scholarly journals Transcriptome Analysis of Kaposi's Sarcoma-Associated Herpesvirus duringDe NovoPrimary Infection of Human B and Endothelial Cells

2014 ◽  
Vol 89 (6) ◽  
pp. 3093-3111 ◽  
Author(s):  
Pravinkumar Purushothaman ◽  
Suhani Thakker ◽  
Subhash C. Verma
Keyword(s):  
Primary Infection ◽  
Kaposi's Sarcoma ◽  
De Novo ◽  
Kaposi’S Sarcoma ◽  
Viral Gene ◽  
Target Cells ◽  
Viral Genes ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACTKaposi's sarcoma-associated herpesvirus (KSHV) infects many target cells (e.g., endothelial, epithelial, and B cells, keratinocytes, and monocytes) to establish lifelong latent infections. Viral latent-protein expression is critical in inducing and maintaining KSHV latency. Infected cells are programmed to retain the incoming viral genomes during primary infection. Immediately after infection, KSHV transcribes many lytic genes that modulate various cellular pathways to establish successful infection. Analysis of the virion particle showed that the virions contain viral mRNAs, microRNAs, and other noncoding RNAs that are transduced into the target cells during infection, but their biological functions are largely unknown. We performed a comprehensive analysis of the KSHV virion packaged transcripts and the profiles of viral genes transcribed afterde novoinfections of various cell types (human peripheral blood mononuclear cells [PBMCs], CD14+monocytes, and telomerase-immortalized vascular endothelial [TIVE] cells), from viral entry until latency establishment. A next-generation sequence analysis of the total transcriptome showed that several viral RNAs (polyadenylated nuclear RNA, open reading frame 58 [ORF58], ORF59, T0.7, and ORF17) were abundantly present in the KSHV virions and effectively transduced into the target cells. Analysis of the transcription profiles of each viral gene showed specific expression patterns in different cell lines, with the majority of the genes, other than latent genes, silencing after 24 h postinfection. We differentiated the actively transcribing genes from the virion-transduced transcripts using a nascent RNA capture approach (Click-iT chemistry), which identified transcription of a number of viral genes during primary infection. Treating the infected cells with phosphonoacetic acid (PAA) to block the activity of viral DNA polymerase confirmed the involvement of lytic DNA replication during primary infection. To further understand the role of DNA replication during primary infection, we performedde novoPBMC infections with a recombinant ORF59-deleted KSHV virus, which showed significantly reduced numbers of viral copies in the latently infected cells. In summary, the transduced KSHV RNAs as well as the actively transcribed genes control critical processes of early infection to establish KSHV latency.IMPORTANCEKaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of multiple human malignancies in immunocompromised individuals. KSHV establishes a lifelong latency in the infected host, during which only a limited number of viral genes are expressed. However, a fraction of latently infected cells undergo spontaneous reactivation to produce virions that infect the surrounding cells. These newly infected cells are primed early to retain the incoming viral genome and induce cell growth. KSHV transcribes a variety of lytic proteins duringde novoinfections that modulate various cellular pathways to establish the latent infection. Interestingly, a large number of viral proteins and RNA are encapsidated in the infectious virions and transduced into the infected cells during ade novoinfection. This study determined the kinetics of the viral gene expression duringde novoKSHV infections and the functional role of the incoming viral transcripts in establishing latency.

scholarly journals Upregulation of the TLR3 Pathway by Kaposi's Sarcoma-Associated Herpesvirus during Primary Infection

2008 ◽  
Vol 82 (11) ◽  
pp. 5440-5449 ◽  
Author(s):  
John West ◽  
Blossom Damania
Keyword(s):  
Primary Infection ◽  
Kaposi's Sarcoma ◽  
De Novo ◽  
Rna Virus ◽  
Primary Effusion Lymphoma ◽  
Kaposi’S Sarcoma ◽  
Small Interfering Rnas ◽  
Cytokines And Chemokines ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with several different human malignancies, including Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. KSHV establishes lifelong latency in the host and modulates the host immune response. Innate immunity is critical for controlling de novo viral infection. Toll-like receptors (TLRs) are key components of the innate immune system, and they serve as pathogen recognition receptors that stimulate the host antiviral response. In particular, TLR3 has been implicated in RNA virus recognition. Currently, there is no information regarding how KSHV infection modulates any TLR pathway. We report the first evidence that KSHV upregulates TLR3 expression in human monocytes during primary infection. This is also the first demonstration of a human DNA tumor virus upregulating TLR3, a TLR that thus far has been associated with the recognition of RNA viruses. We found that KSHV upregulates the TLR3 pathway and induces TLR3-specific cytokines and chemokines, including beta 1 interferon (IFN-β1) and CXCL10 (IP-10). Small interfering RNAs directed against TLR3 greatly reduced the ability of KSHV to upregulate IFN-β1 and CXCL10 upon infection.

scholarly journals HMGB1 knockout decreases Kaposi's sarcoma-associated herpesvirus virion production in iSLK BAC16 cells by attenuating viral gene expression

2021 ◽  
Author(s):  
Su-Kyung Kang ◽  
Yun Hee Kang ◽  
Seung-Min Yoo ◽  
Changhoon Park ◽  
Hong Seok Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Kaposi's Sarcoma ◽  
High Mobility ◽  
Kaposi’S Sarcoma ◽  
Lytic Replication ◽  
Virion Production ◽  
Viral Genes ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Multiple host proteins affect the gene expression of Kaposi's sarcoma-associated herpesvirus (KSHV) during latent and lytic replication. The high mobility group box 1 (HMGB1) serves as a highly conserved chromosomal protein inside the cell and a prototypical damage-associated molecular pattern molecule outside the cell. HMGB1 has been shown to play a pathogenic role in viral infectious diseases and to regulate the lytic replication of KSHV. However, its functional effects on the KSHV life cycle in KSHV-infected cells have not been fully elucidated. Here, we explored the role of the intracellular and extracellular HMGB1 in KSHV virion production by employing CRISPR/Cas9-mediated HMGB1 knockout in the KSHV-producing iSLK BAC16 cell line. Intracellular HMGB1 formed complexes with various proteins, and the abundance of HMGB1-interacting proteins changed during latent and lytic replication. Moreover, extracellular HMGB1 was found to enhance lytic replication by phosphorylating JNK. Of note, the expression of viral genes was attenuated during lytic replication in HMGB1- knockout iSLK BAC16 cells, with significantly decreased production of infectious virions compared to that in wild-type cells. Collectively, our results demonstrate that HMGB1 is an important cellular cofactor that affects the generation of infectious KSHV progeny during lytic replication. Author Summary The high mobility group box 1 protein ( HMGB1 ) has many intra- and extracellular biological functions with an intricate role in various diseases. In certain viral infections, HMGB1 affects the viral life cycle and pathogenesis. In this study, we explored the effects of HMGB1 knockout on the production of Kaposi’s sarcoma-associated herpesvirus (KSHV). HMGB1 knockout decreased virion production in KSHV-producing cells by decreasing the expression of viral genes. The processes by which HMGB1 affects KSHV production may occur inside or outside of infected cells. For instance, several cellular and viral proteins interacted with intracellular HMGB1 in a nucleosomal complex; whereas extracellular HMGB1 induced JNK phosphorylation, thus enhancing lytic replication. Our results suggest that both intracellular and extracellular HMGB1 are necessary for efficient KSHV replication. Thus, HMGB1 may represent an effective therapeutic target for the regulation of KSHV production.

scholarly journals CRISPR Interference Efficiently Silences Latent and Lytic Viral Genes in Kaposi’s Sarcoma-Associated Herpesvirus-Infected Cells

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 783
Author(s):  
Kevin Brackett ◽  
Ameera Mungale ◽  
Mary Lopez-Isidro ◽  
Duncan A. Proctor ◽  
Guillermo Najarro ◽  
...  
Keyword(s):  
Kaposi's Sarcoma ◽  
Single Gene ◽  
Kaposi’S Sarcoma ◽  
Viral Gene ◽  
Loss Of Function ◽  
Genetic Ablation ◽  
Crispr Interference ◽  
Viral Genes ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

Uncovering viral gene functions requires the modulation of gene expression through overexpression or loss-of-function. CRISPR interference (CRISPRi), a modification of the CRISPR-Cas9 gene editing technology, allows specific and efficient transcriptional silencing without genetic ablation. CRISPRi has been used to silence eukaryotic and prokaryotic genes at the single-gene and genome-wide levels. Here, we report the use of CRISPRi to silence latent and lytic viral genes, with an efficiency of ~80–90%, in epithelial and B-cells carrying multiple copies of the Kaposi’s sarcoma-associated herpesvirus (KSHV) genome. Our results validate CRISPRi for the analysis of KSHV viral elements, providing a functional genomics tool for studying virus–host interactions.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus ORF54/dUTPase Downregulates a Ligand for the NK Activating Receptor NKp44

2012 ◽  
Vol 86 (16) ◽  
pp. 8693-8704 ◽  
Author(s):  
Alexis Spain Madrid ◽  
Don Ganem
Keyword(s):  
Protein Trafficking ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Target Cells ◽  
Activating Receptors ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Related Proteins ◽  
Human Herpesviruses

Kaposi's sarcoma-associated herpesvirus (KSHV) establishes long-term latent infection in humans and can cause cancers in endothelial and B cells. A functioning immune system is vital for restricting viral proliferation and preventing KSHV-dependent neoplasms. While natural killer (NK) lymphocytes are known to target virus-infected cells for destruction, their importance in the anti-KSHV immune response is not currently understood. Activating receptors on NK cells recognize ligands on target cells, including the uncharacterized ligand(s) for NKp44, termed NKp44L. Here we demonstrate that several NK ligands are affected when KSHV-infected cells are induced to enter the lytic program. We performed a screen of most of the known KSHV genes and found that the product of the ORF54 gene could downregulate NKp44L. The ORF54-encoded protein is a dUTPase; however, dUTPase activity is neither necessary nor sufficient for the downregulation of NKp44L. In addition, we find that ORF54 can also target proteins of the cytokine receptor family and the mechanism of downregulation involves perturbation of membrane protein trafficking. The ORF54-related proteins of other human herpesviruses do not possess this activity, suggesting that the KSHV homolog has evolved a novel immunoregulatory function and that the NKp44-NKp44L signaling pathway contributes to antiviral immunity.

scholarly journals Envelope Glycoprotein gB of Kaposi's Sarcoma-Associated Herpesvirus Is Essential for Egress from Infected Cells

2005 ◽  
Vol 79 (17) ◽  
pp. 10952-10967 ◽  
Author(s):  
Harinivas H. Krishnan ◽  
Neelam Sharma-Walia ◽  
Ling Zeng ◽  
Shou-Jiang Gao ◽  
Bala Chandran
Keyword(s):  
Envelope Glycoprotein ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Target Cells ◽  
Signal Pathways ◽  
Virus Binding ◽  
Viral Dna ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) envelope glycoprotein gB interacts with cell surface heparan sulfate (HS) and α3β1 integrin and plays roles in the initial binding and entry into the target cells and in the induction of preexisting host cell signal pathways. To define gB function further, using a bacterial artificial chromosome (BAC) system carrying the KSHV genome (BAC36wt-KSHV), we constructed a recombinant virus genome with the gB open reading frame (ORF) deleted by replacing a 2-kb gB ORF with a 1.3-kb Kanr gene. Stable 293T cells carrying BAC36wt-KSHV and ΔgBBAC36-KSHV genomes were generated. Transcript analyses and immunoprecipitation reactions confirmed the absence of gB in the 293T-ΔgBBAC36 cells. When monolayers of 293T-BAC36wt and 293T-ΔgBBAC36 cells were induced with tetradecanoylphorbol-13-acetate, infectious virus was detected only from the 293T-BAC36wt cell supernatants. No significant amount of DNase I-resistant viral DNA was detected in the supernatants of 293T-ΔgBBAC36 cells. BAC36wt-KSHV infected the target cells, and in contrast, no viral DNA and transcripts could be detected in cells infected with ΔgBBAC36-KSHV. Electron microscopy of 293T-ΔgBBAC36 cells revealed capsids in the nuclei, cytoplasmic vesicles with core-containing capsids, and occasional enveloped virions in the cytoplasm. However, enveloped virus particles were observed in the extracellular compartments of 293T-BAC36wt cells only and not in 293T-ΔgBBAC36 cells. Transfection of 293T-ΔgBBAC36 cells with plasmid expressing full-length gB restored the recovery of infectious KSHV in the supernatant. These results suggest that, besides its role in virus binding and entry into the target cells, KSHV gB also plays a role in the maturation and egress of virus from the infected cells.

scholarly journals Bub1 in Complex with LANA Recruits PCNA To Regulate Kaposi's Sarcoma-Associated Herpesvirus Latent Replication and DNA Translesion Synthesis

2015 ◽  
Vol 89 (20) ◽  
pp. 10206-10218 ◽  
Author(s):  
Zhiguo Sun ◽  
Hem Chandra Jha ◽  
Erle S. Robertson
Keyword(s):  
Dna Replication ◽  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Kinase Domain ◽  
Cellular Protein ◽  
Nuclear Antigen ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Molecular Bridge

ABSTRACTLatent DNA replication of Kaposi's sarcoma-associated herpesvirus (KSHV) initiates at the terminal repeat (TR) element and requirestrans-acting elements, both viral and cellular, such as ORCs, MCMs, and latency-associated nuclear antigen (LANA). However, how cellular proteins are recruited to the viral genome is not very clear. Here, we demonstrated that the host cellular protein, Bub1, is involved in KSHV latent DNA replication. We show that Bub1 constitutively interacts with proliferating cell nuclear antigen (PCNA) via a highly conserved PIP box motif within the kinase domain. Furthermore, we demonstrated that Bub1 can form a complex with LANA and PCNA in KSHV-positive cells. This strongly indicated that Bub1 serves as a scaffold or molecular bridge between LANA and PCNA. LANA recruited PCNA to the KSHV genome via Bub1 to initiate viral replication in S phase and interacted with PCNA to promote its monoubiquitination in response to UV-induced damage for translesion DNA synthesis. This resulted in increased survival of KSHV-infected cells.IMPORTANCEDuring latency in KSHV-infected cells, the viral episomal DNA replicates once each cell cycle. KSHV does not express DNA replication proteins during latency. Instead, KSHV LANA recruits the host cell DNA replication machinery to the replication origin. However, the mechanism by which LANA mediates replication is uncertain. Here, we show that LANA is able to form a complex with PCNA, a critical protein for viral DNA replication. Furthermore, our findings suggest that Bub1, a spindle checkpoint protein, serves as a scaffold or molecular bridge between LANA and PCNA. Our data further support a role for Bub1 and LANA in PCNA-mediated cellular DNA replication processes as well as monoubiquitination of PCNA in response to UV damage. These data reveal a therapeutic target for inhibition of KSHV persistence in malignant cells.

scholarly journals Latency-Associated Nuclear Antigen of Kaposi's Sarcoma-Associated Herpesvirus (KSHV) Upregulates Survivin Expression in KSHV-Associated B-Lymphoma Cells and Contributes to Their Proliferation

2009 ◽  
Vol 83 (14) ◽  
pp. 7129-7141 ◽  
Author(s):  
Jie Lu ◽  
Subhash C. Verma ◽  
Masanao Murakami ◽  
Qiliang Cai ◽  
Pankaj Kumar ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Kaposi's Sarcoma ◽  
Survivin Expression ◽  
Kaposi’S Sarcoma ◽  
Nuclear Antigen ◽  
Mrna Levels ◽  
Survivin Promoter ◽  
Infected Cells ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus

ABSTRACT Survivin is a master regulator of cell proliferation and cell viability and is highly expressed in most human tumors. The molecular network linked to survivin expression in tumors has not been completely elucidated. In this study, we show that latency-associated nuclear antigen (LANA), a multifunctional protein of Kaposi's sarcoma-associated herpesvirus (KSHV) that is found in Kaposi's sarcoma tumors, upregulates survivin expression and increases the proliferation of KSHV-infected B cells. Analysis of pathway-specific gene arrays showed that survivin expression was highly upregulated in BJAB cells expressing LANA. The mRNA levels of survivin were also upregulated in HEK 293 and BJAB cells expressing LANA. Similarly, protein levels of survivin were significantly higher in LANA-expressing, as well as KSHV-infected, cells. Survivin promoter activity assays identified GC/Sp1 and p53 cis-acting elements within the core promoter region as being important for LANA activity. Gel mobility shift assays revealed that LANA forms a complex with Sp1 or Sp1-like proteins bound to the GC/Sp1 box of the survivin promoter. In addition, a LANA/p53 complex bound to the p53 cis-acting element within the survivin promoter, indicating that upregulation of survivin expression can also occur through suppression of p53 function. Furthermore, immunohistochemistry analyses revealed that survivin expression was upregulated in KSHV-associated Kaposi's sarcoma tissue, suggesting that LANA plays an important role in the upregulation of survivin expression in KSHV-infected endothelial cells. Knockdown of survivin expression by lentivirus-delivered small hairpin RNA resulted in loss of cell proliferation in KSHV-infected cells. Therefore, upregulation of survivin expression in KSHV-associated human cells contributes to their proliferation.

scholarly journals Early Events in Kaposi's Sarcoma-Associated Herpesvirus Infection of Target Cells

2009 ◽  
Vol 84 (5) ◽  
pp. 2188-2199 ◽  
Author(s):  
Bala Chandran
Keyword(s):  
Kaposi's Sarcoma ◽  
Kaposi’S Sarcoma ◽  
Target Cells ◽  
Mode Of Entry ◽  
Successful Infection ◽  
Kaposi's Sarcoma Associated Herpesvirus ◽  
Kaposi’S Sarcoma Associated Herpesvirus ◽  
Cell Signaling Pathways

ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV), the most recently identified member of the herpesvirus family, infects a variety of target cells in vitro and in vivo. This minireview surveys current information on the early events of KSHV infection, including virus-receptor interactions, involved envelope glycoproteins, mode of entry, intracellular trafficking, and initial viral and host gene expression programs. We describe data supporting the hypothesis that KSHV manipulates preexisting host cell signaling pathways to allow successful infection. The various signaling events triggered by infection, and their potential roles in the different stages of infection and disease pathogenesis, are summarized.

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