Long term herpes simplex virus type 1 infection of nerve growth factor-treated PC12 cells

Block, Timothy M.; Barney, Shawn; Masonis, John L.; Maggioncalda, John; Vályi-Nagy, Tibor; Fraser, Nigel W.

doi:10.1099/0022-1317-75-9-2481

Cited by 25 publications

(27 citation statements)

References 22 publications

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“…After several days, the cultures are free of infectious virus and LATs are detected in a large proportion of cells (14,48). In this and other neuron-based models, latency is dependent on the presence of nerve growth factor (NGF) and latent virus can be reactivated by NGF withdrawal, heat shock, or addition of activators of protein kinases (6,18,59,60). The viral genomes harbored in nonneuronal systems are more resistant to reactivation stimuli, and reactivation of gene expression can be induced only by the provision of IE110 (20).…”

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confidence: 99%

“…The problems are predominantly due to the relatively small proportion of cells within ganglia in which latency is established, the real and perceived asynchronicity of these molecular events in vivo, and the difficulty of addressing latency-dedicated functions of viral gene products that have a role in acute phase replication. To overcome such difficulties, several labs have developed in vitro models of latency using fibroblasts, neuroblastomas, or primary cultures of sensory neurons which, in general, rely on establishing latency through limiting virus replication and spread through the use of antiviral agents or replication-defective virus mutants (6,18,19,60). Such in vitro model systems have several advantages for the study of latency establishment and reactivation.…”

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confidence: 99%

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Herpes Simplex Virus Type 1 Promoter Activity during Latency Establishment, Maintenance, and Reactivation in Primary Dorsal Root Neurons In Vitro

Arthur

Scarpini²,

Connor³

et al. 2001

J Virol

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A neonatal rat dorsal root ganglion-derived neuronal culture system has been utilized to study herpes simplex virus (HSV) latency establishment, maintenance, and reactivation. We present our initial characterization of viral gene expression in neurons following infection with replication-defective HSV recombinants carrying ␤-galactosidase and/or green fluorescent protein reporter genes under the control of lytic cycle-or latency-associated promoters. In this system lytic virus reporter promoter activity was detected in up to 58% of neurons 24 h after infection. Lytic cycle reporter promoters were shut down over time, and long-term survival of neurons harboring latent virus genomes was demonstrated. Latency-associated promoter-driven reporter gene expression was detected in neurons from early times postinfection and was stably maintained in up to 83% of neurons for at least 3 weeks. In latently infected cultures, silent lytic cycle promoters could be activated in up to 53% of neurons by nerve growth factor withdrawal or through inhibition of histone deacetylases by trichostatin A. We conclude that the use of recombinant viruses containing reporter genes, under the regulation of lytic and latency promoter control in neuronal cultures in which latency can be established and reactivation can be induced, is a potentially powerful system in which to study the molecular events that occur during HSV infection of neurons.A defining characteristic of herpesviruses is the ability to establish latent infections in their natural hosts. Herpes simplex virus (HSV) establishes latent infection in neurons of the peripheral nervous system, predominantly in sensory ganglia innervating the site of primary infection (25,53,58). Latent virus has the capacity to reactivate, which can give rise to a peripheral lesion in the dermatome relating to the affected ganglia (reviewed in reference 63). During latency the virus genome exists in a form lacking detectable free ends, consistent with the presence of episomal or concatemeric DNA (16,31,38). The latency-associated transcripts (LATs) are transcribed from a region within the repeats, mapping antisense to the IE110 gene, giving rise to a family of colinear RNAs (54; reviewed in reference 58). The LAT region is the only region of the genome that is abundantly transcribed during latency, giving rise to RNAs which are predominantly nuclear and consist of two highly abundant, nonpolyadenylated RNAs of 2 and 1.5 kb, termed major LATs. The precise mechanism of synthesis of major LATs is unclear (3), although there is compelling evidence that these transcripts are introns derived from a less abundant 8.5-kb polyadenylated precursor RNA termed a minor LAT (1,3,17,32,39,65,67). The function of the LATs is uncertain; investigations using mouse models have shown that LATs are not essential for the establishment or maintenance of a latent infection or for reactivation (5, 23, 52). There is evidence, however, indicating that LATs can increase the number of neurons in which latency is established. Fur...

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confidence: 99%

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confidence: 99%

Herpes Simplex Virus Type 1 Promoter Activity during Latency Establishment, Maintenance, and Reactivation in Primary Dorsal Root Neurons In Vitro

Arthur

Scarpini²,

Connor³

et al. 2001

J Virol

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“…Two factors that have impeded our understanding of latency and reactivation are (i) the lack of definitive in vitro models of HSV latency and (ii) the fact that animalbased models of latency are not amenable to the analysis of HSV reactivation at the molecular level. Regarding the first point, although quiescent infections can be established in several different cell types (2,9,39,47,59), the relevance of existing "in vitro latency models" to HSV latency in vivo is unclear. Regarding the second point, although the establishment of latency in animal models closely parallels the natural history of HSV infection in humans (22,41,48), the effect of eliminating a viral gene product on reactivation is difficult to study because many HSV mutants replicate poorly in animals.…”

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confidence: 99%

Optimized Viral Dose and Transient Immunosuppression Enable Herpes Simplex Virus ICP0-Null Mutants To Establish Wild-Type Levels of Latency In Vivo

Halford

Schaffer

2000

J Virol

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The reduced efficiency with which herpes simplex virus type 1 (HSV-1) mutants establish latent infections in vivo has been a fundamental obstacle in efforts to determine the roles of individual viral genes in HSV-1 reactivation. For example, in the absence of the "nonessential" viral immediate-early protein, ICP0, HSV-1 is severely impaired in its ability to (i) replicate at the site of inoculation and (ii) establish latency in neurons of the peripheral nervous system. The mouse ocular model of HSV latency was used in the present study to determine if the conditions of infection can be manipulated such that replication-impaired, ICP0-null mutants establish wild-type levels of latency, as measured by viral genome loads in latently infected trigeminal ganglia (TG). To this end, the effects of inoculum size and transient immunosuppression on the levels of acute replication in mouse eyes and of viral DNA in latently infected TG were examined. Clinical interest in herpes simplex virus type 1 (HSV-1) and HSV-2 centers on their ability to reactivate from latency and cause recurrent herpetic diseases such as herpes labialis, stromal keratitis, genital herpes, and opportunistic infections of immunosuppressed individuals (37, 58). Despite long-standing interest in the problem (3, 13) and significant advances in our understanding of the molecular events in HSV-1 replication (38), the events that lead from latency to reactivation remain poorly understood. Two factors that have impeded our understanding of latency and reactivation are (i) the lack of definitive in vitro models of HSV latency and (ii) the fact that animalbased models of latency are not amenable to the analysis of HSV reactivation at the molecular level. Regarding the first point, although quiescent infections can be established in several different cell types (2,9,39,47,59), the relevance of existing "in vitro latency models" to HSV latency in vivo is unclear. Regarding the second point, although the establishment of latency in animal models closely parallels the natural history of HSV infection in humans (22,41,48), the effect of eliminating a viral gene product on reactivation is difficult to study because many HSV mutants replicate poorly in animals.Comparison of the reactivation efficiencies of null mutant viruses to that of wild-type virus is a potentially powerful approach to identifying viral genes involved in HSV reactivation. The effect of a mutation in a given gene on reactivation efficiency can be measured accurately, however, only when equal numbers of mutant and wild-type viral genomes are present in latently infected ganglia at the time of reactivation. Given that the efficient establishment of latency is dependent on viral replication at the site of inoculation (27,42,43), a fundamental obstacle to the use of viral mutants to study reactivation is that mutations in many "nonessential" viral genes impair the ability of HSV-1 to replicate in animals. For example, attempts to define the roles of ICP0, ICP22, and the virion host shutoff protein in ...

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“…Nevertheless, Egr-1 expression was first detected and characterized while treating PC-12 cells[3]and dorsal root ganglion (DRG) neurons[22]with nerve growth factor (NGF). NGF has been shown by several laboratories to mediate HSV-1 quiescent infection in various systems such as peripheral sympathetic and sensory neurons in vitro[23,24]and in PC-12 cells[25–27]. Given the fact that PC-12 cells and DRG neurons under NGF influence are frequently used as models for HSV-1 latency study, it would suggest that NGF-mediated HSV-1 gene silencing and quiescent state may result from, at least in part, by Egr-1 triggered inhibition on viral gene expression.…”

Section: Discussionmentioning

confidence: 99%

Induction of Transcription Factor Early Growth Response Protein 1 during HSV-1 Infection Promotes Viral Replication in Corneal Cells

Hsia

Graham

Bedadala

et al. 2013

BMRJ

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Aims To understand the mechanisms of Early Growth Response Protein 1 (Egr-1) induction upon HSV-1 lytic infection and its roles in regulating viral gene expression and replication. Study Design Rabbit corneal cell line SIRC and other cell lines were infected by HSV-1 to investigate the Egr-1 induction and its occupancy on the viral genome in different conditions. UV-inactivated HSV-1 and a recombinant virus over-expressing Egr-1 were generated to evaluate the regulatory effects on viral gene expression and replication during the infection. Methodology Egr-1 induction triggered by viral infection was determined by Western Blot analyses and immune-fluorescent microscopy. Real-time RT-PCR and a novel Cignal™ Reporter Assay were used for quantitative measurement of Egr-1 expression. Chromatin Immuno-precipitation (ChIP) was performed to address the Egr-1 occupancy to the viral regulatory sequences and the influence on viral replication was assessed by plaque assays. Results Our results indicated that Egr-1 expression requires viral gene expression since the UV-inactivated HSV-1 failed to produce Egr-1 protein. Blockade of viral replication did not block the Egr-1 protein synthesis, supporting the hypothesis that HSV-1 replication was not essential for Egr-1 production. Chromatin immune-precipitation (ChIP) and RT-PCR assays demonstrated that induced Egr-1 was able to interact with key regulatory elements near HSV-1 immediate-early (IE) genes and promote viral gene expression. Recombinant virus overexpressing Egr-1 revealed that Egr-1 enhanced the viral replication and the release of infectious virus. Conclusion Together these results concluded that HSV-1 triggers the expression of an important host transcription factor Egr-1 via a unique mechanism and benefit the viral gene expression and replication.

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Long term herpes simplex virus type 1 infection of nerve growth factor-treated PC12 cells

Cited by 25 publications

References 22 publications

Herpes Simplex Virus Type 1 Promoter Activity during Latency Establishment, Maintenance, and Reactivation in Primary Dorsal Root Neurons In Vitro

Herpes Simplex Virus Type 1 Promoter Activity during Latency Establishment, Maintenance, and Reactivation in Primary Dorsal Root Neurons In Vitro

Optimized Viral Dose and Transient Immunosuppression Enable Herpes Simplex Virus ICP0-Null Mutants To Establish Wild-Type Levels of Latency In Vivo

Induction of Transcription Factor Early Growth Response Protein 1 during HSV-1 Infection Promotes Viral Replication in Corneal Cells

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