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Frost TC, Salnikov M, Rice SA. Enhancement of HSV-1 cell-free virion release by the envelope protein gC. Virology 2024; 596:110120. [PMID: 38805801 PMCID: PMC11178091 DOI: 10.1016/j.virol.2024.110120] [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: 03/22/2024] [Revised: 05/08/2024] [Accepted: 05/21/2024] [Indexed: 05/30/2024]
Abstract
Glycoprotein C (gC), one of ∼12 HSV-1 envelope glycoproteins, carries out several important functions during infection, including the enhancement of virion attachment by binding to host cell heparan sulfate proteoglycans (HSPG). Here we report that gC can also enhance the release of cell-free progeny virions at the end of the infectious cycle. This activity was observed in multiple cellular contexts including Vero cells and immortalized human keratinocytes. In the absence of gC, progeny virions bound more tightly to infected cells, suggesting that gC promotes the detachment of virions from the infected cell surface. Given this finding, we analyzed the biochemical interactions that tether progeny virions to cells and report evidence for two distinct modes of binding. One is consistent with a direct interaction between gC and HSPG, whereas the other is gC-independent and likely does not involve HSPG. Together, our results i) identify a novel function for a long-studied HSV-1 glycoprotein, and ii) demonstrate that the extracellular release of HSV-1 virions is a dynamic process involving multiple viral and host components.
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Affiliation(s)
- Thomas C Frost
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | - Mark Salnikov
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
| | - Stephen A Rice
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA.
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2
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Xu H, Vega-Rodriguez W, Campos V, Jarosinski KW. mRNA Splicing of UL44 and Secretion of Alphaherpesvirinae Glycoprotein C (gC) Is Conserved among the Mardiviruses. Viruses 2024; 16:782. [PMID: 38793663 PMCID: PMC11126019 DOI: 10.3390/v16050782] [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: 04/21/2024] [Revised: 05/09/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Marek's disease (MD), caused by gallid alphaherpesvirus 2 (GaAHV2) or Marek's disease herpesvirus (MDV), is a devastating disease in chickens characterized by the development of lymphomas throughout the body. Vaccine strains used against MD include gallid alphaherpesvirus 3 (GaAHV3), a non-oncogenic chicken alphaherpesvirus homologous to MDV, and homologous meleagrid alphaherpesvirus 1 (MeAHV1) or turkey herpesvirus (HVT). Previous work has shown most of the MDV gC produced during in vitro passage is secreted into the media of infected cells although the predicted protein contains a transmembrane domain. We formerly identified two alternatively spliced gC mRNAs that are secreted during MDV replication in vitro, termed gC104 and gC145 based on the size of the intron removed for each UL44 (gC) transcript. Since gC is conserved within the Alphaherpesvirinae subfamily, we hypothesized GaAHV3 (strain 301B/1) and HVT also secrete gC due to mRNA splicing. To address this, we collected media from 301B/1- and HVT-infected cell cultures and used Western blot analyses and determined that both 301B/1 and HVT produced secreted gC. Next, we extracted RNAs from 301B/1- and HVT-infected cell cultures and chicken feather follicle epithelial (FFE) skin cells. RT-PCR analyses confirmed one splicing variant for 301B/1 gC (gC104) and two variants for HVT gC (gC104 and gC145). Interestingly, the splicing between all three viruses was remarkably conserved. Further analysis of predicted and validated mRNA splicing donor, branch point (BP), and acceptor sites suggested single nucleotide polymorphisms (SNPs) within the 301B/1 UL44 transcript sequence resulted in no gC145 being produced. However, modification of the 301B/1 gC145 donor, BP, and acceptor sites to the MDV UL44 sequences did not result in gC145 mRNA splice variant, suggesting mRNA splicing is more complex than originally hypothesized. In all, our results show that mRNA splicing of avian herpesviruses is conserved and this information may be important in developing the next generation of MD vaccines or therapies to block transmission.
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Affiliation(s)
| | | | | | - Keith W. Jarosinski
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA; (H.X.); (W.V.-R.); (V.C.)
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Volkening JD, Spatz SJ, Ponnuraj N, Akbar H, Arrington JV, Vega-Rodriguez W, Jarosinski KW. Viral proteogenomic and expression profiling during productive replication of a skin-tropic herpesvirus in the natural host. PLoS Pathog 2023; 19:e1011204. [PMID: 37289833 PMCID: PMC10284419 DOI: 10.1371/journal.ppat.1011204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/21/2023] [Accepted: 05/29/2023] [Indexed: 06/10/2023] Open
Abstract
Efficient transmission of herpesviruses is essential for dissemination in host populations; however, little is known about the viral genes that mediate transmission, mostly due to a lack of natural virus-host model systems. Marek's disease is a devastating herpesviral disease of chickens caused by Marek's disease virus (MDV) and an excellent natural model to study skin-tropic herpesviruses and transmission. Like varicella zoster virus that causes chicken pox in humans, the only site where infectious cell-free MD virions are efficiently produced is in epithelial skin cells, a requirement for host-to-host transmission. Here, we enriched for heavily infected feather follicle epithelial skin cells of live chickens to measure both viral transcription and protein expression using combined short- and long-read RNA sequencing and LC/MS-MS bottom-up proteomics. Enrichment produced a previously unseen breadth and depth of viral peptide sequencing. We confirmed protein translation for 84 viral genes at high confidence (1% FDR) and correlated relative protein abundance with RNA expression levels. Using a proteogenomic approach, we confirmed translation of most well-characterized spliced viral transcripts and identified a novel, abundant isoform of the 14 kDa transcript family via IsoSeq transcripts, short-read intron-spanning sequencing reads, and a high-quality junction-spanning peptide identification. We identified peptides representing alternative start codon usage in several genes and putative novel microORFs at the 5' ends of two core herpesviral genes, pUL47 and ICP4, along with strong evidence of independent transcription and translation of the capsid scaffold protein pUL26.5. Using a natural animal host model system to examine viral gene expression provides a robust, efficient, and meaningful way of validating results gathered from cell culture systems.
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Affiliation(s)
| | - Stephen J. Spatz
- US National Poultry Research Laboratory, ARS, USDA, Athens, Georgia, United States of America
| | - Nagendraprabhu Ponnuraj
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Haji Akbar
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Justine V. Arrington
- Protein Sciences Facility, Roy J. Carver Biotechnology Center, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Widaliz Vega-Rodriguez
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Keith W. Jarosinski
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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4
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Rice SA. Release of HSV-1 Cell-Free Virions: Mechanisms, Regulation, and Likely Role in Human-Human Transmission. Viruses 2021; 13:v13122395. [PMID: 34960664 PMCID: PMC8704881 DOI: 10.3390/v13122395] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 12/17/2022] Open
Abstract
Herpes simplex virus type 1, or HSV-1, is a widespread human pathogen that replicates in epithelial cells of the body surface and then establishes latent infection in peripheral neurons. When HSV-1 replicates, viral progeny must be efficiently released to spread infection to new target cells. Viral spread occurs via two major routes. In cell-cell spread, progeny virions are delivered directly to cellular junctions, where they infect adjacent cells. In cell-free release, progeny virions are released into the extracellular milieu, potentially allowing the infection of distant cells. Cell-cell spread of HSV-1 has been well studied and is known to be important for in vivo infection and pathogenesis. In contrast, HSV-1 cell-free release has received less attention, and its significance to viral biology is unclear. Here, I review the mechanisms and regulation of HSV-1 cell-free virion release. Based on knowledge accrued in other herpesviral systems, I argue that HSV-1 cell-free release is likely to be tightly regulated in vivo. Specifically, I hypothesize that this process is generally suppressed as the virus replicates within the body, but activated to high levels at sites of viral reactivation, such as the oral mucosa and skin, in order to promote efficient transmission of HSV-1 to new human hosts.
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Affiliation(s)
- Stephen A Rice
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455, USA
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Abstract
Two of the most prevalent human viruses worldwide, herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2, respectively), cause a variety of diseases, including cold sores, genital herpes, herpes stromal keratitis, meningitis and encephalitis. The intrinsic, innate and adaptive immune responses are key to control HSV, and the virus has developed mechanisms to evade them. The immune response can also contribute to pathogenesis, as observed in stromal keratitis and encephalitis. The fact that certain individuals are more prone than others to suffer severe disease upon HSV infection can be partially explained by the existence of genetic polymorphisms in humans. Like all herpesviruses, HSV has two replication cycles: lytic and latent. During lytic replication HSV produces infectious viral particles to infect other cells and organisms, while during latency there is limited gene expression and lack of infectious virus particles. HSV establishes latency in neurons and can cause disease both during primary infection and upon reactivation. The mechanisms leading to latency and reactivation and which are the viral and host factors controlling these processes are not completely understood. Here we review the HSV life cycle, the interaction of HSV with the immune system and three of the best-studied pathologies: Herpes stromal keratitis, herpes simplex encephalitis and genital herpes. We also discuss the potential association between HSV-1 infection and Alzheimer's disease.
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Affiliation(s)
- Shuyong Zhu
- Institute of Virology, Hannover Medical School, Cluster of Excellence RESIST (Exc 2155), Hannover Medical School, Hannover, Germany
| | - Abel Viejo-Borbolla
- Institute of Virology, Hannover Medical School, Cluster of Excellence RESIST (Exc 2155), Hannover Medical School, Hannover, Germany
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You Y, Hagag IT, Kheimar A, Bertzbach LD, Kaufer BB. Characterization of a Novel Viral Interleukin 8 (vIL-8) Splice Variant Encoded by Marek's Disease Virus. Microorganisms 2021; 9:microorganisms9071475. [PMID: 34361910 PMCID: PMC8303658 DOI: 10.3390/microorganisms9071475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 06/29/2021] [Accepted: 07/06/2021] [Indexed: 11/24/2022] Open
Abstract
Marek’s disease virus (MDV) is a highly cell-associated oncogenic alphaherpesvirus that causes lymphomas in various organs in chickens. Like other herpesviruses, MDV has a large and complex double-stranded DNA genome. A number of viral transcripts are generated by alternative splicing, a process that drastically extends the coding capacity of the MDV genome. One of the spliced genes encoded by MDV is the viral interleukin 8 (vIL-8), a CXC chemokine that facilitates the recruitment of MDV target cells and thereby plays an important role in MDV pathogenesis and tumorigenesis. We recently identified a novel vIL-8 exon (vIL-8-E3′) by RNA-seq; however, it remained elusive whether the protein containing the vIL-8-E3′ is expressed and what role it may play in MDV replication and/or pathogenesis. To address these questions, we first generated recombinant MDV harboring a tag that allows identification of the spliced vIL-8-E3′ protein, revealing that it is indeed expressed. We subsequently generated knockout viruses and could demonstrate that the vIL-8-E3′ protein is dispensable for MDV replication as well as secretion of the functional vIL-8 chemokine. Finally, infection of chickens with this vIL-8-E3′ knockout virus revealed that the protein is not important for MDV replication and pathogenesis in vivo. Taken together, our study provides novel insights into the splice forms of the CXC chemokine of this highly oncogenic alphaherpesvirus.
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Affiliation(s)
- Yu You
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (I.T.H.); (A.K.)
| | - Ibrahim T. Hagag
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (I.T.H.); (A.K.)
- Department of Virology, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Ahmed Kheimar
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (I.T.H.); (A.K.)
- Department of Poultry Diseases, Faculty of Veterinary Medicine, Sohag University, Sohag 82424, Egypt
| | - Luca D. Bertzbach
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (I.T.H.); (A.K.)
- Department of Viral Transformation, Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany
- Correspondence: (L.D.B.); (B.B.K.)
| | - Benedikt B. Kaufer
- Institute of Virology, Freie Universität Berlin, 14163 Berlin, Germany; (Y.Y.); (I.T.H.); (A.K.)
- Correspondence: (L.D.B.); (B.B.K.)
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Chen L, Ni Z, Hua J, Ye W, Liu K, Yun T, Zhu Y, Zhang C. Simultaneous tracking of capsid VP26, envelope protein gC localization in living cells infected with double fluorescent duck enteritis virus. Virus Res 2021; 297:198393. [PMID: 33727092 DOI: 10.1016/j.virusres.2021.198393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 01/04/2023]
Abstract
Duck enteritis virus (DEV) can cause an acute, contagious and lethal disease of many species of waterfowl. An infectious bacterial artificial chromosome clone of DEV vaccine strain pE1 (pDEV-EF1) has been constructed in our previous study. Based on pE1, a recombinant mutated clone pDL (pVP26CFP-gCRFP), which carries a red fluorescent protein (mRFP) gene fused to the viral envelope protein gC in combination with a cyan fluorescent protein (CFP) gene fused to the viral capsid VP26, was constructed by two-step Red/ET recombination and the recombinant virus rDL (rVP26CFP-gCRFP) was rescued from chicken embryo fibroblasts (CEFs) by calcium phosphate transfection. Western blot analysis revealed that VP26-CFP and gC-mRFP were both expressed in fusion forms in rDL-infected CEFs, and subcellular localization study showed that gC-mRFP was mainly localized in whole cell at 36, 48 h post infection (p.i.); and then mostly migrated to the cytoplasm after 60 h.p.i., ; whereas VP26-CFP was localized in the nucleus in all stages of virus infection. Additionally, viral particles at different stages of morphogenesis (A capsids, B capsids, C capsids) were observed in virus-infected cells by transmission electron microscopy, indicating that exogenous gene insertion has no effect on virus assembly. This study has laid a foundation for visually studying localization, transportation of DEV capsid proteins and envelope glycoproteins as well as virus assembly, virion movement and virus-cell interaction.
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Affiliation(s)
- Liu Chen
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Zheng Ni
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Jionggang Hua
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Weicheng Ye
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Keshu Liu
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Tao Yun
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Yinchu Zhu
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
| | - Cun Zhang
- Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
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Jones J, Depledge DP, Breuer J, Ebert-Keel K, Elliott G. Genetic and phenotypic intrastrain variation in herpes simplex virus type 1 Glasgow strain 17 syn+-derived viruses. J Gen Virol 2020; 100:1701-1713. [PMID: 31661047 DOI: 10.1099/jgv.0.001343] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Glasgow s17 syn+ strain of herpes simplex virus 1 (HSV1) is arguably the best characterized strain and has provided the reference sequence for HSV1 genetic studies. Here we show that our original s17 syn+ stock was a mixed population from which we have isolated a minor variant that, unlike other strains in the laboratory, fails to be efficiently released from infected cells and spreads predominantly by direct cell-to-cell transmission. Analysis of other s17-derived viruses that had been isolated elsewhere revealed a number with the same release phenotype. Second-generation sequencing of 8 plaque-purified s17-derived viruses revealed sequences that vary by 50 single-nucleotide polymorphisms (SNPs), including approximately 10 coding SNPs. This compared to interstrain variations of around 800 SNPs in strain Sc16, of which a quarter were coding changes. Amongst the variations found within s17, we identified 13 variants of glycoprotein C within the original stock of virus that were predominantly a consequence of altered homopolymeric runs of C residues. Characterization of seven isolates coding for different forms of gC indicated that all were expressed, despite six of them lacking a transmembrane domain. While the release phenotype did not correlate directly with any of these identified gC variations, further demonstration that nine clinical isolates of HSV1 also fail to spread through extracellular release raises the possibility that propagation in tissue culture had altered the HSV1 s17 transmission phenotype. Hence, the s17 intrastrain variation identified here offers an excellent model for understanding both HSV1 transmission and tissue culture adaptation.
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Affiliation(s)
- Juliet Jones
- Section of Virology, Department of Microbial Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Daniel Pearce Depledge
- Present address: Department of Medicine, New York University School of Medicine, New York, USA.,Division of Infection and Immunity, University College London, London, UK
| | - Judith Breuer
- Division of Infection and Immunity, University College London, London, UK
| | - Katja Ebert-Keel
- Section of Virology, Department of Microbial Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Gillian Elliott
- Section of Virology, Department of Microbial Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
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Comprehensive Mutagenesis of Herpes Simplex Virus 1 Genome Identifies UL42 as an Inhibitor of Type I Interferon Induction. J Virol 2019; 93:JVI.01446-19. [PMID: 31511375 DOI: 10.1128/jvi.01446-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 09/02/2019] [Indexed: 12/18/2022] Open
Abstract
In spite of several decades of research focused on understanding the biology of human herpes simplex virus 1 (HSV-1), no tool has been developed to study its genome in a high-throughput fashion. Here, we describe the creation of a transposon insertion mutant library of the HSV-1 genome. Using this tool, we aimed to identify novel viral regulators of type I interferon (IFN-I). HSV-1 evades the host immune system by encoding viral proteins that inhibit the type I interferon response. Applying differential selective pressure, we identified the three strongest viral IFN-I regulators in HSV-1. We report that the viral polymerase processivity factor UL42 interacts with the host transcription factor IFN regulatory factor 3 (IRF-3), inhibiting its phosphorylation and downstream beta interferon (IFN-β) gene transcription. This study represents a proof of concept for the use of high-throughput screening of the HSV-1 genome in investigating viral biology and offers new targets both for antiviral therapy and for oncolytic vector design.IMPORTANCE This work is the first to report the use of a high-throughput mutagenesis method to study the genome of HSV-1. We report three novel viral proteins potentially involved in regulating the host type I interferon response. We describe a novel mechanism by which the viral protein UL42 is able to suppress the production of beta interferon. The tool we introduce in this study can be used to study the HSV-1 genome in great detail to better understand viral gene functions.
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Tombácz D, Moldován N, Balázs Z, Gulyás G, Csabai Z, Boldogkői M, Snyder M, Boldogkői Z. Multiple Long-Read Sequencing Survey of Herpes Simplex Virus Dynamic Transcriptome. Front Genet 2019; 10:834. [PMID: 31608102 PMCID: PMC6769088 DOI: 10.3389/fgene.2019.00834] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 08/13/2019] [Indexed: 12/12/2022] Open
Abstract
Long-read sequencing (LRS) has become increasingly important in RNA research due to its strength in resolving complex transcriptomic architectures. In this regard, currently two LRS platforms have demonstrated adequate performance: the Single Molecule Real-Time Sequencing by Pacific Biosciences (PacBio) and the nanopore sequencing by Oxford Nanopore Technologies (ONT). Even though these techniques produce lower coverage and are more error prone than short-read sequencing, they continue to be more successful in identifying polycistronic RNAs, transcript isoforms including splice and transcript end variants, as well as transcript overlaps. Recent reports have successfully applied LRS for the investigation of the transcriptome of viruses belonging to various families. These studies have substantially increased the number of previously known viral RNA molecules. In this work, we used the Sequel and MinION technique from PacBio and ONT, respectively, to characterize the lytic transcriptome of the herpes simplex virus type 1 (HSV-1). In most samples, we analyzed the poly(A) fraction of the transcriptome, but we also performed random oligonucleotide-based sequencing. Besides cDNA sequencing, we also carried out native RNA sequencing. Our investigations identified more than 2,300 previously undetected transcripts, including coding, and non-coding RNAs, multi-splice transcripts, as well as polycistronic and complex transcripts. Furthermore, we found previously unsubstantiated transcriptional start sites, polyadenylation sites, and splice sites. A large number of novel transcriptional overlaps were also detected. Random-primed sequencing revealed that each convergent gene pair produces non-polyadenylated read-through RNAs overlapping the partner genes. Furthermore, we identified novel replication-associated transcripts overlapping the HSV-1 replication origins, and novel LAT variants with very long 5' regions, which are co-terminal with the LAT-0.7kb transcript. Overall, our results demonstrated that the HSV-1 transcripts form an extremely complex pattern of overlaps, and that entire viral genome is transcriptionally active. In most viral genes, if not in all, both DNA strands are expressed.
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Affiliation(s)
- Dóra Tombácz
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Norbert Moldován
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Balázs
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Gábor Gulyás
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Csabai
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Miklós Boldogkői
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Michael Snyder
- Department of Genetics, School of Medicine, Stanford University, Stanford, CA, United States
| | - Zsolt Boldogkői
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
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Conserved G-Quadruplexes Regulate the Immediate Early Promoters of Human Alphaherpesviruses. Molecules 2019; 24:molecules24132375. [PMID: 31252527 PMCID: PMC6651000 DOI: 10.3390/molecules24132375] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/24/2019] [Accepted: 06/26/2019] [Indexed: 01/15/2023] Open
Abstract
Human Alphaherpesviruses comprise three members, herpes simplex virus (HSV) 1 and 2 and varicella zoster virus (VZV). These viruses are characterized by a lytic cycle in epithelial cells and latency in the nervous system, with lifelong infections that may periodically reactivate and lead to serious complications, especially in immunocompromised patients. The mechanisms that regulate viral transcription have not been fully elucidated, but the master role of the immediate early (IE) genes has been established. G-quadruplexes are non-canonical nucleic-acid structures that control transcription, replication, and recombination in many organisms including viruses and that represent attractive antiviral targets. In this work, we investigate the presence, conservation, folding and activity of G-quadruplexes in the IE promoters of the Alphaherpesviruses. Our analysis shows that all IE promoters in the genome of HSV-1, HSV-2 and VZV contain fully conserved G-quadruplex forming sequences. These comprise sequences with long loops and bulges, and thus deviating from the classic G-quadruplex motifs. Moreover, their location is both on the leading and lagging strand and in some instances they contain exuberant G-tracts. Biophysical and biological analysis proved that all sequences actually fold into G-quadruplex under physiological conditions and can be further stabilized by the G-quadruplex ligand BRACO-19, with subsequent impairment of viral IE gene transcription in cells. These results help shed light on the control of viral transcription and indicate new viral targets to design drugs that impair the early steps of Alphaherpesviruses. In addition, they validate the significance of G-quadruplexes in the general regulation of viral cycles.
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Tang S, Patel A, Krause PR. Hidden regulation of herpes simplex virus 1 pre-mRNA splicing and polyadenylation by virally encoded immediate early gene ICP27. PLoS Pathog 2019; 15:e1007884. [PMID: 31206552 PMCID: PMC6597130 DOI: 10.1371/journal.ppat.1007884] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/27/2019] [Accepted: 06/03/2019] [Indexed: 12/23/2022] Open
Abstract
In contrast to human cells, very few HSV-1 genes are known to be spliced, although the same pre-mRNA processing machinery is shared. Here, through global analysis of splice junctions in cells infected with HSV-1 and an HSV-1 mutant virus with deletion of infectious cell culture protein 27 (ICP27), one of two viral immediate early (IE) genes essential for viral replication, we identify hundreds of novel alternative splice junctions mapping to both previously known HSV-1 spliced genes and previously unknown spliced genes, the majority of which alter the coding potential of viral genes. Quantitative and qualitative splicing efficiency analysis of these novel alternatively spliced genes based on RNA-Seq and RT-PCR reveals that splicing at these novel splice sites is efficient only when ICP27 is absent; while in wildtype HSV-1 infected cells, the splicing of these novel splice junctions is largely silenced in a gene/sequence specific manner, suggesting that ICP27 not only promotes accumulation of ICP27 targeted transcripts but also ensures correctness of the functional coding sequences through inhibition of alternative splicing. Furthermore, ICP27 toggles expression of ICP34.5, the major viral neurovirulence factor, through inhibition of splicing and activation of a proximal polyadenylation signal (PAS) in the newly identified intron, revealing a novel regulatory mechanism for expression of a viral gene. Thus, through the viral IE protein ICP27, HSV-1 co-opts both splicing and polyadenylation machinery to achieve optimal viral gene expression during lytic infection. On the other hand, during latent infection when ICP27 is absent, HSV-1 likely takes advantages of host splicing machinery to restrict expression of randomly activated antigenic viral genes to achieve immune evasion. Little is known regarding to how HSV, a large DNA virus and known to contain very few spliced genes, escapes host pre-mRNA splicing machinery. Here, by establishing a high throughput splice junction identification platform and quantitative analysis method to assess splicing efficiency based on high throughput data, we find that HSV-1 encodes hundreds of previously unknown alternative splice junctions; however, splicing of these novel spliced genes is largely silenced in wild-type HSV-1 infected cells, explaining why only very few spliced genes have been previously identified in HSV-1. Moreover, ICP27 is required for splicing inhibition and 3’ end formation of ICP34.5, the major viral neurovirulence factor and also the major target of latently expressed viral miRNAs. These findings not only fundamentally change the view of HSV gene structure, but also reveal a mechanism by which HSV employs host splicing and polyadenylation machineries to achieve optimal gene expression during acute infection and may also contribute to immune evasion during latency when ICP27 is not expressed.
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Affiliation(s)
- Shuang Tang
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
- * E-mail: (ST); (PRK)
| | - Amita Patel
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Philip R. Krause
- Division of Viral Products, Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
- * E-mail: (ST); (PRK)
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The Herpesviridae Conserved Multifunctional Infected-Cell Protein 27 (ICP27) Is Important but Not Required for Replication and Oncogenicity of Marek's Disease Alphaherpesvirus. J Virol 2019; 93:JVI.01903-18. [PMID: 30518650 DOI: 10.1128/jvi.01903-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 11/27/2018] [Indexed: 02/07/2023] Open
Abstract
The Herpesviridae conserved infected-cell protein 27 (ICP27) is essential for cell culture-based replication of most herpesviruses studied. For members of the Alphaherpesvirinae, ICP27 regulates the expression of many viral genes, including expression of pUL44 (gC), pUL47 (VP13/14), and pUL48 (VP16). These three viral proteins are dysregulated during Marek's disease alphaherpesvirus (MDV) replication in cell culture. MDV replicates in a highly cell-associated manner in cell culture, producing little to no infectious virus. In contrast, infectious cell-free MDV is produced in specialized feather follicle epithelial (FFE) cells of infected chickens, in which these three genes are abundantly expressed. This led us to hypothesize that MDV ICP27, encoded by gene UL54, is a defining factor for the dysregulation of gC, pUL47, and pUL48 and, ultimately, ineffective virus production in cell culture. To address ICP27's role in MDV replication, we generated recombinant MDV with ICP27 deleted (vΔ54). Interestingly, vΔ54 replicated, but plaque sizes were significantly reduced compared to those of parental viruses. The reduced cell-to-cell spread was due to ICP27 since plaque sizes were restored in rescued viruses, as well as when vΔ54 was propagated in cells expressing ICP27 in trans In chickens, vΔ54 replicated, induced disease, and was oncogenic but was unable to transmit from chicken to chicken. To our knowledge, this is the first report showing that the Herpesviridae conserved ICP27 protein is dispensable for replication and disease induction in its natural host.IMPORTANCE Marek's disease (MD) is a devastating oncogenic disease that affects the poultry industry and is caused by MD alphaherpesvirus (MDV). Current vaccines block induction of disease but do not block chicken-to-chicken transmission. There is a knowledge gap in our understanding of how MDV spreads from chicken to chicken. We studied the Herpesviridae conserved ICP27 regulatory protein in cell culture and during MDV infection in chickens. We determined that MDV ICP27 is important but not required for replication in both cell culture and chickens. In addition, MDV ICP27 was not required for disease induction or oncogenicity but was required for chicken-to-chicken transmission. This study is important because it addresses the role of ICP27 during infection in the natural host and provides important information for the development of therapies to protect chickens against MD.
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Rekosh D, Hammarskjold ML. Intron retention in viruses and cellular genes: Detention, border controls and passports. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1470. [PMID: 29508942 DOI: 10.1002/wrna.1470] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/04/2018] [Accepted: 01/24/2018] [Indexed: 02/06/2023]
Abstract
Intron retention (IR), where one or more introns remain in the RNA after splicing, was long thought to be rare in mammalian cells, albeit common in plants and some viruses. Largely due to the development of better methods for RNA analysis, it has now been recognized that IR is much more common than previously thought and that this mechanism is likely to play an important role in mammalian gene regulation. To date, most publications and reviews about IR have described the resulting mRNAs as "dead end" products, with no direct consequence for the proteome. However, there are also many reports of mRNAs with retained introns giving rise to alternative protein isoforms. Although this was originally revealed in viral systems, there are now numerous examples of bona fide cellular proteins that are translated from mRNAs with retained introns. These new isoforms have sometimes been shown to have important regulatory functions. In this review, we highlight recent developments in this area and the research on viruses that led the way to the realization of the many ways in which mRNAs with retained introns can be regulated. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing RNA Export and Localization > Nuclear Export/Import RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- David Rekosh
- The Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia.,Department of Microbiology, University of Venda, Thohoyandou, South Africa
| | - Marie-Louise Hammarskjold
- The Myles H. Thaler Center for AIDS and Human Retrovirus Research and the Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia.,Department of Microbiology, University of Venda, Thohoyandou, South Africa
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15
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Hu B, Huo Y, Yang L, Chen G, Luo M, Yang J, Zhou J. ZIKV infection effects changes in gene splicing, isoform composition and lncRNA expression in human neural progenitor cells. Virol J 2017; 14:217. [PMID: 29116029 PMCID: PMC5688814 DOI: 10.1186/s12985-017-0882-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 10/30/2017] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The Zika virus (ZIKV) is a mosquito-borne flavivirus that causes microcephaly and Guillain-Barré syndrome in infected individuals. To obtain insights into the mechanism of ZIKV infection and pathogenesis, we analyzed the transcriptome of ZIKV infected human neural progenitor cells (hNPCs) for changes in alternative splicing (AS), gene isoform (ISO) composition and long noncoding RNAs (lncRNAs) expression. METHODS We analyzed differentially expressed lncRNAs, AS, ISO from RNA-seq data in ZIKV infected hNPCs. RESULTS We obtained 149 differentially expressed lncRNAs, including potential viral targets to modulate cellular processes such as cell cycle, apoptosis and immune response. The infection induced 262 cases of AS occurring in 229 genes, which were enriched in cell death, RNA processing, transport, and neuron development. Among 691 differentially expressed ISOs, upregulated ISOs were enriched in signaling, regulation of transcription, and amino acid biosynthesis, while downregulated ISOs were mostly enriched in cell cycle. Importantly, these analyses revealed specific links between ZIKV induced changes in cellular pathways and the type of changes in the host transcriptome, suggesting important regulatory mechanisms. CONCLUSIONS Our analyses revealed candidate lncRNAs, AS events and ISOs which may function in ZIKV infection induced cell cycle disruption, apoptosis and attenuation of neurogenesis, and shed light on the roles of lncRNAs, AS and ISOs in virus-host interactions, and would facilitate future studies of ZIKV infection and pathogenesis.
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Affiliation(s)
- Benxia Hu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, China.,Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, China
| | - Yongxia Huo
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, China
| | - Liping Yang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, China
| | - Guijun Chen
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, China
| | - Minhua Luo
- State Key Laboratory of Virology, CAS Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Wuhan Institute of Virology, Wuhan, 430071, China
| | - Jinlong Yang
- BGI-Yunnan, BGI-Shenzhen, Kunming, 650000, China.,College of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Jumin Zhou
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Kunming Institute of Zoology, Kunming, 650223, China.
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16
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Tombácz D, Csabai Z, Szűcs A, Balázs Z, Moldován N, Sharon D, Snyder M, Boldogkői Z. Long-Read Isoform Sequencing Reveals a Hidden Complexity of the Transcriptional Landscape of Herpes Simplex Virus Type 1. Front Microbiol 2017; 8:1079. [PMID: 28676792 PMCID: PMC5476775 DOI: 10.3389/fmicb.2017.01079] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 05/29/2017] [Indexed: 12/23/2022] Open
Abstract
In this study, we used the amplified isoform sequencing technique from Pacific Biosciences to characterize the poly(A)+ fraction of the lytic transcriptome of the herpes simplex virus type 1 (HSV-1). Our analysis detected 34 formerly unidentified protein-coding genes, 10 non-coding RNAs, as well as 17 polycistronic and complex transcripts. This work also led us to identify many transcript isoforms, including 13 splice and 68 transcript end variants, as well as several transcript overlaps. Additionally, we determined previously unascertained transcriptional start and polyadenylation sites. We analyzed the transcriptional activity from the complementary DNA strand in five convergent HSV gene pairs with quantitative RT-PCR and detected antisense RNAs in each gene. This part of the study revealed an inverse correlation between the expressions of convergent partners. Our work adds new insights for understanding the complexity of the pervasive transcriptional overlaps by suggesting that there is a crosstalk between adjacent and distal genes through interaction between their transcription apparatuses. We also identified transcripts overlapping the HSV replication origins, which may indicate an interplay between the transcription and replication machineries. The relative abundance of HSV-1 transcripts has also been established by using a novel method based on the calculation of sequencing reads for the analysis.
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Affiliation(s)
- Dóra Tombácz
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Zsolt Csabai
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Attila Szűcs
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Zsolt Balázs
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Norbert Moldován
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - Donald Sharon
- Department of Genetics, School of Medicine, Stanford UniversityStanford, CA, United States
| | - Michael Snyder
- Department of Genetics, School of Medicine, Stanford UniversityStanford, CA, United States
| | - Zsolt Boldogkői
- Department of Medical Biology, Faculty of Medicine, University of SzegedSzeged, Hungary
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17
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Varicella zoster virus glycoprotein C increases chemokine-mediated leukocyte migration. PLoS Pathog 2017; 13:e1006346. [PMID: 28542541 PMCID: PMC5444840 DOI: 10.1371/journal.ppat.1006346] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/11/2017] [Indexed: 02/07/2023] Open
Abstract
Varicella zoster virus (VZV) is a highly prevalent human pathogen that establishes latency in neurons of the peripheral nervous system. Primary infection causes varicella whereas reactivation results in zoster, which is often followed by chronic pain in adults. Following infection of epithelial cells in the respiratory tract, VZV spreads within the host by hijacking leukocytes, including T cells, in the tonsils and other regional lymph nodes, and modifying their activity. In spite of its importance in pathogenesis, the mechanism of dissemination remains poorly understood. Here we addressed the influence of VZV on leukocyte migration and found that the purified recombinant soluble ectodomain of VZV glycoprotein C (rSgC) binds chemokines with high affinity. Functional experiments show that VZV rSgC potentiates chemokine activity, enhancing the migration of monocyte and T cell lines and, most importantly, human tonsillar leukocytes at low chemokine concentrations. Binding and potentiation of chemokine activity occurs through the C-terminal part of gC ectodomain, containing predicted immunoglobulin-like domains. The mechanism of action of VZV rSgC requires interaction with the chemokine and signalling through the chemokine receptor. Finally, we show that VZV viral particles enhance chemokine-dependent T cell migration and that gC is partially required for this activity. We propose that VZV gC activity facilitates the recruitment and subsequent infection of leukocytes and thereby enhances VZV systemic dissemination in humans. Varicella zoster virus (VZV) causes two main pathologies in humans, chickenpox during primary infection, and shingles following reactivation. The latter is a painful condition that is often followed by chronic pain in a large numbers of shingles patients. Despite the existence of a vaccine, shingles-related complications cause expenses of more than $1 billion per year in the USA alone. Following primary infection, the virus infects leukocytes including T cells, spreading to the skin causing chickenpox. Direct infection of neurons from leukocytes has also been postulated. Given the relevance of leukocytes in VZV biology and the importance of chemokines in directing their migration, we investigated whether VZV modulates the function of chemokines. Our results show that VZV glycoprotein C potentiates the activity of chemokines, inducing higher migration of human leukocytes at low chemokine concentration. This may attract additional susceptible leukocytes to the site of infection enhancing virus spread and pathogenesis.
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18
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You Y, Cheng AC, Wang MS, Jia RY, Sun KF, Yang Q, Wu Y, Zhu D, Chen S, Liu MF, Zhao XX, Chen XY. The suppression of apoptosis by α-herpesvirus. Cell Death Dis 2017; 8:e2749. [PMID: 28406478 PMCID: PMC5477576 DOI: 10.1038/cddis.2017.139] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 02/09/2017] [Accepted: 02/20/2017] [Indexed: 02/07/2023]
Abstract
Apoptosis, an important innate immune mechanism that eliminates pathogen-infected cells, is primarily triggered by two signalling pathways: the death receptor pathway and the mitochondria-mediated pathway. However, many viruses have evolved various strategies to suppress apoptosis by encoding anti-apoptotic factors or regulating apoptotic signalling pathways, which promote viral propagation and evasion of the host defence. During its life cycle, α-herpesvirus utilizes an elegant multifarious anti-apoptotic strategy to suppress programmed cell death. This progress article primarily focuses on the current understanding of the apoptosis-inhibition mechanisms of α-herpesvirus anti-apoptotic genes and their expression products and discusses future directions, including how the anti-apoptotic function of herpesvirus could be targeted therapeutically.
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Affiliation(s)
- Yu You
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - An-Chun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Ming-Shu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Ren-Yong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Kun-Feng Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Ma-Feng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Xin-Xin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
| | - Xiao-Yue Chen
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City 611130, Sichuan, P.R. China
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Sadek J, Read GS. The Splicing History of an mRNA Affects Its Level of Translation and Sensitivity to Cleavage by the Virion Host Shutoff Endonuclease during Herpes Simplex Virus Infections. J Virol 2016; 90:10844-10856. [PMID: 27681125 PMCID: PMC5110170 DOI: 10.1128/jvi.01302-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/19/2016] [Indexed: 12/20/2022] Open
Abstract
During lytic herpes simplex virus (HSV) infections, the virion host shutoff (Vhs) (UL41) endoribonuclease degrades many cellular and viral mRNAs. In uninfected cells, spliced mRNAs emerge into the cytoplasm bound by exon junction complexes (EJCs) and are translated several times more efficiently than unspliced mRNAs that have the same sequence but lack EJCs. Notably, most cellular mRNAs are spliced, whereas most HSV mRNAs are not. To examine the effect of splicing on gene expression during HSV infection, cells were transfected with plasmids harboring an unspliced renilla luciferase (RLuc) reporter mRNA or RLuc constructs with introns near the 5' or 3' end of the gene. After splicing of intron-containing transcripts, all three RLuc mRNAs had the same primary sequence. Upon infection in the presence of actinomycin D, spliced mRNAs were much less sensitive to degradation by copies of Vhs from infecting virions than were unspliced mRNAs. During productive infections (in the absence of drugs), RLuc was expressed at substantially higher levels from spliced than from unspliced mRNAs. Interestingly, the stimulatory effect of splicing on RLuc expression was significantly greater in infected than in uninfected cells. The translational stimulatory effect of an intron during HSV-1 infections could be replicated by artificially tethering various EJC components to an unspliced RLuc transcript. Thus, the splicing history of an mRNA, and the consequent presence or absence of EJCs, affects its level of translation and sensitivity to Vhs cleavage during lytic HSV infections. IMPORTANCE Most mammalian mRNAs are spliced. In contrast, of the more than 80 mRNAs harbored by herpes simplex virus 1 (HSV-1), only 5 are spliced. In addition, synthesis of the immediate early protein ICP27 causes partial inhibition of pre-mRNA splicing, with the resultant accumulation of both spliced and unspliced versions of some mRNAs in the cytoplasm. A common perception is that HSV-1 infection necessarily inhibits the expression of spliced mRNAs. In contrast, this study demonstrates two instances in which pre-mRNA splicing actually enhances the synthesis of proteins from mRNAs during HSV-1 infections. Specifically, splicing stabilized an mRNA against degradation by copies of the Vhs endoribonuclease from infecting virions and greatly enhanced the amount of protein synthesized from spliced mRNAs at late times after infection. The data suggest that splicing, and the resultant presence of exon junction complexes on an mRNA, may play an important role in gene expression during HSV-1 infections.
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Affiliation(s)
- Jouliana Sadek
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - G Sullivan Read
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri, USA
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20
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Herpes simplex virus ICP27 regulates alternative pre-mRNA polyadenylation and splicing in a sequence-dependent manner. Proc Natl Acad Sci U S A 2016; 113:12256-12261. [PMID: 27791013 DOI: 10.1073/pnas.1609695113] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The herpes simplex virus (HSV) infected cell culture polypeptide 27 (ICP27) protein is essential for virus infection of cells. Recent studies suggested that ICP27 inhibits splicing in a gene-specific manner via an unknown mechanism. Here, RNA-sequencing revealed that ICP27 not only inhibits splicing of certain introns in <1% of cellular genes, but also can promote use of alternative 5' splice sites. In addition, ICP27 induced expression of pre-mRNAs prematurely cleaved and polyadenylated from cryptic polyadenylation signals (PAS) located in intron 1 or 2 of ∼1% of cellular genes. These previously undescribed prematurely cleaved and polyadenylated pre-mRNAs, some of which contain novel ORFs, were typically intronless, <2 Kb in length, expressed early during viral infection, and efficiently exported to cytoplasm. Sequence analysis revealed that ICP27-targeted genes are GC-rich (as are HSV genes), contain cytosine-rich sequences near the 5' splice site, and have suboptimal splice sites in the impacted intron, suggesting that a common mechanism is shared between ICP27-mediated alternative polyadenylation and splicing. Optimization of splice site sequences or mutation of nearby cytosines eliminated ICP27-mediated splicing inhibition, and introduction of C-rich sequences to an ICP27-insensitive splicing reporter conferred this phenotype, supporting the inference that specific gene sequences confer susceptibility to ICP27. Although HSV is the first virus and ICP27 is the first viral protein shown to activate cryptic PASs in introns, we suspect that other viruses and cellular genes also encode this function.
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21
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Cellular responses to HSV-1 infection are linked to specific types of alterations in the host transcriptome. Sci Rep 2016; 6:28075. [PMID: 27354008 PMCID: PMC4926211 DOI: 10.1038/srep28075] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/26/2016] [Indexed: 02/06/2023] Open
Abstract
Pathogen invasion triggers a number of cellular responses and alters the host transcriptome. Here we report that the type of changes to cellular transcriptome is related to the type of cellular functions affected by lytic infection of Herpes Simplex Virus type I in Human primary fibroblasts. Specifically, genes involved in stress responses and nuclear transport exhibited mostly changes in alternative polyadenylation (APA), cell cycle genes showed mostly alternative splicing (AS) changes, while genes in neurogenesis, rarely underwent these changes. Transcriptome wide, the infection resulted in 1,032 cases of AS, 161 incidences of APA, 1,827 events of isoform changes, and up regulation of 596 genes and down regulations of 61 genes compared to uninfected cells. Thus, these findings provided important and specific links between cellular responses to HSV-1 infection and the type of alterations to the host transcriptome, highlighting important roles of RNA processing in virus-host interactions.
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22
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Lang FC, Li X, Vladmirova O, Li ZR, Chen GJ, Xiao Y, Li LH, Lu DF, Han HB, Zhou JM. Selective recruitment of host factors by HSV-1 replication centers. DONG WU XUE YAN JIU = ZOOLOGICAL RESEARCH 2015; 36:142-51. [PMID: 26018857 PMCID: PMC4790689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/09/2015] [Indexed: 06/04/2023]
Abstract
Herpes simplex virus type 1 (HSV-1) enters productive infection after infecting epithelial cells, where it controls the host nucleus to make viral proteins, starts viral DNA synthesis and assembles infectious virions. In this process, replicating viral genomes are organized into replication centers to facilitate viral growth. HSV-1 is known to use host factors, including host chromatin and host transcription regulators, to transcribe its genes; however, the invading virus also encounters host defense and stress responses to inhibit viral growth. Recently, we found that HSV-1 replication centers recruit host factor CTCF but exclude γH2A.X. Thus, HSV-1 replication centers may selectively recruit cellular factors needed for viral growth, while excluding host factors that are deleterious for viral transcription or replication. Here we report that the viral replication centers selectively excluded modified histone H3, including heterochromatin mark H3K9me3, H3S10P and active chromatin mark H3K4me3, but not unmodified H3. We found a dynamic association between the viral replication centers and host RNA polymerase II. The centers also recruited components of the DNA damage response pathway, including 53BP1, BRCA1 and host antiviral protein SP100. Importantly, we found that ATM kinase was needed for the recruitment of CTCF to the viral centers. These results suggest that the HSV-1 replication centers took advantage of host signaling pathways to actively recruit or exclude host factors to benefit viral growth.
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Affiliation(s)
- Feng-Chao Lang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China;University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China;University of Chinese Academy of Sciences, Beijing 100049, China
| | - Olga Vladmirova
- The Wistar Institute, Gene Expression and Regulation Program, Philadelphia PA 19104, USA
| | - Zhuo-Ran Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China;University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gui-Jun Chen
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Yu Xiao
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Li-Hong Li
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Dan-Feng Lu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China;University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong-Bo Han
- Biology & Chemistry Engineering College, Panzhihua University, Panzhihua Sichuan 617000, China
| | - Ju-Min Zhou
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China.
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Gennart I, Coupeau D, Pejaković S, Laurent S, Rasschaert D, Muylkens B. Marek's disease: Genetic regulation of gallid herpesvirus 2 infection and latency. Vet J 2015; 205:339-48. [PMID: 26067852 DOI: 10.1016/j.tvjl.2015.04.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 04/27/2015] [Accepted: 04/29/2015] [Indexed: 12/12/2022]
Abstract
Gallid herpesvirus-2 (GaHV-2) is an oncogenic α-herpesvirus that causes Marek's disease (MD), a T cell lymphosarcoma (lymphoma) of domestic fowl (chickens). The GaHV-2 genome integrates by homologous recombination into the host genome and, by modulating expression of viral and cellular genes, induces transformation of latently infected cells. MD is a unique model of viral oncogenesis. Mechanisms implicated in the regulation of viral and cellular genes during GaHV-2 infection operate at transcriptional, post-transcriptional and post-translational levels, with involvement of viral and cellular transcription factors, along with epigenetic modifications, alternative splicing, microRNAs and post-translational modifications of viral proteins. Meq, the major oncogenic protein of GaHV-2, is a viral transcription factor that modulates expression of viral genes, for example by binding to the viral bidirectional promoter of the pp38-pp24/1.8 kb mRNA, and also modulates expression of cellular genes, such as Bcl-2 and matrix metalloproteinase 3. GaHV-2 expresses viral telomerase RNA subunit (vTR), which forms a complex with the cellular telomerase reverse transcriptase (TERT), thus contributing to tumorigenesis, while vTR independent of telomerase activity is implicated in metastasis. Expression of a viral interleukin 8 homologue may contribute to lymphomagenesis. Inhibition of expression of the pro-apoptotic factors JARID2 and SMAD2 by viral microRNAs may promote the survival and proliferation of GaHV-2 latently infected cells, thus enhancing tumorigenesis, while inhibition of interleukin 18 by viral microRNAs may be involved in evasion of immune surveillance. Viral envelope glycoproteins derived from glycoprotein B (gp60 and gp49), as well as glycoprotein C, may also play a role in immune evasion.
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Affiliation(s)
- Isabelle Gennart
- Veterinary Integrated Research Unit, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), 5000 Namur, Belgium
| | - Damien Coupeau
- Veterinary Integrated Research Unit, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), 5000 Namur, Belgium
| | - Srdan Pejaković
- Veterinary Integrated Research Unit, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), 5000 Namur, Belgium
| | - Sylvie Laurent
- Transcription, Lymphome Viro-Induit, University François Rabelais, UFR Sciences et Techniques, Parc de Grandmont, F-37200 Tours, France
| | - Denis Rasschaert
- Transcription, Lymphome Viro-Induit, University François Rabelais, UFR Sciences et Techniques, Parc de Grandmont, F-37200 Tours, France
| | - Benoit Muylkens
- Veterinary Integrated Research Unit, Faculty of Sciences, Namur Research Institute for Life Sciences (NARILIS), University of Namur (UNamur), 5000 Namur, Belgium.
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Functional comparison of herpes simplex virus 1 (HSV-1) and HSV-2 ICP27 homologs reveals a role for ICP27 in virion release. J Virol 2014; 89:2892-905. [PMID: 25540385 DOI: 10.1128/jvi.02994-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Numerous studies have focused on the regulatory functions of ICP27, an immediate-early (IE) protein of herpes simplex virus 1 (HSV-1). However, its homolog in HSV-2, termed ICP27t2, has been little studied. Here, we used two different approaches to functionally compare ICP27t2 and ICP27. In transfection-based assays, ICP27t2 closely resembled ICP27 in its capacity to enhance HSV-1 late gene expression, suppress the splicing of a viral intron, and complement the growth of an HSV-1 ICP27 null mutant. To study ICP27t2 in the context of viral infection, we engineered K2F1, an HSV-1 mutant that encodes ICP27t2 in place of ICP27. In Vero cells, K2F1 replicated with wild-type (WT) kinetics and yields, expressed delayed-early and late proteins normally, and was fully capable of activating several cellular signal transduction pathways that are ICP27 dependent. Thus, we conclude that ICP27t2 and ICP27 are functionally very similar and that ICP27t2 can mediate all ICP27 activities that are required for HSV-1 replication in cell culture. Surprisingly, however, we found that K2F1 forms plaques that are morphologically different from those of WT HSV-1. Investigation of this trait demonstrated that it results from the decreased release of progeny virions into the culture medium. This appears to be due to a reduction in the detachment of K2F1 progeny from the extracellular surface of the infected cell. We identified two HSV-1 ICP27 amino-terminal deletion mutants with a similar release defect. Together, these results demonstrate that ICP27 plays a heretofore-unappreciated role in modulating the efficiency of progeny virion release. IMPORTANCE ICP27 is an essential, multifunctional regulatory protein that has a number of critical roles in the HSV-1 life cycle. Although ICP27 homologs are encoded by all known members of the Herpesviridae, previous work with several of these homologs has shown that they cannot substitute for ICP27 in the context of HSV-1-infected cells. Here, we identify ICP27t2 as the first homolog that can efficiently replace ICP27 in HSV-1 infection. Unexpectedly, our results also reveal that the sequence of the ICP27 gene can affect the release of HSV-1 progeny virions from the infected cell. Thus, our comparative study has revealed a novel function for ICP27 in the regulation of virus release.
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25
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Up to four distinct polypeptides are produced from the γ34.5 open reading frame of herpes simplex virus 2. J Virol 2014; 88:11284-96. [PMID: 25031346 DOI: 10.1128/jvi.01284-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The herpes simplex virus 1 (HSV-1) ICP34.5 protein strongly influences neurovirulence and regulates several cellular antiviral responses. Despite the clinical importance of HSV-2, relatively little is known about its ICP34.5 ortholog. We found that HSV-2 produces up to four distinct forms of ICP34.5 in infected cells: a full-length protein, one shorter form sharing the N terminus, and two shorter forms sharing the C terminus. These forms appeared with similar kinetics and accumulated in cells over much of the replication cycle. We confirmed that the N-terminal form is translated from the primary unspliced transcript to a stop codon within the intron unique to HSV-2 γ34.5. We found that the N-terminal form was produced in a variety of cell types and by 9 of 10 clinical isolates. ICP27 influenced but was not required for expression of the N-terminal form. Western blotting and reverse transcription-PCR indicated the C-terminal forms did not contain the N terminus and were not products of alternative splicing or internal transcript initiation. Expression plasmids encoding methionine at amino acids 56 and 70 generated products that comigrated in SDS-PAGE with the C1 and C2 forms, respectively, and mutation of these sites abolished C1 and C2. Using a recombinant HSV-2 encoding hemagglutinin (HA)-tagged ICP34.5, we demonstrated that the C-terminal forms were also produced during infection of many human and mouse cell types but were not detectable in mouse primary neurons. The protein diversity generated from the HSV-2 γ34.5 open reading frame implies additional layers of cellular regulation through potential independent activities associated with the various forms of ICP34.5. IMPORTANCE The herpes simplex virus 1 (HSV-1) protein ICP34.5, encoded by the γ34.5 gene, interferes with several host defense mechanisms by binding cellular proteins that would otherwise stimulate the cell's autophagic, translational-arrest, and type I interferon responses to virus infection. ICP34.5 also plays a crucial role in determining the severity of nervous system infections with HSV-1 and HSV-2. The HSV-2 γ34.5 gene contains an intron not present in HSV-1 γ34.5. A shorter N-terminal form of HSV-2 ICP34.5 can be translated from the unspliced γ34.5 mRNA. Here, we show that two additional forms consisting of the C-terminal portion of ICP34.5 are generated in infected cells. Production of these N- and C-terminal forms is highly conserved among HSV-2 strains, including many clinical isolates, and they are broadly expressed in several cell types, but not mouse primary neurons. Multiple ICP34.5 polypeptides add additional complexity to potential functional interactions influencing HSV-2 neurovirulence.
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26
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Herpes simplex virus 2 expresses a novel form of ICP34.5, a major viral neurovirulence factor, through regulated alternative splicing. J Virol 2013; 87:5820-30. [PMID: 23487469 DOI: 10.1128/jvi.03500-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Herpes simplex virus 1 (HSV-1) and HSV-2, two closely related neurotropic human herpesviruses, achieve neurotropism through ICP34.5, a major viral neurovirulence factor. In this report, in addition to the full-length 38-kDa protein (ICP34.5α), we identified a 28-kDa novel form of ICP34.5 (ICP34.5β) in HSV-2-infected cells. ICP34.5β is translated from unspliced ICP34.5 mRNA, with the retained intron introducing a premature stop codon. Thus, ICP34.5β lacks the C-terminal conserved GADD34 domain but includes 19 additional amino acids encoded by the intron. Although a fraction of both HSV-2 ICP34.5 proteins are detected in the nucleolus, ICP34.5α is predominantly located in cytoplasm, and ICP34.5β is mainly detected more diffusely in the nucleus. ICP34.5β is unable to counteract PKR-mediated eIF2 phosphorylation but does not interfere with ICP34.5α's function in this process. Efficient expression of ICP34.5β in cell culture assays is dependent on viral infection or expression of ICP27, a multifunctional immediate-early gene. The effect of ICP27 on the ICP34.5β protein level is attributed to its selective inhibition of ICP34.5 splicing, which results in increased expression of ICP34.5β but a reduced level of ICP34.5α. The C- terminal KH3 domain but not the RNA binding domain of ICP27 is required for its specific inhibition of ICP34.5 splicing and promotion of ICP34.5β expression. Our results suggest that the expression of ICP34.5α and ICP34.5β is tightly regulated in HSV-2 and likely contributes to viral pathogenesis.
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27
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Jarosinski KW, Osterrieder N. Marek's disease virus expresses multiple UL44 (gC) variants through mRNA splicing that are all required for efficient horizontal transmission. J Virol 2012; 86:7896-906. [PMID: 22593168 PMCID: PMC3421677 DOI: 10.1128/jvi.00908-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 05/09/2012] [Indexed: 02/03/2023] Open
Abstract
Marek's disease (MD) is a devastating oncogenic viral disease of chickens caused by Gallid herpesvirus 2, or MD virus (MDV). MDV glycoprotein C (gC) is encoded by the alphaherpesvirus UL44 homolog and is essential for the horizontal transmission of MDV (K. W. Jarosinski and N. Osterrieder, J. Virol. 84:7911-7916, 2010). Alphaherpesvirus gC proteins are type 1 membrane proteins and are generally anchored in cellular membranes and the virion envelope by a short transmembrane domain. However, the majority of MDV gC is secreted in vitro, although secondary-structure analyses predict a carboxy-terminal transmembrane domain. In this report, two alternative mRNA splice variants were identified by reverse transcription (RT)-PCR analyses, and the encoded proteins were predicted to specify premature stop codons that would lead to gC proteins that lack the transmembrane domain. Based on the size of the intron removed for each UL44 (gC) transcript, they were termed gC104 and gC145. Recombinant MDV viruses were generated in which only full-length viral gC (vgCfull), gC104 (vgC104), or gC145 (vgC145) was expressed. Predictably, gCfull was expressed predominantly as a membrane-associated protein, while both gC104 and gC145 were secreted, suggesting that the dominant gC variants expressed in vitro are the spliced variants. In experimentally infected chickens, the expression of each of the gC variants individually did not alter replication or disease induction. However, horizontal transmission was reduced compared to that of wild-type or revertant viruses when the expression of only a single gC was allowed, indicating that all three forms of gC are required for the efficient transmission of MDV in chickens.
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Affiliation(s)
- Keith W Jarosinski
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
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28
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Sandri-Goldin RM. The many roles of the highly interactive HSV protein ICP27, a key regulator of infection. Future Microbiol 2012; 6:1261-77. [PMID: 22082288 DOI: 10.2217/fmb.11.119] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human herpes viruses cause an array of illnesses ranging from cancers for Epstein?Barr virus and Kaposi?s sarcoma-associated herpes virus, to painful skin lesions, and more rarely, keratitis and encephalitis for HSV. All herpes viruses encode a multifunctional protein, typified by HSV ICP27, which plays essential roles in viral infection. ICP27 functions in all stages of mRNA biogenesis from transcription, RNA processing and export through to translation. ICP27 has also been implicated in nuclear protein quality control, cell cycle control, activation of stress signaling pathways and prevention of apoptosis. ICP27 interacts with many proteins and it binds RNA. This article focuses on how ICP27 performs its many roles and highlights similarities with its homologs, which could be targets for antiviral intervention.
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Affiliation(s)
- Rozanne M Sandri-Goldin
- Department of Microbiology & Molecular Genetics, University of California, Irvine, CA 92697, USA.
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29
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Grose C, Carpenter JE, Jackson W, Duus KM. Overview of varicella-zoster virus glycoproteins gC, gH and gL. Curr Top Microbiol Immunol 2010; 342:113-28. [PMID: 20186613 DOI: 10.1007/82_2009_4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The VZV genome is smaller than the HSV genome and only encodes nine glycoproteins. This chapter provides an overview of three VZV glycoproteins: gH (ORF37), gL (ORF60), and gC (ORF14). All three glycoproteins are highly conserved among the alpha herpesviruses. However, VZV gC exhibits unexpected differences from its HSV counterpart gC. In particular, both VZV gC transcription and protein expression are markedly delayed in cultured cells. These delays occur regardless of the virus strain or the cell type, and may account in part for the aberrant assembly of VZV particles. In contrast to VZV gC, the general properties of gH and gL more closely resemble their HSV homologs. VZV gL behaves as a chaperone protein to facilitate the maturation of the gH protein. The mature gH protein in turn is a potent fusogen. Its fusogenic activity can be abrogated when infected cultures are treated with monoclonal anti-gH antibodies.
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Affiliation(s)
- Charles Grose
- Department of Pediatrics/2501 JCP, University of Iowa Hospital, Iowa City, IA 52242, USA.
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30
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Lian B, Xu C, Cheng A, Wang M, Zhu D, Luo Q, Jia R, Bi F, Chen Z, Zhou Y, Yang Z, Chen X. Identification and characterization of duck plague virus glycoprotein C gene and gene product. Virol J 2010; 7:349. [PMID: 21110887 PMCID: PMC3004831 DOI: 10.1186/1743-422x-7-349] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Accepted: 11/27/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Viral envelope proteins have been proposed to play significant roles in the process of viral infection. RESULTS In this study, an envelope protein gene, gC (NCBI GenBank accession no. EU076811), was expressed and characterized from duck plague virus (DPV), a member of the family herpesviridae. The gene encodes a protein of 432 amino acids with a predicted molecular mass of 45 kDa. Sequence comparisons, multiple alignments and phylogenetic analysis showed that DPV gC has several features common to other identified herpesvirus gC, and was genetically close to the gallid herpervirus.Antibodies raised in rabbits against the pET32a-gC recombinant protein expressed in Escherichia coli BL21 (DE3) recognized a 45-KDa DPV-specific protein from infected duck embryo fibroblast (DEF) cells. Transcriptional and expression analysis, using real-time fluorescent quantitative PCR (FQ-PCR) and Western blot detection, revealed that the transcripts encoding DPV gC and the protein itself appeared late during infection of DEF cells. Immunofluorescence localization further demonstrated that the gC protein exhibited substantial cytoplasm fluorescence in DPV-infected DEF cells. CONCLUSIONS In this work, the DPV gC protein was successfully expressed in a prokaryotic expression system, and we presented the basic properties of the DPV gC product for the first time. These properties of the gC protein provided a prerequisite for further functional analysis of this gene.
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Affiliation(s)
- Bei Lian
- Avian Diseases Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya'an, Sichuan 625014, China
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31
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The Varicella-Zoster virus IE4 protein: a conserved member of the herpesviral mRNA export factors family and a potential alternative target in antiherpetic therapies. Biochem Pharmacol 2010; 80:1973-80. [PMID: 20650265 DOI: 10.1016/j.bcp.2010.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 07/05/2010] [Accepted: 07/08/2010] [Indexed: 02/07/2023]
Abstract
During a viral infection, in addition to cellular mRNAs, amounts of viral mRNAs have to be efficiently transported to the cytoplasm for translation. It is now established that herpesviruses encode a conserved gene family whose proteins act as viral mRNA export factors that mediate nucleocytoplasmic transport of viral transcripts and eventually modulate through this mechanism the antiviral response. This conserved family of proteins contains the IE4 protein of the Varicella-Zoster virus (VZV). Here, we compared the functional characteristics of IE4 with those of its herpesviral homologues and proposed a model by which IE4 would be able to recruit the essential TAP/NXF1 receptor to viral transcripts. Moreover, on the basis of their crucial roles in the infectious cycle, these conserved viral factors should be considered as alternative targets in therapeutic approaches. Here, we discussed the possibility of developing antiherpetic agents targeting IE4 or its herpesviral homologues.
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32
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Identification of an ICP27-responsive element in the coding region of a herpes simplex virus type 1 late gene. J Virol 2009; 84:2707-18. [PMID: 20042503 DOI: 10.1128/jvi.02005-09] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During productive herpes simplex virus type 1 (HSV-1) infection, a subset of viral delayed-early (DE) and late (L) genes require the immediate-early (IE) protein ICP27 for their expression. However, the cis-acting regulatory sequences in DE and L genes that mediate their specific induction by ICP27 are unknown. One viral L gene that is highly dependent on ICP27 is that encoding glycoprotein C (gC). We previously demonstrated that this gene is posttranscriptionally transactivated by ICP27 in a plasmid cotransfection assay. Based on our past results, we hypothesized that the gC gene possesses a cis-acting inhibitory sequence and that ICP27 overcomes the effects of this sequence to enable efficient gC expression. To test this model, we systematically deleted sequences from the body of the gC gene and tested the resulting constructs for expression. In so doing, we identified a 258-bp "silencing element" (SE) in the 5' portion of the gC coding region. When present, the SE inhibits gC mRNA accumulation from a transiently transfected gC gene, unless ICP27 is present. Moreover, the SE can be transferred to another HSV-1 gene, where it inhibits mRNA accumulation in the absence of ICP27 and confers high-level expression in the presence of ICP27. Thus, for the first time, an ICP27-responsive sequence has been identified in a physiologically relevant ICP27 target gene. To see if the SE functions during viral infection, we engineered HSV-1 recombinants that lack the SE, either in a wild-type (WT) or ICP27-null genetic background. In an ICP27-null background, deletion of the SE led to ICP27-independent expression of the gC gene, demonstrating that the SE functions during viral infection. Surprisingly, the ICP27-independent gC expression seen with the mutant occurred even in the absence of viral DNA synthesis, indicating that the SE helps to regulate the tight DNA replication-dependent expression of gC.
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33
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Johnson KE, Knipe DM. Herpes simplex virus-1 infection causes the secretion of a type I interferon-antagonizing protein and inhibits signaling at or before Jak-1 activation. Virology 2009; 396:21-9. [PMID: 19879619 DOI: 10.1016/j.virol.2009.09.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 07/28/2009] [Accepted: 09/16/2009] [Indexed: 11/18/2022]
Abstract
Host cells respond to viral infection by the production of type I interferons (IFNs), which induce the expression of antiviral genes. Herpes simplex virus I (HSV-1) encodes many mechanisms that inhibit the type I IFN response, including the ICP27-dependent inhibition of type I IFN signaling. Here we show inhibition of Stat-1 nuclear accumulation in cells that express ICP27. ICP27 expression also induces the secretion of a small, heat-stable type I IFN antagonizing protein that inhibits Stat-1 nuclear accumulation. We show that the inhibition of IFN-induced Stat-1 phosphorylation occurs at or upstream of Jak-1 phosphorylation. Finally, we show that ISG15 expression is induced after IFNalpha treatment in mock-infected cells, but not cells infected with WT HSV-1 or ICP27(-) HSV-1. These data suggest that HSV-1 has evolved multiple mechanisms to inhibit IFN signaling not only in infected cells, but also in neighboring cells, thereby allowing for increased viral replication and spread.
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Affiliation(s)
- Karen E Johnson
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
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34
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Nojima T, Oshiro-Ideue T, Nakanoya H, Kawamura H, Morimoto T, Kawaguchi Y, Kataoka N, Hagiwara M. Herpesvirus protein ICP27 switches PML isoform by altering mRNA splicing. Nucleic Acids Res 2009; 37:6515-27. [PMID: 19729513 PMCID: PMC2770646 DOI: 10.1093/nar/gkp633] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Viruses use alternative splicing to produce a broad series of proteins from small genomes by utilizing the cellular splicing machinery. Since viruses use cellular RNA binding proteins for viral RNA processing, it is presumable that the splicing of cellular pre-mRNAs is affected by viral infection. Here, we showed that herpes simplex virus type 2 (HSV-2) modifies the expression of promyelocytic leukemia (PML) isoforms by altering pre-mRNA splicing. Using a newly developed virus-sensitive splicing reporter, we identified the viral protein ICP27 as an alternative splicing regulator of PML isoforms. ICP27 was found to bind preferentially to PML pre-mRNA and directly inhibit the removal of PML intron 7a in vitro. Moreover, we demonstrated that ICP27 functions as a splicing silencer at the 3' splice site of the PML intron 7a. The switching of PML isoform from PML-II to PML-V as induced by ICP27 affected HSV-2 replication, suggesting that the viral protein modulates the splicing code of cellular pre-mRNA(s) governing virus propagation.
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Affiliation(s)
- Takayuki Nojima
- Department of Functional Genomics, Laboratory of Gene Expression, School of Biomedical Science, Tokyo Medical and Dental University, Tokyo
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