scholarly journals Inhibition of infectious human herpesvirus 8 production by gamma interferon and alpha interferon in BCBL-1 cells

2004 ◽  
Vol 85 (10) ◽  
pp. 2779-2787 ◽  
Author(s):  
Veronika P. Pozharskaya ◽  
Laura L. Weakland ◽  
Margaret K. Offermann
Keyword(s):  
Infectious Virus ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Viral Gene Expression ◽  
Lytic Replication ◽  
Human Herpesvirus 8 ◽  
Viral Gene ◽  
Oligoadenylate Synthetase ◽  
Herpesvirus 8 ◽  
Antiviral Proteins

Human herpesvirus-8 (HHV-8) is aetiologically linked to Kaposi's sarcoma and primary effusion lymphoma. Although interferon-α (IFN-α) and interferon-γ (IFN-γ) are both antiviral cytokines, IFN-α blocks entry of HHV-8 into the lytic phase, whereas IFN-γ induces an increase in the percentage of cells undergoing lytic replication. Multiple events in the lytic cascade must be completed to produce infectious virus. The ability of both types of IFN to affect the production of infectious virus was explored. Both IFN-α and IFN-γ induced expression of the antiviral proteins double-stranded RNA-activated protein kinase (PKR) and 2′5′-oligoadenylate synthetase (2′5′-OAS) in HHV-8-infected BCBL-1 cells. Higher levels resulted from incubation with IFN-α than with IFN-γ, whereas IFN-γ induced higher levels of IRF-1 than did IFN-α. IFN-γ induced a minor increase in lytic viral gene expression, which was not accompanied by a detectible increase in infectious virus. When lytic replication of HHV-8 was induced using TPA, high levels of infectious virus appeared in the conditioned medium. When IFN-γ was present during TPA stimulation, the production of infectious virus was reduced by at least a 60 %, and IFN-α fully blocked TPA-induced production of infectious virus. The greater reduction of viral production that occurred with IFN-α is consistent with the higher levels of the antiviral proteins PKR and 2′5′-OAS induced by IFN-α than by IFN-γ. These studies indicate that the augmentation of cellular antiviral defences by IFN-γ was sufficient to prevent production of infectious virus despite IFN-γ-induced entry of some cells into the lytic phase of HHV-8 replication.

scholarly journals Transcription Program of Human Herpesvirus 8 (Kaposi's Sarcoma-Associated Herpesvirus)

2001 ◽  
Vol 75 (10) ◽  
pp. 4843-4853 ◽  
Author(s):  
Mini Paulose-Murphy ◽  
Nguyen-Khoi Ha ◽  
Chunsheng Xiang ◽  
Yidong Chen ◽  
Laura Gillim ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Human Herpesvirus 8 ◽  
Viral Gene ◽  
Herpesvirus 8 ◽  
Transcription Program

ABSTRACT Human herpesvirus 8 (HHV-8), a gammaherpesvirus implicated in Kaposi's sarcoma, primary effusion lymphoma, and Castleman's disease, encodes several pathogenically important cellular homologs. To define the HHV-8 transcription program, RNA obtained from latently infected body cavity-based lymphoma 1 cells induced to undergo lytic replication was used to query a custom HHV-8 DNA microarray containing nearly every known viral open reading frame. The patterns of viral gene expression offer insights into the replication and pathogenic strategies of HHV-8.

scholarly journals The targeting of primary effusion lymphoma cells for apoptosis by inducing lytic replication of human herpesvirus 8 while blocking virus production

Blood ◽  
2005 ◽  
Vol 105 (10) ◽  
pp. 4028-4034 ◽  
Author(s):  
Carmen M. Klass ◽  
Laurie T. Krug ◽  
Veronika P. Pozharskaya ◽  
Margaret K. Offermann
Keyword(s):  
Tumor Cells ◽  
Infectious Virus ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Virus Production ◽  
B Cell Lymphoma ◽  
Lytic Replication ◽  
Human Herpesvirus 8 ◽  
Viral Transcript ◽  
Herpesvirus 8

AbstractPrimary effusion lymphoma (PEL) is a B-cell lymphoma in which human herpesvirus-8 (HHV-8) is found within all tumor cells and represents a target for selectively destroying tumor cells. HHV-8 is latent in most PEL cells and, hence, resistant to antiviral agents that inhibit lytic replication. We demonstrate that PEL cell lines containing HHV-8 without and with coinfection with Epstein-Barr virus responded to the antiseizure medication valproate with entry into the lytic cascade and production of infectious virus. Minimal cell death occurred when noninfected BL-41 cells were incubated with valproate, whereas apoptosis occurred in response to valproate in PELs that supported lytic replication of HHV-8. The anti-viral agents ganciclovir and phosphonoformic acid (PFA) blocked valproate-induced production of infectious virus without blocking entry into the lytic cascade, and apoptosis occurred at levels that were as high as when virus production was not blocked. Ganciclovir and PFA also prevented most valproate-induced expression of the late lytic viral transcript open reading frame 26 (ORF-26), but they did not block the induction of either viral interleukin-6 (vIL-6) or viral G protein-coupled receptor (vGPCR). These studies provide evidence that incubation of PELs with valproate in the presence of ganciclovir or PFA can selectively target tumor cells for apoptosis without increasing viral load.

scholarly journals Inhibition of Infection and Replication of Human Herpesvirus 8 in Microvascular Endothelial Cells by Alpha Interferon and Phosphonoformic Acid

2004 ◽  
Vol 78 (15) ◽  
pp. 8359-8371 ◽  
Author(s):  
Laurie T. Krug ◽  
Veronika P. Pozharskaya ◽  
Yimin Yu ◽  
Naoki Inoue ◽  
Margaret K. Offermann
Keyword(s):  
Endothelial Cells ◽  
Infectious Virus ◽  
Human Herpesvirus ◽  
Lytic Replication ◽  
Alpha Interferon ◽  
Human Herpesvirus 8 ◽  
Microvascular Endothelial Cells ◽  
Herpesvirus 8 ◽  
Phosphonoformic Acid ◽  
Infected Cells

ABSTRACT Infection of endothelial cells with human herpesvirus 8 (HHV-8) is an essential event in the development of Kaposi's sarcoma. When primary microvascular endothelial cells (MECs) were infected with HHV-8 at a low multiplicity of infection, considerable latent replication of HHV-8 occurred, leading to a time-dependent increase in the percentage of virus-infected cells that was accompanied by cellular spindling and growth to a high density with loss of contact inhibition. Only a low percentage of MECs supported lytic replication of HHV-8 and produced infectious virus. Phosphonoformic acid blocked production of infectious virus but did not inhibit the rapid expansion of latently infected MECs. Pretreatment of MECs with alpha interferon (IFN-α) prior to infection effectively reduced HHV-8 viral gene expression, latent replication, and production of infectious virus. High levels of the double-stranded RNA activated protein kinase (PKR) were expressed in HHV-8-infected cells, and incubation with IFN-α increased PKR expression more in virus-infected cells than in uninfected cells. MECs that were immortalized with simian virus 40 large-T antigen differed from nonimmortalized MECs in their response to infection with HHV-8 and demonstrated that cells with elevated levels of expression of antiviral transcripts expressed viral transcripts at reduced levels. These studies demonstrate that MECs respond to HHV-8 with enhanced expression of cellular antiviral genes and that augmentation of innate antiviral defenses with IFN-α is a more effective strategy than inhibition of viral lytic replication to protect MECs from infection with HHV-8 and to restrict proliferation of virus-infected MECs.

scholarly journals A Systems Biology Approach To Identify the Combination Effects of Human Herpesvirus 8 Genes on NF-κB Activation

2009 ◽  
Vol 83 (6) ◽  
pp. 2563-2574 ◽  
Author(s):  
Andreas Konrad ◽  
Effi Wies ◽  
Mathias Thurau ◽  
Gaby Marquardt ◽  
Elisabeth Naschberger ◽  
...  
Keyword(s):  
Systems Biology ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Etiologic Agent ◽  
Lytic Replication ◽  
Fine Tuning ◽  
Human Herpesvirus 8 ◽  
Systematic Analysis ◽  
Herpesvirus 8 ◽  
Infected Cells

ABSTRACT Human herpesvirus 8 (HHV-8) is the etiologic agent of Kaposi's sarcoma and primary effusion lymphoma. Activation of the cellular transcription factor nuclear factor-kappa B (NF-κB) is essential for latent persistence of HHV-8, survival of HHV-8-infected cells, and disease progression. We used reverse-transfected cell microarrays (RTCM) as an unbiased systems biology approach to systematically analyze the effects of HHV-8 genes on the NF-κB signaling pathway. All HHV-8 genes individually (n = 86) and, additionally, all K and latent genes in pairwise combinations (n = 231) were investigated. Statistical analyses of more than 14,000 transfections identified ORF75 as a novel and confirmed K13 as a known HHV-8 activator of NF-κB. K13 and ORF75 showed cooperative NF-κB activation. Small interfering RNA-mediated knockdown of ORF75 expression demonstrated that this gene contributes significantly to NF-κB activation in HHV-8-infected cells. Furthermore, our approach confirmed K10.5 as an NF-κB inhibitor and newly identified K1 as an inhibitor of both K13- and ORF75-mediated NF-κB activation. All results obtained with RTCM were confirmed with classical transfection experiments. Our work describes the first successful application of RTCM for the systematic analysis of pathofunctions of genes of an infectious agent. With this approach, ORF75 and K1 were identified as novel HHV-8 regulatory molecules on the NF-κB signal transduction pathway. The genes identified may be involved in fine-tuning of the balance between latency and lytic replication, since this depends critically on the state of NF-κB activity.

scholarly journals Short Duration of Elevated vIRF-1 Expression during Lytic Replication of Human Herpesvirus 8 Limits Its Ability To Block Antiviral Responses Induced by Alpha Interferon in BCBL-1 Cells

2004 ◽  
Vol 78 (12) ◽  
pp. 6621-6635 ◽  
Author(s):  
Veronika P. Pozharskaya ◽  
Laura L. Weakland ◽  
James C. Zimring ◽  
Laurie T. Krug ◽  
Elizabeth R. Unger ◽  
...  
Keyword(s):  
Infectious Virus ◽  
Human Herpesvirus ◽  
Lytic Replication ◽  
Human Herpesvirus 8 ◽  
Herpesvirus 8 ◽  
Antiviral Responses ◽  
Short Period ◽  
Pml Bodies ◽  
Latently Infected ◽  
Low Levels

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.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus (Human Herpesvirus 8) Contains Hypoxia Response Elements: Relevance to Lytic Induction by Hypoxia

2003 ◽  
Vol 77 (12) ◽  
pp. 6761-6768 ◽  
Author(s):  
Muzammel Haque ◽  
David A. Davis ◽  
Victoria Wang ◽  
Isabelle Widmer ◽  
Robert Yarchoan
Keyword(s):  
Promoter Region ◽  
Kaposi's Sarcoma ◽  
Human Herpesvirus ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Human Herpesvirus 8 ◽  
Viral Gene ◽  
Hypoxia Response ◽  
Herpesvirus 8 ◽  
Response Elements

ABSTRACT Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), also known as human herpesvirus 8, is an etiologic agent of KS, primary effusion lymphoma (PEL), and multicentric Castleman's disease. We recently demonstrated that hypoxia can induce lytic replication of KSHV in PEL cell lines. Hypoxia induces the accumulation of hypoxia-inducible factors (HIF), and we hypothesized that the KSHV genome may respond to hypoxia through functional hypoxia response elements (HREs). Here, we demonstrate the presence of at least two promoters within the KSHV genome that are activated by hypoxia or hypoxia mimics. One is in the promoter region of the gene for Rta, the main lytic switch gene, and the other is within the promoter region of ORF34, a lytic gene of unknown function. The ORF34 promoter contains three putative consensus HREs oriented in the direction of the gene. Dissection and site-directed mutagenesis studies confirmed that one of the HREs of the ORF34 promoter is functional. Under conditions of hypoxia, the ORF34 promoter was strongly upregulated by HIF-1α and HIF-2α. By contrast, the promoter of the gene for Rta appeared to be preferentially upregulated by HIF-2α. Reverse transcription-PCR analysis revealed that specific messages for ORF34 and ORF50 are upregulated in BCBL-1 cells exposed to hypoxia. An HIF-1 binding and competition assay demonstrated that the HRE sequence from the ORF34 promoter can compete for HIF-1α binding to an erythropoietin HRE oligonucleotide while a mutant sequence cannot. Thus, we demonstrated that a viral gene can be activated by hypoxia through activation of a functional viral HRE. To our knowledge, this is the first example of a functional HRE in a viral promoter.

scholarly journals Cellular Tropism and Viral Interleukin-6 Expression Distinguish Human Herpesvirus 8 Involvement in Kaposi’s Sarcoma, Primary Effusion Lymphoma, and Multicentric Castleman’s Disease

1999 ◽  
Vol 73 (5) ◽  
pp. 4181-4187 ◽  
Author(s):  
Katherine A. Staskus ◽  
Ren Sun ◽  
George Miller ◽  
Paul Racz ◽  
Anthony Jaslowski ◽  
...  
Keyword(s):  
B Cell ◽  
Interleukin 6 ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Viral Gene Expression ◽  
Lytic Cycle ◽  
Viral Gene ◽  
Cell Type ◽  
Herpesvirus 8 ◽  
Viral Genes

ABSTRACT Human herpesvirus 8 (HHV-8) infection has been implicated in the etiology of Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman’s disease (MCD), three diseases that frequently develop in immunocompromised, human immunodeficiency virus-positive individuals. One hypothesis that would account for different pathological manifestations of infection by the same virus is that viral genes are differentially expressed in heterogeneous cell types. To test this hypothesis, we analyzed the localization and levels of expression of two viral genes expressed in latent and lytic infections and the viral homologue of interleukin-6 (vIL-6). We show that PEL parallels KS in the pattern of latent and lytic cycle viral gene expression but that the predominant infected cell type is a B cell. We also show that MCD differs from KS not only in the infected cell type (B-cell and T-cell lineage) but also in the pattern of viral gene expression. Only a few cells in the lesion are infected and all of these cells express lytic-cycle genes. Of possibly greater significance is the fact that in a comparison of KS, PEL, and MCD, we found dramatic differences in the levels of expression of vIL-6. Interleukin-6 is a B-cell growth and differentiation factor whose altered expression has been linked to plasma cell abnormalities, as well as myeloid and lymphoid malignancies. Our findings support the hypothesis that HHV-8 plays an important role in the pathogenesis of PEL and MCD, in which vIL-6 acts as an autocrine or paracrine factor in the lymphoproliferative processes common to both.

scholarly journals USP7-Dependent Regulation of TRAF Activation and Signaling by a Viral Interferon Regulatory Factor Homologue

2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Qiwang Xiang ◽  
Hyunwoo Ju ◽  
John Nicholas
Keyword(s):  
Cell Viability ◽  
Catalytic Domain ◽  
Primary Effusion Lymphoma ◽  
Human Herpesvirus ◽  
Lytic Replication ◽  
Targeted Mutagenesis ◽  
Human Herpesvirus 8 ◽  
Antiviral Signaling ◽  
Herpesvirus 8 ◽  
Productive Replication

ABSTRACT Human herpesvirus 8 (HHV-8) encodes four viral interferon regulatory factors (vIRFs 1 to 4), all of which are expressed during lytic replication and inhibit a variety of antiviral signaling pathways. Viral IRFs 1, 2, and 3 are also expressed during latency in primary effusion lymphoma (PEL) cells, and vIRF-1 and vIRF-3 have been reported to promote PEL cell viability. Viral IRFs 1, 3, and 4 are known to interact with ubiquitin-specific protease 7 (USP7); interactions of vIRF-1 and vIRF-3 with USP7 promote PEL cell viability and regulate productive replication. Here, we report that vIRF-2 also targets USP7, utilizing a PSTS motif matching the USP7 N-terminal domain-binding A/PxxS consensus, but uniquely requires catalytic domain residues for intracellular interaction. In functional and mechanistic analyses, tumor necrosis factor receptor-associated factor (TRAF)-mediated signaling and associated polyubiquitination of TRAFs 3 and 6, specifically, were regulated negatively by USP7 and positively by vIRF-2-USP7 interaction, the latter competing for USP7-TRAF association. Using depletion, depletion-complementation, and targeted mutagenesis approaches, vIRF-2 was determined to promote latent PEL cell viability, likely independently of USP7 interaction, while lytic replication was inhibited by vIRF-2, in part or in whole via USP7 interaction. Together, our data identify a new molecular determinant of USP7 recognition, TRAF3/6-specific targeting by the deubiquitinase, associated activation of these TRAFs by vIRF-2, and activities of vIRF-2 and vIRF-2-USP7 interaction in HHV-8 latent and lytic biology. IMPORTANCE Human herpesvirus 8-encoded IRF homologues were the first to be identified in a virus. Through inhibitory interactions with cellular IRFs and other mediators of antiviral signaling, the vIRFs are believed to be essential for productive replication and also for latency in particular cell types. The deubiquitinase USP7 is a regulator of key cellular pathways, modulates HHV-8 latent and lytic infection, and is targeted by vIRFs 1, 3, and 4. Here, we report that vIRF-2 also interacts with USP7, via a means distinguishable from USP7 interactions with other vIRFs and other proteins, that this interaction modulates antiviral signaling via disruption of USP7 interactions with innate immune signaling proteins TRAF3 and TRAF6, and that vIRF-2 targeting of USP7 regulates HHV-8 productive replication. The presented data are the first to identify vIRF-2 targeting of USP7 and its role in HHV-8 biology, expanding our understanding of the repertoire and importance of virus-host interactions.

Association of Primary Pleural Effusion Lymphoma of T-Cell Origin and Human Herpesvirus 8 in a Human Immunodeficiency Virus–Seronegative Man

2001 ◽  
Vol 125 (9) ◽  
pp. 1246-1248 ◽  
Author(s):  
Emmanuèle Lechapt-Zalcman ◽  
Dominique Challine ◽  
Marie-Hélène Delfau-Larue ◽  
Corinne Haioun ◽  
Dominique Desvaux ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Dna Sequences ◽  
Primary Effusion Lymphoma ◽  
Polymerase Chain Reaction Amplification ◽  
Human Herpesvirus ◽  
Body Cavity ◽  
Human Herpesvirus 8 ◽  
Herpesvirus 8 ◽  
Immunodeficiency Virus

Abstract We describe a case of an 87-year-old human immunodeficiency virus (HIV)–negative man who developed a primary pleural lymphoma without any identifiable tumor mass associated with human herpesvirus 8 (HHV-8) infection. A large T-cell lymphoma was diagnosed based on morphologic, immunophenotypic, and molecular findings. The HHV-8 DNA sequences were detected using specific polymerase chain reaction amplification in the lymphomatous effusion. Study of the patient's serum confirmed the HHV-8 infection. This case report displays the characteristic features of HHV-8–related body cavity-based lymphoma/primary effusion lymphoma previously reported in HIV-seronegative patients, except that it is of T-cell origin. Whether this case may be included or not within the primary effusion lymphoma entity, the association of a pleural T-cell non-Hodgkin lymphoma with HHV-8 infection raises the question of the possible occurrence of T cells as the target of malignant transformation associated with HHV-8 infection.

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