DLK-Dependent Biphasic Reactivation of Herpes Simplex Virus Latency Established in the Absence of Antivirals

Dochnal, Sara; Merchant, Husain; Schinlever, Austin; Babnis, Aleksandra; Depledge, Daniel P.; Wilson, Angus C.; Cliffe, Anna R.

doi:10.1128/jvi.00508-22

Cited by 16 publications

(15 citation statements)

References 124 publications

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“…In latently infected neurons, we observed enrichment of H3K27me3 on approximately 31% of latent HSV-1 genomes based on a NucSpotA intensity ratio above 1.5. This is consistent with previous observations that H3K27me3 is both enriched on the latent HSV genomes and its removal is important in reactivation (12,15,34,35,(78)(79)(80)(81). These data also highlight the potential heterogeneity in the epigenetic nature of latent HSV genomes, which may relate to different levels of expression of the latency-associated transcript between individual neurons or differences in sub-nuclear genome localization (82,83).…”

Section: Analysis Of Individual Hsv-1 Genome Foci For Co-localization...supporting

confidence: 92%

Single-genome analysis reveals heterogeneous association of the Herpes Simplex Virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts

Francois,

Rohani,

Loftus

et al. 2023

Preprint

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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.ImportanceInvestigating 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 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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Section: Analysis Of Individual Hsv-1 Genome Foci For Co-localization...supporting

confidence: 92%

Single-genome analysis reveals heterogeneous association of the Herpes Simplex Virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts

Francois,

Rohani,

Loftus

et al. 2023

Preprint

Self Cite

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“…This suggests a model in which transcriptional silencing is either established quickly yielding a low copy number latency-like infection or silencing takes place more slowly and permits some replication but is ultimately abortive and again resolves as a latent infection. This is supported by recent studies using a new reporter virus (HSV-1 Stayput-GFP) that is fully competent for DNA replication and gene expression but cannot spread from neuron-to-neuron [66]. With this virus, latent infections of murine primary SCG and TG neurons can be readily established and maintained for extended periods in the absence of antiviral treatments.…”

Section: Neuronal Latency Modelsmentioning

confidence: 89%

“…Precision studies are needed to determine if there are additional changes in chromatin composition or post-translational modification over time that can explain why reactivation is less efficient after sustained periods. Studies using the new spread-deficient reporter found that although genome copy number and LAT levels remained relatively constant, the proportion of neurons undergoing reactivation at 30 days post-infection was much reduced compared to 8 or 16 days [66].…”

Section: Looking To the Horizonmentioning

confidence: 95%

Impact of Cultured Neuron Models on α-Herpesvirus Latency Research

Wilson

2022

Viruses

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A signature trait of neurotropic α-herpesviruses (α-HV) is their ability to establish stable non-productive infections of peripheral neurons termed latency. This specialized gene expression program is the foundation of an evolutionarily successful strategy to ensure lifelong persistence in the host. Various physiological stresses can induce reactivation in a subset of latently-infected neurons allowing a new cycle of viral productive cycle gene expression and synthesis of infectious virus. Recurring reactivation events ensure transmission of the virus to new hosts and contributes to pathogenesis. Efforts to define the molecular basis of α-HV latency and reactivation have been notoriously difficult because the neurons harboring latent virus in humans and in experimentally infected live-animal models, are rare and largely inaccessible to study. Increasingly, researchers are turning to cultured neuron infection models as simpler experimental platforms from which to explore latency and reactivation at the molecular level. In this review, I reflect on the strengths and weaknesses of existing neuronal models and briefly summarize the important mechanistic insights these models have provided. I also discuss areas where prioritization will help to ensure continued progress and integration.

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“…By expressing HSV-1 ICP0 during this initial phase, the action of IFN is temporally restricted, thereby enabling subsequent lytic replication [43]. Superinfection was used to induce rapid and robust reactivation of HSV, which is likely to result in the delivery of viral tegument proteins [44]. It is therefore possible that UV-inactivated herpesvirus may provide a substantial supply of viral proteins, thereby shortening the duration of the first phase and increasing the success of reactivation.…”

Section: Discussionmentioning

confidence: 99%

Establishment of pseudorabies virus latency and reactivation model in mice dorsal root ganglia culture

Li,

Liu,

Luo

et al. 2023

Journal of General Virology

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Pseudorabies virus (PRV) belongs to the alpha herpesvirus family and is responsible for Aujeszky’s disease in pigs. Similar to other alpha herpesviruses, PRV establishes a lifelong latent infection in trigeminal ganglion. These latently infected pigs serve as a reservoir for recurrent infections when reactivation is triggered, making the eradication of PRV a challenging task. However, the molecular mechanism underlying PRV latency and reactivation in neurons is still poorly understood due to limitations in the in vitro model. To establish a pseudorabies virus latency and reactivation model in primary neuron cultures, we isolated dorsal root ganglion (DRG) from newborn Kunming mice using a method named epineurium-pulling for DRG collection (EPDC) and cultured primary neurons in vitro. A dual-colour recombinant PRV BAC mRuby-VP16 was constructed and 0.5 multiplicity of infection (MOI) was found as an appropriate dose in the presence of aciclovir to establish latency. Reactivation was induced using UV-inactivated herpesviruses or a series of chemical inhibitors. Interestingly, we found that not only UV-PRV, but also UV-HSV-1 and UV-BHoV-5 were able to induce rapid PRV reactivation. The efficiency of reactivation for LY294002, forskolin, etoposide, dexamethasone, and acetylcholine was found to be dependent on their concentration. In conclusion, we developed a valuable model of PRV latency and reactivation, which provides a basis for future mechanism research.

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DLK-Dependent Biphasic Reactivation of Herpes Simplex Virus Latency Established in the Absence of Antivirals

Abstract: Herpes simplex virus-1 (HSV-1) enters a latent infection in neurons and periodically reactivates. Reactivation manifests as a variety of clinical symptoms.

Cited by 16 publications

References 124 publications

Single-genome analysis reveals heterogeneous association of the Herpes Simplex Virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts

Single-genome analysis reveals heterogeneous association of the Herpes Simplex Virus genome with H3K27me2 and the reader PHF20L1 following infection of human fibroblasts

Impact of Cultured Neuron Models on α-Herpesvirus Latency Research

Establishment of pseudorabies virus latency and reactivation model in mice dorsal root ganglia culture

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