scholarly journals The Mouse Cytomegalovirus Immediate-Early 1 Gene Is Not Required for Establishment of Latency or for Reactivation in the Lungs

2009 ◽  
Vol 83 (9) ◽  
pp. 4030-4038 ◽  
Author(s):  
Andreas Busche ◽  
Anja Marquardt ◽  
Andre Bleich ◽  
Peter Ghazal ◽  
Ana Angulo ◽  
...  
Keyword(s):  
Latent Infection ◽  
Acute Infection ◽  
Lytic Replication ◽  
Immediate Early ◽  
Productive Infection ◽  
Viral Gene ◽  
Mouse Cytomegalovirus ◽  
Early Protein ◽  
Latently Infected

ABSTRACT The immediate-early protein IE1 of human and mouse cytomegalovirus (MCMV) is one of the first proteins expressed during the productive infection cycle and upon reactivation from latency. The CMV IE1 proteins have been found to inhibit histone deacetylases, suggesting a role in the epigenetic regulation of viral gene expression. Consequently, the IE1 protein is considered to have a profound effect on reactivation, because small amounts of IE1 may be decisive for the switch to lytic replication. Here we asked if an MCMV Δie1 mutant is able both to establish latency and to reactivate from the lungs of latently infected mice. Since the Δie1 mutant was known to be attenuated during acute infection, we first defined conditions that led to comparable levels of viral genomes during latent infection with mutant and wild-type (wt) MCMV. Viral genome copy numbers dropped considerably at the onset of the latent infection but then remained steady for both viruses even after several months. Reactivation of the Δie1 mutant and of wt MCMV from latency occurred with similar incidences in lung explant cultures at 4, 7, and 12 months postinfection. The increase in the frequency of a subset of MCMV-specific memory T cells, a possible indicator of frequent transcriptional reactivation events during latency, was in a comparable range for both viruses. Recurrence of the Δie1 virus infection in vivo could also be induced by hematoablative treatment of latently infected mice. We conclude that the ie1 gene is not essential for the establishment of latency or for the reactivation of MCMV.

scholarly journals Establishment of Murine Cytomegalovirus Latency In Vivo Is Associated with Changes in Histone Modifications and Recruitment of Transcriptional Repressors to the Major Immediate-Early Promoter

2008 ◽  
Vol 82 (21) ◽  
pp. 10922-10931 ◽  
Author(s):  
Xue-feng Liu ◽  
Shixian Yan ◽  
Michael Abecassis ◽  
Mary Hummel
Keyword(s):  
Gene Expression ◽  
Histone Modifications ◽  
Latent Infection ◽  
Control Point ◽  
Immediate Early ◽  
Productive Infection ◽  
Murine Cytomegalovirus ◽  
Critical Control Point ◽  
Latently Infected

ABSTRACT Human cytomegalovirus (CMV) is a ubiquitous herpesvirus with the ability to establish a lifelong latent infection. The mechanism by which this occurs is not well understood. Regulation of, for example, immediate-early (IE) gene expression is thought to be a critical control point in transcriptional control of the switch between latency and reactivation. Here, we present evidence that supports previous studies showing that the majority of genomes are quiescent with respect to gene expression. To study the possible role of epigenetic factors that may be involved in repression of ie gene expression in latency, we have analyzed changes in the patterns of modifications of histones bound to the major IE promoter (MIEP) in the kidneys of acutely and latently infected mice. Our studies show that, like herpes simplex virus, murine CMV genomes become relatively enriched in histones in latent infection. There are dramatic changes in modifications of histones associated with the MIEP when latency is established: H3 and H4 become hypoacetylated and H3 is hypomethylated at lysine 4, while H3 lysine 9 is hypermethylated in latently infected mice. These changes are accompanied by a relative loss of RNA polymerase and gain of heterochromatin protein 1γ and Yin-Yang 1 bound to the MIEP. Our studies suggest that, in the majority of cells, CMV establishes a true latent infection, defined as the lack of expression of genes associated with productive infection, and that this occurs through changes in histone modifications and recruitment of transcriptional silencing factors to the MIEP.

scholarly journals Immunohistochemical Analysis of Primary Sensory Neurons Latently Infected with Herpes Simplex Virus Type 1

2000 ◽  
Vol 74 (1) ◽  
pp. 209-217 ◽  
Author(s):  
L. Yang ◽  
C. C. Voytek ◽  
T. P. Margolis
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Sensory Neurons ◽  
Latent Infection ◽  
Productive Infection ◽  
Viral Gene ◽  
Primary Sensory Neurons ◽  
Neuronal Populations ◽  
Latently Infected ◽  
Simplex Virus

ABSTRACT We characterized the populations of primary sensory neurons that become latently infected with herpes simplex virus (HSV) following peripheral inoculation. Twenty-one days after ocular inoculation with HSV strain KOS, 81% of latency-associated transcript (LAT)-positive trigeminal ganglion (TG) neurons coexpressed SSEA3, 71% coexpressed TrkA (the high-affinity nerve growth factor receptor), and 68% coexpressed antigen recognized by monoclonal antibody (MAb) A5; less than 5% coexpressed antigen recognized by MAb KH10. The distribution of LAT-positive, latently infected TG neurons contrasted sharply with (i) the overall distribution of neuronal phenotypes in latently infected TG and (ii) the neuronal distribution of viral antigen in productively infected TG. Similar results were obtained following ocular and footpad inoculation with KOS/62, a LAT deletion mutant in which the LAT promoter is used to drive expression of theEscherichia coli lacZ gene. Thus, although all neuronal populations within primary sensory ganglia appear to be capable of supporting a productive infection with HSV, some neuronal phenotypes are more permissive for establishment of a latent infection with LAT expression than others. Furthermore, expression of HSV LAT does not appear to play a role in this process. These findings indicate that there are marked differences in the outcome of HSV infection among the different neuronal populations in the TG and highlight the key role that the host neuron may play in regulating the repertoire of viral gene expression during the establishment of HSV latent infection.

scholarly journals Mouse Cytomegalovirus Immediate-Early Protein 1 Binds with Host Cell Repressors To Relieve Suppressive Effects on Viral Transcription and Replication during Lytic Infection

2003 ◽  
Vol 77 (2) ◽  
pp. 1357-1367 ◽  
Author(s):  
Qiyi Tang ◽  
Gerd G. Maul
Keyword(s):  
Promoter Region ◽  
Trichostatin A ◽  
Immediate Early ◽  
Productive Infection ◽  
Mouse Cytomegalovirus ◽  
Viral Genomes ◽  
Histone Deacetylase 2 ◽  
Early Protein ◽  
Repressive Effect ◽  
In Cells

ABSTRACT Herpesviruses start their transcriptional cascade at nuclear domain 10 (ND10). The deposition of virus genomes at these nuclear sites occurs due to the binding of the interferon-inducible repressor protein promyelocytic leukemia protein (PML) and/or Daxx to a viral DNA-protein complex. However, the presence of repressive proteins at the nuclear site of virus transcription has remained unexplained. We investigated the mouse cytomegalovirus (MCMV) immediate-early 1 protein (IE1), which is necessary for productive infection at low multiplicities of infection and therefore likely to be involved in overcoming cellular repression. Temporal analysis of IE1 distribution revealed its initial segregation into ND10 by binding to PML and/or Daxx and IE1-dependent recruitment of the transcriptional repressor histone deacetylase-2 (HDAC-2) to this site. However, these protein aggregates are dissociated in cells producing sufficient IE1 through titration of PML, Daxx, and HDAC-2. Importantly, binding of IE1 to HDAC-2 decreased deacetylation activity. Moreover, inhibition of HDAC by trichostatin-A resulted in an increase in viral protein synthesis, an increase in cells starting the formation of prereplication compartments, and an increase in the total infectious viruses produced. Thus, IE1, like trichostatin-A, reverses the repressive effect of HDAC evident in the presence of acetylated histones in the immediate-early promoter region. Since HDAC also binds to the promoter region of IE1, as determined by the chromatin immunoprecipitation assay, these combined results suggest that IE1 inhibits or reverses HDAC-mediated repression of the infecting viral genomes, possibly by a process akin to activation of heterochromatin. We propose that even permissive cells can repress transcription of infecting viral genomes through repressors, including HDAC, Daxx, and PML, and the segregation of IE1 to ND10 that would inactivate those repressors. The virus can counter this repression by overexpressing IE1 when present in sufficient copy number, thus reducing the availability and effectiveness of these repressors.

scholarly journals A Novel Viral Transcript with Homology to Human Interleukin-10 Is Expressed during Latent Human Cytomegalovirus Infection

2004 ◽  
Vol 78 (3) ◽  
pp. 1440-1447 ◽  
Author(s):  
Christina Jenkins ◽  
Allison Abendroth ◽  
Barry Slobedman
Keyword(s):  
Human Cytomegalovirus ◽  
Mononuclear Cells ◽  
Latent Infection ◽  
Interleukin 10 ◽  
Productive Infection ◽  
Viral Gene ◽  
Immune Recognition ◽  
Viral Transcript ◽  
Latently Infected ◽  
Latent Phase

ABSTRACT Human cytomegalovirus (CMV) establishes latent infections in hematopoietic cells such as granulocyte-macrophage progenitors (GM-Ps). During latency the virus is sequestered in a nonreplicating state, although limited transcriptional activity has been previously reported. In this study we sought to further examine viral gene expression during the latent phase of infection. Using an experimental model of latency, primary human GM-Ps were latently infected with CMV strain Toledo and extracted RNA subjected to reverse transcription-PCR by using CMV gene-specific primers. Using this approach, we detected transcription from the UL111.5A region of the viral genome. This transcription was also detected in GM-Ps latently infected with AD169 and Towne strains, indicating that expression was CMV strain independent. Significantly, we detected UL111.5A-region transcripts in mononuclear cells from healthy bone marrow and mobilized peripheral blood allograft donors, demonstrating expression during natural latent infection. Mapping experiments with RNA extracted from latently infected GM-Ps revealed the expression of a novel UL111.5A region transcript with a splicing pattern that differed from that reported during productive infection of permissive cells. This UL111.5A region transcript expressed during latent infection is predicted to encode a 139-amino-acid protein with homology to the potent immunosuppressor interleukin-10 (IL-10) and to the viral IL-10 homolog that is expressed during productive CMV infection. Expression of a latency-associated cmvIL-10 may confer upon the virus an ability to avoid immune recognition and clearance during the latent phase of infection.

scholarly journals NK cell activation through the NKG2D ligand MULT-1 is selectively prevented by the glycoprotein encoded by mouse cytomegalovirus gene m145

2005 ◽  
Vol 201 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Astrid Krmpotic ◽  
Milena Hasan ◽  
Andrea Loewendorf ◽  
Tanja Saulig ◽  
Anne Halenius ◽  
...  
Keyword(s):  
Cell Activation ◽  
Nk Cell ◽  
Surface Expression ◽  
Viral Gene ◽  
Nkg2d Ligand ◽  
Mouse Cytomegalovirus ◽  
Mcmv Infection ◽  
Viral Survival ◽  
Necessary And Sufficient

The NK cell–activating receptor NKG2D interacts with three different cellular ligands, all of which are regulated by mouse cytomegalovirus (MCMV). We set out to define the viral gene product regulating murine UL16-binding protein-like transcript (MULT)-1, a newly described NKG2D ligand. We show that MCMV infection strongly induces MULT-1 gene expression, but surface expression of this glycoprotein is nevertheless completely abolished by the virus. Screening a panel of MCMV deletion mutants defined the gene m145 as the viral regulator of MULT-1. The MCMV m145-encoded glycoprotein turned out to be necessary and sufficient to regulate MULT-1 by preventing plasma membrane residence of MULT-1. The importance of MULT-1 in NK cell regulation in vivo was confirmed by the attenuating effect of the m145 deletion that was lifted after NK cell depletion. Our findings underline the significance of escaping MULT-1/NKG2D signaling for viral survival and maintenance.

scholarly journals Herpes Simplex Virus ICP27 Is Required for Virus-Induced Stabilization of the ARE-Containing IEX-1 mRNA Encoded by the Human IER3 Gene

2006 ◽  
Vol 80 (19) ◽  
pp. 9720-9729 ◽  
Author(s):  
Jennifer A. Corcoran ◽  
Wei-Li Hsu ◽  
James R. Smiley
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Mapk Pathway ◽  
Immediate Early ◽  
Productive Infection ◽  
Mrna Stabilization ◽  
Early Protein ◽  
Host Shutoff ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Herpes simplex virus (HSV) stifles cellular gene expression during productive infection of permissive cells, thereby diminishing host responses to infection. Host shutoff is achieved largely through the complementary actions of two viral proteins, ICP27 and virion host shutoff (vhs), that inhibit cellular mRNA biogenesis and trigger global mRNA decay, respectively. Although most cellular mRNAs are thus depleted, some instead increase in abundance after infection; perhaps surprisingly, some of these contain AU-rich instability elements (AREs) in their 3′-untranslated regions. ARE-containing mRNAs normally undergo rapid decay; however, their stability can increase in response to signals such as cytokines and virus infection that activate the p38/MK2 mitogen-activated protein kinase (MAPK) pathway. We and others have shown that HSV infection stabilizes the ARE mRNA encoding the stress-inducible IEX-1 mRNA, and a previous report from another laboratory has suggested vhs is responsible for this effect. However, we now report that ICP27 is essential for IEX-1 mRNA stabilization whereas vhs plays little if any role. A recent report has documented that ICP27 activates the p38 MAPK pathway, and we detected a strong correlation between this activity and stabilization of IEX-1 mRNA by using a panel of HSV type 1 (HSV-1) isolates bearing an array of previously characterized ICP27 mutations. Furthermore, IEX-1 mRNA stabilization was abrogated by the p38 inhibitor SB203580. Taken together, these data indicate that the HSV-1 immediate-early protein ICP27 alters turnover of the ARE-containing message IEX-1 by activating p38. As many ARE mRNAs encode proinflammatory cytokines or other immediate-early response proteins, some of which may limit viral replication, it will be of great interest to determine if ICP27 mediates stabilization of many or all ARE-containing mRNAs.

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 General blockade of human cytomegalovirus immediate-early mRNA expression in the S/G2 phase by a nuclear, Daxx- and PML-independent mechanism

2011 ◽  
Vol 92 (12) ◽  
pp. 2757-2769 ◽  
Author(s):  
Martin Zydek ◽  
Ralf Uecker ◽  
Nina Tavalai ◽  
Thomas Stamminger ◽  
Christian Hagemeier ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Human Cytomegalovirus ◽  
Viral Entry ◽  
Nuclear Genome ◽  
Viral Gene Expression ◽  
Lytic Replication ◽  
Immediate Early ◽  
Viral Gene ◽  
Level Control ◽  
G2 Phase

The onset of human cytomegalovirus (HCMV) lytic replication is strictly controlled by the host cell division cycle. Although viral entry of S/G2-phase cells is unperturbed expression of major immediate-early (MIE) genes IE1 and IE2 is tightly blocked in these cells. Besides the finding that cyclin-dependent kinase (CDK) activity is required for IE1/IE2 repression little is known about the nature of this cell cycle-dependent block. Here, we show that the block occurs after nuclear entry of viral DNA and prevents the accumulation of IE1/IE2 mRNAs, suggesting an inhibition of transcription. Remarkably, the presence of cis-regulatory regions of the MIE locus is neither sufficient nor necessary for IE1/IE2 repression in the S/G2 phase. Furthermore, the block of viral mRNA expression also affects other immediate-early transcribed regions, i.e. the US3 and UL36–38 gene loci. This suggests a mechanism of repression that acts in a general and not a gene-specific fashion. Such a nuclear, genome-wide repression of HCMV is typically mediated by the intrinsic immune defence at nuclear domain 10 (ND10) structures. However, we found that neither Daxx nor PML, the main players of ND10-based immunity, are required for the block to viral gene expression in the S/G2 phase. In addition, the viral tegument protein pp71 (pUL82), a major antagonist of the intrinsic immunity at pre-immediate-early times of infection, proved to be functional in S-phase cells. This suggests the existence of a yet undiscovered, CDK-dependent mechanism exerting higher-level control over immediate-early mRNA expression in HCMV-infected cells.

scholarly journals Daxx-Mediated Accumulation of Human Cytomegalovirus Tegument Protein pp71 at ND10 Facilitates Initiation of Viral Infection at These Nuclear Domains

2002 ◽  
Vol 76 (15) ◽  
pp. 7705-7712 ◽  
Author(s):  
Alexander M. Ishov ◽  
Olga V. Vladimirova ◽  
Gerd G. Maul
Keyword(s):  
Human Cytomegalovirus ◽  
Coiled Coil ◽  
Immediate Early ◽  
Productive Infection ◽  
Tegument Protein ◽  
Knockout Mutant ◽  
Nuclear Site ◽  
Immediate Early Proteins ◽  
Nuclear Domains

ABSTRACT Human cytomegalovirus (HCMV) starts immediate-early transcription at nuclear domains 10 (ND10), forming a highly dynamic immediate transcript environment at this nuclear site. The reason for this spatial correlation remains enigmatic, and the mechanism for induction of transcription at ND10 is unknown. We investigated whether tegument-based transactivators are involved in the specific intranuclear location of HCMV. Here, we demonstrate that the HCMV transactivator tegument protein pp71 accumulates at ND10 before the production of immediate-early proteins. Intracellular trafficking of pp71 is facilitated through binding to a coiled-coil region of Daxx. The C-terminal domain of Daxx then interacts with SUMO-modified PML, resulting in the deposition of pp71 at ND10. In Daxx-deficient cells, pp71 does not accumulate at ND10, proving in vivo the necessity of Daxx for pp71 deposition. Also, HCMV forms immediate transcript environments at sites other than ND10 in Daxx-deficient cells, and so does the HCMV pp71 knockout mutant UL82−/− in normal cells. This result strongly suggests that pp71 and Daxx are essential for HCMV transcription at ND10. Lack of Daxx had the effect of reducing the infection rate. We conclude that the tegument transactivator pp71 facilitates viral genome deposition and transcription at ND10, possibly priming HCMV for more efficient productive infection.

scholarly journals Immune Evasion Proteins Enhance Cytomegalovirus Latency in the Lungs

2009 ◽  
Vol 83 (19) ◽  
pp. 10293-10298 ◽  
Author(s):  
Verena Böhm ◽  
Christof K. Seckert ◽  
Christian O. Simon ◽  
Doris Thomas ◽  
Angélique Renzaho ◽  
...  
Keyword(s):  
T Cells ◽  
Cd8 T Cells ◽  
Viral Gene Expression ◽  
Productive Infection ◽  
Effector Memory ◽  
Viral Gene ◽  
Cmv Infection ◽  
Hematopoietic Reconstitution ◽  
Latently Infected ◽  
Effector Memory Cells

ABSTRACT CD8 T cells control cytomegalovirus (CMV) infection in bone marrow transplantation recipients and persist in latently infected lungs as effector memory cells for continuous sensing of reactivated viral gene expression. Here we have addressed the question of whether viral immunoevasins, glycoproteins that specifically interfere with antigen presentation to CD8 T cells, have an impact on viral latency in the murine model. The data show that deletion of immunoevasin genes in murine CMV accelerates the clearance of productive infection during hematopoietic reconstitution and leads to a reduced latent viral genome load, reduced latency-associated viral transcription, and a lower incidence of recurrence in lung explants.

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