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Salazar S, Luong KTY, Koyuncu OO. Cell Intrinsic Determinants of Alpha Herpesvirus Latency and Pathogenesis in the Nervous System. Viruses 2023; 15:2284. [PMID: 38140525 PMCID: PMC10747186 DOI: 10.3390/v15122284] [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: 10/20/2023] [Revised: 11/10/2023] [Accepted: 11/19/2023] [Indexed: 12/24/2023] Open
Abstract
Alpha herpesvirus infections (α-HVs) are widespread, affecting more than 70% of the adult human population. Typically, the infections start in the mucosal epithelia, from which the viral particles invade the axons of the peripheral nervous system. In the nuclei of the peripheral ganglia, α-HVs establish a lifelong latency and eventually undergo multiple reactivation cycles. Upon reactivation, viral progeny can move into the nerves, back out toward the periphery where they entered the organism, or they can move toward the central nervous system (CNS). This latency-reactivation cycle is remarkably well controlled by the intricate actions of the intrinsic and innate immune responses of the host, and finely counteracted by the viral proteins in an effort to co-exist in the population. If this yin-yang- or Nash-equilibrium-like balance state is broken due to immune suppression or genetic mutations in the host response factors particularly in the CNS, or the presence of other pathogenic stimuli, α-HV reactivations might lead to life-threatening pathologies. In this review, we will summarize the molecular virus-host interactions starting from mucosal epithelia infections leading to the establishment of latency in the PNS and to possible CNS invasion by α-HVs, highlighting the pathologies associated with uncontrolled virus replication in the NS.
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Affiliation(s)
| | | | - Orkide O. Koyuncu
- Department of Microbiology & Molecular Genetics, School of Medicine and Center for Virus Research, University of California, Irvine, CA 92697, USA; (S.S.); (K.T.Y.L.)
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Grose C, Shaban A, Fullerton HJ. Common Features Between Stroke Following Varicella in Children and Stroke Following Herpes Zoster in Adults : Varicella-Zoster Virus in Trigeminal Ganglion. Curr Top Microbiol Immunol 2021; 438:247-272. [PMID: 34224015 DOI: 10.1007/82_2021_236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cerebral arteries are innervated by afferent fibers from the trigeminal ganglia. Varicella-zoster virus (VZV) frequently resides in the trigeminal ganglion. Reports of arterial ischemic stroke due to VZV cerebral vasculopathy in adults after herpes zoster have been described for decades. Reports of arterial ischemic stroke due to post-varicella cerebral arteriopathy in children have also been described for decades. One rationale for this review has been post-licensure studies that have shown an apparent protective effect from stroke in both adults who have received live zoster vaccine and children who have received live varicella vaccine. In this review, we define common features between stroke following varicella in children and stroke following herpes zoster in adults. The trigeminal ganglion and to a lesser extent the superior cervical ganglion are central to the stroke pathogenesis pathway because afferent fibers from these two ganglia provide the circuitry by which the virus can travel to the anterior and posterior circulations of the brain. Based on studies in pseudorabies virus (PRV) models, it is likely that VZV is carried to the cerebral arteries on a kinesin motor via gE, gI and the homolog of PRV US9. The gE product is an essential VZV protein.
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Affiliation(s)
- Charles Grose
- Division of Infectious Diseases and Virology Laboratory, Department of Pediatrics, University of Iowa, Iowa City, Iowa, USA.
- University Hospital/Room BT2001, 200 Hawkins Drive, Iowa City, IA, 52242, USA.
| | - Amir Shaban
- Division of Cerebrovascular Diseases, Department of Neurology, University of Iowa, Iowa City, Iowa, USA
| | - Heather J Fullerton
- Division of Child Neurology and Pediatric Brain Center, Department of Neurology, University of California San Francisco, San Francisco, California, USA
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CRISPR/Cas9-Constructed Pseudorabies Virus Mutants Reveal the Importance of UL13 in Alphaherpesvirus Escape from Genome Silencing. J Virol 2021; 95:JVI.02286-20. [PMID: 33361431 PMCID: PMC8094956 DOI: 10.1128/jvi.02286-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 01/02/2023] Open
Abstract
Latent and recurrent productive infection of long-living cells, such as neurons, enables alphaherpesviruses to persist in their host populations. Still, the viral factors involved in these events remain largely obscure. Using a complementation assay in compartmented primary peripheral nervous system (PNS) neuronal cultures, we previously reported that productive replication of axonally delivered genomes is facilitated by pseudorabies virus (PRV) tegument proteins. Here, we sought to unravel the role of tegument protein UL13 in this escape from silencing. We first constructed four new PRV mutants in the virulent Becker strain using CRISPR/Cas9-mediated gene replacement: (i) PRV Becker defective for UL13 expression (PRV ΔUL13), (ii) PRV where UL13 is fused to eGFP (PRV UL13-eGFP), and two control viruses (iii and iv) PRV where VP16 is fused with mTurquoise at either the N terminus (PRV mTurq-VP16) or the C terminus (PRV VP16-mTurq). Live-cell imaging of PRV capsids showed efficient retrograde transport after axonal infection with PRV UL13-eGFP, although we did not detect dual-color particles. However, immunofluorescence staining of particles in mid-axons indicated that UL13 might be cotransported with PRV capsids in PNS axons. Superinfecting nerve cell bodies with UV-inactivated PRV ΔUL13 failed to efficiently promote escape from genome silencing compared to UV-PRV wild type and UV-PRV UL13-eGFP superinfection. However, UL13 does not act directly in the escape from genome silencing, as adeno-associated virus (AAV)-mediated UL13 expression in neuronal cell bodies was not sufficient to provoke escape from genome silencing. Based on this, we suggest that UL13 may contribute to initiation of productive infection through phosphorylation of other tegument proteins.IMPORTANCE Alphaherpesviruses have mastered various strategies to persist in an immunocompetent host, including the induction of latency and reactivation in peripheral nervous system (PNS) ganglia. We recently discovered that the molecular mechanism underlying escape from latency by the alphaherpesvirus pseudorabies virus (PRV) relies on a structural viral tegument protein. This study aimed at unravelling the role of tegument protein UL13 in PRV escape from latency. First, we confirmed the use of CRISPR/Cas9-mediated gene replacement as a versatile tool to modify the PRV genome. Next, we used our new set of viral mutants and AAV vectors to conclude the indirect role of UL13 in PRV escape from latency in primary neurons, along with its spatial localization during retrograde capsid transport in axons. Based on these findings, we speculate that UL13 phosphorylates one or more tegument proteins, thereby priming these putative proteins to induce escape from genome silencing.
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Grose C, Enquist LW. The round trip model for severe herpes zoster caused by live attenuated varicella vaccine virus. J Med Virol 2020; 92:938-940. [PMID: 31943220 PMCID: PMC7354881 DOI: 10.1002/jmv.25664] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 01/07/2020] [Indexed: 12/14/2022]
Abstract
Varicella vaccine is a live attenuated varicella‐zoster virus. Varicella vaccine can enter latency and later reactivate as herpes zoster. Pseudorabies virus is another herpesvirus closely related to varicella‐zoster virus. The round trip model for pseudorabies virus explains pathogenesis of herpes zoster from vaccine virus.
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Affiliation(s)
- Charles Grose
- Virology Laboratory, Children's Hospital, University of IowaIowaIowa
| | - Lynn W. Enquist
- Department of Molecular BiologyPrinceton UniversityPrincetonNew Jersey
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Nathan L, Daniel S. Single Virion Tracking Microscopy for the Study of Virus Entry Processes in Live Cells and Biomimetic Platforms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1215:13-43. [PMID: 31317494 PMCID: PMC7122913 DOI: 10.1007/978-3-030-14741-9_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The most widely-used assays for studying viral entry, including infectivity, cofloatation, and cell-cell fusion assays, yield functional information but provide low resolution of individual entry steps. Structural characterization provides high-resolution conformational information, but on its own is unable to address the functional significance of these conformations. Single virion tracking microscopy techniques provide more detail on the intermediate entry steps than infection assays and more functional information than structural methods, bridging the gap between these methods. In addition, single virion approaches also provide dynamic information about the kinetics of entry processes. This chapter reviews single virion tracking techniques and describes how they can be applied to study specific virus entry steps. These techniques provide information complementary to traditional ensemble approaches. Single virion techniques may either probe virion behavior in live cells or in biomimetic platforms. Synthesizing information from ensemble, structural, and single virion techniques ultimately yields a more complete understanding of the viral entry process than can be achieved by any single method alone.
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Affiliation(s)
- Lakshmi Nathan
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
| | - Susan Daniel
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA.
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6
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Sorooshyari SK, Taylor MP, Poor HV. Probabilistic Modeling of Pseudorabies Virus Infection in a Neural Circuit. J Comput Biol 2018; 25:1231-1246. [PMID: 30133311 DOI: 10.1089/cmb.2017.0131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Viral transneuronal tracing methods effectively label synaptically connected neurons in a time-dependent manner. However, the modeling of viral vectors has been largely absent. An objective of this article is to motivate and initiate a basis for computational modeling of viral labeling and the questions that can be investigated through modeling of pseudorabies virus (PRV) virion progression in a neural circuit. In particular, a mathematical model is developed for quantitative analysis of PRV infection. Probability expressions are presented to evaluate the progression of viral labeling along the neural circuit. The analysis brings forth various parameters, the numerical values of which must be attained through future experiments. This is the first computational model for PRV viral labeling of a neural circuit.
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Affiliation(s)
| | - Matthew P Taylor
- 2 Department of Microbiology and Immunology, Montana State University , Bozeman, Montana
| | - H Vincent Poor
- 3 Department of Electrical Engineering, Princeton University , Princeton, New Jersey
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Banerjee S, Maurya S, Roy R. Single-molecule fluorescence imaging: Generating insights into molecular interactions in virology. J Biosci 2018; 43:519-540. [PMID: 30002270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Single-molecule fluorescence methods remain a challenging yet information-rich set of techniques that allow one to probe the dynamics, stoichiometry and conformation of biomolecules one molecule at a time. Viruses are small (nanometers) in size, can achieve cellular infections with a small number of virions and their lifecycle is inherently heterogeneous with a large number of structural and functional intermediates. Single-molecule measurements that reveal the complete distribution of properties rather than the average can hence reveal new insights into virus infections and biology that are inaccessible otherwise. This article highlights some of the methods and recent applications of single-molecule fluorescence in the field of virology. Here, we have focused on new findings in virus-cell interaction, virus cell entry and transport, viral membrane fusion, genome release, replication, translation, assembly, genome packaging, egress and interaction with host immune proteins that underline the advantage of single-molecule approach to the question at hand. Finally, we discuss the challenges, outlook and potential areas for improvement and future use of single-molecule fluorescence that could further aid our understanding of viruses.
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Affiliation(s)
- Sunaina Banerjee
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
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8
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Single-molecule fluorescence imaging: Generating insights into molecular interactions in virology. J Biosci 2018. [DOI: 10.1007/s12038-018-9769-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Lyu C, Wang S, Sun M, Tang Y, Peng J, Tian Z, Cai X. Deletion of pseudorabies virus US2 gene enhances viral titers in a porcine cerebral cortex primary culture system. Virus Genes 2018. [PMID: 29541931 DOI: 10.1007/s11262-018-1552-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pseudorabies virus (PRV) is a neurotropic virus with the ability to infect peripheral sensory ganglia. The transport of PRV from the peripheral to the central nervous system can cause lethal encephalitis in young piglets. However, the pathogenicity of PRV in the cerebral cortex remains poorly understood. In the present study, we developed a porcine cerebral cortex primary culture system (PCCS) using cerebral cortex tissue dissected from a 3-day-old piglet to investigate the pathogenicity of wild-type (WT) and US2 deleted (ΔUS2) PRV in the CNS in vitro. Immunofluorescence assays revealed cell bodies and neurites as the cellular locations infected by PRV. Growth kinetic analysis showed a persistent increase in WT and ΔUS2 viral titers in PCCS from 4 to 24 h post infection (hpi), thus indicating that US2 deletion did not disrupt viral growth. However, the mean plaque size was significantly higher in ΔUS2 PRV than in WT PRV in infected Vero cells. The viral titers and DNA levels of ΔUS2 PRV were significantly higher at 8 hpi than at 4 hpi, whereas those of WT showed no significant difference between the two time points in PCCS. Morphological investigation revealed induction of massive amounts of bouton-like swellings (varicosities) along the axon shaft in both WT and ΔUS2 PRV-infected neurons in the PCCS. Our data suggest that PRV US2 gene deletion enhances viral titers in PCCS but does not affect the varicosities induced by the viral infection.
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Affiliation(s)
- Chuang Lyu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Shuwen Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Mingxia Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Yandong Tang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Jinmei Peng
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Zhijun Tian
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China
| | - Xuehui Cai
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Haping Road No. 678, Xiang Fang District, Harbin, 150069, Heilongjiang, People's Republic of China.
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10
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Affiliation(s)
- Julian Scherer
- Department of Molecular Biology & Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - Lynn W Enquist
- Department of Molecular Biology & Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
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11
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Miller KD, Schnell MJ, Rall GF. Keeping it in check: chronic viral infection and antiviral immunity in the brain. Nat Rev Neurosci 2016; 17:766-776. [PMID: 27811921 DOI: 10.1038/nrn.2016.140] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
It is becoming clear that the manner by which the immune response resolves or contains infection by a pathogen varies according to the tissue that is affected. Unlike many peripheral cell types, CNS neurons are generally non-renewable. Thus, the cytolytic and inflammatory strategies that are effective in controlling infections in the periphery could be damaging if deployed in the CNS. Perhaps for this reason, the immune response to some CNS viral infections favours maintenance of neuronal integrity and non-neurolytic viral control. This modified immune response - when combined with the unique anatomy and physiology of the CNS - provides an ideal environment for the maintenance of viral genomes, including those of RNA viruses. Therefore, it is possible that such viruses can reactivate long after initial viral exposure, contributing to CNS disease.
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Affiliation(s)
- Katelyn D Miller
- Program in Cell and Molecular Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.,Program in Blood Cell Development and Function, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
| | - Matthias J Schnell
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Glenn F Rall
- Program in Blood Cell Development and Function, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA
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Abstract
ABSTRACT Enveloped viruses encode proteins that can induce cell fusion to allow spread of infection without exposure to immune surveillance. In this review, we discuss cell fusion events caused by neurotropic α-herpesviruses. Syncytia (large, multinucleated cells) are clinically indicative of α herpesvirus infections, and peripheral neuropathies are clinical hallmarks. We examine the viral and cellular factors required for cell fusion, as well as mutations which confer a more aggressive ‘hypersyncytial’ phenotype. Finally, we consider the causes of fusion events in infected neurons, and the implications for neuronal dysfunction and pathophysiology.
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Affiliation(s)
- Anthony E Ambrosini
- Department of Molecular Biology & Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
| | - Lynn W Enquist
- Department of Molecular Biology & Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, USA
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Bird SW, Kirkegaard K, Agbandje-McKenna M, Freed EO. The ins and outs of viral infection: keystone meeting review. Viruses 2014; 6:3652-62. [PMID: 25256395 PMCID: PMC4189043 DOI: 10.3390/v6093652] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 12/14/2022] Open
Abstract
Newly observed mechanisms for viral entry, assembly, and exit are challenging our current understanding of the replication cycle of different viruses. To address and better understand these mechanisms, a Keystone Symposium was organized in the snowy mountains of Colorado (“The Ins and Outs of Viral Infection: Entry, Assembly, Exit, and Spread”; 30 March–4 April 2014, Beaver Run Resort, Breckenridge, Colorado, organized by Karla Kirkegaard, Mavis Agbandje-McKenna, and Eric O. Freed). The meeting served to bring together cell biologists, structural biologists, geneticists, and scientists expert in viral pathogenesis to discuss emerging mechanisms of viral ins and outs. The conference was organized around different phases of the viral replication cycle, including cell entry, viral assembly and post-assembly maturation, virus structure, cell exit, and virus spread. This review aims to highlight important topics and themes that emerged during the conference.
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Affiliation(s)
- Sara W Bird
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Karla Kirkegaard
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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Murlidharan G, Samulski RJ, Asokan A. Biology of adeno-associated viral vectors in the central nervous system. Front Mol Neurosci 2014; 7:76. [PMID: 25285067 PMCID: PMC4168676 DOI: 10.3389/fnmol.2014.00076] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 09/04/2014] [Indexed: 01/11/2023] Open
Abstract
Gene therapy is a promising approach for treating a spectrum of neurological and neurodegenerative disorders by delivering corrective genes to the central nervous system (CNS). In particular, adeno-associated viruses (AAVs) have emerged as promising tools for clinical gene transfer in a broad range of genetic disorders with neurological manifestations. In the current review, we have attempted to bridge our understanding of the biology of different AAV strains with their transduction profiles, cellular tropisms, and transport mechanisms within the CNS. Continued efforts to dissect AAV-host interactions within the brain are likely to aid in the development of improved vectors for CNS-directed gene transfer applications in the clinic.
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Affiliation(s)
- Giridhar Murlidharan
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Gene Therapy Center, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Richard J Samulski
- Gene Therapy Center, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill NC, USA
| | - Aravind Asokan
- Gene Therapy Center, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Genetics and Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Abstract
Our ability to understand the function of the nervous system is dependent upon defining the connections of its constituent neurons. Development of methods to define connections within neural networks has always been a growth industry in the neurosciences. Transneuronal spread of neurotropic viruses currently represents the best means of defining synaptic connections within neural networks. The method exploits the ability of viruses to invade neurons, replicate, and spread through the intimate synaptic connections that enable communication among neurons. Since the method was first introduced in the 1970s, it has benefited from an increased understanding of the virus life cycle, the function of viral genome, and the ability to manipulate the viral genome in support of directional spread of virus and the expression of transgenes. In this unit, we review these advances in viral tracing technology and the way in which they may be applied for functional dissection of neural networks.
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Affiliation(s)
- J Patrick Card
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
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Abstract
Herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2) are human neurotropic viruses that establish latent infection in dorsal root ganglia (DRG) for the entire life of the host. From the DRG they can reactivate to cause human morbidity and mortality. Although they vary, in part, in the clinical disorders they cause, and in their molecular structure, they share several features that govern the biology of their infection of the human nervous system. HSV-1 is the causative agent of encephalitis, corneal blindness, and several peripheral nervous system disorders; HSV-2 is responsible for meningoencephalitis in neonates and meningitis in adults. The biology of their ability to establish latency, maintain it for the entire life of the host, reactivate, and cause primary and recurrent disease is being studied in animal models and in humans. This review covers recent advances in understanding the biology and pathogenesis of HSV-related disease.
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Affiliation(s)
- Israel Steiner
- Department of Neurology, Rabin Medical Center, Beilinson Campus, 49100, Petach Tikva, Israel,
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In vivo imaging of alphaherpesvirus infection reveals synchronized activity dependent on axonal sorting of viral proteins. Proc Natl Acad Sci U S A 2013; 110:E3516-25. [PMID: 23980169 DOI: 10.1073/pnas.1311062110] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A clinical hallmark of human alphaherpesvirus infections is peripheral pain or itching. Pseudorabies virus (PRV), a broad host range alphaherpesvirus, causes violent pruritus in many different animals, but the mechanism is unknown. Previous in vitro studies have shown that infected, cultured peripheral nervous system (PNS) neurons exhibited aberrant electrical activity after PRV infection due to the action of viral membrane fusion proteins, yet it is unclear if such activity occurs in infected PNS ganglia in living animals and if it correlates with disease symptoms. Using two-photon microscopy, we imaged autonomic ganglia in living mice infected with PRV strains expressing GCaMP3, a genetically encoded calcium indicator, and used the changes in calcium flux to monitor the activity of many neurons simultaneously with single-cell resolution. Infection with virulent PRV caused these PNS neurons to fire synchronously and cyclically in highly correlated patterns among infected neurons. This activity persisted even when we severed the presynaptic axons, showing that infection-induced firing is independent of input from presynaptic brainstem neurons. This activity was not observed after infections with an attenuated PRV recombinant used for circuit tracing or with PRV mutants lacking either viral glycoprotein B, required for membrane fusion, or viral membrane protein Us9, required for sorting virions and viral glycoproteins into axons. We propose that the viral fusion proteins produced by virulent PRV infection induce electrical coupling in unmyelinated axons in vivo. This action would then give rise to the synchronous and cyclical activity in the ganglia and contribute to the characteristic peripheral neuropathy.
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