scholarly journals Experimental Transmission of Kaposi's Sarcoma–Associated Herpesvirus (Kshv/Hhv-8) to Scid-Hu Thy/Liv Mice

1999 ◽  
Vol 190 (12) ◽  
pp. 1857-1868 ◽  
Author(s):  
D. Dittmer ◽  
C. Stoddart ◽  
R. Renne ◽  
V. Linquist-Stepps ◽  
M.E. Moreno ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Quantitative Polymerase Chain Reaction ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Drug Susceptibility ◽  
Lytic Replication ◽  
Viral Gene ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Hiv 1

Kaposi's sarcoma–associated herpesvirus (KSHV/HHV-8) is a novel human lymphotropic herpesvirus linked to several human neoplasms. To date, no animal model for infection by this virus has been described. We have examined the susceptibility of C.B-17 scid/scid mice implanted with human fetal thymus and liver grafts (SCID-hu Thy/Liv mice) to KSHV infection. KSHV virions were inoculated directly into the implants, and viral DNA and mRNA production was assayed using real-time quantitative polymerase chain reaction. This revealed a biphasic infection, with an early phase of lytic replication accompanied and followed by sustained latency. Ultraviolet irradiation of the inoculum abolished all DNA- and mRNA-derived signals, and infection was inhibited by ganciclovir. Viral gene expression was most abundant in CD19+ B lymphocytes, suggesting that this model faithfully mimics the natural tropism of this virus. Short-term coinfection with HIV-1 did not alter the course of KSHV replication, nor did KSHV alter levels of HIV-1 p24 during the acute phase of the infection. Although no disease was evident in infected animals, SCID-hu Thy/Liv mice should allow the detailed study of KSHV tropism, latency, and drug susceptibility.

scholarly journals Principal Role of TRAP/Mediator and SWI/SNF Complexes in Kaposi's Sarcoma-Associated Herpesvirus RTA-Mediated Lytic Reactivation

2003 ◽  
Vol 23 (6) ◽  
pp. 2055-2067 ◽  
Author(s):  
Yousang Gwack ◽  
Hwa Jin Baek ◽  
Hiroyuki Nakamura ◽  
Sun Hwa Lee ◽  
Michael Meisterernst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Viral Gene ◽  
Transcription Activator ◽  
Lytic Reactivation ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT An important step in the herpesvirus life cycle is the switch from latency to lytic reactivation. The RTA transcription activator of Kaposi's sarcoma-associated herpesvirus (KSHV) acts as a molecular switch for lytic reactivation. Here we demonstrate that KSHV RTA recruits CBP, the SWI/SNF chromatin remodeling complex, and the TRAP/Mediator coactivator into viral promoters through interactions with a short acidic sequence in the carboxyl region and that this recruitment is essential for RTA-dependent viral gene expression. The Brg1 subunit of SWI/SNF and the TRAP230 subunit of TRAP/Mediator were shown to interact directly with RTA. Consequently, genetic ablation of these interactions abolished KSHV lytic replication. These results demonstrate that the recruitment of CBP, SWI/SNF, and TRAP/Mediator complexes by RTA is the principal mechanism to direct well-controlled viral gene expression and thereby viral lytic reactivation.

scholarly journals ORF33 and ORF38 of Kaposi's Sarcoma-Associated Herpesvirus Interact and Are Required for Optimal Production of Infectious Progeny Viruses

2015 ◽  
Vol 90 (4) ◽  
pp. 1741-1756 ◽  
Author(s):  
Jian-jun Wu ◽  
Denis Avey ◽  
Wenwei Li ◽  
Joseph Gillen ◽  
Bishi Fu ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Viral Gene ◽  
Virus Propagation ◽  
Progeny Virion ◽  
Cytoplasmic Vesicles ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTWe recently showed that the interaction between Kaposi's sarcoma-associated herpesvirus (KSHV) tegument proteins ORF33 and ORF45 is crucial for progeny virion production, but the exact functions of KSHV ORF33 during lytic replication were unknown (J. Gillen, W. Li, Q. Liang, D. Avey, J. Wu, F. Wu, J. Myoung, and F. Zhu, J Virol89:4918–4931, 2015,http://dx.doi.org/10.1128/JVI.02925-14). Therefore, here we investigated the relationship between ORF33 and ORF38, whose counterparts in both alpha- and betaherpesviruses interact with each other. Using specific monoclonal antibodies, we found that both proteins are expressed during the late lytic cycle with similar kinetics and that both are present in mature virions as components of the tegument. Furthermore, we confirmed that ORF33 interacts with ORF38. Interestingly, we observed that ORF33 tightly associates with the capsid, whereas ORF38 associates with the envelope. We generated ORF33-null, ORF38-null, and double-null mutants and found that these mutants apparently have identical phenotypes: the mutations caused no apparent effect on viral gene expression but reduced the yield of progeny virion by about 10-fold. The progeny virions also lack certain virion component proteins, including ORF45. During viral lytic replication, the virions associate with cytoplasmic vesicles. We also observed that ORF38 associates with the membranes of vesicles and colocalizes with the Golgi membrane or early endosome membrane. Further analyses of ORF33/ORF38 mutants revealed the reduced production of virion-containing vesicles, suggesting that ORF33 and ORF38 are involved in the transport of newly assembled viral particles into cytoplasmic vesicles, a process important for viral maturation and egress.IMPORTANCEHerpesvirus assembly is an essential step in virus propagation that leads to the generation of progeny virions. It is a complicated process that depends on the delicate regulation of interactions among virion proteins. We previously revealed an essential role of ORF45-ORF33 binding for virus assembly. Here, we report that ORF33 and its binding partner, ORF38, are required for infectious virus production due to their important role in the tegumentation process. Moreover, we found that both ORF33 and ORF38 are involved in the transportation of virions through vesicles during maturation and egress. Our results provide new insights into the important roles of ORF33 and ORF38 during viral assembly, a process critical for virus propagation that is intimately linked to KSHV pathobiology.

scholarly journals Activation of the Kaposi's Sarcoma-Associated Herpesvirus Major Latency Locus by the Lytic Switch Protein RTA (ORF50)

2005 ◽  
Vol 79 (13) ◽  
pp. 8493-8505 ◽  
Author(s):  
Satoko Matsumura ◽  
Yuriko Fujita ◽  
Evan Gomez ◽  
Naoko Tanese ◽  
Angus C. Wilson
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Early Gene ◽  
Viral Gene ◽  
Transcription Activator ◽  
Potent Inducer ◽  
Alternative Mrna Splicing ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) maintains a latent infection in primary effusion lymphoma cells but can be induced to enter full lytic replication by exposure to a variety of chemical inducing agents or by expression of the KSHV-encoded replication and transcription activator (RTA) protein. During latency, only a few viral genes are expressed, and these include the three genes of the so-called latency transcript (LT) cluster: v-FLIP (open reading frame 71 [ORF71]), v-cyclin (ORF72), and latency-associated nuclear antigen (ORF73). During latency, all three open reading frames are transcribed from a common promoter as part of a multicistronic mRNA. Subsequent alternative mRNA splicing and internal ribosome entry allows for the expression of each protein. Here, we show that transcription of LT cassette mRNA can be induced by RTA through the activation of a second promoter (LTi) immediately downstream of the constitutively active promoter (LTc). We identified a minimal cis-regulatory region, which overlaps with the promoter for the bicistronic K14/v-GPCR delayed early gene that is transcribed in the opposite direction. In addition to a TATA box at −30 relative to the LTi mRNA start sites, we identified three separate RTA response elements that are also utilized by the K14/v-GPCR promoter. Interestingly, LTi is unresponsive to sodium butyrate, a potent inducer of lytic replication. This suggests there is a previously unrecognized class of RTA-responsive promoters that respond to direct, but not indirect, induction of RTA. These studies highlight the fact that induction method can influence the precise program of viral gene expression during early events in reactivation and also suggest a mechanism by which RTA contributes to establishment of latency during de novo infections.

scholarly journals NF-κB Serves as a Cellular Sensor of Kaposi's Sarcoma-Associated Herpesvirus Latency and Negatively Regulates K-Rta by Antagonizing the RBP-Jκ Coactivator

2009 ◽  
Vol 83 (9) ◽  
pp. 4435-4446 ◽  
Author(s):  
Yoshihiro Izumiya ◽  
Chie Izumiya ◽  
Datsun Hsia ◽  
Thomas J. Ellison ◽  
Paul A. Luciw ◽  
...  
Keyword(s):  
Viral Protein ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Host Cells ◽  
Early Gene ◽  
Viral Gene ◽  
Viral Promoters ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Successful viral replication is dependent on a conducive cellular environment; thus, viruses must be sensitive to the state of their host cells. We examined the idea that an interplay between viral and cellular regulatory factors determines the switch from Kaposi's sarcoma-associated herpesvirus (KSHV) latency to lytic replication. The immediate-early gene product K-Rta is the first viral protein expressed and an essential factor in reactivation; accordingly, this viral protein is in a key position to serve as a viral sensor of cellular physiology. Our approach aimed to define a host transcription factor, i.e., host sensor, which modulates K-Rta activity on viral promoters. To this end, we developed a panel of reporter plasmids containing all 83 putative viral promoters for a comprehensive survey of the response to both K-Rta and cellular transcription factors. Interestingly, members of the NF-κB family were shown to be strong negative regulators of K-Rta transactivation for all but two viral promoters (Ori-RNA and K12). Recruitment of K-Rta to the ORF57 and K-bZIP promoters, but not the K12 promoter, was significantly impaired when NF-κB expression was induced. Many K-Rta-responsive promoters modulated by NF-κB contain the sequence of the RBP-Jκ binding site, a major coactivator which anchors K-Rta to target promoters via consensus motifs which overlap with that of NF-κB. Gel shift assays demonstrated that NF-κB inhibits the binding of RBP-Jκ and forms a complex with RBP-Jκ. Our results support a model in which a balance between K-Rta/RBP-Jκ and NF-κB activities determines KSHV reactivation. An important feature of this model is that the interplay between RBP-Jκ and NF-κB on viral promoters controls viral gene expression mediated by K-Rta.

scholarly journals HIV-1 Vpr Inhibits Kaposi's Sarcoma-Associated Herpesvirus Lytic Replication by Inducing MicroRNA miR-942-5p and Activating NF-κB Signaling

2016 ◽  
Vol 90 (19) ◽  
pp. 8739-8753 ◽  
Author(s):  
Qin Yan ◽  
Chenyou Shen ◽  
Jie Qin ◽  
Wan Li ◽  
Minmin Hu ◽  
...  
Keyword(s):  
Life Cycle ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Expression Profiles ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Luciferase Reporter ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Hiv 1

ABSTRACTKaposi's sarcoma-associated herpesvirus (KSHV) infection is required for the development of several AIDS-related malignancies, including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). The high incidence of AIDS-KS has been ascribed to the interaction of KSHV and HIV-1. We have previously shown that HIV-1-secreted proteins Tat and Nef regulate the KSHV life cycle and synergize with KSHV oncogenes to promote angiogenesis and tumorigenesis. Here, we examined the regulation of KSHV latency by HIV-1 viral protein R (Vpr). We found that soluble Vpr inhibits the expression of KSHV lytic transcripts and proteins, as well as viral particle production by activating NF-κB signaling following internalization into PEL cells. By analyzing the expression profiles of microRNAs combined with target search by bioinformatics and luciferase reporter analyses, we identified a Vpr-upregulated cellular microRNA (miRNA), miR-942-5p, that directly targeted IκBα. Suppression of miR-942-5p relieved the expression of IκBα and reduced Vpr inhibition of KSHV lytic replication, while overexpression of miR-942-5p enhanced Vpr inhibition of KSHV lytic replication. Our findings collectively illustrate that, by activating NF-κB signaling through upregulating a cellular miRNA to target IκBα, internalized HIV-1 Vpr inhibits KSHV lytic replication. These results have demonstrated an essential role of Vpr in the life cycle of KSHV.IMPORTANCECoinfection by HIV-1 promotes the aggressive growth of Kaposi's sarcoma-associated herpesvirus (KSHV)-related malignancies, including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). In this study, we have shown that soluble HIV-1 Vpr inhibits KSHV lytic replication by activating NF-κB signaling following internalization into PEL cells. Mechanistic studies revealed that a cellular microRNA upregulated by Vpr, miR-942-5p, directly targeted IκBα. Suppression of miR-942-5p relieved IκBα expression and reduced Vpr inhibition of KSHV replication, while overexpression of miR-942-5p enhanced Vpr inhibition of KSHV replication. These results indicate that by activating NF-κB signaling through upregulating a cellular miRNA to target IκBα, internalized Vpr inhibits KSHV lytic replication. This work illustrates a molecular mechanism by which HIV-1-secreted regulatory protein Vpr regulates KSHV latency and the pathogenesis of AIDS-related malignancies.

scholarly journals Upregulation of MicroRNA 711 Mediates HIV-1 Vpr Promotion of Kaposi's Sarcoma-Associated Herpesvirus Latency and Induction of Pro-proliferation and Pro-survival Cytokines by Targeting the Notch/NF-κB-Signaling Axis

2018 ◽  
Vol 92 (18) ◽  
Author(s):  
Qin Yan ◽  
Runran Zhao ◽  
Chenyou Shen ◽  
Fei Wang ◽  
Wan Li ◽  
...  
Keyword(s):  
Life Cycle ◽  
Notch Signaling ◽  
Kaposi's Sarcoma ◽  
Promoter Activity ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Alternative Mechanism ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Hiv 1

ABSTRACTCoinfection with HIV-1 and Kaposi's sarcoma-associated herpesvirus (KSHV) often leads to AIDS-related malignancies, including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). The interaction between HIV and KSHV plays a pivotal role in the progression of these malignancies. We have previously demonstrated that, by upregulating miR-942-5p, HIV-1 viral protein R (Vpr) inhibits KSHV lytic replication by targeting IκBα to activate the NF-κB signaling (Q. Yan, C. Shen, J. Qin, W. Li, M. Hu, H. Lu, D. Qin, J. Zhu, S. J. Gao, C. Lu, J Virol 90:8739–8753, 2016). Here, we show that Vpr inactivates Notch signaling, resulting in inhibition of KSHV lytic replication and induction of pro-proliferative and -survival cytokines, including interleukin-2 (IL-2), TIMP-1, IGF-1, and NT-4. Mechanistically, Vpr upregulates miR-711, which directly targets the Notch1 3′ untranslated region. Suppression of miR-711 relieved Notch1 and reduced Vpr inhibition of KSHV lytic replication and Vpr induction of pro-proliferation and -survival cytokines, while overexpression of miR-711 exhibited the opposite effect. Finally, overexpression of Notch1 reduced Vpr induction of NF-κB activity by promoting IκBα promoter activity. Our novel findings reveal that by upregulating miR-711 to target Notch1, Vpr silences Notch signaling to activate the NF-κB pathway by reducing IκBα expression, leading to inhibition of KSHV lytic replication and induction of pro-proliferation and -survival cytokines. Therefore, the miR-711/Notch/NF-κB axis is important in the pathogenesis of AIDS-related malignancies and could be an attractive therapeutic target.IMPORTANCEHIV-1 infection significantly increases the risk of KS and PEL in KSHV-infected individuals. Our previous study has shown that HIV-1 Vpr regulates the KSHV life cycle by targeting IκBα to activate NF-κB signaling through upregulating cellular miR-942-5p. In this study, we have further found that Vpr inactivates Notch signaling to promote KSHV latency and production of pro-proliferation and -survival cytokines. Another Vpr-upregulated cellular microRNA, miR-711, participates in this process by directly targeting Notch1. As a result, Notch1 upregulation of the IκBα promoter activity is attenuated, resulting in reduced levels of IκBα transcript and protein. Overall, these results illustrate an alternative mechanism of HIV-1 Vpr regulation of KSHV latency and aberrant cytokines through the miR-711/Notch/NF-κB axis. Our novel findings further demonstrate the role of an HIV-1-secreted regulatory protein in the KSHV life cycle and KSHV-related malignancies.

scholarly journals Modulation of Cellular and Viral Gene Expression by the Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus

2001 ◽  
Vol 75 (1) ◽  
pp. 458-468 ◽  
Author(s):  
Rolf Renne ◽  
Chris Barry ◽  
Dirk Dittmer ◽  
Nicole Compitello ◽  
Patrick O. Brown ◽  
...  
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Kaposi's Sarcoma ◽  
Primary Effusion Lymphoma ◽  
Viral Gene Expression ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Viral Gene ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is the likely etiological agent of Kaposi's sarcoma and primary effusion lymphoma. Common to these malignancies is that tumor cells are latently infected with KSHV. Viral gene expression is limited to a few genes, one of which is the latency-associated nuclear antigen (LANA), the product of ORF73. Examination of the primary sequence of LANA reveals some structural features reminiscent of transcription factors, leading us to hypothesize that LANA may regulate viral and cellular transcription during latency. In reporter gene-based transient transfection assays, we found that LANA can have either positive or negative effects on gene expression. While expression of a reporter gene from several synthetic promoters was increased in the presence of LANA, expression from the human immunodeficiency virus (HIV) long terminal repeat (LTR)—and from NF-κB-dependent reporter genes—was reduced by LANA expression. In addition, the promoter of KSHV ORF73 itself is activated up to 5.5-fold by LANA. This autoregulation may be important in tumorigenesis, because two other genes (v-cyclin and v-FLIP) with likely roles in cell growth and survival are also controlled by this element. To identify cellular genes influenced by LANA, we employed cDNA array-based expression profiling. Six known genes (and nine expressed sequence tags) were found to be upregulated in LANA-expressing cell lines. One of these, Staf-50, is known to inhibit expression from the HIV LTR; most of the other known genes are interferon inducible, although the interferon genes themselves were not induced by LANA. These data demonstrate that LANA expression has effects on cellular and viral gene expression. We suggest that, whether direct or indirect in origin, these effects may play important roles in the pathobiology of KSHV infection.

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