Viral Fusion ◽  
Viral Spread ◽  
Hiv 1

ABSTRACT Along with CD4+ T lymphocytes, macrophages are a major cellular source of HIV-1 replication and a potential viral reservoir. Following entry and reverse transcription in macrophages, cloaking of the viral cDNA by the HIV-1 capsid limits its cytosolic detection, enabling efficient replication. However, whether incoming HIV-1 particles are sensed by macrophages prior to reverse transcription remains unclear. Here, we show that HIV-1 triggers a broad expression of interferon (IFN)-stimulated genes (ISG) in monocyte-derived macrophages within a few hours after infection. This response does not require viral reverse transcription or the presence of HIV-1 RNA within particles, but viral fusion is essential. This response is elicited by viruses carrying different envelope proteins and thus different receptors to proceed for viral entry. Expression of ISG in response to viral entry requires TBK1 activity and type I IFNs signaling. Remarkably, the ISG response is transient but affects subsequent viral spread. Together, our results shed light on an early step of HIV-1 sensing by macrophages at the level of entry, which confers an early protection through type I IFN signaling and has potential implications in controlling the infection. IMPORTANCE HIV infection is restricted to T lymphocytes and macrophages. HIV-1-infected macrophages are found in many tissues of infected patients, even under antiretroviral therapy, and are considered a viral reservoir. How HIV-1 is detected and what type of responses are elicited upon sensing remain in great part elusive. The kinetics and localization of the production of cytokines such as interferons in response to HIV is of critical importance to understanding how the infection and the immune response are established. Our study provides evidence that macrophages can detect HIV-1 as soon as it enters the cell. Interestingly, this sensing is independent of the presence of viral nucleic acids within the particles but requires their fusion with the macrophages. This triggers a low interferon response, which activates an antiviral program protecting cells against further viral challenge and thus potentially limiting the spread of the infection.

scholarly journals Characterization of intact proviruses in blood and lymph node from HIV-infected individuals undergoing analytical treatment interruption

2018 ◽  
Author(s):  
Line K. Vibholm ◽  
Julio C.C. Lorenzi ◽  
Joy A. Pai ◽  
Yehuda Z. Cohen ◽  
Thiago Y. Oliveira ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
Antiretroviral Therapy ◽  
Treatment Interruption ◽  
Latent Reservoir ◽  
Lymphoid Tissues ◽  
Analytical Treatment ◽  
Hiv 1

AbstractThe role of lymphoid tissue as a potential source of HIV-1 rebound following interruption of antiretroviral therapy is uncertain. To address this issue, we compared the latent viruses obtained from CD4+ T cells in peripheral blood and lymph nodes to viruses emerging during treatment interruption. Latent viruses were characterized by sequencing near full-length (NFL) proviral DNA, and env from viral outgrowth cultures (VOAs). 5 HIV-1 infected individuals on antiretroviral therapy (ART) were studied, 4 of whom participated in a clinical trial that included an analytical treatment interruption. Intact or replication competent clonal sequences from blood and lymph node overlapped. In contrast, there was no overlap between 205 latent reservoir and 125 rebound sequences in the 4 individuals who underwent treatment interruption. However, rebound viruses could be accounted for by recombination. The data suggests that CD4+ T cells carrying latent viruses circulate between blood and lymphoid tissues in individuals on ART and support the idea that recombination may play a role in the emergence of rebound viremia.

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