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Chen X, Yu Z. Insight into the Interaction Mechanism of Pseudorabies Virus Infection. BIOLOGY 2024; 13:1013. [PMID: 39765680 PMCID: PMC11673216 DOI: 10.3390/biology13121013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2024] [Revised: 11/26/2024] [Accepted: 12/03/2024] [Indexed: 01/11/2025]
Abstract
The pseudorabies virus (PRV), also known as suid alphaherpesvirus 1 (SuAHV-1), has garnered significant attention due to its broad host range and the economic losses it incurs in the swine industry. This review aims to provide a comprehensive understanding of the intricate virus-host interactions during PRV infection, focusing on the evasion strategies of the virus against the host responses. We also summarize the mechanisms by which PRV manipulates the host cell machinery to facilitate its replication and spread, while simultaneously evading detection and clearance by the immune system. Furthermore, we discuss the latest advancements, such as metabolic, autophagic, and apoptotic pathways in studying these interactions, highlighting the role of various cellular factors and pathways in elucidating virus-host dynamics. By integrating these insights, the article aims to provide a comprehensive overview of the molecular mechanisms underlying PRV pathogenesis and host response, paving the way for the development of novel therapeutic strategies against this virus.
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Affiliation(s)
- Xiaoyong Chen
- Xingzhi College, Zhejiang Normal University, Lanxi 321100, China
| | - Ziding Yu
- College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
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2
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Bergeman MH, Hernandez MQ, Diefenderfer J, Drewes JA, Velarde K, Tierney WM, Enow JA, Glenn HL, Rahman MM, Hogue IB. Individual herpes simplex virus 1 (HSV-1) particles exit by exocytosis and accumulate at preferential egress sites. J Virol 2024; 98:e0178523. [PMID: 38193690 PMCID: PMC10883806 DOI: 10.1128/jvi.01785-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 11/16/2023] [Indexed: 01/10/2024] Open
Abstract
The human pathogen herpes simplex virus 1 (HSV-1) produces a lifelong infection in the majority of the world's population. While the generalities of alpha herpesvirus assembly and egress pathways are known, the precise molecular and spatiotemporal details remain unclear. In order to study this aspect of HSV-1 infection, we engineered a recombinant HSV-1 strain expressing a pH-sensitive reporter, gM-pHluorin. Using a variety of fluorescent microscopy modalities, we can detect individual virus particles undergoing intracellular transport and exocytosis at the plasma membrane. We show that particles exit from epithelial cells individually, not bulk release of many particles at once, as has been reported for other viruses. In multiple cell types, HSV-1 particles accumulate over time at the cell periphery and cell-cell contacts. We show that this accumulation effect is the result of individual particles undergoing exocytosis at preferential sites and that these egress sites can contribute to cell-cell spread. We also show that the viral membrane proteins gE, gI, and US9, which have important functions in intracellular transport in neurons, are not required for preferential egress and clustering in non-neuronal cells. Importantly, by comparing HSV-1 to a related alpha herpesvirus, pseudorabies virus, we show that this preferential exocytosis and clustering effect are cell type dependent, not virus dependent. This preferential egress and clustering appear to be the result of the arrangement of the microtubule cytoskeleton, as virus particles co-accumulate at the same cell protrusions as an exogenous plus end-directed kinesin motor.IMPORTANCEAlpha herpesviruses produce lifelong infections in their human and animal hosts. The majority of people in the world are infected with herpes simplex virus 1 (HSV-1), which typically causes recurrent oral or genital lesions. However, HSV-1 can also spread to the central nervous system, causing severe encephalitis, and might also contribute to the development of neurodegenerative diseases. Many of the steps of how these viruses infect and replicate inside host cells are known in depth, but the final step, exiting from the infected cell, is not fully understood. In this study, we engineered a novel variant of HSV-1 that allows us to visualize how individual virus particles exit from infected cells. With this imaging assay, we investigated preferential egress site formation in certain cell types and their contribution to the cell-cell spread of HSV-1.
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Affiliation(s)
- Melissa H. Bergeman
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University, Tempe, Arizona, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Michaella Q. Hernandez
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University, Tempe, Arizona, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | | | - Jake A. Drewes
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Kimberly Velarde
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Wesley M. Tierney
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University, Tempe, Arizona, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Junior A. Enow
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Biodesign Center for Personalized Diagnostics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Honor L. Glenn
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Structural Discovery, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Masmudur M. Rahman
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Biodesign Center for Personalized Diagnostics, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Ian B. Hogue
- ASU-Banner Neurodegenerative Disease Research Center, Arizona State University, Tempe, Arizona, USA
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
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3
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Bergeman MH, Hernandez MQ, Diefenderfer J, Drewes JA, Velarde K, Tierney WM, Enow JA, Glenn HL, Rahman MM, Hogue IB. LIVE-CELL FLUORESCENCE MICROSCOPY OF HSV-1 CELLULAR EGRESS BY EXOCYTOSIS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.27.530373. [PMID: 36909512 PMCID: PMC10002666 DOI: 10.1101/2023.02.27.530373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
The human pathogen Herpes Simplex Virus 1 (HSV-1) produces a lifelong infection in the majority of the world's population. While the generalities of alpha herpesvirus assembly and egress pathways are known, the precise molecular and spatiotemporal details remain unclear. In order to study this aspect of HSV-1 infection, we engineered a recombinant HSV-1 strain expressing a pH-sensitive reporter, gM-pHluorin. Using a variety of fluorescent microscopy modalities, we can detect individual virus particles undergoing intracellular transport and exocytosis at the plasma membrane. We show that particles exit from epithelial cells individually, not bulk release of many particles at once, as has been reported for other viruses. In multiple cell types, HSV-1 particles accumulate over time at the cell periphery and cell-cell contacts. We show that this accumulation effect is the result of individual particles undergoing exocytosis at preferential sites and that these egress sites can contribute to cell-cell spread. We also show that the viral membrane proteins gE, gI, and US9, which have important functions in intracellular transport in neurons, are not required for preferential egress and clustering in non-neuronal cells. Importantly, by comparing HSV-1 to a related alpha herpesvirus, pseudorabies virus, we show that this preferential exocytosis and clustering effect is cell type-dependent, not virus dependent. This preferential egress and clustering appears to be the result of the arrangement of the microtubule cytoskeleton, as virus particles co-accumulate at the same cell protrusions as an exogenous plus end-directed kinesin motor.
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Affiliation(s)
- Melissa H Bergeman
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Michaella Q Hernandez
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Jenna Diefenderfer
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Jake A Drewes
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Kimberly Velarde
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Wesley M Tierney
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Junior A Enow
- Biodesign Center for Personalized Diagnostics, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Honor L Glenn
- Biodesign Center for Structural Discovery, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Masmudur M Rahman
- Biodesign Center for Structural Discovery, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
| | - Ian B Hogue
- ASU-Banner Neurodegenerative Research Center, Arizona State University, Tempe, Arizona, United States
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States
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4
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Vezzani G, Pimazzoni S, Ferranti R, Calò S, Monda G, Amendola D, Frigimelica E, Maione D, Cortese M, Merola M. Human immunoglobulins are transported to HCMV viral envelope by viral Fc gamma receptors-dependent and independent mechanisms. Front Microbiol 2023; 13:1106401. [PMID: 36726564 PMCID: PMC9885202 DOI: 10.3389/fmicb.2022.1106401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/20/2022] [Indexed: 01/18/2023] Open
Abstract
Human cytomegaloviruses (HCMVs) employ many different mechanisms to escape and subvert the host immune system, including expression of the viral IgG Fcγ receptors (vFcγRs) RL11 (gp34), RL12 (gp95), RL13 (gpRL13), and UL119 (gp68) gene products. The role of vFcγRs in HCMV pathogenesis has been reported to operate in infected cells by interfering with IgG-mediated effector functions. We found that gp34 and gp68 are envelope proteins that bind and internalize human IgGs on the surface of infected cells. Internalized IgGs are then transported on the envelope of viral particles in a vFcR-dependent mechanism. This mechanism is also responsible for the incorporation on the virions of the anti-gH neutralizing antibody MSL-109. Intriguingly, we show that gp68 is responsible for MSL-109 incorporation, but it is dispensable for other anti-HCMV antibodies that do not need this function to be transported on mature virions. HCMV-infected cells grown in presence of anti-HCMV monoclonal antibodies generate a viral progeny still infective and possible to be neutralized. This is the first example of a virus carrying neutralizing IgGs on its surface and their possible role is discussed.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Mirko Cortese
- GSK, Siena, Italy,Department of Environmental Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, Caserta, Italy,Mirko Cortese, ✉
| | - Marcello Merola
- GSK, Siena, Italy,Department of Biology, University of Naples Federico II, Naples, Italy,*Correspondence: Marcello Merola, ✉
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5
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Pseudorabies virus glycoprotein gE suppresses interferon-β production via CREB-binding protein degradation. Virus Res 2020; 291:198220. [PMID: 33152381 DOI: 10.1016/j.virusres.2020.198220] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 12/24/2022]
Abstract
Cyclic GMP-AMP synthase (cGAS) is a main sensor used to detect microbial DNA in the cytoplasm, which subsequently induces the production of interferon (IFN) via the cGAS/STING/IRF3 signaling pathway, leading to an antiviral response. However, some viruses have evolved multiple strategies to escape this process. Pseudorabies virus (PRV) is a double-stranded DNA virus belonging to the Alphaherpesvirinae subfamily, which can cause serious damage to the porcine industry. Many herpesvirus components have been reported to counteract IFN production, whereas little is known of PRV. In the present study, we found that PRV glycoprotein E (gE) was involved in counteracting cGAS/STING-mediated IFN production. Ectopic expression of gE decreased cGAS/STING-mediated IFN-β promoter activity and the level of mRNA expression. Moreover, gE targeted at or downstream of IRF3 was found to inhibit IFN-β production. However, gE did not affect the phosphorylation, dimerization and nuclear translocation of IRF3. Furthermore, gE is located on the nuclear membrane and could subsequently degrade CREB-binding protein (CBP). MG132, a proteasome inhibitor, decreased CBP degradation and restored the IFN-β production induced by gE. Finally, gE-deleted PRV induced a higher level of IFN-β production and reduced CBP degradation compared to wild-type PRV. Together, these results demonstrate that PRV gE can inhibit cGAS/STING-mediated IFN-β production by degrading CBP to interrupt the enhanced assembly of IRF3 and CBP.
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6
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Two Separate Tyrosine-Based YXXL/Φ Motifs within the Glycoprotein E Cytoplasmic Tail of Bovine Herpesvirus 1 Contribute in Virus Anterograde Neuronal Transport. Viruses 2020; 12:v12091025. [PMID: 32937797 PMCID: PMC7551581 DOI: 10.3390/v12091025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/31/2020] [Accepted: 09/12/2020] [Indexed: 12/30/2022] Open
Abstract
Bovine herpesvirus 1 (BHV-1) causes respiratory infection and abortion in cattle. Following a primary infection, BHV-1 establishes lifelong latency in the trigeminal ganglia (TG). Periodic reactivation of the latent virus in TG neurons results in anterograde virus transport to nerve endings in the nasal mucosa and nasal virus shedding. The BHV-1 glycoprotein E cytoplasmic tail (gE-CT) is necessary for virus cell-to-cell spread in epithelial cells and neuronal anterograde transport. Recently, we identified two tyrosine residues, Y467 and Y563, within the tyrosine-based motifs 467YTSL470 and 563YTVV566, which, together, account for the gE CT-mediated efficient cell-to-cell spread of BHV-1 in epithelial cells. Here, we determined that in primary neuron cultures in vitro, the individual alanine exchange Y467A or Y563A mutants had significantly diminished anterograde axonal spread. Remarkably, the double-alanine-exchanged Y467A/Y563A mutant virus was not transported anterogradely. Following intranasal infection of rabbits, both wild-type (wt) and the Y467A/Y563A mutant viruses established latency in the TG. Upon dexamethasone-induced reactivation, both wt and the mutant viruses reactivated and replicated equally efficiently in the TG. However, upon reactivation, only the wt, not the mutant, was isolated from nasal swabs. Therefore, the gE-CT tyrosine residues Y467 and Y563 together are required for gE CT-mediated anterograde neuronal transport.
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7
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Ahmad I, Wilson DW. HSV-1 Cytoplasmic Envelopment and Egress. Int J Mol Sci 2020; 21:ijms21175969. [PMID: 32825127 PMCID: PMC7503644 DOI: 10.3390/ijms21175969] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 12/25/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) is a structurally complex enveloped dsDNA virus that has evolved to replicate in human neurons and epithelia. Viral gene expression, DNA replication, capsid assembly, and genome packaging take place in the infected cell nucleus, which mature nucleocapsids exit by envelopment at the inner nuclear membrane then de-envelopment into the cytoplasm. Once in the cytoplasm, capsids travel along microtubules to reach, dock, and envelope at cytoplasmic organelles. This generates mature infectious HSV-1 particles that must then be sorted to the termini of sensory neurons, or to epithelial cell junctions, for spread to uninfected cells. The focus of this review is upon our current understanding of the viral and cellular molecular machinery that enables HSV-1 to travel within infected cells during egress and to manipulate cellular organelles to construct its envelope.
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Affiliation(s)
- Imran Ahmad
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
| | - Duncan W. Wilson
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA;
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
- Correspondence:
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8
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Yezid H, Pannhorst K, Wei H, Chowdhury SI. Bovine herpesvirus 1 (BHV-1) envelope protein gE subcellular trafficking is contributed by two separate YXXL/Φ motifs within the cytoplasmic tail which together promote efficient virus cell-to-cell spread. Virology 2020; 548:136-151. [PMID: 32838935 DOI: 10.1016/j.virol.2020.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/15/2020] [Accepted: 05/22/2020] [Indexed: 11/16/2022]
Abstract
Bovine herpesvirus envelope glycoprotein E (gE) and, in particular, the gE cytoplasmic tail (CT) is a virulence determinant in cattle. Also, the gE CT contributes to virus cell-to-cell spread and anterograde neuronal transport. In this study, our goal was to map the gE CT sub-domains that contribute to virus cell-to-cell spread property. A panel of gE-CT specific mutant viruses was constructed and characterized, in vitro, with respect to their plaque phenotypes, gE recycling and gE basolateral membrane targeting. The results revealed that disruption of the tyrosine-based motifs, 467YTSL470 and 563YTVV566, individually produced smaller plaque phenotypes than the wild type. However, they were slightly larger than the gE CT-null virus plaques. The Y467A mutation affected the gE endocytosis, gE trans-Golgi network (TGN) recycling, and gE virion incorporation properties. However, the Y563A mutation affected only the gE basolateral cell-surface redistribution function. Notably, the simultaneous Y467A/Y563A mutations produced gE CT-null virus-like plaque phenotypes.
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Affiliation(s)
- Hocine Yezid
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Katrin Pannhorst
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Huiyong Wei
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Shafiqul I Chowdhury
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, 70803, United States.
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9
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Lee Y, Maes R, Kiupel M, Nauwynck H, Soboll Hussey G. Characterization of feline herpesvirus-1 deletion mutants in tissue explant cultures. Virus Res 2020; 284:197981. [PMID: 32315701 DOI: 10.1016/j.virusres.2020.197981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 02/06/2023]
Abstract
Feline herpesvirus-1 (FHV-1) is the primary cause of viral respiratory and ocular disease in cats. While commercial vaccines can provide clinical protection, they do not protect from infection or prevent latency. Moreover, they are not safe for intranasal administration. Our overall objective is to develop a new mucosal vaccine against FHV-1 disease to address these shortcomings. Feline herpesvirus-1 deletion mutants of glycoprotein C (gC-), gE (gE-), US3-encoded serine/threonine protein kinase (PK-), and both gE and thymidine kinase (gE-TK-) were generated by bacterial artificial chromosome (BAC) mutagenesis. Tracheal tissue explants from eight cats were used to compare the pattern of viral infection and associated tissue damage, as well as virus spread through the basement membrane following inoculation with wild-type virus (WT), and gE-, gE-TK-, PK-, and gC- mutants. Tissues were collected at 24, 48, or 72 hours post-inoculation (hpi) followed by immunohistochemistry (IHC) for FHV-1. Histological changes were graded based on the distribution of virus infected cells and the severity of tissue damage. Inoculations with the WT virus resulted in maximal scores at 72 hpi both at a multiplicity of infection (MOI) of 1 and 0.1. Inoculation with the gE- mutant produced scores similar to scores of explants inoculated with the WT virus at 24 and 48 hpi, but scores were significantly decreased at 72 hpi. Explants inoculated with the gE-TK- mutant showed significantly decreased scores at all time points. Further, the majority of explants inoculated with the PK- mutant resulted in scores of zero at all time points, regardless of MOI. Finally, inoculation with WT resulted in significant stromal invasion below the infected epithelium, while stromal invasion was observed in less than 50 % of the samples following inoculation with gE-, gE-TK-, PK-, or gC- mutants and confined closely to the area surrounding the infected epithelium. In conclusion, the gE-TK- and PK- mutants exhibited significantly reduced virulence, tissue damage and spread to the underlying stroma, suggesting that they may be good vaccine candidates for in vivo testing.
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Affiliation(s)
- Yao Lee
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, 784 Wilson Road, East Lansing, MI 48824, USA.
| | - Roger Maes
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, 784 Wilson Road, East Lansing, MI 48824, USA; Veterinary Diagnostic Laboratory, Michigan State University, 4125 Beaumont Road, Lansing, MI 48910, USA.
| | - Matti Kiupel
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, 784 Wilson Road, East Lansing, MI 48824, USA; Veterinary Diagnostic Laboratory, Michigan State University, 4125 Beaumont Road, Lansing, MI 48910, USA.
| | - Hans Nauwynck
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - Gisela Soboll Hussey
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, 784 Wilson Road, East Lansing, MI 48824, USA.
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10
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Huang H, Koyuncu OO, Enquist LW. Pseudorabies Virus Infection Accelerates Degradation of the Kinesin-3 Motor KIF1A. J Virol 2020; 94:e01934-19. [PMID: 32075931 PMCID: PMC7163149 DOI: 10.1128/jvi.01934-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/10/2020] [Indexed: 12/11/2022] Open
Abstract
Alphaherpesviruses, including pseudorabies virus (PRV), are neuroinvasive pathogens that establish lifelong latency in peripheral ganglia following the initial infection at mucosal surfaces. The establishment of latent infection and subsequent reactivations, during which newly assembled virions are sorted into and transported anterogradely inside axons to the initial mucosal site of infection, rely on axonal bidirectional transport mediated by microtubule-based motors. Previous studies using cultured peripheral nervous system (PNS) neurons have demonstrated that KIF1A, a kinesin-3 motor, mediates the efficient axonal sorting and transport of newly assembled PRV virions. Here we report that KIF1A, unlike other axonal kinesins, is an intrinsically unstable protein prone to proteasomal degradation. Interestingly, PRV infection of neuronal cells leads not only to a nonspecific depletion of KIF1A mRNA but also to an accelerated proteasomal degradation of KIF1A proteins, leading to a near depletion of KIF1A protein late in infection. Using a series of PRV mutants deficient in axonal sorting and anterograde spread, we identified the PRV US9/gE/gI protein complex as a viral factor facilitating the proteasomal degradation of KIF1A proteins. Moreover, by using compartmented neuronal cultures that fluidically and physically separate axons from cell bodies, we found that the proteasomal degradation of KIF1A occurs in axons during infection. We propose that the PRV anterograde sorting complex, gE/gI/US9, recruits KIF1A to viral transport vesicles for axonal sorting and transport and eventually accelerates the proteasomal degradation of KIF1A in axons.IMPORTANCE Pseudorabies virus (PRV) is an alphaherpesvirus related to human pathogens herpes simplex viruses 1 and 2 and varicella-zoster virus. Alphaherpesviruses are neuroinvasive pathogens that establish lifelong latent infections in the host peripheral nervous system (PNS). Following reactivation from latency, infection spreads from the PNS back via axons to the peripheral mucosal tissues, a process mediated by kinesin motors. Here, we unveil and characterize the underlying mechanisms for a PRV-induced, accelerated degradation of KIF1A, a kinesin-3 motor promoting the sorting and transport of PRV virions in axons. We show that PRV infection disrupts the synthesis of KIF1A and simultaneously promotes the degradation of intrinsically unstable KIF1A proteins by proteasomes in axons. Our work implies that the timing of motor reduction after reactivation would be critical because progeny particles would have a limited time window for sorting into and transport in axons for further host-to-host spread.
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Affiliation(s)
- Hao Huang
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Orkide O Koyuncu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Lynn W Enquist
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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11
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Huang J, Zhu L, Zhao J, Yin X, Feng Y, Wang X, Sun X, Zhou Y, Xu Z. Genetic evolution analysis of novel recombinant pseudorabies virus strain in Sichuan, China. Transbound Emerg Dis 2020; 67:1428-1432. [PMID: 31968152 DOI: 10.1111/tbed.13484] [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: 10/04/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 01/21/2023]
Abstract
Pseudorabies is a disease that seriously endangers the pig industry in China. Recently, we successfully isolated a pseudorabies virus from the brain tissue of piglets at a farm in Sichuan, China, and named it the FJ62 strain. In order to understand the molecular biological characteristics of the strain, primers were designed for glycoproteins gB, gC, gD and gE, which were amplified by a polymerase chain reaction (PCR) and sequenced. After comparing the sequence with the GenBank 22 pseudorabies virus reference strains and establishing the genetic evolutionary tree, it was found that the gB gene of pseudorabies virus was highly homologous (up to 100%) with the MY-1 strain which is isolated from a wild boar in Japan (AP018925) but that homology with other strains in China was low. The gC gene was in the same branch as most of the representative strains in China, with 99.5% homology. The gD gene is in the same branch as the domestic strain LA in China (KU552118), and the homology was 99.9%. The gE gene was in the same branch as the domestic BJ/YT strain in China (KC981239), with 99.9% homology. The results showed that the FJ62 strain of the pseudorabies virus isolated here may be a variant strain of FJ62 isolated from a domestic pig after natural recombination of pseudorabies virus genotype I from wild boar and genotype II from pigs in China. There have been no similar reports in Sichuan. The discovery of the recombinant virus strain provides a reference basis for the prevention and control of pseudorabies and a design strategy for a vaccine in Sichuan, China, in the future.
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Affiliation(s)
- Jianbo Huang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Jun Zhao
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinhuan Yin
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yu Feng
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xvetao Wang
- Livestock and Poultry Biological Products Key Laboratory of Sichuan Province, Animtech Bioengineering Co. Ltd., Chengdu, China
| | - Xiangang Sun
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yuancheng Zhou
- Livestock and Poultry Biological Products Key Laboratory of Sichuan Province, Animtech Bioengineering Co. Ltd., Chengdu, China
| | - Zhiwen Xu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China
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Scherer J, Hogue IB, Yaffe ZA, Tanneti NS, Winer BY, Vershinin M, Enquist LW. A kinesin-3 recruitment complex facilitates axonal sorting of enveloped alpha herpesvirus capsids. PLoS Pathog 2020; 16:e1007985. [PMID: 31995633 PMCID: PMC7010296 DOI: 10.1371/journal.ppat.1007985] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 02/10/2020] [Accepted: 12/15/2019] [Indexed: 12/13/2022] Open
Abstract
Axonal sorting, the controlled passage of specific cargoes from the cell soma into the axon compartment, is critical for establishing and maintaining the polarity of mature neurons. To delineate axonal sorting events, we took advantage of two neuroinvasive alpha-herpesviruses. Human herpes simplex virus 1 (HSV-1) and pseudorabies virus of swine (PRV; suid herpesvirus 1) have evolved as robust cargo of axonal sorting and transport mechanisms. For efficient axonal sorting and subsequent egress from axons and presynaptic termini, progeny capsids depend on three viral membrane proteins (Us7 (gI), Us8 (gE), and Us9), which engage axon-directed kinesin motors. We present evidence that Us7-9 of the veterinary pathogen pseudorabies virus (PRV) form a tripartite complex to recruit Kif1a, a kinesin-3 motor. Based on multi-channel super-resolution and live TIRF microscopy, complex formation and motor recruitment occurs at the trans-Golgi network. Subsequently, progeny virus particles enter axons as enveloped capsids in a transport vesicle. Artificial recruitment of Kif1a using a drug-inducible heterodimerization system was sufficient to rescue axonal sorting and anterograde spread of PRV mutants devoid of Us7-9. Importantly, biophysical evidence suggests that Us9 is able to increase the velocity of Kif1a, a previously undescribed phenomenon. In addition to elucidating mechanisms governing axonal sorting, our results provide further insight into the composition of neuronal transport systems used by alpha-herpesviruses, which will be critical for both inhibiting the spread of infection and the safety of herpesvirus-based oncolytic therapies. Alpha-herpesviruses represent a group of large, enveloped DNA viruses that are capable to establish a quiescent (also called latent) but reactivatable form of infection in the peripheral nervous system of their hosts. Following reactivation of latent genomes, virus progeny is formed in the soma of neuronal cells and depend on sorting into the axon for anterograde spread of infection to mucosal sites and potentially new host. We studied two alpha-herpesviruses (the veterinary pathogen pseudorabies virus (PRV) and human herpes simplex virus 1 (HSV-1)) and found viral membrane proteins Us7, Us8, and Us9 form a complex, which is able to recruit kinsin-3 motors. Motor recruitment facilitates axonal sorting and subsequent transport to distal egress sites. Complex formation occurs at the trans-Golgi network and mediates efficiency of axonal sorting and motility characteristics of egressing capsids. We also used an artificial kinesin-3 recruitment system, which allows controlled induction of axonal sorting and transport of virus mutants lacking Us7, Us8, and Us9. Overall, these data contribute to our understanding of anterograde alpha-herpesvirus spread and kinesin-mediated sorting of vesicular axonal cargoes.
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Affiliation(s)
- Julian Scherer
- Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Ian B. Hogue
- Center for Immunotherapy, Vaccines, and Virotherapy, Biodesign Institute & School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Zachary A. Yaffe
- University of Washington, Seattle, Washington, United States of America
| | - Nikhila S. Tanneti
- Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Benjamin Y. Winer
- Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Michael Vershinin
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, United States of America
| | - Lynn W. Enquist
- Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
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Identification of functional lncRNAs in pseudorabies virus type II infected cells. Vet Microbiol 2019; 242:108564. [PMID: 32122616 DOI: 10.1016/j.vetmic.2019.108564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/14/2022]
Abstract
Long noncoding RNAs (lncRNAs) play important roles in the antiviral responses. However, little is known about the identification and functions of swine lncRNAs in response to pseudorabies virus type II (PRV-II). Here, we detected the expression profiles of host lncRNAs from a wild-type (PRV-II DX) and gE/TK deficient (gE-TK-PRV) PRV-II infected cells. RNA-seq identified 664 differentially expressed (DE) lncRNAs from PRV-DX infected cells, 654 DE lncRNAs from gE-TK-PRV infected cells and 276 DE lncRNAs between PRV-DX and gE-TK-PRV infected cells. The potential functions of the significant differentially expressed (SDE) lncRNAs were involved in interleukin secretion, axon extension and metabolic process based on the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Moreover, the expression patterns of sixteen SDE lncRNAs determined by RT-qPCR exhibited high correlation (r > 0.95) with those by RNA-seq results. Western blotting assay displayed the lncA02830 did not code for protein, and the silencing of lncA02830 could significantly up-regulate the transcription levels of IRF3, IFNβ as well as MX1 and inhibit the replication of PRV-II. Taken together, these data highlighted the potentials of lncRNA as targets for antiviral therapy and provided some novel knowledge of the mechanisms underlying the host interaction with PRV-II.
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The Apical Region of the Herpes Simplex Virus Major Capsid Protein Promotes Capsid Maturation. J Virol 2018; 92:JVI.00821-18. [PMID: 29976665 DOI: 10.1128/jvi.00821-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/27/2018] [Indexed: 01/12/2023] Open
Abstract
The herpesvirus capsid assembles in the nucleus as an immature procapsid precursor built around viral scaffold proteins. The event that initiates procapsid maturation is unknown, but it is dependent upon activation of the VP24 internal protease. Scaffold cleavage triggers angularization of the shell and its decoration with the VP26 and pUL25 capsid-surface proteins. In both the procapsid and mature angularized capsid, the apical region of the major capsid protein (VP5) is surface exposed. We investigated whether the VP5 apical region contributes to intracellular transport dynamics following entry into primary sensory neurons and also tested the hypothesis that conserved negatively charged amino acids in the apical region contribute to VP26 acquisition. To our surprise, neither hypothesis proved true. Instead, mutation of glutamic acid residues in the apical region delayed viral propagation and induced focal capsid accumulations in nuclei. Examination of capsid morphogenesis based on epitope unmasking, capsid composition, and ultrastructural analysis indicated that these clusters consisted of procapsids. The results demonstrate that, in addition to established events that occur inside the capsid, the exterior capsid shell promotes capsid morphogenesis and maturation.IMPORTANCE Herpesviruses assemble capsids and encapsidate their genomes by a process that is unlike those of other mammalian viruses but is similar to those of some bacteriophage. Many important aspects of herpesvirus morphogenesis remain enigmatic, including how the capsid shell matures into a stable angularized configuration. Capsid maturation is triggered by activation of a protease that cleaves an internal protein scaffold. We report on the fortuitous discovery that a region of the major capsid protein that is exposed on the outer surface of the capsid also contributes to capsid maturation, demonstrating that the morphogenesis of the capsid shell from its procapsid precursor to the mature angularized form is dependent upon internal and external components of the megastructure.
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15
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Close WL, Anderson AN, Pellett PE. Betaherpesvirus Virion Assembly and Egress. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1045:167-207. [PMID: 29896668 DOI: 10.1007/978-981-10-7230-7_9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Virions are the vehicle for cell-to-cell and host-to-host transmission of viruses. Virions need to be assembled reliably and efficiently, be released from infected cells, survive in the extracellular environment during transmission, recognize and then trigger entry of appropriate target cells, and disassemble in an orderly manner during initiation of a new infection. The betaherpesvirus subfamily includes four human herpesviruses (human cytomegalovirus and human herpesviruses 6A, 6B, and 7), as well as viruses that are the basis of important animal models of infection and immunity. Similar to other herpesviruses, betaherpesvirus virions consist of four main parts (in order from the inside): the genome, capsid, tegument, and envelope. Betaherpesvirus genomes are dsDNA and range in length from ~145 to 240 kb. Virion capsids (or nucleocapsids) are geometrically well-defined vessels that contain one copy of the dsDNA viral genome. The tegument is a collection of several thousand protein and RNA molecules packed into the space between the envelope and the capsid for delivery and immediate activity upon cellular entry at the initiation of an infection. Betaherpesvirus envelopes consist of lipid bilayers studded with virus-encoded glycoproteins; they protect the virion during transmission and mediate virion entry during initiation of new infections. Here, we summarize the mechanisms of betaherpesvirus virion assembly, including how infection modifies, reprograms, hijacks, and otherwise manipulates cellular processes and pathways to produce virion components, assemble the parts into infectious virions, and then transport the nascent virions to the extracellular environment for transmission.
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Affiliation(s)
- William L Close
- Department of Microbiology & Immunology, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Department of Biochemistry, Microbiology, & Immunology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Ashley N Anderson
- Department of Biochemistry, Microbiology, & Immunology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Philip E Pellett
- Department of Biochemistry, Microbiology, & Immunology, Wayne State University School of Medicine, Detroit, MI, USA.
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16
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Richards AL, Sollars PJ, Pitts JD, Stults AM, Heldwein EE, Pickard GE, Smith GA. The pUL37 tegument protein guides alpha-herpesvirus retrograde axonal transport to promote neuroinvasion. PLoS Pathog 2017; 13:e1006741. [PMID: 29216315 PMCID: PMC5749899 DOI: 10.1371/journal.ppat.1006741] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/02/2018] [Accepted: 11/10/2017] [Indexed: 01/07/2023] Open
Abstract
A hallmark property of the neurotropic alpha-herpesvirinae is the dissemination of infection to sensory and autonomic ganglia of the peripheral nervous system following an initial exposure at mucosal surfaces. The peripheral ganglia serve as the latent virus reservoir and the source of recurrent infections such as cold sores (herpes simplex virus type I) and shingles (varicella zoster virus). However, the means by which these viruses routinely invade the nervous system is not fully understood. We report that an internal virion component, the pUL37 tegument protein, has a surface region that is an essential neuroinvasion effector. Mutation of this region rendered herpes simplex virus type 1 (HSV-1) and pseudorabies virus (PRV) incapable of spreading by retrograde axonal transport to peripheral ganglia both in culture and animals. By monitoring the axonal transport of individual viral particles by time-lapse fluorescence microscopy, the mutant viruses were determined to lack the characteristic sustained intracellular capsid motion along microtubules that normally traffics capsids to the neural soma. Consistent with the axonal transport deficit, the mutant viruses did not reach sites of latency in peripheral ganglia, and were avirulent. Despite this, viral propagation in peripheral tissues and in cultured epithelial cell lines remained robust. Selective elimination of retrograde delivery to the nervous system has long been sought after as a means to develop vaccines against these ubiquitous, and sometimes devastating viruses. In support of this potential, we find that HSV-1 and PRV mutated in the effector region of pUL37 evoked effective vaccination against subsequent nervous system challenges and encephalitic disease. These findings demonstrate that retrograde axonal transport of the herpesviruses occurs by a virus-directed mechanism that operates by coordinating opposing microtubule motors to favor sustained retrograde delivery of the virus to the peripheral ganglia. The ability to selectively eliminate the retrograde axonal transport mechanism from these viruses will be useful in trans-synaptic mapping studies of the mammalian nervous system, and affords a new vaccination paradigm for human and veterinary neurotropic herpesviruses.
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MESH Headings
- Amino Acid Sequence
- Animals
- Axonal Transport/genetics
- Axonal Transport/physiology
- Axons/virology
- Ganglia/virology
- Genes, Viral
- Herpesvirus 1, Human/genetics
- Herpesvirus 1, Human/pathogenicity
- Herpesvirus 1, Human/physiology
- Herpesvirus 1, Suid/genetics
- Herpesvirus 1, Suid/pathogenicity
- Herpesvirus 1, Suid/physiology
- Host-Pathogen Interactions/genetics
- Host-Pathogen Interactions/physiology
- Humans
- Male
- Mice
- Mice, Inbred DBA
- Models, Molecular
- Mutation
- Neurons/virology
- Rats
- Rats, Long-Evans
- Viral Structural Proteins/chemistry
- Viral Structural Proteins/genetics
- Viral Structural Proteins/physiology
- Viral Vaccines/genetics
- Virulence/genetics
- Virulence/physiology
- Virus Release/genetics
- Virus Release/physiology
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Affiliation(s)
- Alexsia L. Richards
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Patricia J. Sollars
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Jared D. Pitts
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Austin M. Stults
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Ekaterina E. Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Gary E. Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska
| | - Gregory A. Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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17
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Póka N, Csabai Z, Pásti E, Tombácz D, Boldogkői Z. Deletion of the us7 and us8 genes of pseudorabies virus exerts a differential effect on the expression of early and late viral genes. Virus Genes 2017; 53:603-612. [PMID: 28477233 DOI: 10.1007/s11262-017-1465-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/02/2017] [Indexed: 11/30/2022]
Abstract
The pseudorabies virus (PRV; also known as Suid herpesvirus-1) is a neurotropic herpesvirus of swine. The us7 and us8 genes of this virus encode the glycoprotein I and E membrane proteins that form a heterodimer that is known to control cell-to-cell spread in tissue culture and in animals. In this study, we investigated the effect of the deletion of the PRV us7 and us8 genes on the genome-wide transcription and DNA replication using a multi-time-point quantitative reverse transcriptase-based real-time PCR technique. Abrogation of the us7/8 gene function was found to exert a drastic but differential effect on the expression of PRV genes during lytic infection. In the mutant virus, all kinetic classes of viral genes were significantly down-regulated at the first 6 h of infection, while having been upregulated later. The level of upregulation was the highest in the immediate-early (IE) and the early (E) genes; lower in the early-late (E/L) genes; and the lowest in the late (L) genes. The relative contribution of the L transcripts to the global transcriptome became lower, while the rest of the transcripts were expressed at a higher level in the mutant than in the wild-type virus.
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Affiliation(s)
- Nándor Póka
- 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
| | - Emese Pásti
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Dóra Tombácz
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Boldogkői
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
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18
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Visualizing Herpesvirus Procapsids in Living Cells. J Virol 2016; 90:10182-10192. [PMID: 27581983 DOI: 10.1128/jvi.01437-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 08/24/2016] [Indexed: 01/16/2023] Open
Abstract
A complete understanding of herpesvirus morphogenesis requires studies of capsid assembly dynamics in living cells. Although fluorescent tags fused to the VP26 and pUL25 capsid proteins are available, neither of these components is present on the initial capsid assembly, the procapsid. To make procapsids accessible to live-cell imaging, we made a series of recombinant pseudorabies viruses that encoded green fluorescent protein (GFP) fused in frame to the internal capsid scaffold and maturation protease. One recombinant, a GFP-VP24 fusion, maintained wild-type propagation kinetics in vitro and approximated wild-type virulence in vivo The fusion also proved to be well tolerated in herpes simplex virus. Viruses encoding GFP-VP24, along with a traditional capsid reporter fusion (pUL25/mCherry), demonstrated that GFP-VP24 was a reliable capsid marker and revealed that the protein remained capsid associated following entry into cells and upon nuclear docking. These dual-fluorescent viruses made possible the discrimination of procapsids during infection and monitoring of capsid shell maturation kinetics. The results demonstrate the feasibility of imaging herpesvirus procapsids and their morphogenesis in living cells and indicate that the encapsidation machinery does not substantially help coordinate capsid shell maturation. IMPORTANCE The family Herpesviridae consists of human and veterinary pathogens that cause a wide range of diseases in their respective hosts. These viruses share structurally related icosahedral capsids that encase the double-stranded DNA (dsDNA) viral genome. The dynamics of capsid assembly and maturation have been inaccessible to examination in living cells. This study has overcome this technical hurdle and provides new insights into this fundamental stage of herpesvirus infection.
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Richards AL, Sollars PJ, Smith GA. New tools to convert bacterial artificial chromosomes to a self-excising design and their application to a herpes simplex virus type 1 infectious clone. BMC Biotechnol 2016; 16:64. [PMID: 27580861 PMCID: PMC5006514 DOI: 10.1186/s12896-016-0295-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/21/2016] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Infectious clones are fundamental tools for the study of many viruses, allowing for efficient mutagenesis and reproducible production of genetically-defined strains. For the large dsDNA genomes of the herpesviridae, bacterial artificial chromosomes have become the cloning vector of choice due to their capacity to house full-length herpesvirus genomes as single contiguous inserts. Furthermore, while maintained as plasmids in Escherichia coli, the clones can be mutated using robust prokaryotic recombination systems. An important consideration in the design of these clones is the means by which the vector backbone is removed from the virus genome upon delivery into mammalian cells. A common approach to vector excision is to encode loxP sites flanking the vector sequences and rely on Cre recombinase expression from a transformed cell line. Here we examine the efficiency of vector removal using this method, and describe a "self-excising" infectious clone of HSV-1 strain F that offers enhancements in virus production and utility. RESULTS Insertion of a fluorescent protein expression cassette into the vector backbone of the HSV-1 strain F clone, pYEbac102, demonstrated that 2 serial passages on cells expressing Cre recombinase was required to achieve > 95 % vector removal from the virus population, with 3 serial passages resulting in undetectable vector retention. This requirement was eliminated by replacing the reporter coding sequence with the CREin gene, which consists of a Cre coding sequence disrupted by a synthetic intron. This self-excising variant of the infectious clone produced virus that propagated with wild-type kinetics in culture and lacked vector attenuation in a mouse neurovirulence model. CONCLUSION Conversion of a herpesvirus infectious clone into a self-excising variant enables rapid production of viruses lacking bacterial vector sequences, and removes the requirement to initially propagate viruses in cells that express Cre recombinase. The self-excising bacterial artificial chromosome described here allows for efficient production of the F strain of herpes simplex virus type 1.
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Affiliation(s)
- Alexsia L Richards
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave., Morton Building, Room 3-603, Chicago, IL, 60611, USA
| | - Patricia J Sollars
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, 68583, USA
| | - Gregory A Smith
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave., Morton Building, Room 3-603, Chicago, IL, 60611, USA.
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20
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Growth characteristics and complete genomic sequence analysis of a novel pseudorabies virus in China. Virus Genes 2016; 52:474-83. [DOI: 10.1007/s11262-016-1324-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/18/2016] [Indexed: 12/22/2022]
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21
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The pseudorabies virus protein, pUL56, enhances virus dissemination and virulence but is dispensable for axonal transport. Virology 2015; 488:179-86. [PMID: 26655235 DOI: 10.1016/j.virol.2015.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/11/2015] [Accepted: 11/15/2015] [Indexed: 11/23/2022]
Abstract
Neurotropic herpesviruses exit the peripheral nervous system and return to exposed body surfaces following reactivation from latency. The pUS9 protein is a critical viral effector of the anterograde axonal transport that underlies this process. We recently reported that while pUS9 increases the frequency of sorting of newly assembled pseudorabies virus particles to axons from the neural soma during egress, subsequent axonal transport of individual virus particles occurs with wild-type kinetics in the absence of the protein. Here, we examine the role of a related pseudorabies virus protein, pUL56, during neuronal infection. The findings indicate that pUL56 is a virulence factor that supports virus dissemination in vivo, yet along with pUS9, is dispensable for axonal transport.
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22
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Preventing Cleavage of the Respiratory Syncytial Virus Attachment Protein in Vero Cells Rescues the Infectivity of Progeny Virus for Primary Human Airway Cultures. J Virol 2015; 90:1311-20. [PMID: 26581976 DOI: 10.1128/jvi.02351-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 11/05/2015] [Indexed: 01/20/2023] Open
Abstract
UNLABELLED All live attenuated respiratory syncytial virus (RSV) vaccines that have advanced to clinical trials have been produced in Vero cells. The attachment (G) glycoprotein in virions produced in these cells is smaller than that produced in other immortalized cells due to cleavage. These virions are 5-fold less infectious for primary well-differentiated human airway epithelial (HAE) cell cultures. Because HAE cells are isolated directly from human airways, Vero cell-grown vaccine virus would very likely be similarly inefficient at initiating infection of the nasal epithelium following vaccination, and therefore, a larger inoculum would be required for effective vaccination. We hypothesized that Vero cell-derived virus containing an intact G protein would be more infectious for HAE cell cultures. Using protease inhibitors with increasing specificity, we identified cathepsin L to be the protease responsible for cleavage. Our evidence suggests that cleavage occurs in the late endosome or lysosome during endocytic recycling. Cathepsin L activity was 100-fold greater in Vero cells than in HeLa cells. In addition, cathepsin L was able to cleave the G protein in Vero cell-grown virions but not in HeLa cell-grown virions, suggesting a difference in G-protein posttranslational modification in the two cell lines. We identified by mutagenesis amino acids important for cleavage, and these amino acids included a likely cathepsin L cleavage site. Virus containing a modified, noncleavable G protein produced in Vero cells was 5-fold more infectious for HAE cells in culture, confirming our hypothesis and indicating the value of including such a mutation in future live attenuated RSV vaccines. IMPORTANCE Worldwide, RSV is the second leading infectious cause of infant death, but no vaccine is available. Experimental live attenuated RSV vaccines are grown in Vero cells, but during production the virion attachment (G) glycoprotein is cleaved. Virions containing a cleaved G protein are less infectious for primary airway epithelial cells, the natural RSV target. In the study described here we identified the protease responsible, located the cleavage site, and demonstrated that cleavage likely occurs during endocytic recycling. Moreover, we showed that the infectivity of Vero cell-derived virus for primary airway epithelial cells is increased 5-fold if the virus contains a mutation in the G protein that prevents cleavage. The blocking of cleavage should improve RSV vaccine yield, consequently reducing production costs. Posttranslational cleavage of the fusion glycoprotein of many viruses plays an essential role in activation; however, cleavage of the RSV G protein is a novel example of a detrimental effect of cleavage on virus infectivity.
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HSV-1 gM and the gK/pUL20 complex are important for the localization of gD and gH/L to viral assembly sites. Viruses 2015; 7:915-38. [PMID: 25746217 PMCID: PMC4379555 DOI: 10.3390/v7030915] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 02/06/2015] [Accepted: 02/22/2015] [Indexed: 11/30/2022] Open
Abstract
Herpes simplex virus-1 (HSV-1), like all herpesviruses, is a large complex DNA virus containing up to 16 different viral membrane proteins in its envelope. The assembly of HSV-1 particles occurs by budding/wrapping at intracellular membranes producing infectious virions contained within the lumen of cytoplasmic membrane-bound compartments that are then released by secretion. To ensure incorporation of all viral membrane proteins into the envelope, they need to be localized to the appropriate intracellular membranes either via the endocytic pathway or by direct targeting to assembly sites from the biosynthetic secretory pathway. Many HSV-1 envelope proteins encode targeting motifs that direct their endocytosis and targeting, while others do not, including the essential entry proteins gD and the gH/gL complex, and so it has been unclear how these envelope proteins reach the appropriate assembly compartments. We now show that efficient endocytosis of gD and gH/gL and their incorporation into mature virions relies upon the presence of the HSV-1 envelope proteins gM and the gK/pUL20 complex. Our data demonstrate both redundant and synergistic roles for gM and gK/pUL20 in controlling the targeting of gD and gH/L to the appropriate intracellular virus assembly compartments.
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Pseudorabies virus triggers glycoprotein gE-mediated ERK1/2 activation and ERK1/2-dependent migratory behavior in T cells. J Virol 2014; 89:2149-56. [PMID: 25473050 DOI: 10.1128/jvi.02549-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED The interaction between viruses and immune cells of the host may lead to modulation of intracellular signaling pathways and to subsequent changes in cellular behavior that are of benefit for either virus or host. ERK1/2 (extracellular signal regulated kinase 1/2) signaling represents one of the key cellular signaling axes. Here, using wild-type and gE null virus, recombinant gE, and gE-transfected cells, we show that the gE glycoprotein of the porcine Varicellovirus pseudorabies virus (PRV) triggers ERK1/2 phosphorylation in Jurkat T cells and primary porcine T lymphocytes. PRV-induced ERK1/2 signaling resulted in homotypic T cell aggregation and increased motility of T lymphocytes. Our study reveals a new function of the gE glycoprotein of PRV and suggests that PRV, through activation of ERK1/2 signaling, has a substantial impact on T cell behavior. IMPORTANCE Herpesviruses are known to be highly successful in evading the immune system of their hosts, subverting signaling pathways of the host to their own advantage. The ERK1/2 signaling pathway, being involved in many cellular processes, represents a particularly attractive target for viral manipulation. Glycoprotein E (gE) is an important virulence factor of alphaherpesviruses, involved in viral spread. In this study, we show that gE has the previously uncharacterized ability to trigger ERK1/2 phosphorylation in T lymphocytes. We also show that virus-induced ERK1/2 signaling leads to increased migratory behavior of T cells and that migratory T cells can spread the infection to susceptible cells. In conclusion, our results point to a novel function for gE and suggest that virus-induced ERK1/2 activation may trigger PRV-carrying T lymphocytes to migrate and infect other cells susceptible to PRV replication.
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Human cytomegalovirus infection of langerhans-type dendritic cells does not require the presence of the gH/gL/UL128-131A complex and is blocked after nuclear deposition of viral genomes in immature cells. J Virol 2013; 88:403-16. [PMID: 24155395 DOI: 10.1128/jvi.03062-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Human cytomegalovirus (CMV) enters its host via the oral and genital mucosae. Langerhans-type dendritic cells (LC) are the most abundant innate immune cells at these sites, where they constitute a first line of defense against a variety of pathogens. We previously showed that immature LC (iLC) are remarkably resistant to CMV infection, while mature LC (mLC) are more permissive, particularly when exposed to clinical-strain-like strains of CMV, which display a pentameric complex consisting of the viral glycoproteins gH, gL, UL128, UL130, and UL131A on their envelope. This complex was recently shown to be required for the infection of immature monocyte-derived dendritic cells. We thus sought to establish if the presence of this complex is also necessary for virion penetration of LC and if defects in entry might be the source of iLC resistance to CMV. Here we report that the efficiency of LC infection is reduced, but not completely abolished, in the absence of the pentameric complex. While virion penetration and nuclear deposition of viral genomes are not impaired in iLC, the transcription of the viral immediate early genes UL122 and UL123 and of the delayed early gene UL50 is substantially lower than that in mLC. Together, these data show that the UL128, UL130, and UL131A proteins are dispensable for CMV entry into LC and that progression of the viral cycle in iLC is restricted at the step of viral gene expression.
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Zaichick SV, Bohannon KP, Hughes A, Sollars PJ, Pickard GE, Smith GA. The herpesvirus VP1/2 protein is an effector of dynein-mediated capsid transport and neuroinvasion. Cell Host Microbe 2013; 13:193-203. [PMID: 23414759 DOI: 10.1016/j.chom.2013.01.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 11/13/2012] [Accepted: 01/11/2013] [Indexed: 12/23/2022]
Abstract
Microtubule transport of herpesvirus capsids from the cell periphery to the nucleus is imperative for viral replication and, in the case of many alphaherpesviruses, transmission into the nervous system. Using the neuroinvasive herpesvirus, pseudorabies virus (PRV), we show that the viral protein 1/2 (VP1/2) tegument protein associates with the dynein/dynactin microtubule motor complex and promotes retrograde microtubule transport of PRV capsids. Functional activation of VP1/2 requires binding to the capsid protein pUL25 or removal of the capsid-binding domain. A proline-rich sequence within VP1/2 is required for the efficient interaction with the dynein/dynactin microtubule motor complex as well as for PRV virulence and retrograde axon transport in vivo. Additionally, in the absence of infection, functionally active VP1/2 is sufficient to move large surrogate cargoes via the dynein/dynactin microtubule motor complex. Thus, VP1/2 tethers PRV capsids to dynein/dynactin to enhance microtubule transport, neuroinvasion, and pathogenesis.
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Affiliation(s)
- Sofia V Zaichick
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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Directional spread of alphaherpesviruses in the nervous system. Viruses 2013; 5:678-707. [PMID: 23435239 PMCID: PMC3640521 DOI: 10.3390/v5020678] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 02/04/2013] [Accepted: 02/05/2013] [Indexed: 12/30/2022] Open
Abstract
Alphaherpesviruses are pathogens that invade the nervous systems of their mammalian hosts. Directional spread of infection in the nervous system is a key component of the viral lifecycle and is critical for the onset of alphaherpesvirus-related diseases. Many alphaherpesvirus infections originate at peripheral sites, such as epithelial tissues, and then enter neurons of the peripheral nervous system (PNS), where lifelong latency is established. Following reactivation from latency and assembly of new viral particles, the infection typically spreads back out towards the periphery. These spread events result in the characteristic lesions (cold sores) commonly associated with herpes simplex virus (HSV) and herpes zoster (shingles) associated with varicella zoster virus (VZV). Occasionally, the infection spreads transsynaptically from the PNS into higher order neurons of the central nervous system (CNS). Spread of infection into the CNS, while rarer in natural hosts, often results in severe consequences, including death. In this review, we discuss the viral and cellular mechanisms that govern directional spread of infection in the nervous system. We focus on the molecular events that mediate long distance directional transport of viral particles in neurons during entry and egress.
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Hollinshead M, Johns HL, Sayers CL, Gonzalez-Lopez C, Smith GL, Elliott G. Endocytic tubules regulated by Rab GTPases 5 and 11 are used for envelopment of herpes simplex virus. EMBO J 2012; 31:4204-20. [PMID: 22990238 PMCID: PMC3492727 DOI: 10.1038/emboj.2012.262] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 08/24/2012] [Indexed: 02/08/2023] Open
Abstract
Enveloped viruses employ diverse and complex strategies for wrapping at cellular membranes, many of which are poorly understood. Here, an ultrastructural study of herpes simplex virus 1 (HSV1)-infected cells revealed envelopment in tubular membranes. These tubules were labelled by the fluid phase marker horseradish peroxidase (HRP), and were observed to wrap capsids as early as 2 min after HRP addition, indicating that the envelope had recently cycled from the cell surface. Consistent with this, capsids did not colocalise with either the trans-Golgi network marker TGN46 or late endosomal markers, but showed coincidence with the transferrin receptor. Virus glycoproteins were retrieved from the plasma membrane (PM) to label wrapping capsids, a process that was dependent on both dynamin and Rab5. Combined depletion of Rab5 and Rab11 reduced virus yield to <1%, resulting in aberrant localisation of capsids. These results suggest that endocytosis from the PM into endocytic tubules provides the main source of membrane for HSV1, and reveal a new mechanism for virus exploitation of the endocytic pathway.
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Affiliation(s)
- Michael Hollinshead
- Section of Virology, Faculty of Medicine, Imperial College London, London, UK
| | - Helen L Johns
- Section of Virology, Faculty of Medicine, Imperial College London, London, UK
| | - Charlotte L Sayers
- Section of Virology, Faculty of Medicine, Imperial College London, London, UK
| | | | - Geoffrey L Smith
- Section of Virology, Faculty of Medicine, Imperial College London, London, UK
| | - Gillian Elliott
- Section of Virology, Faculty of Medicine, Imperial College London, London, UK
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Nuclear egress of pseudorabies virus capsids is enhanced by a subspecies of the large tegument protein that is lost upon cytoplasmic maturation. J Virol 2012; 86:6303-14. [PMID: 22438563 DOI: 10.1128/jvi.07051-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Herpesviruses morphogenesis occurs stepwise both temporally and spatially, beginning in the nucleus and concluding with the emergence of an extracellular virion. The mechanisms by which these viruses interact with and penetrate the nuclear envelope and subsequent compartments of the secretory pathway remain poorly defined. In this report, a conserved viral protein (VP1/2; pUL36) that directs cytoplasmic stages of egress is identified to have multiple isoforms. Of these, a novel truncated VP1/2 species translocates to the nucleus and assists the transfer of DNA-containing capsids to the cytoplasm. The capsids are handed off to full-length VP1/2, which replaces the nuclear isoform on the capsids and is required for the final cytoplasmic stages of viral particle maturation. These results document that distinct VP1/2 protein species serve as effectors of nuclear and cytoplasmic egress.
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Abstract
Addition of methylated β-lactoglobulin (Met-BLG) in the medium of MDCK cell lines infected with influenza virus subtype H1N1 reduced hemagglutination activity (HA) in a concentration dependent manner. Antiviral activity of Met-BLG depended on its concentration, viral load, and duration of infection. Using 17 μg/ml of Met-BLG inhibited 50% of HA of H1N1 grown in MDCK cells at 1 MOI after 24 h incubation at 37°C and in 5% CO₂. Extension of incubation time enhanced antiviral action since the same concentration of Met-BLG inhibited about 61% of viral activity after 48 h. This viral inhibition was accompanied by a protection of MDCK cells as observed by using neutral red or by direct microscope examination. Reduction of viral RNA replication upon the addition of Met-BLG (50 μg/ml) was observed by real time-PCR showing a reduction of viral log value of about 0·9. When viral stock solution was mixed with 25 μg/ml Met-BLG in absence of cell lines, the morphology and viability of virus particles were significantly affected as observed by electron microscopy, and the number of intact virus particles was reduced by roughly 65%.
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Optimal replication of human cytomegalovirus correlates with endocytosis of glycoprotein gpUL132. J Virol 2010; 84:7039-52. [PMID: 20444903 DOI: 10.1128/jvi.01644-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Envelopment of a herpesvirus particle is a complex process of which much is still to be learned. We previously identified the glycoprotein gpUL132 of human cytomegalovirus (HCMV) as an envelope component of the virion. In its carboxy-terminal portion, gpUL132 contains at least four motifs for sorting of transmembrane proteins to endosomes; among them are one dileucine-based signal and three tyrosine-based signals of the YXXØ and NPXY (where X stands for any amino acid, and Ø stands for any bulky hydrophobic amino acid) types. To investigate the role of each of these trafficking signals in intracellular localization and viral replication, we constructed a panel of expression plasmids and recombinant viruses in which the signals were rendered nonfunctional by mutagenesis. In transfected cells wild-type gpUL132 was mainly associated with the trans-Golgi network. Consecutive mutation of the trafficking signals resulted in increasing fractions of the protein localized at the cell surface, with gpUL132 mutated in all four trafficking motifs predominantly associated with the plasma membrane. Concomitant with increased surface expression, endocytosis of mutant gpUL132 was reduced, with a gpUL132 expressing all four motifs in mutated form being almost completely impaired in endocytosis. The replication of recombinant viruses harboring mutations in single trafficking motifs was comparable to replication of wild-type virus. In contrast, viruses containing mutations in three or four of the trafficking signals showed pronounced deficits in replication with a reduction of approximately 100-fold. Moreover, recombinant viruses expressing gpUL132 with three or four trafficking motifs mutated failed to incorporate the mutant protein into the virus particle. These results demonstrate a role of endocytosis of an HCMV envelope glycoprotein for incorporation into the virion and optimal virus replication.
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Molecular epidemiology of Brazilian pseudorabies viral isolates. Vet Microbiol 2009; 141:238-45. [PMID: 19828266 DOI: 10.1016/j.vetmic.2009.09.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 09/09/2009] [Accepted: 09/22/2009] [Indexed: 11/23/2022]
Abstract
Pseudorabies is a disease caused by pseudorabies virus (PRV) and is responsible for considerable economic losses in the swine industry. The objective of this work was to use molecular epidemiology as a tool to facilitate the study of PRV outbreaks in Brazil. The standard PRV strain Shope, the vaccine strain Bartha and isolates from the south and the southeast regions of Brazil, were amplified for gE and gC partial genes by PCR. Results indicated that Brazilian PRV isolates are grouped in two clusters, A and B, except for one isolate that grouped with Bartha and Shope. Most Brazilian PRV isolates belonged to cluster B and diverged from virus isolated from other countries.
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Virion-incorporated glycoprotein B mediates transneuronal spread of pseudorabies virus. J Virol 2009; 83:7796-804. [PMID: 19494011 DOI: 10.1128/jvi.00745-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Transneuronal spread of pseudorabies virus (PRV) is a multistep process that requires several virally encoded proteins. Previous studies have shown that PRV glycoprotein B (gB), a component of the viral fusion machinery, is required for the transmission of infection to postsynaptic, second-order neurons. We sought to identify the gB-mediated step in viral transmission. We determined that gB is not required for the sorting of virions into axons of infected neurons, anterograde transport, or the release of virions from the axon. trans or cis expression of gB on the cell surface was not sufficient for transneuronal spread of the virus; instead, efficient incorporation of gB into virions was required. Additionally, neuron-to-cell spread of PRV most likely does not proceed through syncytial connections. We conclude that, upon gB-independent release of virions at the site of neuron-cell contacts, the virion-incorporated gB/gH/gL fusion complex mediates entry into the axonally contacted cell by fusion of the closely apposed membranes.
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Xiao J, Palefsky JM, Herrera R, Berline J, Tugizov SM. EBV BMRF-2 facilitates cell-to-cell spread of virus within polarized oral epithelial cells. Virology 2009; 388:335-43. [PMID: 19394065 DOI: 10.1016/j.virol.2009.03.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 03/20/2009] [Accepted: 03/21/2009] [Indexed: 12/12/2022]
Abstract
We previously reported that the Epstein-Barr virus (EBV) BMRF-2 protein plays an important role in EBV infection of polarized oral epithelial cells by interacting with beta1 and alphav family integrins. Here we show that infection of polarized oral epithelial cells with B27-BMRF-2(low) recombinant virus, expressing a low level of BMRF-2, resulted in significantly smaller plaques compared with infection by parental B95-8 virus. BMRF-2 localized in the trans-Golgi network (TGN) and basolateral sorting vesicles and was transported to the basolateral membranes of polarized epithelial cells. Mutation of the tyrosine- and dileucine-containing basolateral sorting signal, YLLV, in the cytoplasmic domain of BMRF-2 led to the failure of its accumulation in the TGN and its basolateral transport. These data show that BMRF-2 may play an important role in promoting the spread of EBV progeny virions through lateral membranes of oral epithelial cells.
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Affiliation(s)
- Jianqiao Xiao
- Department of Medicine, University of California, San Francisco, USA
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35
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Lee JI, Sollars PJ, Baver SB, Pickard GE, Leelawong M, Smith GA. A herpesvirus encoded deubiquitinase is a novel neuroinvasive determinant. PLoS Pathog 2009; 5:e1000387. [PMID: 19381253 PMCID: PMC2663050 DOI: 10.1371/journal.ppat.1000387] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 03/19/2009] [Indexed: 01/08/2023] Open
Abstract
The neuroinvasive property of several alpha-herpesviruses underlies an uncommon infectious process that includes the establishment of life-long latent infections in sensory neurons of the peripheral nervous system. Several herpesvirus proteins are required for replication and dissemination within the nervous system, indicating that exploiting the nervous system as a niche for productive infection requires a specialized set of functions encoded by the virus. Whether initial entry into the nervous system from peripheral tissues also requires specialized viral functions is not known. Here we show that a conserved deubiquitinase domain embedded within a pseudorabies virus structural protein, pUL36, is essential for initial neural invasion, but is subsequently dispensable for transmission within and between neurons of the mammalian nervous system. These findings indicate that the deubiquitinase contributes to neurovirulence by participating in a previously unrecognized initial step in neuroinvasion. Subsets of herpesviruses, such as herpes simplex virus and pseudorabies virus, are neuroinvasive pathogens. Upon infection, these viruses efficiently target peripheral nervous system tissue and establish a life-long infection for which there is no cure. Very few pathogens are known that invade the nervous system proficiently, and the mechanism by which herpesviruses achieve neuroinvasion is largely unknown. In this study, we demonstrate that a viral protease plays a critical and specific role allowing the virus to cross the threshold of the nervous system, but is dispensable for subsequent replication and encephalitic spread within the brain.
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Affiliation(s)
- Joy I. Lee
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Patricia J. Sollars
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Scott B. Baver
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Gary E. Pickard
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Mindy Leelawong
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Gregory A. Smith
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail:
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36
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37
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A bovine herpesvirus type 1 mutant virus specifying a carboxyl-terminal truncation of glycoprotein E is defective in anterograde neuronal transport in rabbits and calves. J Virol 2008; 82:7432-42. [PMID: 18480434 DOI: 10.1128/jvi.00379-08] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bovine herpesvirus type 1 (BHV-1) is an important component of the bovine respiratory disease complex (BRDC) in cattle. The ability of BHV-1 to transport anterogradely from neuronal cell bodies in trigeminal ganglia (TG) to nerve ending in the noses and corneas of infected cattle following reactivation from latency plays a significant role in the pathogenesis of BRDC and maintenance of BHV-1 in the cattle population. We have constructed a BHV-1 bacterial artificial chromosome (BAC) clone by inserting an excisable BAC plasmid sequence in the long intergenic region between the glycoprotein B (gB) and UL26 genes. A BAC-excised, reconstituted BHV-1 containing only the 34-bp loxP sequence within the gB-UL26 intergenic region was highly infectious in calves, retained wild-type virulence properties, and reactivated from latency following treatment with dexamethasone. Using a two-step Red-mediated mutagenesis system in Escherichia coli, we constructed a gE cytoplasmic tail-truncated BHV-1 and a gE-rescued BHV-1. Following primary infection, the gE cytoplasmic tail-truncated virus was efficiently transported retrogradely from the nerve endings in the nose and eye to cell bodies in the TG of calves and rabbits. However, following dexamethasone-induced reactivation from latency, the gE mutant virus was not isolated from nasal and ocular sheddings. Reverse transcriptase PCR assays detected VP5 transcription in the TG of rabbits infected with gE-rescued and gE cytoplasmic tail-truncated viruses during primary infection and after dexamethasone treatment but not during latency. Therefore, the BHV-1gE cytoplasmic tail-truncated virus reactivated in the TG; however, it had defective anterograde transport from TG to nose and eye in calves and rabbits.
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38
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Melancon JM, Fulmer PA, Kousoulas KG. The herpes simplex virus UL20 protein functions in glycoprotein K (gK) intracellular transport and virus-induced cell fusion are independent of UL20 functions in cytoplasmic virion envelopment. Virol J 2007; 4:120. [PMID: 17996071 PMCID: PMC2186317 DOI: 10.1186/1743-422x-4-120] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 11/08/2007] [Indexed: 11/17/2022] Open
Abstract
The HSV-1 UL20 protein (UL20p) and glycoprotein K (gK) are both important determinants of cytoplasmic virion morphogenesis and virus-induced cell fusion. In this manuscript, we examined the effect of UL20 mutations on the coordinate transport and Trans Golgi Network (TGN) localization of UL20p and gK, virus-induced cell fusion and infectious virus production. Deletion of 18 amino acids from the UL20p carboxyl terminus (UL20 mutant 204t) inhibited intracellular transport and cell-surface expression of both gK and UL20, resulting in accumulation of UL20p and gK in the endoplasmic reticulum (ER) in agreement with the inability of 204t to complement UL20-null virus replication and virus-induced cell fusion. In contrast, less severe carboxyl terminal deletions of either 11 or six amino acids (UL20 mutants 211t and 216t, respectively) allowed efficient UL20p and gK intracellular transport, cell-surface expression and TGN colocalization. However, while both 211t and 216t failed to complement for infectious virus production, 216t complemented for virus-induced cell fusion, but 211t did not. These results indicated that the carboxyl terminal six amino acids of UL20p were crucial for infectious virus production, but not involved in intracellular localization of UL20p/gK and concomitant virus-induced cell fusion. In the amino terminus of UL20, UL20p mutants were produced changing one or both of the Y38 and Y49 residues found within putative phosphorylation sites. UL20p tyrosine-modified mutants with both tyrosine residues changed enabled efficient intracellular transport and TGN localization of UL20p and gK, but failed to complement for either infectious virus production, or virus-induced cell fusion. These results show that UL20p functions in cytoplasmic envelopment are separable from UL20 functions in UL20p intracellular transport, cell surface expression and virus-induced cell fusion.
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Affiliation(s)
- Jeffrey M Melancon
- Division of Biotechnology and Molecular Medicine, School of Veterinary Medicine, Louisiana State University, Baton Rouge, USA.
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39
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Beitia Ortiz de Zarate I, Cantero-Aguilar L, Longo M, Berlioz-Torrent C, Rozenberg F. Contribution of endocytic motifs in the cytoplasmic tail of herpes simplex virus type 1 glycoprotein B to virus replication and cell-cell fusion. J Virol 2007; 81:13889-903. [PMID: 17913800 PMCID: PMC2168835 DOI: 10.1128/jvi.01231-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The use of endocytic pathways by viral glycoproteins is thought to play various functions during viral infection. We previously showed in transfection assays that herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) is transported from the cell surface back to the trans-Golgi network (TGN) and that two motifs of gB cytoplasmic tail, YTQV and LL, function distinctly in this process. To investigate the role of each of these gB trafficking signals in HSV-1 infection, we constructed recombinant viruses in which each motif was rendered nonfunctional by alanine mutagenesis. In infected cells, wild-type gB was internalized from the cell surface and concentrated in the TGN. Disruption of YTQV abolished internalization of gB during infection, whereas disruption of LL induced accumulation of internalized gB in early recycling endosomes and impaired its return to the TGN. The growth of both recombinants was moderately diminished. Moreover, the fusion phenotype of cells infected with the gB recombinants differed from that of cells infected with the wild-type virus. Cells infected with the YTQV-mutated virus displayed reduced cell-cell fusion, whereas giant syncytia were observed in cells infected with the LL-mutated virus. Furthermore, blocking gB internalization or impairing gB recycling to the cell surface, using drugs or a transdominant negative form of Rab11, significantly reduced cell-cell fusion. These results favor a role for endocytosis in virus replication and suggest that gB intracellular trafficking is involved in the regulation of cell-cell fusion.
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Al-Mubarak A, Simon J, Coats C, Okemba JD, Burton MD, Chowdhury SI. Glycoprotein E (gE) specified by bovine herpesvirus type 5 (BHV-5) enables trans-neuronal virus spread and neurovirulence without being a structural component of enveloped virions. Virology 2007; 365:398-409. [PMID: 17477950 DOI: 10.1016/j.virol.2007.03.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 02/26/2007] [Accepted: 03/21/2007] [Indexed: 11/29/2022]
Abstract
Bovine herpesvirus 5 (BHV-5) is a neurovirulent alpha-herpesvirus that causes fatal encephalitis in calves. We previously demonstrated that deletion of a glycine-rich epitope in the gE ectodomain dramatically reduced BHV-5 neurovirulence. To investigate the role of gE cytoplasmic tail sequences in the neuropathogenesis of BHV-5 in rabbits, we constructed a BHV-5gE recombinant virus with a short residual cytoplasmic domain lacking the YXXL motifs and the acidic (BHV-5gEAm480). In vitro, BHV-5gEAm480 produced on the average smaller plaques, compared with wild-type BHV-5, but it produced on the average substantially larger plaques than the gE ORF-deleted BHV-5. The truncated gE was not phosphorylated, and was not endocytosed from the cell surface. Importantly, the truncated gE was not incorporated into enveloped infectious virions, but its glycosylation and interaction with gI were not affected. In a rabbit model of infection, the BHV-5gEAm480 remained highly virulent, while the gE-null virus was avirulent. The gEAm480 mutant virus invaded most of the central nervous system (CNS) structures that are invaded by the wild-type BHV-5. The number of neurons infected by BHV-5gEAm480 was very similar to the number infected by BHV-5 wild-type and gEAm480-rescued viruses. Collectively, the results suggest that gE functions in transsynaptic transmission of BHV-5 and neurovirulence without being a structural component of the virion particle.
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Affiliation(s)
- A Al-Mubarak
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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41
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Luxton GWG, Lee JIH, Haverlock-Moyns S, Schober JM, Smith GA. The pseudorabies virus VP1/2 tegument protein is required for intracellular capsid transport. J Virol 2007; 80:201-9. [PMID: 16352544 PMCID: PMC1317523 DOI: 10.1128/jvi.80.1.201-209.2006] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Transport of capsids in cells is critical to alphaherpesvirus infection and pathogenesis; however, viral factors required for transport have yet to be identified. Here we provide a detailed examination of capsid dynamics during the egress phase of infection in Vero cells infected with pseudorabies virus. We demonstrate that the VP1/2 tegument protein is required for processive microtubule-based transport of capsids in the cytoplasm. A second tegument protein that binds to VP1/2, UL37, was necessary for wild-type transport but was not essential for this process. Both proteins were also required for efficient nuclear egress of capsids to the cytoplasm.
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Affiliation(s)
- G W Gant Luxton
- Department of Microbiology-Immunology, Ward Bldg., Rm. 10-105, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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42
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Lee JIH, Luxton GWG, Smith GA. Identification of an essential domain in the herpesvirus VP1/2 tegument protein: the carboxy terminus directs incorporation into capsid assemblons. J Virol 2006; 80:12086-94. [PMID: 17005660 PMCID: PMC1676267 DOI: 10.1128/jvi.01184-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The herpesvirus tegument is a layer of viral and cellular proteins located between the capsid and envelope of the virion. The VP1/2 tegument protein is critical for the propagation of all herpesviruses examined. Using an infectious clone of the alphaherpesvirus pseudorabies virus, we have made a collection of truncation and in-frame deletion mutations within the VP1/2 gene (UL36) and examined the resulting viruses for spread between cells. We found that the majority of the VP1/2 protein either was essential for virus propagation or did not tolerate large deletions. A recently described amino-terminal deubiquitinase-encoding domain was dispensable for alphaherpesvirus propagation, but the rate of propagation in an epithelial cell line and the frequency of transport in axons of primary sensory neurons were both reduced. We mapped one essential domain to a conserved sequence at the VP1/2 carboxy terminus and demonstrated that this domain sufficient to redirect the green fluorescent protein to capsid assemblons in nuclei of infected cells.
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Affiliation(s)
- Joy I-Hsuan Lee
- Department of Microbiology-Immunology, Ward Bldg., Rm. 10-105, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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Blanchard Y, Le Meur N, Le Cunff M, Blanchard P, Léger J, Jestin A. Cellular gene expression survey of PseudoRabies Virus (PRV) infected Human Embryonic Kidney cells (HEK-293). Vet Res 2006; 37:705-23. [PMID: 16820135 DOI: 10.1051/vetres:2006027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 02/21/2006] [Indexed: 11/14/2022] Open
Abstract
Pseudorabies virus (PRV) is an alpha herpesvirus that causes Aujezsky disease in the pig. To characterize the impact of PRV infection on cellular expression, we used microarrays consisting of 9850 oligonucleotides corresponding to human genes and examined the expression levels of mRNA isolated 0.5, 3, 6, and 9 h post infection (hpi) from cultures of infected HEK-293 cells. Very few changes were observed during the first 3 h of infection but significant modifications in the cell expression of more than 1000 genes were clearly apparent by 6 hpi. More than 2400 genes were either up- or down-regulated during the 9 h experiment. These results were then analyzed using gene ontology and the MAPP and MAPPFinder software. This comprehensive analysis clearly shows that the down-regulated genes were mainly involved in macromolecular synthesis (DNA, RNA and proteins) and the cell cycle. The up-regulated genes primarily concerned the regulation of DNA transcription, developmental processes (central nervous system development, neurogenesis, angiogenesis), cell adhesion and potassium transport. This study is the first qualitative analysis of a gene expression survey in a human cell line following PRV infection. It demonstrates global changes in the cell expression profile, and identifies the main biological processes that are altered during virus replication.
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Affiliation(s)
- Yannick Blanchard
- Laboratoire de Génétique Virale et Biosécurité, Agence Française de Sécurité Sanitaire des Aliments, BP 53, 22440 Ploufragan, France.
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Pomeranz LE, Reynolds AE, Hengartner CJ. Molecular biology of pseudorabies virus: impact on neurovirology and veterinary medicine. Microbiol Mol Biol Rev 2005; 69:462-500. [PMID: 16148307 PMCID: PMC1197806 DOI: 10.1128/mmbr.69.3.462-500.2005] [Citation(s) in RCA: 599] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Pseudorabies virus (PRV) is a herpesvirus of swine, a member of the Alphaherpesvirinae subfamily, and the etiological agent of Aujeszky's disease. This review describes the contributions of PRV research to herpesvirus biology, neurobiology, and viral pathogenesis by focusing on (i) the molecular biology of PRV, (ii) model systems to study PRV pathogenesis and neurovirulence, (iii) PRV transsynaptic tracing of neuronal circuits, and (iv) veterinary aspects of pseudorabies disease. The structure of the enveloped infectious particle, the content of the viral DNA genome, and a step-by-step overview of the viral replication cycle are presented. PRV infection is initiated by binding to cellular receptors to allow penetration into the cell. After reaching the nucleus, the viral genome directs a regulated gene expression cascade that culminates with viral DNA replication and production of new virion constituents. Finally, progeny virions self-assemble and exit the host cells. Animal models and neuronal culture systems developed for the study of PRV pathogenesis and neurovirulence are discussed. PRV serves asa self-perpetuating transsynaptic tracer of neuronal circuitry, and we detail the original studies of PRV circuitry mapping, the biology underlying this application, and the development of the next generation of tracer viruses. The basic veterinary aspects of pseudorabies management and disease in swine are discussed. PRV infection progresses from acute infection of the respiratory epithelium to latent infection in the peripheral nervous system. Sporadic reactivation from latency can transmit PRV to new hosts. The successful management of PRV disease has relied on vaccination, prevention, and testing.
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Affiliation(s)
- Lisa E Pomeranz
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08540, USA.
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Abstract
Many viruses express membrane proteins. For enveloped viruses in particular, membrane proteins are frequently structural components of the virus that mediate the essential tasks of receptor recognition and membrane fusion. The functional activities of these proteins require that they are sorted correctly in infected cells. These sorting events often depend on the ability of the virus to mimic cellular protein trafficking signals and to interact with the cellular trafficking machinery. Importantly, loss or modification of these signals can influence virus infectivity and pathogenesis.
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Affiliation(s)
- R Byland
- MRC-LMCB and Department of Biochemistry and Molecular Biology, University College London, London, WC1E 6BT, UK
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Polcicova K, Goldsmith K, Rainish BL, Wisner TW, Johnson DC. The extracellular domain of herpes simplex virus gE is indispensable for efficient cell-to-cell spread: evidence for gE/gI receptors. J Virol 2005; 79:11990-2001. [PMID: 16140775 PMCID: PMC1212635 DOI: 10.1128/jvi.79.18.11990-12001.2005] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus (HSV) spreads rapidly and efficiently within epithelial and neuronal tissues. The HSV glycoprotein heterodimer gE/gI plays a critical role in promoting cell-to-cell spread but does not obviously function during entry of extracellular virus into cells. Thus, gE/gI is an important molecular handle on the poorly understood process of cell-to-cell spread. There was previous evidence that the large extracellular (ET) domains of gE/gI might be important in cell-to-cell spread. First, gE/gI extensively accumulates at cell junctions, consistent with being tethered there. Second, expression of gE/gI in trans interfered with HSV spread between epithelial cells. To directly test whether the gE ET domain was necessary for gE/gI to promote virus spread, a panel of gE mutants with small insertions in the ET domain was constructed. Cell-to-cell spread was reduced when insertions were made within either of two regions, residues 256 to 291 or 348 to 380. There was a strong correlation between loss of cell-to-cell spread function and binding of immunoglobulin. gE ET domain mutants 277, 291, and 348 bound gI, produced mature forms of gE that reached the cell surface, and were incorporated into virions yet produced plaques similar to gE null mutants. Moreover, all three mutants were highly restricted in spread within the corneal epithelium, in the case of mutant 277 to only 4 to 6% of the number of cells compared with wild-type HSV. Therefore, the ET domain of gE is indispensable for efficient cell-to-cell spread. These observations are consistent with our working hypothesis that gE/gI can bind extracellular ligands, so-called gE/gI receptors that are concentrated at epithelial cell junctions. This fits with similarities in structure and function of gE/gI and gD, which is a receptor binding protein.
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Affiliation(s)
- Katarina Polcicova
- L-220, Room 6366/BSc, Department of Molecular Microbiology & Immunology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA
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Ch'ng TH, Enquist LW. Efficient axonal localization of alphaherpesvirus structural proteins in cultured sympathetic neurons requires viral glycoprotein E. J Virol 2005; 79:8835-46. [PMID: 15994777 PMCID: PMC1168755 DOI: 10.1128/jvi.79.14.8835-8846.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudorabies virus (PRV) glycoprotein E (gE) is a type I viral membrane protein that facilitates the anterograde spread of viral infection from the peripheral nervous system to the brain. In animal models, a gE-null mutant infection spreads inefficiently from presynaptic neurons to postsynaptic neurons (anterograde spread of infection). However, the retrograde spread of infection from post- to presynaptic neurons remains unaffected. Here we show that gE is required for wild-type localization of viral structural proteins in axons of infected neurons. During a gE-null PRV infection, a subset of viral glycoproteins, capsids, and tegument proteins enter and localize to the axon inefficiently. This defect is most obvious in the distal axon and growth cones. However, axonal entry and localization of other viral membrane proteins and endogenous cellular proteins remains unaffected. Neurons infected with gE-null mutants produce wild-type levels of viral structural proteins and infectious virions in the cell body. Our results indicate that reduced axonal targeting of viral structural proteins is a compelling explanation for the lack of anterograde spread in neural circuits following infection by a gE-null mutant.
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Affiliation(s)
- T H Ch'ng
- Dept. of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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Turcotte S, Letellier J, Lippé R. Herpes simplex virus type 1 capsids transit by the trans-Golgi network, where viral glycoproteins accumulate independently of capsid egress. J Virol 2005; 79:8847-60. [PMID: 15994778 PMCID: PMC1168770 DOI: 10.1128/jvi.79.14.8847-8860.2005] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Egress of herpes capsids from the nucleus to the plasma membrane is a complex multistep transport event that is poorly understood. The current model proposes an initial envelopment at the inner nuclear membrane of capsids newly assembled in the nucleus. The capsids are then released in cytosol by fusion with the outer nuclear membrane. They are finally reenveloped at a downstream organelle before traveling to the plasma membrane for their extracellular release. Although the trans-Golgi network (TGN) is often cited as a potential site of reenvelopment, other organelles have also been proposed, including the Golgi, endoplasmic reticulum-Golgi intermediate compartment, aggresomes, tegusomes, and early or late endosomes. To clarify this important issue, we followed herpes simplex virus type 1 egress by immunofluorescence under conditions that slowed intracellular transport and promoted the accumulation of the otherwise transient reenvelopment intermediate. The data show that the capsids transit by the TGN and point to this compartment as the main reenvelopment site, although a contribution by endosomes cannot formally be excluded. Given that viral glycoproteins are expected to accumulate where capsids acquire their envelope, we examined this prediction and found that all tested could indeed be detected at the TGN. Moreover, this accumulation occurred independently of capsid egress. Surprisingly, capsids were often found immediately adjacent to the viral glycoproteins at the TGN.
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Affiliation(s)
- Sophie Turcotte
- Department of Pathology and Cell Biology, University of Montreal, P.O. Box 6128, Succursale Centre-Ville Montreal, Quebec, Canada H3C 3J7
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Ficinska J, Van Minnebruggen G, Nauwynck HJ, Bienkowska-Szewczyk K, Favoreel HW. Pseudorabies virus glycoprotein gD contains a functional endocytosis motif that acts in concert with an endocytosis motif in gB to drive internalization of antibody-antigen complexes from the surface of infected monocytes. J Virol 2005; 79:7248-54. [PMID: 15890963 PMCID: PMC1112093 DOI: 10.1128/jvi.79.11.7248-7254.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Viral glycoproteins gB and gD of the swine alphaherpesvirus pseudorabies virus (PRV), which is closely related to human herpes simplex virus and varicella-zoster virus, are able to drive internalization of antibody-antigen complexes that may form at the cell surface of infected monocytes, thereby protecting these cells from efficient antibody-mediated lysis. We found earlier that gB relies on an endocytosis motif in its cytoplasmic domain for its function during this internalization process. Here, we report that the PRV gD protein also contains a functional endocytosis motif (YRLL) in its cytoplasmic domain that drives spontaneous endocytosis of gD from the cell surface early in infection and that acts in concert with the endocytosis motif in gB to contribute to efficient internalization of antibody-antigen complexes in PRV-infected monocytes.
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Affiliation(s)
- Jolanta Ficinska
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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Abstract
Nipah virus (NiV), a highly pathogenic member of the family Paramyxoviridae, encodes the surface glycoproteins F and G. Since internalization of the NiV envelope proteins from the cell surface might be of functional importance for viral pathogenesis either by regulating cytopathogenicity or by modulating recognition of infected cells by the immune system, we analyzed the endocytosis of the NiV F and G proteins. Interestingly, we found both glycoproteins to be internalized in infected and transfected cells. As endocytosis is normally mediated by tyrosine- or dileucine-dependent signals in the cytoplasmic tails of transmembrane proteins, all potential internalization signals in the NiV glycoproteins were mutated. Whereas the G protein appeared to be constitutively internalized with the bulk flow during membrane turnover, uptake of the F protein was found to be signal mediated. F endocytosis clearly depended on a membrane-proximal YXXPhi motif and was found to be of functional importance for the biological activity of the protein.
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Affiliation(s)
- Carola Vogt
- Institut für Virologie, Philipps University of Marburg, Germany
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