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Boruah AP, Thakur KT. Arthropod-borne encephalitis: an overview for the clinician and emerging considerations. Postgrad Med J 2023; 99:826-833. [PMID: 37130817 PMCID: PMC10464853 DOI: 10.1136/pmj-2022-142002] [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: 06/08/2022] [Accepted: 08/18/2022] [Indexed: 11/04/2022]
Abstract
The rapid spread of arboviral infections in recent years has continually established arthropod-borne encephalitis to be a pressing global health concern. Causing a wide range of clinical presentations ranging from asymptomatic infection to fulminant neurological disease, the hallmark features of arboviral infection are important to clinically recognise. Arboviral infections may cause severe neurological presentations such as meningoencephalitis, epilepsy, acute flaccid paralysis and stroke. While the pathogenesis of arboviral infections is still being investigated, shared neuroanatomical pathways among these viruses may give insight into future therapeutic targets. The shifting infection transmission patterns and evolving distribution of arboviral vectors are heavily influenced by global climate change and human environmental disruption, therefore it is of utmost importance to consider this potential aetiology when assessing patients with encephalitic presentations.
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Affiliation(s)
- Abhilasha Pankaj Boruah
- Department of Neurology, NewYork-Presbyterian/Columbia University Irving Medical Center, New York, New York, USA
- Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Kiran T Thakur
- Department of Neurology, NewYork-Presbyterian/Columbia University Irving Medical Center, New York, New York, USA
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2
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Feng F, Bouma EM, Hu G, Zhu Y, Yu Y, Smit JM, Diamond MS, Zhang R. Colocalization of Chikungunya Virus with Its Receptor MXRA8 during Cell Attachment, Internalization, and Membrane Fusion. J Virol 2023; 97:e0155722. [PMID: 37133449 PMCID: PMC10231136 DOI: 10.1128/jvi.01557-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 04/11/2023] [Indexed: 05/04/2023] Open
Abstract
Arthritogenic alphaviruses, including chikungunya virus (CHIKV), preferentially target joint tissues and cause chronic rheumatic disease that adversely impacts the quality of life of patients. Viruses enter target cells via interaction with cell surface receptor(s), which determine the viral tissue tropism and pathogenesis. Although MXRA8 is a recently identified receptor for several clinically relevant arthritogenic alphaviruses, its detailed role in the cell entry process has not been fully explored. We found that in addition to its localization on the plasma membrane, MXRA8 is present in acidic organelles, endosomes, and lysosomes. Moreover, MXRA8 is internalized into cells without a requirement for its transmembrane and cytoplasmic domains. Confocal microscopy and live cell imaging revealed that MXRA8 interacts with CHIKV at the cell surface and then enters cells along with CHIKV particles. At the moment of membrane fusion in the endosomes, many viral particles are still colocalized with MXRA8. These findings provide insight as to how MXRA8 functions in alphavirus internalization and suggest possible targets for antiviral development. IMPORTANCE The globally distributed arthritogenic alphaviruses have infected millions of humans and induce rheumatic disease, such as severe polyarthralgia/polyarthritis, for weeks to years. Alphaviruses infect target cells through receptor(s) followed by clathrin-mediated endocytosis. MXRA8 was recently identified as an entry receptor that shapes the tropism and pathogenesis for multiple arthritogenic alphaviruses, including chikungunya virus (CHIKV). Nonetheless, the exact functions of MXRA8 during the process of viral cell entry remain undetermined. Here, we have provided compelling evidence for MXRA8 as a bona fide entry receptor that mediates the uptake of alphavirus virions. Small molecules that disrupt MXRA8-dependent binding of alphaviruses or internalization steps could serve as a platform for unique classes of antiviral drugs.
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Affiliation(s)
- Fei Feng
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ellen M. Bouma
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gaowei Hu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yunkai Zhu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yin Yu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jolanda M. Smit
- Department of Medical Microbiology and Infection Prevention, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Michael S. Diamond
- Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
- Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Rong Zhang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Institute of Infectious Disease and Biosecurity, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
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3
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Ogorek TJ, Golden JE. Advances in the Development of Small Molecule Antivirals against Equine Encephalitic Viruses. Viruses 2023; 15:413. [PMID: 36851628 PMCID: PMC9958955 DOI: 10.3390/v15020413] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Venezuelan, western, and eastern equine encephalitic alphaviruses (VEEV, WEEV, and EEEV, respectively) are arboviruses that are highly pathogenic to equines and cause significant harm to infected humans. Currently, human alphavirus infection and the resulting diseases caused by them are unmitigated due to the absence of approved vaccines or therapeutics for general use. These circumstances, combined with the unpredictability of outbreaks-as exemplified by a 2019 EEE surge in the United States that claimed 19 patient lives-emphasize the risks posed by these viruses, especially for aerosolized VEEV and EEEV which are potential biothreats. Herein, small molecule inhibitors of VEEV, WEEV, and EEEV are reviewed that have been identified or advanced in the last five years since a comprehensive review was last performed. We organize structures according to host- versus virus-targeted mechanisms, highlight cellular and animal data that are milestones in the development pipeline, and provide a perspective on key considerations for the progression of compounds at early and later stages of advancement.
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Affiliation(s)
- Tyler J. Ogorek
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jennifer E. Golden
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA
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4
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Members of Venezuelan Equine Encephalitis complex entry into host cells by clathrin-mediated endocytosis in a pH-dependent manner. Sci Rep 2022; 12:14556. [PMID: 36008558 PMCID: PMC9411563 DOI: 10.1038/s41598-022-18846-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 08/22/2022] [Indexed: 01/20/2023] Open
Abstract
Pixuna virus (PIXV) and Río Negro virus (RNV) are mosquito-borne alphaviruses belonging to the Venezuelan Equine Encephalitis (VEE) complex, which includes pathogenic epizootic and enzootic subtypes responsible for life-threatening diseases in equines. Considering that the first steps in viral infection are crucial for the efficient production of new progeny, the aim of this study was to elucidate the early events of the replication cycle of these two viruses. To this end, we used chemical inhibitors and the expression of dominant-negative constructs to study the dependence of clathrin and endosomal pH on PIXV and RNV internalization mechanisms. We demonstrated that both viruses are internalized primarily via clathrin-mediated endocytosis, where the low pH in endosomes is crucial for viral replication. Contributing knowledge regarding the entry route of VEE complex members is important to understand the pathogenesis of these viruses and also to develop new antiviral strategies.
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5
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Noguera P, Klinger M, Örün H, Grunow B, Del-Pozo J. Ultrastructural insights into the replication cycle of salmon pancreas disease virus (SPDV) using salmon cardiac primary cultures (SCPCs). JOURNAL OF FISH DISEASES 2021; 44:2031-2041. [PMID: 34424537 DOI: 10.1111/jfd.13518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Salmon pancreas disease virus (SPDV) has been affecting the salmon farming industry for over 30 years, but despite the substantial amount of studies, there are still a number of recognized knowledge gaps, for example in the transmission of the virus. In this work, an ultrastructural morphological approach was used to describe observations after infection by SPDV of an ex vivo cardiac model generated from Atlantic salmon embryos. The observations in this study and those available on previous ultrastructural work on SPDV are compared and contrasted with the current knowledge on terrestrial mammalian and insect alphaviral replication cycles, which is deeper than that of SPDV both morphologically and mechanistically. Despite their limitations, morphological descriptions remain an excellent way to generate novel hypotheses, and this has been the aim of this work. This study has used a target host, ex vivo model and resulted in some previously undescribed features, including filopodial membrane projections, cytoplasmic stress granules or putative intracytoplasmic budding. The latter suggests a new hypothesis that warrants further mechanistic research: SPDV in salmon may have retained the capacity for non-cytolytic (persistent) infections by intracellular budding, similar to that noted in arthropod vectors of other alphaviruses. In the notable absence of a known intermediate host for SPDV, the presence of this pattern suggests that both cytopathic and persistent infections may coexist in the same host. It is our hope that the ultrastructural comparison presented here stimulates new research that brings the knowledge on SPDV replication cycle up to a similar level to that of terrestrial alphaviruses.
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Affiliation(s)
| | | | - Histro Örün
- Institute of Anatomy, University of Lübeck, Lübeck, Germany
| | - Bianka Grunow
- Leibniz-Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
| | - Jorge Del-Pozo
- Royal Dick School of Veterinary Sciences, University of Edinburgh, Roslin, UK
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6
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Enhancing Antibodies' Binding Capacity through Oriented Functionalization of Plasmonic Surfaces. NANOMATERIALS 2021; 11:nano11102620. [PMID: 34685056 PMCID: PMC8538552 DOI: 10.3390/nano11102620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/27/2021] [Accepted: 09/30/2021] [Indexed: 11/29/2022]
Abstract
Protein A has long been used in different research fields due to its ability to specifically recognize immunoglobulins (Ig). The protein derived from Staphylococcus aureus binds Ig through the Fc region of the antibody, showing its strongest binding in immunoglobulin G (IgG), making it the most used protein in its purification and detection. The research presented here integrates, for the first time, protein A to a silicon surface patterned with gold nanoparticles for the oriented binding of IgG. The signal detection is conveyed through a metal enhanced fluorescence (MEF) system. Orienting immunoglobulins allows the exposition of the fragment antigen-binding (Fab) region for the binding to its antigen, substantially increasing the binding capacity per antibody immobilized. Antibodies orientation is of crucial importance in many diagnostics devices, particularly when either component is in limited quantities.
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7
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Ware-Gilmore F, Sgrò CM, Xi Z, Dutra HLC, Jones MJ, Shea K, Hall MD, Thomas MB, McGraw EA. Microbes increase thermal sensitivity in the mosquito Aedes aegypti, with the potential to change disease distributions. PLoS Negl Trop Dis 2021; 15:e0009548. [PMID: 34292940 PMCID: PMC8297775 DOI: 10.1371/journal.pntd.0009548] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 06/10/2021] [Indexed: 11/21/2022] Open
Abstract
The mosquito Aedes aegypti is the primary vector of many disease-causing viruses, including dengue (DENV), Zika, chikungunya, and yellow fever. As consequences of climate change, we expect an increase in both global mean temperatures and extreme climatic events. When temperatures fluctuate, mosquito vectors will be increasingly exposed to temperatures beyond their upper thermal limits. Here, we examine how DENV infection alters Ae. aegypti thermotolerance by using a high-throughput physiological 'knockdown' assay modeled on studies in Drosophila. Such laboratory measures of thermal tolerance have previously been shown to accurately predict an insect's distribution in the field. We show that DENV infection increases thermal sensitivity, an effect that may ultimately limit the geographic range of the virus. We also show that the endosymbiotic bacterium Wolbachia pipientis, which is currently being released globally as a biological control agent, has a similar impact on thermal sensitivity in Ae. aegypti. Surprisingly, in the coinfected state, Wolbachia did not provide protection against DENV-associated effects on thermal tolerance, nor were the effects of the two infections additive. The latter suggests that the microbes may act by similar means, potentially through activation of shared immune pathways or energetic tradeoffs. Models predicting future ranges of both virus transmission and Wolbachia's efficacy following field release may wish to consider the effects these microbes have on host survival.
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Affiliation(s)
- Fhallon Ware-Gilmore
- Department of Entomology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Carla M. Sgrò
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Zhiyong Xi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Heverton L. C. Dutra
- Department of Entomology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Matthew J. Jones
- Department of Entomology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Katriona Shea
- Department of Biology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Matthew D. Hall
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Matthew B. Thomas
- Department of Entomology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Elizabeth A. McGraw
- Department of Entomology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biology & The Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
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8
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Abstract
Recent field trials have demonstrated that dengue incidence can be substantially reduced by introgressing strains of the endosymbiotic bacterium Wolbachia into Aedes aegypti mosquito populations. This strategy relies on Wolbachia reducing the susceptibility of Ae. aegypti to disseminated infection by positive-sense RNA viruses like dengue. However, RNA viruses are well known to adapt to antiviral pressures. Here, we review the viral infection stages where selection for Wolbachia-resistant virus variants could occur. We also consider the genetic constraints imposed on viruses that alternate between vertebrate and invertebrate hosts, and the likely selection pressures to which dengue virus might adapt in order to be effectively transmitted by Ae. aegypti that carry Wolbachia. While there are hurdles to dengue viruses developing resistance to Wolbachia, we suggest that long-term surveillance for resistant viruses should be an integral component of Wolbachia-introgression biocontrol programs.
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Affiliation(s)
| | - Heather A. Flores
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
| | - Cameron P. Simmons
- World Mosquito Program, Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
- Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Johanna E. Fraser
- Institute of Vector-Borne Disease, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
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9
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Pseudotyping Lentiviral Vectors: When the Clothes Make the Virus. Viruses 2020; 12:v12111311. [PMID: 33207797 PMCID: PMC7697029 DOI: 10.3390/v12111311] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/12/2022] Open
Abstract
Delivering transgenes to human cells through transduction with viral vectors constitutes one of the most encouraging approaches in gene therapy. Lentivirus-derived vectors are among the most promising vectors for these approaches. When the genetic modification of the cell must be performed in vivo, efficient specific transduction of the cell targets of the therapy in the absence of off-targeting constitutes the Holy Grail of gene therapy. For viral therapy, this is largely determined by the characteristics of the surface proteins carried by the vector. In this regard, an important property of lentiviral vectors is the possibility of being pseudotyped by envelopes of other viruses, widening the panel of proteins with which they can be armed. Here, we discuss how this is achieved at the molecular level and what the properties and the potentialities of the different envelope proteins that can be used for pseudotyping these vectors are.
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10
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De Caluwé L, Ariën KK, Bartholomeeusen K. Host Factors and Pathways Involved in the Entry of Mosquito-Borne Alphaviruses. Trends Microbiol 2020; 29:634-647. [PMID: 33208275 DOI: 10.1016/j.tim.2020.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 11/17/2022]
Abstract
Chikungunya virus (CHIKV) is an arthropod-borne virus that has re-emerged recently and has spread to previously unaffected regions, resulting in millions of infections worldwide. The genus Alphavirus, in the family Togaviridae, contains several members with a similar potential for epidemic emergence. In order for CHIKV to replicate in targeted cell types it is essential for the virus to enter these cells. In this review, we summarize our current understanding of the versatile and promiscuous steps in CHIKV binding and entry into human and mosquito host cells. We describe the different entry pathways, receptors, and attachment factors so far described for CHIKV and other mosquito-borne alphaviruses and discuss them in the context of tissue tropism and potential therapeutic targeting.
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Affiliation(s)
- Lien De Caluwé
- Virology Unit, Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium
| | - Kevin K Ariën
- Virology Unit, Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium; Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
| | - Koen Bartholomeeusen
- Virology Unit, Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium.
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11
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Abstract
Alphaviruses cause severe human illnesses including persistent arthritis and fatal encephalitis. As alphavirus entry into target cells is the first step in infection, intensive research efforts have focused on elucidating aspects of this pathway, including attachment, internalization, and fusion. Herein, we review recent developments in the molecular understanding of alphavirus entry both in vitro and in vivo and how these advances might enable the design of therapeutics targeting this critical step in the alphavirus life cycle.
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12
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Bellone R, Failloux AB. The Role of Temperature in Shaping Mosquito-Borne Viruses Transmission. Front Microbiol 2020; 11:584846. [PMID: 33101259 PMCID: PMC7545027 DOI: 10.3389/fmicb.2020.584846] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/07/2020] [Indexed: 12/28/2022] Open
Abstract
Mosquito-borne diseases having the greatest impact on human health are typically prevalent in the tropical belt of the world. However, these diseases are conquering temperate regions, raising the question of the role of temperature on their dynamics and expansion. Temperature is one of the most significant abiotic factors affecting, in many ways, insect vectors and the pathogens they transmit. Here, we debate the veracity of this claim by synthesizing current knowledge on the effects of temperature on arboviruses and their vectors, as well as the outcome of their interactions.
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Affiliation(s)
- Rachel Bellone
- Department of Virology, Arboviruses and Insect Vectors, Institut Pasteur, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Anna-Bella Failloux
- Department of Virology, Arboviruses and Insect Vectors, Institut Pasteur, Paris, France
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13
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Ahearn YP, Saredy JJ, Bowers DF. The Alphavirus Sindbis Infects Enteroendocrine Cells in the Midgut of Aedes aegypti. Viruses 2020; 12:E848. [PMID: 32759668 PMCID: PMC7472040 DOI: 10.3390/v12080848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 07/24/2020] [Accepted: 07/29/2020] [Indexed: 12/25/2022] Open
Abstract
Transit of the arthropod-borne-virus (arbovirus) Sindbis (SINV) throughout adult female mosquitoes initiates with its attachment to the gut lumen, entry and amplification in midgut cells, followed by dissemination into the hemolymph. Free-mated adult females, aged day 5-7, were proffered a viremic blood suspension via sausage casings containing SINV-TaV-Green Fluorescent Protein (GFP) at a final titer of 106 PFU/mL. Midguts (MGs) from fully engorged mosquitoes were resected on days 5 and 7 post-bloodmeal, and immunolabeled using FMRFamide antibody against enteroendocrine cells (ECs) with a TX-Red secondary antibody. Following immunolabeling, the organs were investigated via laser confocal microscopy to identify the distribution of GFP and TX-Red. Infection using this reporter virus was observed as multiple GFP expression foci along the posterior midgut (PMG) epithelium and ECs were observed as TX-Red labeled cells scattered along the entire length of the MG. Our results demonstrated that SINVGFP did infect ECs, as indicated by the overlapping GFP and TX-Red channels shown as yellow in merged images. We propose that ECs may be involved in the SINV infection pathway in the mosquito MG. Due to the unique role that ECs have in the exocytosis of secretory granules from the MG and the apical-basolateral position of ECs in the PMG monolayer, we speculate that these cells may assist as a mechanism for arboviruses to cross the gut barriers. These findings suggest that MG ECs are involved in arbovirus infection of the invertebrate host.
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Affiliation(s)
- Yani P. Ahearn
- Department of Health, TB Lab, 1217 N Pearl St., Jacksonville, FL 32202, USA;
| | - Jason J. Saredy
- Department of Biology, Temple University, 1900 N 12th St., Philadelphia, PA 19122-6078, USA;
| | - Doria F. Bowers
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
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14
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The use of green fluorescent protein-tagged virus-like particles as a tracer in the early phase of chikungunya infection. Virus Res 2019; 272:197732. [PMID: 31445103 DOI: 10.1016/j.virusres.2019.197732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/13/2019] [Accepted: 08/20/2019] [Indexed: 11/22/2022]
Abstract
To visually examine the early phase of chikungunya virus (CHIKV) infection in target cells, we constructed a virus-like particle (VLP) in which the envelope protein E1 is fused with green fluorescent protein (GFP). This chikungunya VLP-GFP (CHIK-VLP-EGFP), purified by density gradient fractionation, was observed as 60-70 nm-dia. particles and was detected as tiny puncta of fluorescence in the cells. CHIK-VLP-EGFP showed binding properties similar to those of the wild-type viruses. Most of the fluorescence signals that had bound on Vero cells disappeared within 30 min at 37 °C, but not in the presence of anti-CHIKV neutralizing serum or an endosomal acidification inhibitor (bafilomycin A1), suggesting that the loss of fluorescence signals is due to the disassembly of the viral envelope following the internalization of CHIK-VLP-EGFP. In addition to these results, the fluorescence signals disappeared in highly susceptible Vero and U251MG cells but not in poorly susceptible A549 cells. Thus, CHIK-VLP-EGFP is a useful tool to examine the effects of the CHIKV neutralizing antibodies and antiviral compounds that are effective in the entry phase of CHIKV.
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15
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Hernandez R, Glaros T, Rizzo G, Ferreira DF. Purification and Proteomic Analysis of Alphavirus Particles from Sindbis Virus Grown in Mammalian and Insect Cells. Bio Protoc 2019; 9:e3239. [PMID: 33654768 DOI: 10.21769/bioprotoc.3239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/16/2019] [Accepted: 04/26/2019] [Indexed: 11/02/2022] Open
Abstract
Current mass spectrometry (MS) methods and new instrumentation now allow for more accurate identification of proteins in low abundance than previous protein fractionation and identification methods. It was of interest if this method could serve to define the virus proteome of a membrane-containing virus. To evaluate the efficacy of mass spec to determine the proteome of medically important viruses, Sindbis virus (SINV), the prototypical alphavirus was chosen for evaluation. This model system was chosen specifically because the alphaviruses contain members which are human pathogens, this virus is well defined biochemically and structurally, and grows to high titers in both vertebrate and non-vertebrate host cells. The SINV proteome was investigated using this method to determine if host proteins are specifically packaged into infectious virions. It was also of interest if the SINV proteome, when grown in multiple host cells representing vertebrate and mosquito hosts, incorporated specific host proteins from all hosts. Observation of recurrent or distinctive proteins in the virus proteome aided in the determination of proteins incorporated into the virion as opposed to those bound to the particle exterior. Mass spectrometry analysis identified the total protein content of purified virions within limits of detection. The most significant finding was that in addition to the host proteins, SINV non-structural protein 2 (nsP2) was detected within virions grown in all host cells examined. This analysis identified host factors not previously associated with alphavirus entry, replication, or egress, identifying at least one host factor integrally involved in alphavirus replication. Key to the success of this analysis is the method of virus purification which must deliver measurably infectious virus free of high levels of contaminants. For SINV and other members of the alphavirus family, this is accomplished by isopycnic centrifugation through potassium tartrate, followed by a high salt wash.
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Affiliation(s)
- Raquel Hernandez
- Department of Molecular and Structural Biology, North Carolina State University, Raleigh, USA
| | - Trevor Glaros
- U.S. Army Combat Capabilities Development Command (CCDC) Chemical Biological Center, Aberdeen Proving Ground, MD 21010, USA
| | - Gabrielle Rizzo
- Excet, Inc. 6225 Brandon Ave, Suite 360, Springfield, VA 22150, USA
| | - Davis F Ferreira
- Department of Molecular and Structural Biology, North Carolina State University, Raleigh, USA.,Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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16
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Robinson M, Schor S, Barouch-Bentov R, Einav S. Viral journeys on the intracellular highways. Cell Mol Life Sci 2018; 75:3693-3714. [PMID: 30043139 PMCID: PMC6151136 DOI: 10.1007/s00018-018-2882-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/01/2018] [Accepted: 07/19/2018] [Indexed: 12/24/2022]
Abstract
Viruses are obligate intracellular pathogens that are dependent on cellular machineries for their replication. Recent technological breakthroughs have facilitated reliable identification of host factors required for viral infections and better characterization of the virus-host interplay. While these studies have revealed cellular machineries that are uniquely required by individual viruses, accumulating data also indicate the presence of broadly required mechanisms. Among these overlapping cellular functions are components of intracellular membrane trafficking pathways. Here, we review recent discoveries focused on how viruses exploit intracellular membrane trafficking pathways to promote various stages of their life cycle, with an emphasis on cellular factors that are usurped by a broad range of viruses. We describe broadly required components of the endocytic and secretory pathways, the Endosomal Sorting Complexes Required for Transport pathway, and the autophagy pathway. Identification of such overlapping host functions offers new opportunities to develop broad-spectrum host-targeted antiviral strategies.
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Affiliation(s)
- Makeda Robinson
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Stanford Schor
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
| | - Rina Barouch-Bentov
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA
| | - Shirit Einav
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Lane Building, Rm L127, Stanford, CA, 94305, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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17
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Schuchman RM, Vancini R, Piper A, Breuer D, Ribeiro M, Ferreira D, Magliocca J, Emmerich V, Hernandez R, Brown DT. Role of the vacuolar ATPase in the Alphavirus replication cycle. Heliyon 2018; 4:e00701. [PMID: 30094371 PMCID: PMC6074608 DOI: 10.1016/j.heliyon.2018.e00701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 06/07/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023] Open
Abstract
We have shown that Alphaviruses can enter cells by direct penetration at the plasma membrane (R. Vancini, G. Wang, D. Ferreira, R. Hernandez, and D. Brown, J Virol, 87:4352–4359, 2013). Direct penetration removes the requirement for receptor-mediated endocytosis exposure to low pH and membrane fusion in the process of RNA entry. Endosomal pH as well as the pH of the cell cytoplasm is maintained by the activity of the vacuolar ATPase (V-ATPase). Bafilomycin is a specific inhibitor of V-ATPase. To characterize the roll of the V-ATPase in viral replication we generated a Bafilomycin A1(BAF) resistant mutant of Sindbis virus (BRSV). BRSV produced mature virus and virus RNA in greater amounts than parent virus in BAF-treated cells. Sequence analysis revealed mutations in the E2 glycoprotein, T15I/Y18H, were responsible for the phenotype. These results show that a functional V-ATPase is required for efficient virus RNA synthesis and virus maturation in Alphavirus infection.
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Affiliation(s)
- Ryan M Schuchman
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Ricardo Vancini
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Amanda Piper
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Denitra Breuer
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Mariana Ribeiro
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Davis Ferreira
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA.,Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Joseph Magliocca
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Veronica Emmerich
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Raquel Hernandez
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
| | - Dennis T Brown
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, USA
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18
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Sun L, Gao Y, Wang Y, Wei Q, Shi J, Chen N, Li D, Fan C. Guiding protein delivery into live cells using DNA-programmed membrane fusion. Chem Sci 2018; 9:5967-5975. [PMID: 30079211 PMCID: PMC6050539 DOI: 10.1039/c8sc00367j] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 06/14/2018] [Indexed: 11/21/2022] Open
Abstract
Intracellular delivery of proteins provides a direct means to manipulate cell function and probe the intracellular environment. However, direct cytoplasmic delivery of proteins suffers from limited availability of efficient toolsets, and thus remains challenging in research and therapeutic applications. Natural biological cargo delivery processes, like SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex mediated membrane fusion and other vesicle fusion in live cells, enable targeted delivery with high efficiency. A surrogate of SNARE machinery represents a new direction in intracellular protein delivery. Here, we report a DNA-programmed membrane fusion strategy for guiding the efficient intracellular delivery of proteins into live cells. The inherent programmability of DNA hybridization provides spatiotemporal control of the fusion between protein-encapsulated liposomes and cell membranes, enabling rapid release of proteins directly into the cytoplasm, while still remaining functional due to the bypassing of the endosomal trap. We further demonstrate that delivered exogenous Cytochrome c effectively regulates the cell fate. Hence, this DNA-mediated fusion strategy holds great potential for protein drug delivery, regenerative medicine and gene editing.
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Affiliation(s)
- Lele Sun
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Yanjing Gao
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Yaoguang Wang
- Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong , School of Chemistry and Chemical Engineering , University of Jinan , Jinan 250022 , China
| | - Qin Wei
- Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong , School of Chemistry and Chemical Engineering , University of Jinan , Jinan 250022 , China
| | - Jiye Shi
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
| | - Nan Chen
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
| | - Di Li
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
- School of Chemistry and Molecular Engineering , East China Normal University , Shanghai 200241 , China
| | - Chunhai Fan
- Division of Physical Biology & Bioimaging Centre , Shanghai Synchrotron Radiation Facility , Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics , Chinese Academy of Sciences , Shanghai 201800 , China .
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19
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Comparative Characterization of the Sindbis Virus Proteome from Mammalian and Invertebrate Hosts Identifies nsP2 as a Component of the Virion and Sorting Nexin 5 as a Significant Host Factor for Alphavirus Replication. J Virol 2018; 92:JVI.00694-18. [PMID: 29743363 PMCID: PMC6026752 DOI: 10.1128/jvi.00694-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 04/27/2018] [Indexed: 01/08/2023] Open
Abstract
Recent advances in mass spectrometry methods and instrumentation now allow for more accurate identification of proteins in low abundance. This technology was applied to Sindbis virus, the prototypical alphavirus, to investigate the viral proteome. To determine if host proteins are specifically packaged into alphavirus virions, Sindbis virus (SINV) was grown in multiple host cells representing vertebrate and mosquito hosts, and total protein content of purified virions was determined. This analysis identified host factors not previously associated with alphavirus entry, replication, or egress. One host protein, sorting nexin 5 (SNX5), was shown to be critical for the replication of three different alphaviruses, Sindbis, Mayaro, and Chikungunya viruses. The most significant finding was that in addition to the host proteins, SINV nonstructural protein 2 (nsP2) was detected within virions grown in all host cells examined. The protein and RNA-interacting capabilities of nsP2 coupled with its presence in the virion support a role for nsP2 during packaging and/or entry of progeny virus. This function has not been identified for this protein. Taken together, this strategy identified at least one host factor integrally involved in alphavirus replication. Identification of other host proteins provides insight into alphavirus-host interactions during viral replication in both vertebrate and invertebrate hosts. This method of virus proteome analysis may also be useful for the identification of protein candidates for host-based therapeutics. IMPORTANCE Pathogenic alphaviruses, such as Chikungunya and Mayaro viruses, continue to plague public health in developing and developed countries alike. Alphaviruses belong to a group of viruses vectored in nature by hematophagous (blood-feeding) insects and are termed arboviruses (arthropod-borne viruses). This group of viruses contains many human pathogens, such as dengue fever, West Nile, and Yellow fever viruses. With few exceptions, there are no vaccines or prophylactics for these agents, leaving one-third of the world population at risk of infection. Identifying effective antivirals has been a long-term goal for combating these diseases not only because of the lack of vaccines but also because they are effective during an ongoing epidemic. Mass spectrometry-based analysis of the Sindbis virus proteome can be effective in identifying host genes involved in virus replication and novel functions for virus proteins. Identification of these factors is invaluable for the prophylaxis of this group of viruses.
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20
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The Regulation of Translation in Alphavirus-Infected Cells. Viruses 2018; 10:v10020070. [PMID: 29419763 PMCID: PMC5850377 DOI: 10.3390/v10020070] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 12/12/2022] Open
Abstract
Sindbis virus (SINV) contains an RNA genome of positive polarity with two open reading frames (ORFs). The first ORF is translated from the genomic RNA (gRNA), rendering the viral non-structural proteins, whereas the second ORF is translated from a subgenomic mRNA (sgRNA), which directs the synthesis of viral structural proteins. SINV infection strongly inhibits host cell translation through a variety of different mechanisms, including the phosphorylation of the eukaryotic initiation factor eIF2α and the redistribution of cellular proteins from the nucleus to the cytoplasm. A number of motifs have been identified in SINV sgRNA, including a hairpin downstream of the AUG initiation codon, which is involved in the translatability of the viral sgRNA when eIF2 is inactivated. Moreover, a 3′-UTR motif containing three stem-loop structures is involved in the enhancement of translation in insect cells, but not in mammalian cells. Accordingly, SINV sgRNA has evolved several structures to efficiently compete for the cellular translational machinery. Mechanistically, sgRNA translation involves scanning of the 5′-UTR following a non-canonical mode and without the requirement for several initiation factors. Indeed, sgRNA-directed polypeptide synthesis occurs even after eIF4G cleavage or inactivation of eIF4A by selective inhibitors. Remarkably, eIF2α phosphorylation does not hamper sgRNA translation during the late phase of SINV infection. SINV sgRNA thus constitutes a unique model of a capped viral mRNA that is efficiently translated in the absence of several canonical initiation factors. The present review will mainly focus in the non-canonical mechanism of translation of SINV sgRNA.
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21
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Sousa IP, Carvalho CAM, Mendes YS, Weissmuller G, Oliveira AC, Gomes AMO. Fusion of a New World Alphavirus with Membrane Microdomains Involving Partially Reversible Conformational Changes in the Viral Spike Proteins. Biochemistry 2017; 56:5823-5830. [PMID: 28956592 DOI: 10.1021/acs.biochem.7b00650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alphaviruses are enveloped arboviruses mainly proposed to infect host cells by receptor-mediated endocytosis followed by fusion between the viral envelope and the endosomal membrane. The fusion reaction is triggered by low pH and requires the presence of both cholesterol and sphingolipids in the target membrane, suggesting the involvement of lipid rafts in the cell entry mechanism. In this study, we show for the first time the interaction of an enveloped virus with membrane microdomains isolated from living cells. Using Mayaro virus (MAYV), a New World alphavirus, we verified that virus fusion to these domains occurred to a significant extent upon acidification, although its kinetics was quite slow when compared to that of fusion with artificial liposomes demonstrated in a previous work. Surprisingly, when virus was previously exposed to acidic pH, a condition previously shown to inhibit alphavirus binding and fusion to target membranes as well as infectivity, and then reneutralized, its ability to fuse with membrane microdomains at low pH was retained. Interestingly, this observation correlated with a partial reversion of low pH-induced conformational changes in viral proteins and retention of virus infectivity upon reneutralization. Our results suggest that MAYV entry into host cells could alternatively involve internalization via lipid rafts and that the conformational changes triggered by low pH in the viral spike proteins during the entry process are partially reversible.
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Affiliation(s)
- Ivanildo P Sousa
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Carlos A M Carvalho
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Ygara S Mendes
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Gilberto Weissmuller
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Andréa C Oliveira
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
| | - Andre M O Gomes
- Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde and ‡Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro , Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
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22
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Díaz-Menéndez M, Crespillo-Andújar C. Risk of Globalization of the Disease in Europe. ZIKA VIRUS INFECTION 2017. [PMCID: PMC7123135 DOI: 10.1007/978-3-319-59406-4_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Risk of dissemination of ZIKV disease is based on multiple factors, including environmental (climate, socioeconomically, deforestation or industrialization) and travel/traveller factors. Both the disease (viremic travellers) and vector movement to mosquito-free area contributes to the introduction and establishment of autochthonous ZIKV transmission. Mass gathering events can contribute to magnify transmission due to close crowd life in a confined area. Also, multitudinary events can promote the introduction of an infectious disease to a previously naïve area when returning home. Although mathematical models estimate a low risk for introduction of ZIKV in Europe, specific European regions (mainly Portuguese Island of Madeira) account with suitable and efficient vector and opportune climate conditions to harbour the disease. Clinicians should be aware to enable early detection of autochthonous ZIKV cases. International and local guidelines can help clinicians on how to handle suspicious cases, how to confirm the infection and how to report suspected and confirmed cases. In case of autochthonous ZIKV detection, public authorities should perform surveillance and provide adequate resources to sustain enhanced mosquito control.
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Affiliation(s)
- Marta Díaz-Menéndez
- Tropical Medicine Department, Hospital Universitario La Paz-Carlos III, Madrid, Spain
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23
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Herpes Simplex Virus 1 Enters Human Keratinocytes by a Nectin-1-Dependent, Rapid Plasma Membrane Fusion Pathway That Functions at Low Temperature. J Virol 2016; 90:10379-10389. [PMID: 27630229 PMCID: PMC5105671 DOI: 10.1128/jvi.01582-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/01/2016] [Indexed: 01/10/2023] Open
Abstract
Herpes simplex virus 1 (HSV-1) infects humans through stratified epithelia that are composed primarily of keratinocytes. The route of HSV-1 entry into keratinocytes has been the subject of limited investigation, but it is proposed to involve pH-dependent endocytosis, requiring the gD-binding receptor nectin-1. Here, we have utilized the nTERT human keratinocyte cell line as a new model for dissecting the mechanism of HSV-1 entry into the host. Although immortalized, these cells nonetheless retain normal growth and differentiation properties of primary cells. Using short interfering RNA (siRNA) depletion studies, we confirm that, despite nTERT cells expressing high levels of the alternative gD receptor HVEM, HSV-1 requires nectin-1, not HVEM, to enter these cells. Strikingly, virus entry into nTERT cells occurred with unusual rapidity, such that maximum penetration was achieved within 5 min. Moreover, HSV-1 was able to enter keratinocytes but not other cell types at temperatures as low as 7°C, conditions where endocytosis was shown to be completely inhibited. Transmission electron microscopy of early entry events at both 37°C and 7°C identified numerous examples of naked virus capsids located immediately beneath the plasma membrane, with no evidence of virions in cytoplasmic vesicles. Taken together, these results imply that HSV-1 uses the nectin-1 receptor to enter human keratinocyte cells via a previously uncharacterized rapid plasma membrane fusion pathway that functions at low temperature. These studies have important implications for current understanding of the relationship between HSV-1 and its relevant in vivo target cell. IMPORTANCE The gold standard of antiviral treatment for any human virus infection is the prevention of virus entry into the host cell. In the case of HSV-1, primary infection in the human begins in the epidermis of the skin or the oral mucosa, where the virus infects keratinocytes, and it is therefore important to understand the molecular events involved in HSV-1 entry into this cell type. Nonetheless, few studies have looked specifically at entry into these relevant human cells. Our results reveal a new route for virus entry that is specific to keratinocytes, involves rapid entry, and functions at low temperatures. This may reflect the environmental conditions encountered by HSV-1 when entering its host through the skin and emphasizes the importance of studying virus-host interactions in physiologically relevant cells.
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24
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Gupta N, Noël R, Goudet A, Hinsinger K, Michau A, Pons V, Abdelkafi H, Secher T, Shima A, Shtanko O, Sakurai Y, Cojean S, Pomel S, Liévin-Le Moal V, Leignel V, Herweg JA, Fischer A, Johannes L, Harrison K, Beard PM, Clayette P, Le Grand R, Rayner JO, Rudel T, Vacus J, Loiseau PM, Davey RA, Oswald E, Cintrat JC, Barbier J, Gillet D. Inhibitors of retrograde trafficking active against ricin and Shiga toxins also protect cells from several viruses, Leishmania and Chlamydiales. Chem Biol Interact 2016; 267:96-103. [PMID: 27712998 DOI: 10.1016/j.cbi.2016.10.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 08/09/2016] [Accepted: 10/03/2016] [Indexed: 11/25/2022]
Abstract
Medical countermeasures to treat biothreat agent infections require broad-spectrum therapeutics that do not induce agent resistance. A cell-based high-throughput screen (HTS) against ricin toxin combined with hit optimization allowed selection of a family of compounds that meet these requirements. The hit compound Retro-2 and its derivatives have been demonstrated to be safe in vivo in mice even at high doses. Moreover, Retro-2 is an inhibitor of retrograde transport that affects syntaxin-5-dependent toxins and pathogens. As a consequence, it has a broad-spectrum activity that has been demonstrated both in vitro and in vivo against ricin, Shiga toxin-producing O104:H4 entero-hemorrhagic E. coli and Leishmania sp. and in vitro against Ebola, Marburg and poxviruses and Chlamydiales. An effect is anticipated on other toxins or pathogens that use retrograde trafficking and syntaxin-5. Since Retro-2 targets cell components of the host and not directly the pathogen, no selection of resistant pathogens is expected. These lead compounds need now to be developed as drugs for human use.
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Affiliation(s)
- Neetu Gupta
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Romain Noël
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Amélie Goudet
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Karen Hinsinger
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Aurélien Michau
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Valérie Pons
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Hajer Abdelkafi
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | | | | | - Olena Shtanko
- Texas Biomedical Research Institute, San Antonio, TX, USA
| | | | - Sandrine Cojean
- Antiparasitic Chemotherapy, UMR 8076, CNRS BioCIS, LabEx LERMIT, Université Paris-Sud, Université Paris-Saclay, F-92290, Chatenay-Malabry, France
| | - Sébastien Pomel
- Antiparasitic Chemotherapy, UMR 8076, CNRS BioCIS, LabEx LERMIT, Université Paris-Sud, Université Paris-Saclay, F-92290, Chatenay-Malabry, France
| | - Vanessa Liévin-Le Moal
- Antiparasitic Chemotherapy, UMR 8076, CNRS BioCIS, LabEx LERMIT, Université Paris-Sud, Université Paris-Saclay, F-92290, Chatenay-Malabry, France
| | - Véronique Leignel
- DRUGABILIS (French Research Performer SME), F-92290, Chatenay-Malabry, France
| | - Jo-Ana Herweg
- University of Würzburg, Biocenter, Chair of Microbiology, Am Hubland, D-97074, Würzburg, Germany
| | - Annette Fischer
- University of Würzburg, Biocenter, Chair of Microbiology, Am Hubland, D-97074, Würzburg, Germany
| | - Ludger Johannes
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, F-75248, Paris Cedex 05, France; CNRS, UMR3666, F-75005, Paris, France; INSERM, U1143, F-75005, Paris, France
| | - Kate Harrison
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, EH25 9RG, United Kingdom
| | - Philippa M Beard
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian, EH25 9RG, United Kingdom; The Pirbright Institute, Ash Rd, Pirbright, Surrey GH24 0NF, United Kingdom
| | - Pascal Clayette
- ImmunoPharmacology and Biosafety Laboratory, BERTIN Pharma, CEA, F-92265, Fontenay-aux-Roses, France
| | - Roger Le Grand
- Institute of Emerging Diseases and Innovative Therapies, CEA, U1184, Immunology of Viral Infections and Autoimmune Diseases, Infectious Disease Models and Innovative Therapies Infrastructure, F-92265, Fontenay-aux-Roses, France; INSERM, U1184, F-94276, Le Kremlin-Bicêtre, France; University of Paris South, U1184, F-92265, Fontenay-aux-Roses, France; Vaccine Research Institute, Henri Mondor Hospital, F-94010, Créteil, France
| | - Jonathan O Rayner
- Infectious Disease Research, Southern Research, 2000 Ninth Avenue South, Birmingham, AL 35205, USA
| | - Thomas Rudel
- University of Würzburg, Biocenter, Chair of Microbiology, Am Hubland, D-97074, Würzburg, Germany
| | - Joël Vacus
- DRUGABILIS (French Research Performer SME), F-92290, Chatenay-Malabry, France
| | - Philippe M Loiseau
- Antiparasitic Chemotherapy, UMR 8076, CNRS BioCIS, LabEx LERMIT, Université Paris-Sud, Université Paris-Saclay, F-92290, Chatenay-Malabry, France
| | - Robert A Davey
- Texas Biomedical Research Institute, San Antonio, TX, USA
| | | | - Jean-Christophe Cintrat
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Julien Barbier
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France
| | - Daniel Gillet
- Institute of Biology and Technology of Saclay (IBITECS), CEA, LabEx LERMIT, Université Paris-Saclay, F-91191, Gif Sur Yvette, France.
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25
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Single-Site Glycoprotein Mutants Inhibit a Late Event in Sindbis Virus Assembly. J Virol 2016; 90:8372-80. [PMID: 27412592 DOI: 10.1128/jvi.00948-16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/23/2016] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED A panel of Sindbis virus mutants that were suspected to have deficiencies in one or more aspects of their replication cycles was examined in baby hamster kidney (BHK) cells. These included an amino acid deletion (ΔH230) and substitution (H230A) in the Sindbis glycoprotein E1_H230 and similar mutants in E2_G209 (G209A, G209D, and ΔG209). Neither H230 mutation produced a measurable titer, but repeated passaging of the H230A mutant in BHK cells produced a second-site compensatory mutant (V231I) that partially rescued both H230 mutants. Electron micrograph (EM) images of these mutants showed assembled viral nucleocapsids but no completed, mature virions. EM of the compensatory mutant strains showed complete virus particles, but these now formed paracrystalline arrays. None of the E2_G209 substitution mutants had any effect on virus production; however, the deletion mutant (ΔG209) showed a very low titer when grown at 37°C and no titer when grown at 28°C. When the deletion mutant grown at 28°C was examined by EM, partially budded virions were observed at the cell surface. (35)S labeling of this mutant confirmed the presence of mutant virus protein in the transfected BHK cell lysate. We conclude that H230 is essential for the assembly of complete infectious Sindbis virus virions and that the presence of an amino acid at E2 position 209 is required for complete budding of Sindbis virus particles although several different amino acids can be at this location without affecting the titer. IMPORTANCE Our data show the importance of single-site mutations at E1_H230 and E2_G209 in Sindbis virus glycoproteins. These sites have been shown to affect assembly and antibody binding in previous studies. Our data indicate that mutation of one histidine residue in E1 is detrimental to the assembly of Sindbis virus particles in baby hamster kidney cells. Repeated passaging leads to a second-site substitution that partially restores the titer although EM still shows an altered phenotype. Substitutions at position G209 in E2 have no effect on titer, but deletion of this residue greatly reduces titer and again prevents assembly. When this mutant is grown at a lower temperature, virus particles bud from the host cell, but budding arrests before the progeny virus escapes. These results allow us to conclude that these sites have essential roles in assembly, and E2_G209 shows us a new viral egress phenotype.
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Parham PE, Waldock J, Christophides GK, Hemming D, Agusto F, Evans KJ, Fefferman N, Gaff H, Gumel A, LaDeau S, Lenhart S, Mickens RE, Naumova EN, Ostfeld RS, Ready PD, Thomas MB, Velasco-Hernandez J, Michael E. Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2013.0551. [PMID: 25688012 DOI: 10.1098/rstb.2013.0551] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems.
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Affiliation(s)
- Paul E Parham
- Department of Public Health and Policy, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3GL, UK Grantham Institute for Climate Change, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Joanna Waldock
- The Cyprus Institute, Nicosia, Cyprus Imperial College London, London SW7 2AZ, UK
| | | | - Deborah Hemming
- Meteorological Office Hadley Centre, UK Meteorological Office, Fitzroy Road, Exeter, EX1 3PB, UK
| | - Folashade Agusto
- Department of Mathematics, Austin Peay State University, Clarksville, TN 37044, USA
| | - Katherine J Evans
- Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Nina Fefferman
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA
| | - Holly Gaff
- Department of Biological Sciences, Old Dominium University, Norfolk, VA 23529, USA
| | - Abba Gumel
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1904, USA School of Mathematical and Natural Sciences, Arizona State University, Phoenix, AZ 85069-7100, USA
| | - Shannon LaDeau
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996-1300, USA
| | - Ronald E Mickens
- Department of Physics, Clark Atlanta University, PO Box 172, Atlanta, GA 30314, USA
| | - Elena N Naumova
- Department of Civil and Environmental Engineering, Tufts University School of Engineering, Medford, MA 02155, USA
| | - Richard S Ostfeld
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Paul D Ready
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jorge Velasco-Hernandez
- Universidad Nacional Autnoma de Mexico Institute of Mathematics Mexico City, Distrito Federal, Mexico
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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Analysis of Dengue Virus Genetic Diversity during Human and Mosquito Infection Reveals Genetic Constraints. PLoS Negl Trop Dis 2015; 9:e0004044. [PMID: 26327586 PMCID: PMC4556638 DOI: 10.1371/journal.pntd.0004044] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 08/10/2015] [Indexed: 12/15/2022] Open
Abstract
Dengue viruses (DENV) cause debilitating and potentially life-threatening acute disease throughout the tropical world. While drug development efforts are underway, there are concerns that resistant strains will emerge rapidly. Indeed, antiviral drugs that target even conserved regions in other RNA viruses lose efficacy over time as the virus mutates. Here, we sought to determine if there are regions in the DENV genome that are not only evolutionarily conserved but genetically constrained in their ability to mutate and could hence serve as better antiviral targets. High-throughput sequencing of DENV-1 genome directly from twelve, paired dengue patients’ sera and then passaging these sera into the two primary mosquito vectors showed consistent and distinct sequence changes during infection. In particular, two residues in the NS5 protein coding sequence appear to be specifically acquired during infection in Ae. aegypti but not Ae. albopictus. Importantly, we identified a region within the NS3 protein coding sequence that is refractory to mutation during human and mosquito infection. Collectively, these findings provide fresh insights into antiviral targets and could serve as an approach to defining evolutionarily constrained regions for therapeutic targeting in other RNA viruses. Dengue viruses cause debilitating and potentially life-threatening acute disease throughout the tropical world. While drug development efforts are underway, there are concerns that drug-resistant strains will emerge rapidly. Indeed, many antiviral drugs for other RNA viruses lose efficacy over time as the virus mutates. Here, we sought to determine if there are regions in the dengue virus genome that are constrained in their ability to mutate and could therefore serve as better targets for antiviral drugs. Deep sequencing of the dengue virus 1 genome directly from the blood of twelve dengue patients and from mosquitoes given this blood showed consistent and distinct mutation patterns during infection. Importantly, we identified regions within the viral genome that are resistant to mutation during human and mosquito infection. Collectively, these findings provide fresh insights into potential antiviral targets and could serve as an approach to defining better regions for therapeutic targeting in other RNA viruses.
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van Duijl-Richter MKS, Blijleven JS, van Oijen AM, Smit JM. Chikungunya virus fusion properties elucidated by single-particle and bulk approaches. J Gen Virol 2015; 96:2122-2132. [DOI: 10.1099/vir.0.000144] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Mareike K. S. van Duijl-Richter
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
| | - Jelle S. Blijleven
- Centre for Synthetic Biology, Zernike Institute of Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Antoine M. van Oijen
- Centre for Synthetic Biology, Zernike Institute of Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
- School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Jolanda M. Smit
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
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Abstract
Chikungunya virus (CHIKV) is a rapidly emerging mosquito-borne alphavirus causing millions of infections in the tropical and subtropical regions of the world. CHIKV infection often leads to an acute self-limited febrile illness with debilitating myalgia and arthralgia. A potential long-term complication of CHIKV infection is severe joint pain, which can last for months to years. There are no vaccines or specific therapeutics available to prevent or treat infection. This review describes the critical steps in CHIKV cell entry. We summarize the latest studies on the virus-cell tropism, virus-receptor binding, internalization, membrane fusion and review the molecules and compounds that have been described to interfere with virus cell entry. The aim of the review is to give the reader a state-of-the-art overview on CHIKV cell entry and to provide an outlook on potential new avenues in CHIKV research.
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Residue-level resolution of alphavirus envelope protein interactions in pH-dependent fusion. Proc Natl Acad Sci U S A 2015; 112:2034-9. [PMID: 25646410 DOI: 10.1073/pnas.1414190112] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Alphavirus envelope proteins, organized as trimers of E2-E1 heterodimers on the surface of the pathogenic alphavirus, mediate the low pH-triggered fusion of viral and endosomal membranes in human cells. The lack of specific treatment for alphaviral infections motivates our exploration of potential antiviral approaches by inhibiting one or more fusion steps in the common endocytic viral entry pathway. In this work, we performed constant pH molecular dynamics based on an atomic model of the alphavirus envelope with icosahedral symmetry. We have identified pH-sensitive residues that cause the largest shifts in thermodynamic driving forces under neutral and acidic pH conditions for various fusion steps. A series of conserved interdomain His residues is identified to be responsible for the pH-dependent conformational changes in the fusion process, and ligand binding sites in their vicinity are anticipated to be potential drug targets aimed at inhibiting viral infections.
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Self-Amplifying mRNA Vaccines. NONVIRAL VECTORS FOR GENE THERAPY - PHYSICAL METHODS AND MEDICAL TRANSLATION 2015; 89:179-233. [DOI: 10.1016/bs.adgen.2014.10.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Kenney JL, Brault AC. The role of environmental, virological and vector interactions in dictating biological transmission of arthropod-borne viruses by mosquitoes. Adv Virus Res 2014; 89:39-83. [PMID: 24751194 DOI: 10.1016/b978-0-12-800172-1.00002-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Arthropod-borne viruses (arboviruses) are transmitted between vertebrate hosts and arthropod vectors. An inherently complex interaction among virus, vector, and the environment determines successful transmission of the virus. Once believed to be "flying syringes," recent advances in the field have demonstrated that mosquito genetics, microbiota, salivary components, and mosquito innate immune responses all play important roles in modulating arbovirus transmissibility. The literature on the interaction among virus, mosquito, and environment has expanded dramatically in the preceding decade and the utilization of next-generation sequencing and transgenic vector methodologies assuredly will increase the pace of knowledge acquisition in this field. This chapter outlines the interplay among the three factors in both direct physical and biochemical manners as well as indirectly through superinfection barriers and altered induction of innate immune responses in mosquito vectors. The culmination of the aforementioned interactions and the arms race between the mosquito innate immune response and the capacity of arboviruses to antagonize such a response ultimately results in the subjugation of mosquito cells for viral replication and subsequent transmission.
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Affiliation(s)
- Joan L Kenney
- Arbovirus Research Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
| | - Aaron C Brault
- Arbovirus Research Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, Colorado, USA.
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Abstract
Viruses have evolved to exploit the vast complexity of cellular processes for their success within the host cell. The entry mechanisms of enveloped viruses (viruses with a surrounding outer lipid bilayer membrane) are usually classified as being either endocytotic or fusogenic. Different mechanisms have been proposed for Alphavirus entry and genome delivery. Indirect observations led to a general belief that enveloped viruses can infect cells either by protein-assisted fusion with the plasma membrane in a pH-independent manner or by endocytosis and fusion with the endocytic vacuole in a low-pH environment. The mechanism of Alphavirus penetration has been recently revisited using direct observation of the processes by electron microscopy under conditions of different temperatures and time progression. Under conditions nonpermissive for endocytosis or any vesicular transport, events occur which allow the entry of the virus genome into the cells. When drug inhibitors of cellular functions are used to prevent entry, only ionophores are found to significantly inhibit RNA delivery. Arboviruses are agents of significant human and animal disease; therefore, strategies to control infections are needed and include development of compounds which will block critical steps in the early infection events. It appears that current evidence points to an entry mechanism, in which alphaviruses infect cells by direct penetration of cell plasma membranes through a pore structure formed by virus and, possibly, host proteins.
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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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Structural differences observed in arboviruses of the alphavirus and flavivirus genera. Adv Virol 2014; 2014:259382. [PMID: 25309597 PMCID: PMC4182009 DOI: 10.1155/2014/259382] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/28/2014] [Accepted: 08/18/2014] [Indexed: 12/22/2022] Open
Abstract
Arthropod borne viruses have developed a complex life cycle adapted to alternate between insect and vertebrate hosts. These arthropod-borne viruses belong mainly to the families Togaviridae, Flaviviridae, and Bunyaviridae. This group of viruses contains many pathogens that cause febrile, hemorrhagic, and encephalitic disease or arthritic symptoms which can be persistent. It has been appreciated for many years that these viruses were evolutionarily adapted to function in the highly divergent cellular environments of both insect and mammalian phyla. These viruses are hybrid in nature, containing viral-encoded RNA and proteins which are glycosylated by the host and encapsulate viral nucleocapsids in the context of a host-derived membrane. From a structural perspective, these virus particles are macromolecular machines adapted in design to assemble into a packaging and delivery system for the virus genome and, only when associated with the conditions appropriate for a productive infection, to disassemble and deliver the RNA cargo. It was initially assumed that the structures of the virus from both hosts were equivalent. New evidence that alphaviruses and flaviviruses can exist in more than one conformation postenvelopment will be discussed in this review. The data are limited but should refocus the field of structural biology on the metastable nature of these viruses.
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Deering RP, Kommareddy S, Ulmer JB, Brito LA, Geall AJ. Nucleic acid vaccines: prospects for non-viral delivery of mRNA vaccines. Expert Opin Drug Deliv 2014; 11:885-99. [PMID: 24665982 DOI: 10.1517/17425247.2014.901308] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Nucleic acid-based vaccines are being developed as a means to combine the positive attributes of both live-attenuated and subunit vaccines. Viral vectors and plasmid DNA vaccines have been extensively evaluated in human clinical trials and have been shown to be safe and immunogenic, although none have been licensed for human use. More recently, mRNA-based vaccine alternatives have emerged and might offer certain advantages over their DNA-based counterparts. AREAS COVERED This review describes the two main categories of mRNA vaccines: conventional non-amplifying and self-amplifying mRNA. It summarizes the initial clinical proof-of-concept studies and outlines the preclinical testing of the next wave of innovations for the technology. Finally, this review highlights the versatile functionality of the mRNA molecule and introduces opportunities for future improvements in vaccine design. EXPERT OPINION The prospects for mRNA vaccines are very promising. Like other types of nucleic acid vaccines, mRNA vaccines have the potential to combine the positive attributes of live attenuated vaccines while obviating many potential safety limitations. Although data from initial clinical trials appear encouraging, mRNA vaccines are far from a commercial product. These initial approaches have spurred innovations in vector design, non-viral delivery, large-scale production and purification of mRNA to quickly move the technology forward. Some improvements have already been tested in preclinical models for both prophylactic and therapeutic vaccine targets and have demonstrated their ability to elicit potent and broad immune responses, including functional antibodies, type 1 T helper cells-type T cell responses and cytotoxic T cells. Though the initial barriers for this nucleic acid vaccine approach seem to be overcome, in our opinion, the future and continued success of this approach lies in a more extensive evaluation of the many non-viral delivery systems described in the literature and gaining a better understanding of the mechanism of action to allow rational design of next generation technologies.
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Affiliation(s)
- Raquel P Deering
- Novartis Vaccines, Inc. , 350 Massachusetts Ave, Cambridge, MA 02139 , USA +1 617 871 3745 ;
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