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Klaus JP, Botten J. Highly Sensitive Assay for Measurement of Arenavirus-cell Attachment. J Vis Exp 2016:e53682. [PMID: 26966937 DOI: 10.3791/53682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Arenaviruses are a family of enveloped RNA viruses that cause severe human disease. The first step in the arenavirus life cycle is attachment of viral particles to host cells. While virus-cell attachment can be measured through the use of virions labeled with biotin, radioactive isotopes, or fluorescent dyes, these approaches typically require high multiplicities of infection (MOI) to enable detection of bound virus. We describe a quantitative (q)RT-PCR-based assay that measures Junin virus strain Candid 1 attachment via quantitation of virion-packaged viral genomic RNA. This assay has several advantages including its extreme sensitivity and ability to measure attachment over a large dynamic range of MOIs without the need to purify or label input virus. Importantly, this approach can be easily tailored for use with other viruses through the use of virus-specific qRT-PCR reagents. Further, this assay can be modified to permit measurement of particle endocytosis and genome uncoating. In conclusion, we describe a simple, yet robust assay for highly sensitive measurement of arenavirus-cell attachment.
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Affiliation(s)
- Joseph P Klaus
- Department of Medicine, Division of Immunobiology, University of Vermont
| | - Jason Botten
- Department of Medicine, Division of Immunobiology, University of Vermont; Department of Microbiology & Molecular Genetics, University of Vermont;
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Functional Genomic Strategies for Elucidating Human-Virus Interactions: Will CRISPR Knockout RNAi and Haploid Cells? Adv Virus Res 2016; 94:1-51. [PMID: 26997589 PMCID: PMC7112329 DOI: 10.1016/bs.aivir.2015.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Over the last several years a wealth of transformative human–virus interaction discoveries have been produced using loss-of-function functional genomics. These insights have greatly expanded our understanding of how human pathogenic viruses exploit our cells to replicate. Two technologies have been at the forefront of this genetic revolution, RNA interference (RNAi) and random retroviral insertional mutagenesis using haploid cell lines (haploid cell screening), with the former technology largely predominating. Now the cutting edge gene editing of the CRISPR/Cas9 system has also been harnessed for large-scale functional genomics and is poised to possibly displace these earlier methods. Here we compare and contrast these three screening approaches for elucidating host–virus interactions, outline their key strengths and weaknesses including a comparison of an arrayed multiple orthologous RNAi reagent screen to a pooled CRISPR/Cas9 human rhinovirus 14–human cell interaction screen, and recount some notable insights made possible by each. We conclude with a brief perspective on what might lie ahead for the fast evolving field of human–virus functional genomics.
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Alberdi P, Mansfield KL, Manzano-Román R, Cook C, Ayllón N, Villar M, Johnson N, Fooks AR, de la Fuente J. Tissue-Specific Signatures in the Transcriptional Response to Anaplasma phagocytophilum Infection of Ixodes scapularis and Ixodes ricinus Tick Cell Lines. Front Cell Infect Microbiol 2016; 6:20. [PMID: 26904518 PMCID: PMC4748044 DOI: 10.3389/fcimb.2016.00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/26/2016] [Indexed: 11/13/2022] Open
Abstract
Anaplasma phagocytophilum are transmitted by Ixodes spp. ticks and have become one of the most common and relevant tick-borne pathogens due to their impact on human and animal health. Recent results have increased our understanding of the molecular interactions between Ixodes scapularis and A. phagocytophilum through the demonstration of tissue-specific molecular pathways that ensure pathogen infection, development and transmission by ticks. However, little is known about the Ixodes ricinus genes and proteins involved in the response to A. phagocytophilum infection. The tick species I. scapularis and I. ricinus are evolutionarily closely related and therefore similar responses are expected in A. phagocytophilum-infected cells. However, differences may exist between I. scapularis ISE6 and I. ricinus IRE/CTVM20 tick cells associated with tissue-specific signatures of these cell lines. To address this hypothesis, the transcriptional response to A. phagocytophilum infection was characterized by RNA sequencing and compared between I. scapularis ISE6 and I. ricinus IRE/CTVM20 tick cell lines. The transcriptional response to infection of I. scapularis ISE6 cells resembled that of tick hemocytes while the response in I. ricinus IRE/CTVM20 cells was more closely related to that reported previously in infected tick midguts. The inhibition of cell apoptosis by A. phagocytophilum appears to be a key adaptation mechanism to facilitate infection of both vertebrate and tick cells and was used to investigate further the tissue-specific response of tick cell lines to pathogen infection. The results supported a role for the intrinsic pathway in the inhibition of cell apoptosis by A. phagocytophilum infection of I. scapularis ISE6 cells. In contrast, the results in I. ricinus IRE/CTVM20 cells were similar to those obtained in tick midguts and suggested a role for the JAK/STAT pathway in the inhibition of apoptosis in tick cells infected with A. phagocytophilum. Nevertheless, tick cell lines were derived from embryonated eggs and may contain various cell populations with different morphology and behavior that could affect transcriptional response to infection. These results suggested tissue-specific signatures in I. scapularis ISE6 and I. ricinus IRE/CTVM20 tick cell line response to A. phagocytophilum infection that support their use as models for the study of tick-pathogen interactions.
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Affiliation(s)
- Pilar Alberdi
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-Consejo Superior de Investigaciones Científicas- Universidad de Castilla-La Mancha-Junta de Comunidades de Castilla-La Mancha Ciudad Real, Spain
| | | | - Raúl Manzano-Román
- Parasitología Animal, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA, Consejo Superior de Investigaciones Científicas) Salamanca, Spain
| | | | - Nieves Ayllón
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-Consejo Superior de Investigaciones Científicas- Universidad de Castilla-La Mancha-Junta de Comunidades de Castilla-La Mancha Ciudad Real, Spain
| | - Margarita Villar
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-Consejo Superior de Investigaciones Científicas- Universidad de Castilla-La Mancha-Junta de Comunidades de Castilla-La Mancha Ciudad Real, Spain
| | | | - Anthony R Fooks
- Animal and Plant Health AgencyNew Haw, Surrey, UK; Department of Clinical Infection, Microbiology and Immunology, University of LiverpoolLiverpool, UK
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-Consejo Superior de Investigaciones Científicas- Universidad de Castilla-La Mancha-Junta de Comunidades de Castilla-La ManchaCiudad Real, Spain; Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State UniversityStillwater, OK, USA
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Abstract
Several arenavirus cause hemorrhagic fever disease in humans and pose a significant public health problem in their endemic regions. To date, no licensed vaccines are available to combat human arenavirus infections, and anti-arenaviral drug therapy is limited to an off-label use of ribavirin that is only partially effective. The development of arenavirus reverse genetics approaches provides investigators with a novel and powerful approach for the investigation of the arenavirus molecular and cell biology. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in arenavirus replication and transcription and the identification of novel anti-arenaviral drug targets without requiring the use of live forms of arenaviruses. Likewise, it is now feasible to rescue infectious arenaviruses entirely from cloned cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of pathogenesis, as well as to facilitate screens to identify anti-arenaviral drugs and development of novel live-attenuated arenavirus vaccines. Recently, reverse genetics have also allowed the generation of tri-segmented arenaviruses expressing foreign genes, facilitating virus detection and opening the possibility of implementing live-attenuated arenavirus-based vaccine vector approaches. Likewise, the development of single-cycle infectious, reporter-expressing, arenaviruses has provided a new experimental method to study some aspects of the biology of highly pathogenic arenaviruses without the requirement of high-security biocontainment required to study HF-causing arenaviruses. In this chapter we summarize the current knowledge on arenavirus reverse genetics and the implementation of plasmid-based reverse genetics techniques for the development of arenavirus vaccines and vaccine vectors.
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Affiliation(s)
- Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA.
| | - Benson Yee Hin Cheng
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY, 14642, USA
| | - Juan Carlos de la Torre
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, 92037, USA.
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Superinfection exclusion is absent during acute Junin virus infection of Vero and A549 cells. Sci Rep 2015; 5:15990. [PMID: 26549784 PMCID: PMC4637830 DOI: 10.1038/srep15990] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 10/07/2015] [Indexed: 11/08/2022] Open
Abstract
Many viruses have evolved strategies of so-called "superinfection exclusion" to prevent re-infection of a cell that the same virus has already infected. Although Old World arenavirus infection results in down-regulation of its viral receptor and thus superinfection exclusion, whether New World arenaviruses have evolved such a mechanism remains unclear. Here we show that acute infection by the New World Junin virus (JUNV) failed to down-regulate the transferrin receptor and did not induce superinfection exclusion. We observed that Vero cells infected by a first round of JUNV (Candid1 strain) preserve an ability to internalize new incoming JUNV particles that is comparable to that of non-infected cells. Moreover, we developed a dual infection assay with the wild-type Candid1 JUNV and a recombinant JUNV-GFP virus to discriminate between first and second infections at the transcriptional and translational levels. We found that Vero and A549 cells already infected by JUNV were fully competent to transcribe viral RNA from a second round of infection. Furthermore, flow cytometry analysis of viral protein expression indicated that viral translation was normal, regardless of whether cells were previously infected or not. We conclude that in acutely infected cells, Junin virus lacks a superinfection exclusion mechanism.
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Calcium Regulation of Hemorrhagic Fever Virus Budding: Mechanistic Implications for Host-Oriented Therapeutic Intervention. PLoS Pathog 2015; 11:e1005220. [PMID: 26513362 PMCID: PMC4634230 DOI: 10.1371/journal.ppat.1005220] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/21/2015] [Indexed: 12/19/2022] Open
Abstract
Hemorrhagic fever viruses, including the filoviruses (Ebola and Marburg) and arenaviruses (Lassa and Junín viruses), are serious human pathogens for which there are currently no FDA approved therapeutics or vaccines. Importantly, transmission of these viruses, and specifically late steps of budding, critically depend upon host cell machinery. Consequently, strategies which target these mechanisms represent potential targets for broad spectrum host oriented therapeutics. An important cellular signal implicated previously in EBOV budding is calcium. Indeed, host cell calcium signals are increasingly being recognized to play a role in steps of entry, replication, and transmission for a range of viruses, but if and how filoviruses and arenaviruses mobilize calcium and the precise stage of virus transmission regulated by calcium have not been defined. Here we demonstrate that expression of matrix proteins from both filoviruses and arenaviruses triggers an increase in host cytoplasmic Ca2+ concentration by a mechanism that requires host Orai1 channels. Furthermore, we demonstrate that Orai1 regulates both VLP and infectious filovirus and arenavirus production and spread. Notably, suppression of the protein that triggers Orai activation (Stromal Interaction Molecule 1, STIM1) and genetic inactivation or pharmacological blockade of Orai1 channels inhibits VLP and infectious virus egress. These findings are highly significant as they expand our understanding of host mechanisms that may broadly control enveloped RNA virus budding, and they establish Orai and STIM1 as novel targets for broad-spectrum host-oriented therapeutics to combat these emerging BSL-4 pathogens and potentially other enveloped RNA viruses that bud via similar mechanisms. Filoviruses (Ebola and Marburg viruses) and arenaviruses (Lassa and Junín viruses) are high-priority pathogens that hijack host proteins and pathways to complete their replication cycles and spread from cell to cell. Here we provide genetic and pharmacological evidence to demonstrate that the host calcium channel protein Orai1 and ER calcium sensor protein STIM1 regulate efficient budding and spread of BSL-4 pathogens Ebola, Marburg, Lassa, and Junín viruses. Our findings are of broad significance as they provide new mechanistic insight into fundamental, immutable, and conserved mechanisms of hemorrhagic fever virus pathogenesis. Moreover, this strategy of targeting highly conserved host cellular protein(s) and mechanisms required by these viruses to complete their life cycle should elicit minimal drug resistance.
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Abstract
Deciphering the many interactions that occur between a virus and host cell over the course of infection is paramount to understanding mechanisms of pathogenesis and to the future development of antiviral therapies. Over the past decade, researchers have started to understand these complicated relationships through the development of methodologies, including advances in RNA interference, proteomics, and the development of genetic tools such as haploid cell lines, allowing high-throughput screening to identify critical contact points between virus and host. These advances have produced a wealth of data regarding host factors hijacked by viruses to promote infection, as well as antiviral factors responsible for subverting viral infection. This review highlights findings from virus-host screens and discusses our thoughts on the direction of screening strategies moving forward.
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Affiliation(s)
- Holly Ramage
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104; ,
| | - Sara Cherry
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104; ,
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Abstract
Two-pore channels (TPCs) are evolutionarily important members of the voltage-gated ion channel superfamily. TPCs localize to acidic Ca(2+) stores within the endolysosomal system. Most evidence indicate that TPCs mediate Ca(2+) signals through the Ca(2+)-mobilizing messenger nicotinic acid adenine dinucleotide phosphate (NAADP) to control a range of Ca(2+)-dependent events. Recent studies clarify the mechanism of TPC activation and identify roles for TPCs in disease, highlighting the regulation of endolysosomal membrane traffic by local Ca(2+) fluxes. Chemical targeting of TPCs to maintain endolysosomal "well-being" may be beneficial in disorders as diverse as Parkinson's disease, fatty liver disease, and Ebola virus infection.
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Affiliation(s)
- Sandip Patel
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK. E-mail:
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Novel Arenavirus Entry Inhibitors Discovered by Using a Minigenome Rescue System for High-Throughput Drug Screening. J Virol 2015; 89:8428-43. [PMID: 26041296 DOI: 10.1128/jvi.00997-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 05/26/2015] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Certain members of the Arenaviridae family are category A agents capable of causing severe hemorrhagic fevers in humans. Specific antiviral treatments do not exist, and the only commonly used drug, ribavirin, has limited efficacy and can cause severe side effects. The discovery and development of new antivirals are inhibited by the biohazardous nature of the viruses, making them a relatively poorly understood group of human pathogens. We therefore adapted a reverse-genetics minigenome (MG) rescue system based on Junin virus, the causative agent of Argentine hemorrhagic fever, for high-throughput screening (HTS). The MG rescue system recapitulates all stages of the virus life cycle and enables screening of small-molecule libraries under biosafety containment level 2 (BSL2) conditions. The HTS resulted in the identification of four candidate compounds with potent activity against a broad panel of arenaviruses, three of which were completely novel. The target for all 4 compounds was the stage of viral entry, which positions the compounds as potentially important leads for future development. IMPORTANCE The arenavirus family includes several members that are highly pathogenic, causing acute viral hemorrhagic fevers with high mortality rates. No specific effective treatments exist, and although a vaccine is available for Junin virus, the causative agent of Argentine hemorrhagic fever, it is licensed for use only in areas where Argentine hemorrhagic fever is endemic. For these reasons, it is important to identify specific compounds that could be developed as antivirals against these deadly viruses.
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Sorting of small infectious virus particles by flow virometry reveals distinct infectivity profiles. Nat Commun 2015; 6:6022. [PMID: 25641385 PMCID: PMC4315362 DOI: 10.1038/ncomms7022] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/03/2014] [Indexed: 12/25/2022] Open
Abstract
The nature and concentration of lipids and proteins at the surface of viruses are essential parameters for determining particle infectiveness. Historically, averaged bulk analysis of viral particles has been the primary method to quantitatively investigate these parameters, though this neglects heterogeneity within populations. Here we analyze the properties of Junin virus particles using a sensitive flow virometry assay and further sort virions, while conserving their infectivness. This method allows us to characterize the relationship between infectivity, virus size, and RNA content and to compare particles secreted by Vero cells with those from physiologically relevant human primary macrophages. Our study highlights significant differences in particle infectivity according to its nature, the type of producer cells and the lipid membrane composition at the budding site. Together, our results present the flow virometry assay as a powerful and versatile tool to define virus particle profiles.
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61
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Abstract
The rodent arenavirus glycoprotein complex encodes a stable signal peptide (SSP) that is an essential structural component of mature virions. The SSP, GP1, and GP2 subunits of the trimeric glycoprotein complex noncovalently interact to stud the surface of virions and initiate arenavirus infectivity. Nascent glycoprotein production undergoes two proteolytic cleavage events: first within the endoplasmic reticulum (ER) to cleave SSP from the remaining precursor GP1/2 (glycoprotein complex [GPC]) glycoprotein and second within the Golgi stacks by the cellular SKI-1/S1P for GP1/2 processing to yield GP1 and GP2 subunits. Cleaved SSP is not degraded but retained as an essential glycoprotein subunit. Here, we defined functions of the 58-amino-acid lymphocytic choriomeningitis virus (LCMV) SSP in regard to glycoprotein complex processing and maturation. Using molecular biology techniques, confocal microscopy, and flow cytometry, we detected SSP at the plasma membrane of transfected cells. Further, we identified a sorting signal (FLLL) near the carboxyl terminus of SSP that is required for glycoprotein maturation and trafficking. In the absence of SSP, the glycoprotein accumulated within the ER and was unable to undergo processing by SKI-1/S1P. Mutation of this highly conserved FLLL motif showed impaired glycoprotein processing and secretory pathway trafficking, as well as defective surface expression and pH-dependent membrane fusion. Immunoprecipitation of SSP confirmed an interaction between the signal peptide and the GP2 subunit; however, mutations within this FLLL motif disrupted the association of the GP1 subunit with the remaining glycoprotein complex. Several members of the Arenaviridae family are neglected human pathogens capable of causing illness ranging from a nondescript flu-like syndrome to fulminant hemorrhagic fever. Infections by arenaviruses are mediated by attachment of the virus glycoprotein to receptors on host cells and virion internalization by fusion within an acidified endosome. SSP plays a critical role in the fusion of the virus with the host cell membrane. Within infected cells, the retained glycoprotein SSP plays a neglected yet essential role in glycoprotein biosynthesis. Without this 6-kDa polypeptide, the glycoprotein precursor is retained within the endoplasmic reticulum, and trafficking to the plasma membrane where SSP, GP1, and GP2 localize for glycoprotein assembly into infectious virions is inhibited. To investigate SSP contributions to glycoprotein maturation and function, we created an SSP-tagged glycoprotein to directly detect and manipulate this subunit. This resource will aid future studies to identify host factors that mediate glycoprotein maturation.
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Gehring G, Rohrmann K, Atenchong N, Mittler E, Becker S, Dahlmann F, Pöhlmann S, Vondran FWR, David S, Manns MP, Ciesek S, von Hahn T. The clinically approved drugs amiodarone, dronedarone and verapamil inhibit filovirus cell entry. J Antimicrob Chemother 2014; 69:2123-31. [PMID: 24710028 PMCID: PMC7110251 DOI: 10.1093/jac/dku091] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Objectives Filoviruses such as Ebola virus and Marburg virus cause a severe haemorrhagic fever syndrome in humans for which there is no specific treatment. Since filoviruses use a complex route of cell entry that depends on numerous cellular factors, we hypothesized that there may be drugs already approved for human use for other indications that interfere with signal transduction or other cellular processes required for their entry and hence have anti-filoviral properties. Methods We used authentic filoviruses and lentiviral particles pseudotyped with filoviral glycoproteins to identify and characterize such compounds. Results We discovered that amiodarone, a multi-ion channel inhibitor and adrenoceptor antagonist, is a potent inhibitor of filovirus cell entry at concentrations that are routinely reached in human serum during anti-arrhythmic therapy. A similar effect was observed with the amiodarone-related agent dronedarone and the L-type calcium channel blocker verapamil. Inhibition by amiodarone was concentration dependent and similarly affected pseudoviruses as well as authentic filoviruses. Inhibition of filovirus entry was observed with most but not all cell types tested and was accentuated by the pre-treatment of cells, indicating a host cell-directed mechanism of action. The New World arenavirus Guanarito was also inhibited by amiodarone while the Old World arenavirus Lassa and members of the Rhabdoviridae (vesicular stomatitis virus) and Bunyaviridae (Hantaan) families were largely resistant. Conclusions The ion channel blockers amiodarone, dronedarone and verapamil inhibit filoviral cell entry.
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Affiliation(s)
- Gerrit Gehring
- Institute for Molecular Biology, Hannover Medical School, Hannover, Germany Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Katrin Rohrmann
- Institute for Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Nkacheh Atenchong
- Institute for Molecular Biology, Hannover Medical School, Hannover, Germany Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Eva Mittler
- Institute for Virology, University of Marburg, Marburg, Germany
| | - Stephan Becker
- Institute for Virology, University of Marburg, Marburg, Germany
| | | | - Stefan Pöhlmann
- Infection Biology Unit, German Primate Center, Göttingen, Germany
| | - Florian W R Vondran
- Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
| | - Sascha David
- Department of Nephrology, Hannover Medical School, Hannover, Germany
| | - Michael P Manns
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Sandra Ciesek
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Thomas von Hahn
- Institute for Molecular Biology, Hannover Medical School, Hannover, Germany Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
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