scholarly journals The Early Gene hhi1 Reactivates Heliothis zea Nudivirus 1 in Latently Infected Cells

2009 ◽  
Vol 84 (2) ◽  
pp. 1057-1065 ◽  
Author(s):  
Yueh-Lung Wu ◽  
Carol P. Wu ◽  
Song-Tay Lee ◽  
Han Tang ◽  
Chi-Hua Chang ◽  
...  
Keyword(s):  
Viral Infection ◽  
Critical Role ◽  
Heliothis Zea ◽  
Virus Titer ◽  
Viral Reactivation ◽  
Early Gene ◽  
Mechanistic Study ◽  
Early Genes ◽  
Latently Infected ◽  
Infected Cells

ABSTRACT Heliothis zea nudivirus 1 (HzNV-1), previously known as Hz-1 virus, is an insect virus able to establish both productive and latent infections in several lepidopteran insect cells. Here, we have cloned and characterized one of the HzNV-1 early genes, hhi1, which maps to the HindIII-I fragment of the viral genome. During the productive viral infection, a 6.2-kb hhi1 transcript was detectable as early as 0.5 h postinfection (hpi). The level of transcript reached a maximum at 2 hpi and gradually decreased after 4 hpi. The transcript was not detectable during the latent phase of viral infection. Upon cycloheximide treatment, much higher levels of hhi1 transcript were detected throughout the productive viral infection cycle, suggesting that newly synthesized proteins are not needed for the expression of hhi1. Nevertheless, viral coinfection can further stimulate the expression of transfected hhi1 promoter in a plasmid. Transient hhi1 expression in latently infected cells resulted in a significant increase in virus titer and viral DNA propagation, suggesting that hhi1 plays a critical role in viral reactivation. Additional experiments showed that six early genes, which possibly function in transcription or DNA replication, were activated in the latent cells upon hhi1 transfection. Among these six genes, orf90 and orf121 expression could be induced by hhi1 alone without the need for other viral genes. Our discovery should be useful for future mechanistic study of the switches of latent/productive HzNV-1 viral infections.

scholarly journals Targeting the latent human cytomegalovirus reservoir for T-cell-mediated killing with virus-specific nanobodies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Timo W. M. De Groof ◽  
Elizabeth G. Elder ◽  
Eleanor Y. Lim ◽  
Raimond Heukers ◽  
Nick D. Bergkamp ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Early Gene ◽  
Latent Reservoir ◽  
Solid Organ ◽  
Cell Transplant ◽  
Viral Receptor ◽  
Transplant Patients ◽  
Latently Infected ◽  
Infected Cells

AbstractLatent human cytomegalovirus (HCMV) infection is characterized by limited gene expression, making latent HCMV infections refractory to current treatments targeting viral replication. However, reactivation of latent HCMV in immunosuppressed solid organ and stem cell transplant patients often results in morbidity. Here, we report the killing of latently infected cells via a virus-specific nanobody (VUN100bv) that partially inhibits signaling of the viral receptor US28. VUN100bv reactivates immediate early gene expression in latently infected cells without inducing virus production. This allows recognition and killing of latently infected monocytes by autologous cytotoxic T lymphocytes from HCMV-seropositive individuals, which could serve as a therapy to reduce the HCMV latent reservoir of transplant patients.

scholarly journals The gammaherpesvirus 68 viral cyclin facilitates reactivation by promoting latent gene expression

2019 ◽  
Author(s):  
Brian F Niemeyer ◽  
Joy E Gibson ◽  
Jennifer N Berger ◽  
Lauren M Oko ◽  
Eva Medina ◽  
...  
Keyword(s):  
Gene Expression ◽  
Critical Role ◽  
Productive Infection ◽  
Viral Gene ◽  
Cellular Distribution ◽  
Viral Cyclin ◽  
Latently Infected ◽  
Infected Cells ◽  
Virally Encoded ◽  
The Impact

AbstractGammaherpesviruses establish life-long infections within their host and have been shown to be the causative agents of devastating malignancies. Chronic infection within the host is mediated through cycles of transcriptionally quiescent stages of latency with periods of reactivation into more active lytic and productive infection. The mechanisms that regulate reactivation from latency remain poorly understood. Previously, we defined a critical role for the viral cyclin in promoting reactivation from latency. Disruption of the viral cyclin had no impact on the frequency of cells containing viral genome during latency, yet it remains unclear whether the viral cyclin influences latently infected cells in a qualitative manner. To define the impact of the viral cyclin on latent gene expression, we utilized a viral cyclin deficient variant expressing a LANA-beta-lactamase fusion protein (LANA::βla), to enumerate both the cellular distribution and frequency of latent gene expression. Disruption of the viral cyclin did not affect the cellular distribution of latently infected cells, but did result in a significant decrease in the frequency of cells that expressed LANA::βla across multiple tissues and in both immunocompetent and immunodeficient hosts. Strikingly, whereas the cyclin-deficient virus had a reactivation defect in bulk culture, sort purified cyclin-deficient LANA::βla expressing cells were fully capable of reactivation. These data emphasize that the γHV68 latent reservoir is comprised of at least two distinct stages of infection characterized by differential latent gene expression, and that a primary function of the viral cyclin is to promote latent gene expression within infected cells in vivo.AUTHOR SUMMARYGammaherpesviruses are ubiquitous viruses with oncogenic potential that establish latency for the life of the host. These viruses can emerge from latency through reactivation, a process that is controlled by the immune system. Control of viral latency and reactivation is thought to be critical to prevent γHV-associated disease. This study focuses on a virally-encoded cyclin that is required for reactivation from latency. By characterizing how the viral cyclin influences latent infection in pure cell populations, we find that the viral cyclin has a vital role in promoting viral gene expression during latency. This work provides new insight into the function of a virally encoded cyclin in promoting reactivation from latency.

scholarly journals Cyclin-Dependent Kinase Activity Is Required for Efficient Expression and Posttranslational Modification of Human Cytomegalovirus Proteins and for Production of Extracellular Particles

2006 ◽  
Vol 80 (12) ◽  
pp. 5886-5896 ◽  
Author(s):  
Veronica Sanchez ◽  
Deborah H. Spector
Keyword(s):  
Steady State ◽  
Human Cytomegalovirus ◽  
Virus Titer ◽  
State Level ◽  
Early Gene ◽  
Tegument Protein ◽  
Cyclin Dependent Kinase ◽  
Viral Dna ◽  
Infected Cells ◽  
Steady State Levels

ABSTRACT We have previously shown that the addition of the cyclin-dependent kinase (cdk) inhibitor Roscovitine at the beginning of infection of cells with human cytomegalovirus (HCMV) significantly disrupts immediate-early gene expression and the progression of the infection. In the present study, we have examined the effects of cdk inhibition on late viral events by delaying addition of Roscovitine until 24 h postinfection. Although viral DNA replication was inhibited two- to threefold by treatment of infected cells with Roscovitine, the drop did not correspond to the 1- to 2-log-unit decrease in virus titer. Quantification of viral DNA in the supernatant from cells revealed that there was a significant reduction in the production or release of extracellular particles. We observed a lag in the expression of several viral proteins but there was a significant decrease in the steady-state levels of IE2-86. Likewise, the steady-state level of the essential tegument protein UL32 (pp150) was reduced. The levels of pp150 and IE2-86 mRNA were not greatly affected by treatment with Roscovitine and thus did not correlate with the reduced levels of protein. In contrast, the expression of the tegument protein ppUL69 was higher in drug-treated samples, and the protein accumulated in a hyperphosphorylated form. ppUL69 localized to intranuclear aggregates that did not overlap with viral replication centers in cells treated with Roscovitine. Taken together, these data indicate that cdk activity is required at multiple steps during HCMV infection, including the expression, modification, and localization of virus-encoded proteins.

scholarly journals Glycolysis, Glutaminolysis, and Fatty Acid Synthesis Are Required for Distinct Stages of Kaposi's Sarcoma-Associated Herpesvirus Lytic Replication

2017 ◽  
Vol 91 (10) ◽  
Author(s):  
Erica L. Sanchez ◽  
Thomas H. Pulliam ◽  
Terri A. Dimaio ◽  
Angel B. Thalhofer ◽  
Tracie Delgado ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Metabolic Pathways ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Acid Synthesis ◽  
Lytic Replication ◽  
Early Gene ◽  
Latently Infected ◽  
Infected Cells

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). KSHV infection induces and requires multiple metabolic pathways, including the glycolysis, glutaminolysis, and fatty acid synthesis (FAS) pathways, for the survival of latently infected endothelial cells. To determine the metabolic requirements for productive KSHV infection, we induced lytic replication in the presence of inhibitors of different metabolic pathways. We found that glycolysis, glutaminolysis, and FAS are all required for maximal KSHV virus production and that these pathways appear to participate in virus production at different stages of the viral life cycle. Glycolysis and glutaminolysis, but not FAS, inhibit viral genome replication and, interestingly, are required for different early steps of lytic gene expression. Glycolysis is necessary for early gene transcription, while glutaminolysis is necessary for early gene translation but not transcription. Inhibition of FAS resulted in decreased production of extracellular virions but did not reduce intracellular genome levels or block intracellular virion production. However, in the presence of FAS inhibitors, the intracellular virions are noninfectious, indicating that FAS is required for virion assembly or maturation. KS tumors support both latent and lytic KSHV replication. Previous work has shown that multiple cellular metabolic pathways are required for latency, and we now show that these metabolic pathways are required for efficient lytic replication, providing novel therapeutic avenues for KS tumors. IMPORTANCE KSHV is the etiologic agent of Kaposi's sarcoma, the most common tumor of AIDS patients. KS spindle cells, the main tumor cells, all contain KSHV, mostly in the latent state, during which there is limited viral gene expression. However, a percentage of spindle cells support lytic replication and production of virus and these cells are thought to contribute to overall tumor formation. Our previous findings showed that latently infected cells are sensitive to inhibitors of cellular metabolic pathways, including glycolysis, glutaminolysis, and fatty acid synthesis. Here we found that these same inhibitors block the production of infectious virus from lytically infected cells, each at a different stage of viral replication. Therefore, inhibition of specific cellular metabolic pathways can both eliminate latently infected cells and block lytic replication, thereby inhibiting infection of new cells. Inhibition of metabolic pathways provides novel therapeutic approaches for KS tumors.

scholarly journals Effect of Xanthium Strumarium on HIV-1 5′-LTR Transcriptional Activity and Viral Reactivation in Latently Infected Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Chao-Jung Chen ◽  
Mu-Lin Chiu ◽  
Chien-Hui Hung ◽  
Wen-Miin Liang ◽  
Mao-Wang Ho ◽  
...  
Keyword(s):  
Host Cell ◽  
Transcriptional Activity ◽  
Regulatory Protein ◽  
Regulatory Proteins ◽  
Viral Reactivation ◽  
Xanthium Strumarium ◽  
Latently Infected ◽  
Infected Cells ◽  
Hiv 1

Chinese herbal medicines (CHMs) are widely used in Asian countries. They show multiple pharmacological activities, including antiviral activities. The 5′-long terminal repeat (LTR) region of HIV-1, required for viral transcription, is a potential drug target for HIV-1 reactivation and intrinsic cell death induction of infected or latently infected cells. Modulation of HIV-1 reactivation requires interactions between host cell proteins and viral 5′-LTR elements. By evaluation of two CHMs- Xanthium strumarium and Pueraria montana, we found that 1) X. strumarium reactivated HIV-1 latently infected cells in J-Lat 8.4, J-Lat 9.2, U1, and ACH-2 cells in vitro; 2) 27 nuclear regulatory proteins were associated with HIV-1 5′-LTR using deoxyribonucleic acid affinity pull-down and LC-MS/MS analyses; and 3) among them, silencing of XRCC6 reactivated HIV-1 5′-LTR transcriptional activity. We found that X. strumarium inhibits the 5′-LTR associated XRCC6 nuclear regulatory proteins, increases its viral 5′-LTR promoter transcriptional activity, and reactivates HIV-1 latently infected cells in vitro. These findings may contribute to understanding the 5′-LTR activity and the host cell nuclear regulatory protein machinery for reactivating HIV-1 and for future investigations to eradicate and cure HIV-1 infection.

scholarly journals Glycolysis downregulation is a hallmark of HIV-1 latency and sensitizes infected cells to oxidative stress

2020 ◽  
Author(s):  
Iart Luca Shytaj ◽  
Francesco Andrea Procopio ◽  
Mohammad Tarek ◽  
Irene Carlon-Andres ◽  
Hsin-Yao Tang ◽  
...  
Keyword(s):  
Pentose Phosphate ◽  
Viral Reactivation ◽  
People Living With Hiv ◽  
Cellular Models ◽  
Downstream Effectors ◽  
Latently Infected ◽  
Infected Cells ◽  
Latent Hiv ◽  
Living With Hiv ◽  
Hiv 1

AbstractHIV-1 infects lymphoid and myeloid cells, which can harbor a latent proviral reservoir responsible for maintaining lifelong infection. Glycolytic metabolism has been identified as a determinant of susceptibility to HIV-1 infection, but its role in the development and maintenance of HIV-1 latency has not been elucidated. By combining transcriptomic, proteomic and metabolomic analysis, we here show that transition to latent HIV-1 infection downregulates glycolysis, while viral reactivation by conventional stimuli reverts this effect. Decreased glycolytic output in latently infected cells is associated with downregulation of NAD+/NADH. Consequently, infected cells rely on the parallel pentose phosphate pathway and its main product, the antioxidant NADPH, fueling antioxidant pathways maintaining HIV-1 latency. Of note, blocking NADPH downstream effectors, thioredoxin and glutathione, favors HIV-1 reactivation from latency in lymphoid and myeloid cellular models. This provides a “shock and kill effect” decreasing proviral DNA in cells from people-living-with-HIV/AIDS. Overall, our data show that downmodulation of glycolysis is a metabolic signature of HIV-1 latency that can be exploited to target latently infected cells with eradication strategies.

scholarly journals Expanded cellular clones carrying replication-competent HIV-1 persist, wax, and wane

2018 ◽  
Vol 115 (11) ◽  
pp. E2575-E2584 ◽  
Author(s):  
Zheng Wang ◽  
Evelyn E. Gurule ◽  
Timothy P. Brennan ◽  
Jeffrey M. Gerold ◽  
Kyungyoon J. Kwon ◽  
...  
Keyword(s):  
T Cell ◽  
Cellular Proliferation ◽  
Integration Site ◽  
Virus Production ◽  
Viral Reactivation ◽  
Latent Reservoir ◽  
Major Barrier ◽  
Latently Infected ◽  
Infected Cells ◽  
Hiv 1

The latent reservoir for HIV-1 in resting CD4+ T cells is a major barrier to cure. Several lines of evidence suggest that the latent reservoir is maintained through cellular proliferation. Analysis of this proliferative process is complicated by the fact that most infected cells carry defective proviruses. Additional complications are that stimuli that drive T cell proliferation can also induce virus production from latently infected cells and productively infected cells have a short in vivo half-life. In this ex vivo study, we show that latently infected cells containing replication-competent HIV-1 can proliferate in response to T cell receptor agonists or cytokines that are known to induce homeostatic proliferation and that this can occur without virus production. Some cells that have proliferated in response to these stimuli can survive for 7 d while retaining the ability to produce virus. This finding supports the hypothesis that both antigen-driven and cytokine-induced proliferation may contribute to the stability of the latent reservoir. Sequencing of replication-competent proviruses isolated from patients at different time points confirmed the presence of expanded clones and demonstrated that while some clones harboring replication-competent virus persist longitudinally on a scale of years, others wax and wane. A similar pattern is observed in longitudinal sampling of residual viremia in patients. The observed patterns are not consistent with a continuous, cell-autonomous, proliferative process related to the HIV-1 integration site. The fact that the latent reservoir can be maintained, in part, by cellular proliferation without viral reactivation poses challenges to cure.

scholarly journals 20 Rapid CTL recognition of HIV-1 latently infected cells depends on the levels of inducible viral reactivation and CTL activation status

2017 ◽  
Vol 3 ◽  
pp. 13
Author(s):  
A. Ruiz ◽  
O. Blanch-Lombarte ◽  
E. Jimenez-Moyano ◽  
R. Peña ◽  
M. Genescà ◽  
...  
Keyword(s):  
Viral Reactivation ◽  
Latently Infected ◽  
Infected Cells ◽  
Hiv 1 ◽  
Activation Status

scholarly journals Alpha/Beta Interferons Regulate Murine Gammaherpesvirus Latent Gene Expression and Reactivation from Latency

2005 ◽  
Vol 79 (22) ◽  
pp. 14149-14160 ◽  
Author(s):  
Erik S. Barton ◽  
Mary L. Lutzke ◽  
Rosemary Rochford ◽  
Herbert W. Virgin
Keyword(s):  
Gene Expression ◽  
Virus Infection ◽  
Virus Replication ◽  
Critical Role ◽  
Latent Virus ◽  
Viral Reactivation ◽  
Murine Gammaherpesvirus ◽  
Infected Cells ◽  
Alpha Beta

ABSTRACT Alpha/beta interferon (IFN-α/β) protects the host from virus infection by inhibition of lytic virus replication in infected cells and modulation of the antiviral cell-mediated immune response. To determine whether IFN-α/β also modulates the virus-host interaction during latent virus infection, we infected mice lacking the IFN-α/β receptor (IFN-α/βR−/−) and wild-type (wt; 129S2/SvPas) mice with murine gammaherpesvirus 68 (γHV68), a lymphotropic gamma-2-herpesvirus that establishes latent infection in B cells, macrophages, and dendritic cells. IFN-α/βR−/− mice cleared low-dose intranasal γHV68 infection with wt kinetics and harbored essentially wt frequencies of latently infected cells in both peritoneum and spleen by 28 days postinfection. However, latent virus in peritoneal cells and splenocytes from IFN-α/βR−/− mice reactivated ex vivo with >40-fold- and 5-fold-enhanced efficiency, respectively, compared to wt cells. Depletion of IFN-α/β from wt mice during viral latency also significantly increased viral reactivation, demonstrating an antiviral function of IFN-α/β during latency. Viral reactivation efficiency was temporally regulated in both wt and IFN-α/βR−/− mice. The mechanism of IFN-α/βR action was distinct from that of IFN-γR, since IFN-α/βR−/− mice did not display persistent virus replication in vivo. Analysis of viral latent gene expression in vivo demonstrated specific upregulation of the latency-associated gene M2, which is required for efficient reactivation from latency, in IFN-α/βR−/− splenocytes. These data demonstrate that an IFN-α/β-induced pathway regulates γHV68 gene expression patterns during latent viral infection in vivo and that IFN-α/β plays a critical role in inhibiting viral reactivation during latency.

Global properties of nonlinear humoral immunity viral infection models

2015 ◽  
Vol 08 (05) ◽  
pp. 1550058 ◽  
Author(s):  
A. M. Elaiw ◽  
N. H. AlShamrani
Keyword(s):  
Viral Infection ◽  
Humoral Immunity ◽  
Nonlinear Models ◽  
Removal Rate ◽  
Lyapunov Theory ◽  
Target Cells ◽  
Global Dynamics ◽  
Virus Particles ◽  
Latently Infected ◽  
Infected Cells

In this paper, we consider two nonlinear models for viral infection with humoral immunity. The first model contains four compartments; uninfected target cells, actively infected cells, free virus particles and B cells. The second model is a modification of the first one by including the latently infected cells. The incidence rate, removal rate of infected cells, production rate of viruses and the latent-to-active conversion rate are given by more general nonlinear functions. We have established a set of conditions on these general functions and determined two threshold parameters for each model which are sufficient to determine the global dynamics of the models. The global asymptotic stability of all equilibria of the models has been proven by using Lyapunov theory and applying LaSalle's invariance principle. We have performed some numerical simulations for the models with specific forms of the general functions. We have shown that, the numerical results are consistent with the theoretical results.

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