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Cuddy SR, Flores ME, Krakowiak PA, Whitford AL, Dochnal SA, Babnis A, Miyake T, Tigano M, Engel DA, Cliffe AR. Co-option of mitochondrial nucleic acid sensing pathways by HSV-1 UL12.5 for reactivation from latent Infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.06.601241. [PMID: 39005440 PMCID: PMC11245091 DOI: 10.1101/2024.07.06.601241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Although viruses subvert innate immune pathways for their replication, there is evidence they can also co-opt anti-viral responses for their benefit. The ubiquitous human pathogen, Herpes Simplex Virus-1 (HSV-1), encodes a protein (UL12.5) that induces the release of mitochondrial nucleic acid into the cytosol, which activates immune sensing pathways and reduces productive replication in non-neuronal cells. HSV-1 establishes latency in neurons and can reactivate to cause disease. We found that UL12.5 is required for HSV-1 reactivation in neurons and acts to directly promote viral lytic gene expression during initial exit from latency. Further, the direct activation of innate immune sensing pathways triggered HSV reactivation and compensated for a lack of UL12.5. Finally, we found that the induction of HSV-1 lytic genes during reactivation required intact RNA and DNA sensing pathways, demonstrating that HSV-1 can both respond to and active antiviral nucleic acid sensing pathways to reactivate from a latent infection.
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Affiliation(s)
- Sean R. Cuddy
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, 22908
| | - Matthew E. Flores
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Patryk A. Krakowiak
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Abigail L. Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Sara A. Dochnal
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Aleksandra Babnis
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Tsuyoshi Miyake
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Marco Tigano
- Department of Pathology and Genomic Medicine, Thomas Jefferson University, 1020 Locust Street, Philadelphia 19107
| | - Daniel A. Engel
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Anna. R Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
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Francois AK, Rohani A, Loftus M, Dochnal S, Hrit J, McFarlane S, Whitford A, Lewis A, Krakowiak P, Boutell C, Rothbart SB, Kashatus D, Cliffe AR. Single-genome analysis reveals a heterogeneous association of the herpes simplex virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts. mBio 2024; 15:e0327823. [PMID: 38411116 PMCID: PMC11005365 DOI: 10.1128/mbio.03278-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/05/2024] [Indexed: 02/28/2024] Open
Abstract
The fate of herpesvirus genomes following entry into different cell types is thought to regulate the outcome of infection. For the Herpes simplex virus 1 (HSV-1), latent infection of neurons is characterized by association with repressive heterochromatin marked with Polycomb silencing-associated lysine 27 methylation on histone H3 (H3K27me). However, whether H3K27 methylation plays a role in repressing lytic gene expression in non-neuronal cells is unclear. To address this gap in knowledge, and with consideration that the fate of the viral genome and outcome of HSV-1 infection could be heterogeneous, we developed an assay to quantify the abundance of histone modifications within single viral genome foci of infected fibroblasts. Using this approach, combined with bulk epigenetic techniques, we were unable to detect any role for H3K27me3 during HSV-1 lytic infection of fibroblasts. By contrast, we could detect the lesser studied H3K27me2 on a subpopulation of viral genomes, which was consistent with a role for H3K27 demethylases in promoting lytic gene expression. In addition, viral genomes co-localized with the H3K27me2 reader protein PHF20L1, and this association was enhanced by inhibition of the H3K27 demethylases UTX and JMJD3. Notably, targeting of H3K27me2 to viral genomes was enhanced following infection with a transcriptionally defective virus in the absence of Promyelocytic leukemia nuclear bodies. Collectively, these studies implicate a role for H3K27me2 in fibroblast-associated HSV genome silencing in a manner dependent on genome sub-nuclear localization and transcriptional activity. IMPORTANCE Investigating the potential mechanisms of gene silencing for DNA viruses in different cell types is important to understand the differential outcomes of infection, particularly for viruses like herpesviruses that can undergo distinct types of infection in different cell types. In addition, investigating chromatin association with viral genomes informs on the mechanisms of epigenetic regulation of DNA processes. However, there is a growing appreciation for heterogeneity in the outcome of infection at the single cell, and even single viral genome, level. Here we describe a novel assay for quantifying viral genome foci with chromatin proteins and show that a portion of genomes are targeted for silencing by H3K27me2 and associate with the reader protein PHF20L1. This study raises important questions regarding the mechanism of H3K27me2-specific targeting to viral genomes, the contribution of epigenetic heterogeneity to herpesvirus infection, and the role of PHF20L1 in regulating the outcome of DNA virus infection.
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Affiliation(s)
- Alison K. Francois
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Ali Rohani
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Matt Loftus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Sara Dochnal
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Joel Hrit
- Department of Epigenetics, Van Andel Institute, Grand Rapids, USA
| | - Steven McFarlane
- MRC - University of Glasgow, Centre for Virus Research, Glasgow, United Kingdom
| | - Abigail Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Anna Lewis
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Patryk Krakowiak
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Chris Boutell
- MRC - University of Glasgow, Centre for Virus Research, Glasgow, United Kingdom
| | | | - David Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Anna R. Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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3
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Dochnal SA, Whitford AL, Francois AK, Krakowiak PA, Cuddy S, Cliffe AR. c-Jun signaling during initial HSV-1 infection modulates latency to enhance later reactivation in addition to directly promoting the progression to full reactivation. J Virol 2024; 98:e0176423. [PMID: 38193709 PMCID: PMC10878265 DOI: 10.1128/jvi.01764-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 12/12/2023] [Indexed: 01/10/2024] Open
Abstract
Herpes simplex virus-1 (HSV-1) establishes a latent infection in peripheral neurons and periodically reactivates to permit transmission, which can result in clinical manifestations. Viral transactivators required for lytic infection are largely absent during latent infection, and therefore, HSV-1 relies on the co-option of neuronal host signaling pathways to initiate its gene expression. The activation of the neuronal c-Jun N-terminal kinase (JNK) cell stress pathway is central to initiating biphasic reactivation in response to multiple stimuli. However, how host factors work with JNK to stimulate the initial wave of gene expression (known as Phase I) or the progression to full Phase II reactivation remains unclear. Here, we found that c-Jun, the primary target downstream of neuronal JNK cell stress signaling, functions during reactivation but not during the JNK-mediated initiation of Phase I gene expression. Instead, c-Jun was required to transition from Phase I to full HSV-1 reactivation and was detected in viral replication compartments of reactivating neurons. Interestingly, we also identified a role for both c-Jun and enhanced neuronal stress during initial neuronal infection in promoting a more reactivation-competent form of HSV-1 latency. Therefore, c-Jun functions at multiple stages during the HSV latent infection of neurons to promote reactivation but not during the initial JNK-dependent Phase I. Importantly, by demonstrating that initial infection conditions can contribute to later reactivation abilities, this study highlights the potential for latently infected neurons to maintain a molecular scar of previous exposure to neuronal stressors.IMPORTANCEThe molecular mechanisms that regulate the reactivation of herpes simplex virus-1 (HSV-1) from latent infection are unknown. The host transcription and pioneer factor c-Jun is the main target of the JNK cell stress pathway that is known to be important in exit of HSV from latency. Surprisingly, we found that c-Jun does not act with JNK during exit from latency but instead promotes the transition to full reactivation. Moreover, c-Jun and enhanced neuronal stress during initial neuronal infection promoted a more reactivation-competent form of HSV-1 latency. c-Jun, therefore, functions at multiple stages during HSV-1 latent infection of neurons to promote reactivation. Importantly, this study contributes to a growing body of evidence that de novo HSV-1 infection conditions can modulate latent infection and impact future reactivation events, raising important questions on the clinical impact of stress during initial HSV-1 acquisition on future reactivation events and consequences.
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Affiliation(s)
- Sara A. Dochnal
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Abigail L. Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Alison K. Francois
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Patryk A. Krakowiak
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Sean Cuddy
- Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia, USA
| | - Anna R. Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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4
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Francois AK, Rohani A, Loftus M, Dochnal S, Hrit J, McFarlane S, Whitford A, Lewis A, Krakowiak P, Boutell C, Rothbart SB, Kashatus D, Cliffe AR. Single-genome analysis reveals heterogeneous association of the Herpes Simplex Virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.03.569766. [PMID: 38076966 PMCID: PMC10705572 DOI: 10.1101/2023.12.03.569766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The fate of herpesvirus genomes following entry into different cell types is thought to regulate the outcome of infection. For the Herpes simplex virus 1 (HSV-1), latent infection of neurons is characterized by association with repressive heterochromatin marked with Polycomb silencing-associated lysine 27 methylation on histone H3 (H3K27me). However, whether H3K27 methylation plays a role in repressing lytic gene expression in non-neuronal cells is unclear. To address this gap in knowledge, and with consideration that the fate of the viral genome and outcome of HSV-1 infection could be heterogeneous, we developed an assay to quantify the abundance of histone modifications within single viral genome foci of infected fibroblasts. Using this approach, combined with bulk epigenetic techniques, we were unable to detect any role for H3K27me3 during HSV-1 lytic infection of fibroblasts. In contrast, we could detect the lesser studied H3K27me2 on a subpopulation of viral genomes, which was consistent with a role for H3K27 demethylases in promoting lytic gene expression. This was consistent with a role for H3K27 demethylases in promoting lytic gene expression. In addition, viral genomes co-localized with the H3K27me2 reader protein PHF20L1, and this association was enhanced by inhibition of the H3K27 demethylases UTX and JMJD3. Notably, targeting of H3K27me2 to viral genomes was enhanced following infection with a transcriptionally defective virus in the absence of Promyelocytic leukemia nuclear bodies. Collectively, these studies implicate a role for H3K27me2 in fibroblast-associated HSV genome silencing in a manner dependent on genome sub-nuclear localization and transcriptional activity.
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Affiliation(s)
- Alison K Francois
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Ali Rohani
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Matt Loftus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Sara Dochnal
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Joel Hrit
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI, 49503
| | - Steven McFarlane
- MRC-University of Glasgow Centre for Virus Research (CVR), Glasgow, Scotland
| | - Abigail Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Anna Lewis
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Patryk Krakowiak
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Chris Boutell
- MRC-University of Glasgow Centre for Virus Research (CVR), Glasgow, Scotland
| | - Scott B. Rothbart
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI, 49503
| | - David Kashatus
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Anna R Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
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Hassan STS, Šudomová M, Mazurakova A, Kubatka P. Insights into Antiviral Properties and Molecular Mechanisms of Non-Flavonoid Polyphenols against Human Herpesviruses. Int J Mol Sci 2022; 23:ijms232213891. [PMID: 36430369 PMCID: PMC9693824 DOI: 10.3390/ijms232213891] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/30/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
Herpesviruses are one of the most contagious DNA viruses that threaten human health, causing severe diseases, including, but not limited to, certain types of cancer and neurological complications. The overuse and misuse of anti-herpesvirus drugs are key factors leading to drug resistance. Therefore, targeting human herpesviruses with natural products is an attractive form of therapy, as it might improve treatment efficacy in therapy-resistant herpesviruses. Plant polyphenols are major players in the health arena as they possess diverse bioactivities. Hence, in this article, we comprehensively summarize the recent advances that have been attained in employing plant non-flavonoid polyphenols, such as phenolic acids, tannins and their derivatives, stilbenes and their derivatives, lignans, neolignans, xanthones, anthraquinones and their derivatives, curcuminoids, coumarins, furanocoumarins, and other polyphenols (phloroglucinol) as promising anti-herpesvirus drugs against various types of herpesvirus such as alpha-herpesviruses (herpes simplex virus type 1 and 2 and varicella-zoster virus), beta-herpesviruses (human cytomegalovirus), and gamma-herpesviruses (Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus). The molecular mechanisms of non-flavonoid polyphenols against the reviewed herpesviruses are also documented.
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Affiliation(s)
- Sherif T. S. Hassan
- Department of Applied Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 00 Prague, Czech Republic
- Correspondence: ; Tel.: +420-774-630-604
| | - Miroslava Šudomová
- Museum of Literature in Moravia, Klášter 1, 664 61 Rajhrad, Czech Republic
| | - Alena Mazurakova
- Department of Medical Biology, Jessenius Faculty of Medicine, Comenius University in Bratislava, 03601 Martin, Slovakia
- Biomedical Centre Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Mala Hora 4D, 03601 Martin, Slovakia
| | - Peter Kubatka
- Department of Medical Biology, Jessenius Faculty of Medicine, Comenius University in Bratislava, 03601 Martin, Slovakia
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Scholl A, De S. Epigenetic Regulation by Polycomb Complexes from Drosophila to Human and Its Relation to Communicable Disease Pathogenesis. Int J Mol Sci 2022; 23:ijms232012285. [PMID: 36293135 PMCID: PMC9603650 DOI: 10.3390/ijms232012285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 10/04/2022] [Accepted: 10/10/2022] [Indexed: 12/05/2022] Open
Abstract
Although all cells in the human body are made of the same DNA, these cells undergo differentiation and behave differently during development, through integration of external and internal stimuli via 'specific mechanisms.' Epigenetics is one such mechanism that comprises DNA/RNA, histone modifications, and non-coding RNAs that regulate transcription without changing the genetic code. The discovery of the first Polycomb mutant phenotype in Drosophila started the study of epigenetics more than 80 years ago. Since then, a considerable number of Polycomb Group (PcG) genes in Drosophila have been discovered to be preserved in mammals, including humans. PcG proteins exert their influence through gene repression by acting in complexes, modifying histones, and compacting the chromatin within the nucleus. In this article, we discuss how our knowledge of the PcG repression mechanism in Drosophila translates to human communicable disease research.
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Hernández-Romero IA, Valdes VJ. De Novo Polycomb Recruitment and Repressive Domain Formation. EPIGENOMES 2022; 6:25. [PMID: 35997371 PMCID: PMC9397058 DOI: 10.3390/epigenomes6030025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/15/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022] Open
Abstract
Every cell of an organism shares the same genome; even so, each cellular lineage owns a different transcriptome and proteome. The Polycomb group proteins (PcG) are essential regulators of gene repression patterning during development and homeostasis. However, it is unknown how the repressive complexes, PRC1 and PRC2, identify their targets and elicit new Polycomb domains during cell differentiation. Classical recruitment models consider the pre-existence of repressive histone marks; still, de novo target binding overcomes the absence of both H3K27me3 and H2AK119ub. The CpG islands (CGIs), non-core proteins, and RNA molecules are involved in Polycomb recruitment. Nonetheless, it is unclear how de novo targets are identified depending on the physiological context and developmental stage and which are the leading players stabilizing Polycomb complexes at domain nucleation sites. Here, we examine the features of de novo sites and the accessory elements bridging its recruitment and discuss the first steps of Polycomb domain formation and transcriptional regulation, comprehended by the experimental reconstruction of the repressive domains through time-resolved genomic analyses in mammals.
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Affiliation(s)
| | - Victor Julian Valdes
- Department of Cell Biology and Development, Institute of Cellular Physiology (IFC), National Autonomous University of Mexico (UNAM), Mexico City 04510, Mexico
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Affiliation(s)
- Abigail L. Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Anna R. Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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Whitford AL, Clinton CA, Kennedy EBL, Dochnal SA, Suzich JB, Cliffe AR. Ex Vivo Herpes Simplex Virus Reactivation Involves a Dual Leucine Zipper Kinase-Dependent Wave of Lytic Gene Expression That Is Independent of Histone Demethylase Activity and Viral Genome Synthesis. J Virol 2022; 96:e0047522. [PMID: 35604215 PMCID: PMC9215252 DOI: 10.1128/jvi.00475-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/27/2022] [Indexed: 12/22/2022] Open
Abstract
Herpes simplex virus 1 (HSV-1) maintains a lifelong latent infection in neurons and periodically reactivates, resulting in the production of infectious virus. The exact cellular pathways that induce reactivation are not understood. In primary neuronal models of HSV latency, the cellular protein dual leucine zipper kinase (DLK) has been found to initiate a wave of viral gene expression known as phase I. Phase I occurs independently of both viral DNA replication and the activities of histone demethylase enzymes required to remove repressive heterochromatin modifications associated with the viral genome. In this study, we investigated whether phase I-like gene expression occurs in ganglia reactivated from infected mice. Using the combined trigger of explant-induced axotomy and inhibition of phosphatidylinositide 3-kinase (PI3K) signaling, we found that HSV lytic gene expression was induced rapidly from both sensory and sympathetic neurons. Ex vivo reactivation involved a wave of viral late gene expression that occurred independently of viral genome synthesis and histone demethylase activity and preceded the detection of infectious virus. Importantly, we found that DLK was required for the initial induction of lytic gene expression. These data confirm the essential role of DLK in inducing HSV-1 gene expression from the heterochromatin-associated genome and further demonstrate that HSV-1 gene expression during reactivation occurs via mechanisms that are distinct from lytic replication. IMPORTANCE Reactivation of herpes simplex virus from a latent infection is associated with clinical disease. To develop new therapeutics that prevent reactivation, it is important to understand how viral gene expression initiates following a reactivation stimulus. Dual leucine zipper kinase (DLK) is a cellular protein that has previously been found to be required for HSV reactivation from sympathetic neurons in vitro. Here, we show that DLK is essential for reactivation from sensory ganglia isolated from infected mice. Furthermore, we show that DLK-dependent gene expression ex vivo occurs via mechanisms that are distinct from production replication, namely, lytic gene expression that is independent of viral DNA replication and histone demethylase activity. The identification of a DLK-dependent wave of lytic gene expression from sensory ganglia will ultimately permit the development of novel therapeutics that target lytic gene expression and prevent the earliest stage of reactivation.
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Affiliation(s)
- Abigail L. Whitford
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Corinne A. Clinton
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - E. B. Lane Kennedy
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Sara A. Dochnal
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Jon B. Suzich
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Anna R. Cliffe
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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10
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Dochnal S, Merchant HY, Schinlever AR, Babnis A, Depledge DP, Wilson AC, Cliffe AR. DLK-Dependent Biphasic Reactivation of Herpes Simplex Virus Latency Established in the Absence of Antivirals. J Virol 2022; 96:e0050822. [PMID: 35608347 PMCID: PMC9215246 DOI: 10.1128/jvi.00508-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/30/2022] [Indexed: 01/07/2023] Open
Abstract
Understanding the molecular mechanisms of herpes simplex virus 1 (HSV-1) latent infection and reactivation in neurons requires the use of in vitro model systems. Establishing a quiescent infection in cultured neurons is problematic, as any infectious virus released can superinfect the cultures. Previous studies have used the viral DNA replication inhibitor acyclovir to prevent superinfection and promote latency establishment. Data from these previous models have shown that reactivation is biphasic, with an initial phase I expression of all classes of lytic genes, which occurs independently of histone demethylase activity and viral DNA replication but is dependent on the cell stress protein DLK. Here, we describe a new model system using HSV-1 Stayput-GFP, a reporter virus that is defective for cell-to-cell spread and establishes latent infections without the need for acyclovir. The establishment of a latent state requires a longer time frame than previous models using DNA replication inhibitors. This results in a decreased ability of the virus to reactivate using established inducers, and as such, a combination of reactivation triggers is required. Using this system, we demonstrate that biphasic reactivation occurs even when latency is established in the absence of acyclovir. Importantly, phase I lytic gene expression still occurs in a histone demethylase and viral DNA replication-independent manner and requires DLK activity. These data demonstrate that the two waves of viral gene expression following HSV-1 reactivation are independent of secondary infection and not unique to systems that require acyclovir to promote latency establishment. IMPORTANCE Herpes simplex virus-1 (HSV-1) enters a latent infection in neurons and periodically reactivates. Reactivation manifests as a variety of clinical symptoms. Studying latency and reactivation in vitro is invaluable, allowing the molecular mechanisms behind both processes to be targeted by therapeutics that reduce the clinical consequences. Here, we describe a novel in vitro model system using a cell-to-cell spread-defective HSV-1, known as Stayput-GFP, which allows for the study of latency and reactivation at the single neuron level. We anticipate this new model system will be an incredibly valuable tool for studying the establishment and reactivation of HSV-1 latent infection in vitro. Using this model, we find that initial reactivation events are dependent on cellular stress kinase DLK but independent of histone demethylase activity and viral DNA replication. Our data therefore further validate the essential role of DLK in mediating a wave of lytic gene expression unique to reactivation.
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Affiliation(s)
- Sara Dochnal
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Husain Y. Merchant
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Austin R. Schinlever
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Aleksandra Babnis
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Daniel P. Depledge
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Angus C. Wilson
- Department of Microbiology, New York University School of Medicine, New York, New York, USA
| | - Anna R. Cliffe
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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