Download or read book HIV 1 Latency written by Guido Silvestri and published by Springer. This book was released on 2018-10-11 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume summarizes recent advances in understanding the mechanisms of HIV-1 latency, in characterizing residual viral reservoirs, and in developing targeted interventions to reduce HIV-1 persistence during antiretroviral therapy. Specific chapters address the molecular mechanisms that govern and regulate HIV-1 transcription and latency; assays and technical approaches to quantify viral reservoirs in humans and animal models; the complex interchange between viral reservoirs and the host immune system; computational strategies to model viral reservoir dynamics; and the development of therapeutic approaches that target viral reservoir cells. With contributions from an interdisciplinary group of investigators that cover a broad spectrum of subjects, from molecular virology to proof-of-principle clinical trials, this book is a valuable resource for basic scientists, translational investigators, infectious-disease physicians, individuals living with HIV/AIDS and the general public.
Download or read book Eradication of the Latent HIV Viral Reservoir written by Nixon Niyonzima and published by . This book was released on 2016 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major barrier to HIV cure is the establishment of a long-lived latent viral reservoir that is not affected by combination ant-retroviral therapy and is not cleared by the immune system. When HIV positive patients on combination anti-retroviral therapy with undetectable viremia interrupt therapy, viremic rebound occurs within two weeks of discontinuing cART. This viral rebound is due to stochastic reactivation of HIV transcription and replication in the long-lived viral reservoir. HIV cure necessitates eradication of this long-lived reservoir. To eradicate the HIV proviral reservoir, we are using HIV-specific engineered meganucleases. Mutations in essential HIV genes can disrupt the integrated provirus and could prevent reactivation from latency. I demonstrate that engineered meganucleases can introduce mutations in an integrated HIV provirus. The HIV-specific engineered meganucleases also cleave and introduce mutations in genomic off-target sites. We show that a second generation of an HIV-specific meganuclease developed using structure guided protein engineering, has an improved off-target toxicity profile and retains activity at the HIV target site. I further demonstrate that expression of the three prime repair exonuclease-2 (Trex2) in combination with either the meganuclease or fusion megaTALs increases the frequency of mutations at the HIV target site. The compact size of meganucleases and the increasing ease with which they can be redesigned to recognize new DNA sequences makes meganucleases an attractive tool for HIV cure applications. HIV cure also requires precise quantitation of the viral reservoir. Current assays used to measure the HIV viral reservoir are imprecise and tend to either over or underestimate the size of the functional reservoir. In the setting of both structured and analytical treatment interruptions it is critical that the reservoir is measured accurately so that patients do not discontinue cART in the setting of large functional reservoirs. I describe here a multiplex ddPCR assay that can simultaneously detect up to six viral genes in the same reaction. The multiplex ddPCR assay gives an estimate of the completeness of the integrated provirus, which can be used to measure levels of functional integrated HIV provirus. I hypothesize that this multiplex ddPCR assay gives a truer estimate of the size of the functional HIV reservoir.
Download or read book HIV Cure Through Eradication of Viral Reservoirs written by Maher M. Elsheikh and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Persistence of the latent HIV reservoir is the main obstacle in preventing or curing HIV. Even though a combination of antiretroviral therapy (cART) is effective in controlling the virus by suppressing its replication and infectivity to below detection levels, cART cannot eliminate the latent reservoir, and must be taken for life. After encountering HIV, some infected CD4+ T cells revert to a resting state and persist as memory T cells that remain quiescent while containing the stable HIV proviral DNA (latent reservoir). With a stable and long-lived reservoir, HIV remains a global health problem because the proviral DNA is transcriptionally silent but is capable of producing infectious particles when cART is interrupted. According to WHO, more than 34 million people died due to AIDS over the past three decades, and about 37 million are currently living with it. In addition, there are approximately two million new cases each year. HIV-infected individuals do not achieve complete immunologic reconstitution because viral suppression is incomplete, and immune activation occurs chronically. The inability of cART to eradicate HIV from latent viral reservoirs necessitates the development of novel therapeutic approaches to eradicate the virus from infected individuals so that cART can be discontinued. The goal of this work was to investigate innovative experimental approaches to eradicate the latent HIV reservoir by targeting specific molecular mechanisms within the PKC/NF-kB and p-TEFb signaling pathways of HIV-infected resting memory CD4+ T cells involved in viral replication and silencing during the HIV life cycle. This goal was successfully achieved by implementing two independent experimental approaches: 1) Eliminating HIV infected cells by inducing reactivation of latent HIV and targeting the activated cells for apoptosis (sterilizing cure). 2) Inducing permanent silencing of HIV in the latent viral reservoir by shutting down the HIV replication machinery, which could permanently inhibit viral replication in the infected cells (functional cure). Subsequently, we were able to identify latency reactivating agents and apoptosis inducing agents that, when used in combination, dramatically reduced the latent HIV reservoir. We were also able to identify several viral silencing agents (VSA) that target essential cellular and viral proteins within the NF-[kappa]B and PKC signaling pathways in infected cells. These VSAs curtail HIV proviral transcription and elongation, which permanently silence latent HIV for multi-generations. They were also effective in reducing viral transcription. Although our data demonstrated that this combination treatment has great potential as an effective anti-HIV therapy, additional testing using larger sample sizes and multiple latency cell models that target various cell reservoirs is needed in order to demonstrate that this therapy is effective and fully functional against various viral sanctuaries in the human body, and is capable of completely eliminating the reservoir with minimal cytotoxicity. Nevertheless, this was an important initial step to prove that our proposed strategy can be successful and should be evaluated further. This novel treatment strategy has the possibility of eliminating the latent HIV reservoir to achieve a drug-free remission and to cure HIV in the future.
Download or read book HIV Reservoirs written by Guido Poli and published by . This book was released on 2022 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book details the development of methods and models to study the HIV-1 viral reservoir with the ultimate goal of achieving a functional cure of HIV infection. Chapters are divided into six parts covering cell lines, in vitro and ex vivo primary cell models of persistent infection, in vitro and ex vivo tissue-derived models, infected animal models human immune cells, methods of detection and analysis of the reservoir, and current approaches to achieve either a functional cure or cART-free long-term remission. Written in the format of the highly successful Methods in Molecular Biology series, each chapter includes an introduction to the topic, lists necessary materials and reagents, includes tips on troubleshooting and known pitfalls, and step-by-step, readily reproducible protocols. Authoritative and cutting-edge, HIV Reservoirs: Methods and Protocols provides a comprehensive, updated collection of state-of-art methodologies and models to tackle the HIV-1 viral reservoir.
Download or read book Novel Approaches for the Eradication of HIV Latently Affected Cells written by Sally Al Ali and published by . This book was released on 2013 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of a suitable experimental cell model to study HIV latency in primary cells could have a massive effect on the current approaches to eradicate virus in latently infected cells. The main proposal of this paper is to develop an in vitro HIV cell model that represents HIV latency in vivo, then to create a more effective viral vector in order to target HIV reservoirs. For this goal, a directed evolution method is suggested to be used in order to mutate the AAV cap gene to generate a recombinant AAV vector that is capable of infecting primary resting CD4+ T cells previously infected with HIV-1 and in a latent stage.
Download or read book Dynamics of the HIV 1 Latent Reservoir written by Mark David Pankau and published by . This book was released on 2019 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human immunodeficiency virus type 1 (HIV) has caused more than 35 million deaths world-wide and contributes significantly to the global burden of disease. Currently, the only effective treatment to suppress viral replication and prevent HIV transmission is combination antiretroviral therapy (ART), which prevents HIV from infecting new cells. Despite the efficacy of ART, long lived latently infected cells persist, with an estimated half-life of 44 months, and circulate throughout the infected host necessitating life-long treatment. These cells, known as the latent reservoir, contain an integrated form of the HIV genome (HIV DNA) that is transcriptionally silent, but can reactivate to produce virus. Therefore, interruption of ART inevitably leads to viral recrudescence stemming from the latent reservoir. Studying the latent reservoir is difficult because these cells contain no known biomarkers and do not always produce replication competent virus upon cellular activation. Additionally, latent reservoir cells are rare, and many proviral genomes contain defects that prevent them from producing replication competent virus. They do however confound efforts to measure the replication competent reservoir. Understanding the dynamics and correlates of reservoir seeding will be essential to develop novel cure strategies that target this latent reservoir. There is limited data on the dynamics of reservoir seeding throughout HIV infection, the impact of treatment interruption on reservoir size, and whether antibodies can play a role in limiting reservoir seeding. I focused my thesis on characterizing the seeding dynamics of latent reservoir cells containing HIV DNA (HIV DNA Reservoir) to better understand when the latent reservoir was generated and how it changed following treatment interruption. In the first part of this thesis I adapt, optimize, and validate a molecular based assay to quantitate HIV DNA from latently infected cells, as well as develop a novel cell line to detect replication competent HIV reactivated from latent reservoirs. In the second part of this thesis I demonstrate that the HIV DNA reservoir is limited by early ART and does not significantly increase following randomization to short treatment interruption in a cohort of Kenyan infants, suggesting that short treatment interruption studies may pose little risk to reservoir reseeding. I also examine the role of ADCC activity in preventing re-seeding of the latent reservoir and demonstrate that ADCC activity does not correlate with change in HIV DNA reservoir size following treatment interruption. Finally, I demonstrate that the HIV DNA reservoir is comprised mostly of viral variants circulating just prior to ART initiation, suggesting that during untreated infection the HIV DNA reservoir decays at a much faster rate than during suppressive ART. Together, these data demonstrate that the HIV DNA reservoir is limited by early ART, is not significantly reseeded with short treatment interruption, and that contrary to previous assumptions about reservoir dynamics, is decaying at a significantly faster rate pre-ART than after ART initiation, and suggest that targeting the HIV latent reservoir prior to early ART initiation may be an effective strategy to limit reservoir size, and that short treatment interruption can limit re-seeding of the latent reservoir.
Download or read book Virus Dynamics Mathematical Principles of Immunology and Virology written by Martin Nowak and published by Oxford University Press, UK. This book was released on 2000-11-23 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: This groundbreaking book describes the emerging field of theoretical immunology, in particular the use of mathematical models to describe the spread of infectious diseases within patients. It reveals fascinating insights into the dynamics of viral and other infections, and the interactions between infectious agents and immune responses. Structured around the examples of HIV/AIDS and hepatitis B, Nowak and May show how mathematical models can help researchers to understand the detailed dynamics of infection and the effects of antiviral therapy. Models are developed to describe the dynamics of drug resistance, immune responses, viral evolution and mutation, and to optimise the design of therapy and vaccines. - ;We know, down to the tiniest details, the molecular structure of the human immunodeficiency virus (HIV). Yet despite this tremendous accomplishment, and despite other remarkable advances in our understanding of individual viruses and cells of the immune system, we still have no agreed understanding of the ultimate course and variability of the pathogenesis of AIDS. Gaps in our understanding like these impede our efforts towards developing effective therapies and preventive vaccines. Martin Nowak and Robert M May describe the emerging field of theoretical immunology in this accessible and well- written text. Using mathematical modelling techniques, the authors set out their ideas about how populations of viruses and populations of immune system cells may interact in various circumstances, and how infectious diseases spread within patients. They explain how this approach to understanding infectious diseases can reveal insights into the dynamics of viral and other infections, and the interactions between infectious agents and immune responses. The book is structured around the examples of HIV/AIDS and Hepatitis B virus, although the approaches described will be more widely applicable. The authors use mathematical tools to uncover the detailed dynamics of the infection and the effects of antiviral therapy. Models are developed to describe the emergence of drug resistance, and the dynamics of immune responses, viral evolution, and mutation. The practical implications of this work for optimisation of the design of therapy and vaccines are discussed. The book concludes with a glance towards the future of this fascinating, and potentially highly useful, field of study. - ;... an excellent introduction to a field that has the potential to advance substantially our understanding of the complex interplay between virus and host - Nature
Download or read book The Dynamics of Intermittent Latent Reservoir Stimulation as a Tool for Eradication of Human Immunodeficiency Virus HIV Infection written by Ellen Rice and published by . This book was released on 2012 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Strategies to Facilitate the Eradication of the HIV 1 Reservoir written by Shariq Mujib and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nearly 40 million individuals are currently living with Human Immunodeficiency Virus type 1 (HIV-1) infection globally and more than 70 million deaths can be attributed to the pathogen so far. HIV-1 primarily infects CD4 T cells leading to their widespread destruction that eventually manifests as Acquired Immunodeficiency Syndrome (AIDS), characterized by debilitating immune failure that gives rise to opportunistic malignancies resulting in death. Daily lifelong administration of antiretroviral therapy known as HAART is the only treatment for HIV-1 infection and adds several years of life if adherence is maintained; but treatment alone does not cure infection. However, despite HAART therapy, HIV-infected individuals exhibit chronic inflammation that is negatively associated with health outcomes. Additionally, mutations give rise to drug resistant viral strains. Therefore, developing a cure remains a top priority. However, HIV-1 constantly evades the immune response and establishes a persistent lifelong viral reservoir making it challenging to cure. In this thesis, I detail three unique strategies to facilitate eradication of the viral reservoir. Specifically, we demonstrated that HIV-1 Nef blockade enhanced the elimination of latently HIV-1-infected CD4 T cells by peptide-expanded autologous CD8 T cells. Nef blockade has never been tested as means to eradicate HIV-1 and represents a novel approach. We further demonstrated that expanded CD8 T cells more efficiently recognize autologous endogenous virus from CD4 T cells undergoing bryostatin-1-mediated virus reactivation in a "shock and kill" approach. Lastly, we discovered that bnAb recognition of HIV-1 envelopes on the surface of infected cells is highly variable and particularly the V1/V2 targeting bnAbs were capable of not only recognition of targets but of induction of antibody-mediated elimination of HIV-1-infected CD4 T cells. All experiments presented here were conducted on primary human cells for physiological relevance and in order to capture the ability of ex vivo immune cells to recognize and kill virus-infected cells. The next step with each of the proposed mechanisms to eliminate the viral reservoir is to assess their safety and efficacy in vivo in order to develop a cure against HIV/AIDS.
Download or read book Oncolytic Viruses as a Potential Approach to Eliminate Cells That Constitute the Latent HIV Reservoir written by Nischal Ranganath and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: HIV infection represents a major health and socioeconomic challenge worldwide. Despite significant advances in therapy, a cure for HIV continues to be elusive. The design of novel curative strategies will require targeting and elimination of cells that constitute the latent HIV-1 reservoir. However, such an approach is impeded by the inability to distinguish latently HIV-infected cells from uninfected cells. The type-I interferon (IFN-I) response is an integral antiviral defense mechanism, but is impaired at multiple levels during productive HIV infection. Interestingly, similar global impairments in IFN-I signaling have been observed in various human cancers. This led to the development of IFN-sensitive oncolytic viruses, including the recombinant Vesicular Stomatitis Virus (VSV 51) and Maraba virus (MG1), as virotherapy designed to treat various cancers. Based on this, it was hypothesized that IFN-I signaling is impaired in latently HIV-infected cells (as observed in productively infected cells) and that VSV 51 and MG1 may be able to exploit such intracellular defects to target and eliminate latently HIV-infected cells, while sparing healthy cells. First, using cell line models of HIV-1 latency, intracellular defects in IFN-I responses, including impaired IFN / production and expression of IFNAR1, MHC-I, ISG15, and PKR, were demonstrated to represent an important feature of latently HIV-infected cells. Consistent with this, the latently HIV-infected cell lines were observed to have a greater sensitivity to VSV 51 and MG1 infection, and MG1-mediated killing, than the HIV-uninfected parental cells. Next, the ability of oncolytic viruses to kill latently HIV-infected human primary cells was demonstrated using an in vitro resting CD4+ T cell model of latency. Interestingly, while both VSV 51 and MG1 infection resulted in a significant reduction in inducible p24 expression, a dose-dependent decrease in integrated HIV-1 DNA was only observed following MG1 infection. In keeping with this, MG1 infection of memory CD4+ T cells from HIV-1 infected individuals on HAART also resulted in a significant decrease in inducible HIV-1 gag RNA expression. By targeting an intracellular pathway that is impaired in latently HIV-infected cells, the findings presented in this dissertation highlight a novel, proof-of-concept approach to eliminate the latent HIV-1 reservoir. Given that VSV 51 and MG1 are currently being studied in cancer clinical trials, there is significant potential to translate this work to in vivo studies.
Download or read book Reactivating Latent HIV 1 written by Prajit Limsirichai and published by . This book was released on 2016 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complete eradication of HIV-1 infection is impeded by the existence of cells that harbor chromosomally integrated but transcriptionally inactive provirus. These latently-infected cells can persist for years without producing viral progeny, rendering them refractory to immune surveillance and antiretroviral therapy and providing a permanent reservoir for the stochastic reactivation and reseeding of HIV-1. Strategies for purging this latent reservoir are thus needed to eradicate infection. Here we show that engineered transcriptional activation systems based on CRISPR/Cas9 can be harnessed to activate HIV-1 expression in cell line models of latency. We utilized two distinct CRISPR transcriptional activation systems, dCas9-VP64 and the synergistic activation mediator (SAM) complex, to target numerous sites across the HIV-1 long terminal repeat (LTR) promoter and observed robust expression from the full-length HIV-1 promoter in multiple cell line models of HIV-1 latency. We further demonstrated that complementing Cas9 activators with latency-reversing compounds can enhance latent HIV-1 transcription and that epigenome modulation using CRISPR-based acetyltransferases could also promote viral gene activation. Finally, we showed that latent HIV-1 expression could also be stimulated by CRISPR-mediated activation of endogenous factors not previously implicated in HIV-1 pathogenesis but whose expression could nonetheless reactivate viral gene expression. Collectively, these results demonstrate that CRISPR systems are potentially effective tools for inducing latent HIV-1 expression and that their use, in combination with antiretroviral therapy, could lead to improved therapies for HIV-1 infection.
Download or read book Molecular Mechanisms Controlling HIV Transcription and Latency Implications for Therapeutic Viral Reactivation written by Michael D. Röling and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Persistence of transcriptionally silent replication competent HIV-1 is a major barrier to clearance of the virus from patients; current combinatorial antiretroviral therapies are successful in abrogating active viral replication, but are unable to eradicate latent HIV-1. A "shock and kill" strategy has been proposed as a curative approach in which latent virus is activated and infected cells are removed by immune clearance, while new rounds of infection are prevented by antiretroviral therapy. Much effort has been put toward understanding the molecular mechanisms maintaining HIV latency and the nature of reservoirs, to provide novel therapeutic targets. This has led to the development of latency reversal agents (LRAs), some of which are undergoing clinical trials. Targeting multiple mechanisms underlying HIV latency via a combination of LRAs is likely to result in more potent activation of the latent reservoir. Therefore, novel as well as synergistic combinations of therapeutic molecules are required to accomplish more potent latency reversal.
Download or read book Human Virology written by John Sidney Oxford and published by Oxford University Press. This book was released on 2016 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by leading authors in the field with both clinical and molecular expertise, Human Virology provides an accessible introduction to this fascinating and important field, making the text ideal for students encountering virology for the first time.
Download or read book Viral Persistence Latent Reservoir and Blips written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: HIV-1 eradication from infected individuals has not been achieved with the use of highly active antiretroviral therapy (HAART) for a prolonged period of time. The cellular reservoir for HIV-1 in resting memory CD4 T cells remains a major obstacle to viral elimination. The reservoir does not decay significantly over long periods of time as is able to release replication competent HIV-1 upon cell activation. Residual ongoing viral replication may likely occur in many patients because low levels of virus can be detected in plasma by sensitive assays and transient episodes of viremia, or HIV-1 blips, are often observed in patients even with successful viral suppression for many years. Here we review our current knowledge of the factors contributing to viral persistence, the latent reservoir, and blips, and mathematical models developed to explore them and their relationships. We show how mathematical modeling can help improve our understanding of HIV-1 dynamics in patients on HAART and the quantitative events underlying HIV-1 latency, reservoir stability, low-level viremic persistence, and emergence of intermittent viral blips. We also discuss treatment implications related to these studies.
Download or read book Encyclopedia of AIDS written by Thomas J. Hope and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Human Retrovirus Protocols written by Tuofu Zhu and published by Springer Science & Business Media. This book was released on 2008-02-04 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: A cutting-edge collection of basic and state-of-the-art methods optimized for investigating the molecular biology of this class of retrovirus. These readily reproducible techniques range from methods for the isolation and detection of human retroviruses to cutting-edge methods for exploring the interplay between the viruses and the host. Here, the researcher will find up-to-date techniques for the isolation and propagation of HIV, HTLV, and foamy virus from a variety of sources. There are also assays for determining the cell tropism of HIV-1, the coreceptor usage of HIV-1, and human gene expression with HIV-1 infection by microarrays, as well as for phenotyping HIV-1 infected monocytes and examining their fitness. Highlights include the detection and quantification of HIV-1 in resting CD4+, a new cloning system for making recombinent virus, cDNA microarrays, and the determination of genetic polymorphisms in two recently identified HIV-1 co-factors that are critical for HIV-1 infection.
Download or read book Factors Important for the Establishment and Maintenance of HIV 1 Latency in CD4 T Cells written by Paula Campos Soto and published by . This book was released on 2008 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Highly active antiretroviral therapy (HAART) in individuals infected with HIV-1 often lowers plasma viremia to below detection limits. However, cessation of therapy in such individuals results in rebound of virus replication, indicating that HIV-infected cells persist. Resting, memory CD4 T cells in the blood and lymph nodes comprise the major reservoir for persistent HIV infection. To devise new efficient strategies targeted toward the eradication of the latently infected HIV reservoir, a better understanding of the molecular and cellular basis for viral latency is needed. Dr. Spina's research group has developed a unique in vitro T cell model to study HIV latency. In my thesis project, I have used and modified this cell model to investigate: 1) the cellular proliferation and activation requirements for the development of latently infected CD4 cells, and 2) the transcriptional activity of the HIV provirus in a nonproductive, persistent infection. Results from the first research phase demonstrated that HIV infection immediately prior to T cell stimulation resulted in production of the greatest number of latently infected cells. Infected cells that did not divide, or divided only a few times, following stimulation went on to form the latently infected cell pool. The vast majority of acutely infected, activated CD4 cells were not able to survive multiple rounds of cell division in combination with the cytopathic effects of HIV. Rather, the subset of CD4 cells that exhibited minimal activation, in the presence of fully-activated and productively infected T cells, survived with latent HIV infection. In the second phase of research, a sensitive qRT-PCR assay was used to examine the transcriptional activity of the HIV provirus in resting, infected CD4 cells. Multiple different species of HIV mRNA were found, with unspliced gag transcripts being the most abundant followed by singly-spliced env, total multiply-spliced, nef, and tat species. Detection of viral RNA transcription in latently infected T cells from our in vitro model has raised the possibility that HIV latency is not maintained by a simple passive mechanism, but may involve active interactions between viral products and cell processes that influence viral latency and reactivation.
