scholarly journals The Latency-Associated Nuclear Antigen of Rhesus Monkey Rhadinovirus Inhibits Viral Replication through Repression of Orf50/Rta Transcriptional Activation

2005 ◽  
Vol 79 (5) ◽  
pp. 3127-3138 ◽  
Author(s):  
Scott M. DeWire ◽  
Blossom Damania

ABSTRACT Rhesus monkey rhadinovirus (RRV) is a gamma-2-herpesvirus that is closely related to Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8. We have previously reported that the transcript for RRV latency-associated nuclear antigen (R-LANA) is expressed during lytic replication in rhesus fibroblasts. In this article, we report the development of a latent culture system for RRV and show that mRNA specific for R-LANA is expressed during latency as well. We have characterized the R-LANA protein and demonstrate that it exhibits a nuclear speckled localization and possesses the ability to homodimerize. When expressed in rhesus fibroblasts, R-LANA can inhibit RRV lytic replication in vitro. We have investigated the mechanism behind this inhibition and find that, while R-LANA itself has very little effect on lytic promoters, it can dramatically decrease the transactivation function of RRV Orf50 (Rta), which is the major viral transcription factor. We further show that the mechanism for this repression involves the recruitment of histone deacetylase complexes (HDACs), because R-LANA's ability to repress Orf50 transactivation is completely reversed by the addition of the HDAC inhibitor trichostatin A (TSA). We also report that TSA alone can significantly reactivate RRV from latently infected cells. We propose that the repressive effects of R-LANA on RRV Orf50 transactivation serve to downregulate the transcription of early genes at late times during the lytic cycle and also help to maintain viral latency by preventing viral reactivation.

2001 ◽  
Vol 75 (3) ◽  
pp. 1378-1386 ◽  
Author(s):  
Jeffrey Vieira ◽  
Patricia O'Hearn ◽  
Louise Kimball ◽  
Bala Chandran ◽  
Lawrence Corey

ABSTRACT The majority of Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells identified in vivo contain latent KSHV, with lytic replication in only a few percent of cells, as is the case for the cells of Kaposi's sarcoma (KS) lesions. Factors that influence KSHV latent or lytic replication are not well defined. Because persons with KS are often immunosuppressed and susceptible to many infectious agents, including human cytomegalovirus (HCMV), we have investigated the potential for HCMV to influence the replication of KSHV. Important to this work was the construction of a recombinant KSHV, rKSHV.152, expressing the green fluorescent protein (GFP) andneo (conferring resistance to G418). The expression of GFP was a marker of KSHV infection in cells of both epithelial and endothelial origin. The rKSHV.152 virus was used to establish cells, including human fibroblasts (HF), containing only latent KSHV, as demonstrated by latency-associated nuclear antigen expression and Gardella gel analysis. HCMV infection of KSHV latently infected HF activated KSHV lytic replication with the production of infectious KSHV. Dual-color immunofluorescence detected both the KSHV lytic open reading frame 59 protein and the HCMV glycoprotein B in coinfected cells, and UV-inactivated HCMV did not activate the production of infectious KSHV-GFP. In addition, HCMV coinfection increased the production of KSHV from endothelial cells and activated lytic cycle gene expression in keratinocytes. These data demonstrate that HCMV can activate KSHV lytic replication and suggest that HCMV could influence KSHV pathogenesis.


2002 ◽  
Vol 76 (19) ◽  
pp. 9819-9831 ◽  
Author(s):  
Scott M. DeWire ◽  
Michael A. McVoy ◽  
Blossom Damania

ABSTRACT Rhesus monkey rhadinovirus (RRV) is a close relative of Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8). RRV serves as an in vitro and an in vivo model for KSHV, and the mapping of its transcription program during lytic replication is significant since it represents de novo infection in the absence of stimulation with phorbol esters. Further, the RRV lytic system facilitates the making of recombinant viruses, and hence transcription profiling of the wild-type virus is important. Currently, the kinetics of lytic gene expression of RRV, the function of the RRV Orf50/Rta gene, and the presence of the RRV R8 and R8.1 genes are not known. This study details the transcription profile seen during RRV lytic replication and shows that RRV latency-associated nuclear antigen, viral FLIP (vFLIP), and vCyclin are transcribed during the RRV lytic phase. In addition, this study describes the identification of three new spliced products of the RRV Orf50, R8, and R8.1 genes, which are structural homologs of the KSHV Orf50, K8, and K8.1 genes, respectively. Characterization of the RRV Orf50 protein identifies it as a strong transcriptional transactivator capable of activating three early RRV promoters. Interestingly, the KSHV Orf50 transactivator can also activate these simian virus promoters, suggesting that there exists a conservation of gene function between the key transcription factors of KSHV and RRV.


Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 401 ◽  
Author(s):  
Anirban Sanyal ◽  
Nina Wallaschek ◽  
Mandy Glass ◽  
Louis Flamand ◽  
Darren Wight ◽  
...  

Human herpesvirus 6A (HHV-6A) replicates in peripheral blood mononuclear cells (PBMCs) and various T-cell lines in vitro. Intriguingly, the virus can also establish latency in these cells, but it remains unknown what influences the decision between lytic replication and the latency of the virus. Incoming virus genomes are confronted with the nuclear domain 10 (ND10) complex as part of an intrinsic antiviral response. Most herpesviruses can efficiently subvert ND10, but its role in HHV-6A infection remains poorly understood. In this study, we investigated if the ND10 complex affects HHV-6A replication and contributes to the silencing of the virus genome during latency. We could demonstrate that ND10 complex was not dissociated upon infection, while the number of ND10 bodies was reduced in lytically infected cells. Virus replication was significantly enhanced upon knock down of the ND10 complex using shRNAs against its major constituents promyelocytic leukemia protein (PML), hDaxx, and Sp100. In addition, we could demonstrate that viral genes are more efficiently silenced in the presence of a functional ND10 complex. Our data thereby provides the first evidence that the cellular ND10 complex plays an important role in suppressing HHV-6A lytic replication and the silencing of the virus genome in latently infected cells.


2018 ◽  
Author(s):  
Calum Forrest ◽  
Andrew D. Hislop ◽  
Alan B Rickinson ◽  
Jianmin Zuo

ABSTRACT (286 words)Human herpesviruses are antigenically rich agents that induce strong CD8+T cell responses in primary infection yet persist for life, continually challenging T cell memory through recurrent lytic replication and potentially influencing the spectrum of antigen-specific responses. Here we describe the first lytic proteome-wide analysis of CD8+ T cell responses to the Epstein-Barr gamma1-herpesvirus (EBV), and the first such proteome-wide analysis of primary versus memory CD8 responses to any human herpesvirus. Primary effector preparations were generated directly from activated CD8+ T cells in the blood of infectious mononucleosis (IM) patients by in vitro mitogenic expansion. For memory preparations, EBV-specific cells in the blood of long-term virus carriers were first re-stimulated in vitro by autologous dendritic cells loaded with a lysate of lytically-infected cells, then expanded as for IM cells. Preparations from 7 donors of each type were screened against each of 70 EBV lytic cycle proteins in combination with the donor’s individual HLA class I alleles. Multiple reactivities against immediate early (IE), early (E) and late (L) lytic cycle proteins, including many hitherto unrecognised targets, were detected in both contexts. Interestingly however, the two donor cohorts showed a different balance between IE, E and L reactivities. Primary responses targeted IE and a small group of E proteins preferentially, seemingly in line with their better presentation on the infected cell surface before later-expressed viral evasins take full hold. By contrast, target choice equilibrates in virus carriage with responses to key IE and E antigens still present but with responses to a select subset of L proteins now often prominent. We infer that, for EBV at least, long-term virus carriage with its low level virus replication and lytic antigen release is associated with a re-shaping of the virus-specific response.


2004 ◽  
Vol 78 (12) ◽  
pp. 6585-6594 ◽  
Author(s):  
Ke Lan ◽  
Daniel A. Kuppers ◽  
Subhash C. Verma ◽  
Erle S. Robertson

ABSTRACT Like other herpesviruses, Kaposi's sarcoma-associated herpesvirus (KSHV, also designated human herpesvirus 8) can establish a latent infection in the infected host. During latency a small number of genes are expressed. One of those genes encodes latency-associated nuclear antigen (LANA), which is constitutively expressed in cells during latent as well as lytic infection. LANA has previously been shown to be important for the establishment of latent episome maintenance through tethering of the viral genome to the host chromosomes. Under specific conditions, KSHV can undergo lytic replication, with the production of viral progeny. The immediate-early Rta, encoded by open reading frame 50 of KSHV, has been shown to play a critical role in switching from viral latent replication to lytic replication. Overexpression of Rta from a heterologous promoter is sufficient for driving KSHV lytic replication and the production of viral progeny. In the present study, we show that LANA down-modulates Rta's promoter activity in transient reporter assays, thus repressing Rta-mediated transactivation. This results in a decrease in the production of KSHV progeny virions. We also found that LANA interacts physically with Rta both in vivo and in vitro. Taken together, our results demonstrate that LANA can inhibit viral lytic replication by inhibiting expression as well as antagonizing the function of Rta. This suggests that LANA may play a critical role in maintaining latency by controlling the switch between viral latency and lytic replication.


2003 ◽  
Vol 77 (7) ◽  
pp. 4261-4272 ◽  
Author(s):  
Jason S. Knight ◽  
Ke Lan ◽  
Chitra Subramanian ◽  
Erle S. Robertson

ABSTRACT Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is a known regulatory transcription factor that has been shown to interact with histone deacetylase 1 (HDAC1) when cotransfected in human cell lines and by in vitro binding experiments. Previous studies have shown that EBNA3C interacts with p300 and prothymosin alpha (ProTα) in EBV-infected cells and may be involved in recruiting acetyltransferases to the chromatin for acetylation of histones and transcriptional activation. EBNA3C has also been shown to function as a repressor of transcription when directed to promoters. In this report, we show that EBNA3C complexed with ProTα can also recruit deacetylase activity and associates in a complex that includes HDAC1 and HDAC2 in human B cells. A complex of EBNA3C and ProTα coimmunoprecipitated with HDAC1 and HDAC2 in cell lines stably expressing EBNA3C. Additionally, this complex associated with the mSin3A and NCoR corepressors in EBNA3C-expressing cell lines and may function in a complex with additional transcription factors known to be repressors of transcription. EBNA3C in complex with ProTα recruited deacetylase activity in cell lines stably expressing EBNA3C, and this activity was shown to be partially sensitive to trichostatin A (TSA). This suggests an association with other deacetylases that are insensitive to the general inhibitory effects of TSA, as the entire activity was not abolished in multiple assays. The association between EBNA3C and the corepressors as well as HDACs is likely to depend on the presence of ProTα in the complex. Immunoprecipitation with anti-ProTα antibody immunoprecipitated EBNA3C and the other repressors, whereas immunoprecipitation with anti-EBNA3C antibody resulted in little or no association with these molecules associated with transcription repression. Clearly, EBNA3C functions as a component of a number of dynamic complexes which function in repression and activation of transcription.


2020 ◽  
Vol 94 (7) ◽  
Author(s):  
Tiffany R. Frey ◽  
Jozan Brathwaite ◽  
Xiaofan Li ◽  
Sandeepta Burgula ◽  
Ibukun A. Akinyemi ◽  
...  

ABSTRACT Lytic activation from latency is a key transition point in the life cycle of herpesviruses. Epstein-Barr virus (EBV) is a human herpesvirus that can cause lymphomas, epithelial cancers, and other diseases, most of which require the lytic cycle. While the lytic cycle of EBV can be triggered by chemicals and immunologic ligands, the lytic cascade is activated only when expression of the EBV latent-to-lytic switch protein ZEBRA is turned on. ZEBRA then transcriptionally activates other EBV genes and, together with some of those gene products, ensures completion of the lytic cycle. However, not every latently infected cell exposed to a lytic trigger turns on the expression of ZEBRA, resulting in responsive and refractory subpopulations. What governs this dichotomy? By examining the nascent transcriptome following exposure to a lytic trigger, we find that several cellular genes are transcriptionally upregulated temporally upstream of ZEBRA. These genes regulate lytic susceptibility to various degrees in latently infected cells that respond to mechanistically distinct lytic triggers. While increased expression of these cellular genes defines a prolytic state, such upregulation also runs counter to the well-known mechanism of viral-nuclease-mediated host shutoff that is activated downstream of ZEBRA. Furthermore, a subset of upregulated cellular genes is transcriptionally repressed temporally downstream of ZEBRA, indicating an additional mode of virus-mediated host shutoff through transcriptional repression. Thus, increased transcription of a set of host genes contributes to a prolytic state that allows a subpopulation of cells to support the EBV lytic cycle. IMPORTANCE Transition from latency to the lytic phase is necessary for herpesvirus-mediated pathology as well as viral spread and persistence in the population at large. Yet, viral genomes in only some cells in a population of latently infected cells respond to lytic triggers, resulting in subpopulations of responsive/lytic and refractory cells. Our investigations into this partially permissive phenotype of the herpesvirus Epstein-Barr virus (EBV) indicate that upon exposure to lytic triggers, certain cellular genes are transcriptionally upregulated, while viral latency genes are downregulated ahead of expression of the viral latent-to-lytic switch protein. These cellular genes contribute to lytic susceptibility to various degrees. Apart from indicating that there may be a cellular “prolytic” state, our findings indicate that (i) early transcriptional upregulation of cellular genes counters the well-known viral-nuclease-mediated host shutoff and (ii) subsequent transcriptional downregulation of a subset of early upregulated cellular genes is a previously undescribed mode of host shutoff.


2004 ◽  
Vol 78 (12) ◽  
pp. 6621-6635 ◽  
Author(s):  
Veronika P. Pozharskaya ◽  
Laura L. Weakland ◽  
James C. Zimring ◽  
Laurie T. Krug ◽  
Elizabeth R. Unger ◽  
...  

ABSTRACT Human herpesvirus 8 (HHV-8) encodes multiple proteins that disrupt the host antiviral response, including viral interferon (IFN) regulatory factor 1 (vIRF-1). The product of the vIRF-1 gene blocks responses to IFN when overexpressed by transfection, but the functional consequence of vIRF-1 that is expressed during infection with HHV-8 is not known. These studies demonstrate that BCBL-1 cells that were latently infected with HHV-8 expressed low levels of vIRF-1 that were associated with PML bodies, whereas much higher levels of vIRF-1 were transiently expressed during the lytic phase of HHV-8 replication. The low levels of vIRF-1 that were associated with PML bodies were insufficient to block alpha IFN (IFN-α)-induced alterations in gene expression, whereas cells that expressed high levels of vIRF-1 were resistant to some changes induced by IFN-α, including the expression of the double-stranded-RNA-activated protein kinase. High levels of vIRF-1 were expressed for only a short period during the lytic cascade, so many cells with HHV-8 in the lytic phase responded to IFN-α with increased expression of antiviral genes and enhanced apoptosis. Furthermore, the production of infectious virus was severely compromised when IFN-α was present early during the lytic cascade. These studies indicate that the transient expression of high levels of vIRF-1 is inadequate to subvert many of the antiviral effects of IFN-α so that IFN-α can effectively induce apoptosis and block production of infectious virus when present early in the lytic cascade of HHV-8.


2009 ◽  
Vol 21 (1) ◽  
pp. 194
Author(s):  
N. Mtango ◽  
K. Latham

After fertilization, cell division is required for development during the transition from a zygote to an embryo. Degradation of oocyte transcripts, transcriptional activation of the nucleus, and chromatin remodeling occur during early cleavage divisions. Defects in cell cycle regulation decrease the ability of embryo to grow and can be detrimental. In the rhesus monkey, embryos derived by fertilization of oocytes from prepubertal females or oocytes collected during the non-breeding season undergo cleavage arrest (Schramm and Bavister 1994; Zheng et al. 2001). We employed the Primate Embryo Gene Expression Resource (PREGER; www.Preger.org) to examine the expression pattern of 70 mRNAs involved in cell cycle regulation in rhesus monkey oocytes and embryos derived from different stimulation protocols (non-stimulated, FSH stimulated-in vitro matured, and FSH and hCG stimulated-in vivo matured; Mtango and Latham 2007, 2008; Zheng et al. 2005). The resource encompasses a large, biologically rich set of more than 170 samples with 1 to 4 oocytes or embryos which were constructed using the quantitative amplification and dot blotting method. This method entails the direct lysis of small numbers of oocytes or embryos in a reverse transcription buffer supplemented with nonionic detergent, thereby avoiding RNA losses associated with organic extractions (Brady and Iscove 1993). We find that aberrant regulation of cell cycle regulatory gene mRNAs is a prominent feature of oocytes and embryos of compromised developmental potential (FSH stimulated-moderate reduced potential and NS-severely compromised potential). Of the 56 mRNAs for which expression was detected, there was significant aberrations related to oocyte and embryo quality in the expression of more than half (n = 30), P < 0.05), 26 of 30 display significant differences in metaphase II stage oocytes, 20 being altered in FSH stimulated females and 24 of 30 being altered in NS females. The comparison between monkey and previously reported mouse array expression data (Zeng et al. 2004) revealed striking differences between 2 species. These data provide novel information about disruptions in the expression of genes controlling the cell cycle in oocytes and embryos of compromised developmental potential. We thank Bela Patel, Malgorzata McMenamin, and Ann Marie Paprocki for their technical assistance. We also thank R. Dee Schramm for his contribution to the development of the PREGER resource. This work was supported by National Centers for Research Resources Grant RR-15253.


2016 ◽  
Vol 90 (17) ◽  
pp. 8013-8028 ◽  
Author(s):  
Alexander S. Hahn ◽  
Anna K. Großkopf ◽  
Doris Jungnickl ◽  
Brigitte Scholz ◽  
Armin Ensser

ABSTRACTNuclear domain 10 (ND10) components restrict herpesviral infection, and herpesviruses antagonize this restriction by a variety of strategies, including degradation or relocalization of ND10 proteins. The rhesus monkey rhadinovirus (RRV) shares many key biological features with the closely related Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) and readily infects cells of both human and rhesus monkey origin. We used the clustered regularly interspaced short palindromic repeat-Cas9 (CRISPR-Cas9) technique to generate knockout (ko) cells for each of the four ND10 components, PML, SP100, DAXX, and ATRX. These ko cells were analyzed with regard to permissiveness for RRV infection. In addition, we analyzed the fate of the individual ND10 components in infected cells by immunofluorescence and Western blotting. Knockout of the ND10 component DAXX markedly increased RRV infection, while knockout of PML or SP100 had a less pronounced effect. In line with these observations, RRV infection resulted in rapid degradation of SP100, followed by degradation of PML and the loss of ND10 structures, whereas the protein levels of ATRX and DAXX remained constant. Notably, inhibition of the proteasome but not inhibition ofde novogene expression prevented the loss of SP100 and PML in cells that did not support lytic replication, compatible with proteasomal degradation of these ND10 components through the action of a viral tegument protein. Expression of the RRV FGARAT homolog ORF75 was sufficient to effect the loss of SP100 and PML in transfected or transduced cells, implicating ORF75 as the viral effector protein.IMPORTANCEOur findings highlight the antiviral role of ND10 and its individual components and further establish the viral FGARAT homologs of the gammaherpesviruses to be important viral effectors that counteract ND10-instituted intrinsic immunity. Surprisingly, even closely related viruses like KSHV and RRV evolved to use different strategies to evade ND10-mediated restriction. RRV first targets SP100 for degradation and then targets PML with a delayed kinetic, a strategy which clearly differs from that of other gammaherpesviruses. Despite efficient degradation of these two major ND10 components, RRV is still restricted by DAXX, another abundant ND10 component, as evidenced by a marked increase in RRV infection and replication upon knockout of DAXX. Taken together, our findings substantiate PML, SP100, and DAXX as key antiviral proteins, in that the first two are targeted for degradation by RRV and the last one still potently restricts replication of RRV.


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