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Ohta K, Saka N, Nishi Y, Nishio M. Nairovirus polymerase mutations associated with the establishment of persistent infection in human cells. J Virol 2024; 98:e0169823. [PMID: 38358288 PMCID: PMC10949423 DOI: 10.1128/jvi.01698-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/23/2024] [Indexed: 02/16/2024] Open
Abstract
Crimean-Congo hemorrhagic fever virus (CCHFV), a tick-borne virus of the Orthonairovirus genus, persistently infects tick cells. It has been reported to establish persistent infection in non-human primates, but virological analysis has not yet been performed in human cells. Here, we investigated whether and how nairoviruses persistently infect human cells using Hazara orthonairovirus (HAZV), a surrogate model for CCHFV. We established a human cell line that was persistently infected with HAZV. Surprisingly, virions of persistently infected HAZV (HAZVpi) were not observed in the culture supernatants. There were five mutations (mut1, mut2, mut3, mut4, and mut5) in L protein of HAZVpi. Mutations in L protein of HAZVpi contribute to non-detection of virion in the supernatants. Lmut4 was found to cause low viral growth rate, despite its high polymerase activity. The low growth rate was restored by Lmut2, Lmut3, and Lmut5. The polymerase activity of Lmut1 was extremely low, and recombinant HAZV carrying Lmut1 (rHAZV/Lmut1) was not released into the supernatants. However, genomes of rHAZV/Lmut1 were retained in the infected cells. All mutations (Lmut1-5) found in L protein of HAZVpi were required for experimental reproduction of HAZVpi, and only Lmut1 and Lmut4 were insufficient. We demonstrated that point mutations in viral polymerase contribute to the establishment of persistent HAZV infection. Furthermore, innate immunity was found to be suppressed in HAZVpi-infected cells, which also potentially contributes to viral persistence. This is the first presentation of a possible mechanism behind how nairoviruses establish persistent infection in human cells. IMPORTANCE We investigated whether and how nairoviruses persistently infect human cells, using Hazara orthonairovirus (HAZV), a surrogate model for Crimean-Congo hemorrhagic fever virus. We established a human cell line that was persistently infected with HAZV. Five mutations were found in L protein of persistently infected HAZV (HAZVpi): mut1, mut2, mut3, mut4, and mut5. Among them, Lmut1 and Lmut4 restricted viral growth by low polymerase activity and low growth rate, respectively, leading to inhibition of viral overgrowth. The restriction of viral growth caused by Lmut1 and Lmut4 was compensated by other mutations, including Lmut2, Lmut3, and Lmut5. Each of the mutations found in L protein of HAZVpi was concluded to cooperatively modulate viral growth, which facilitates the establishment of persistent infection. Suppression of innate immunity also potentially contributes to virus persistence. This is the first presentation of a possible mechanism behind how nairoviruses establish persistent infection in human cells.
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Affiliation(s)
- Keisuke Ohta
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Naoki Saka
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Yuzuha Nishi
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Machiko Nishio
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
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Taniguchi S, Maruyama J, Saito T, Littlefield K, Reyna RA, Manning JT, Huang C, Saijo M, Paessler S. Development of reverse genetics system for Guanarito virus: substitution of E1497K in the L protein of Guanarito virus S-26764 strain changes plaque phenotype and growth kinetics. J Virol 2024; 98:e0196423. [PMID: 38289100 PMCID: PMC10878084 DOI: 10.1128/jvi.01964-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 12/21/2023] [Indexed: 02/16/2024] Open
Abstract
Guanarito virus (GTOV) is the causative agent of Venezuelan hemorrhagic fever. GTOV belongs to the genus Mammarenavirus, family Arenaviridae and has been classified as a Category A bioterrorism agent by the United States Centers for Disease Control and Prevention. Despite being a high-priority agent, vaccines and drugs against Venezuelan hemorrhagic fever are not available. GTOV S-26764, isolated from a non-fatal human case, produces an unclear cytopathic effect (CPE) in Vero cells, posing a significant obstacle to research and countermeasure development efforts. Vero cell-adapted GTOV S-26764 generated in this study produced clear CPE and demonstrated rapid growth and high yield in Vero cells compared to the original GTOV S-26764. We developed a reverse genetics system for GTOV to study amino acid changes acquired through Vero cell adaptation and leading to virus phenotype changes. The results demonstrated that E1497K in the L protein was responsible for the production of clear plaques as well as enhanced viral RNA replication and transcription efficiency. Vero cell-adapted GTOV S-26764, capable of generating CPE, will allow researchers to easily perform neutralization assays and anti-drug screening against GTOV. Moreover, the developed reverse genetics system will accelerate vaccine and antiviral drug development.IMPORTANCEGuanarito virus (GTOV) is a rodent-borne virus. GTOV causes fever, prostration, headache, arthralgia, cough, sore throat, nausea, vomiting, diarrhea, epistaxis, bleeding gums, menorrhagia, and melena in humans. The lethality rate is 23.1% or higher. Vero cell-adapted GTOV S-26764 shows a clear cytopathic effect (CPE), whereas the parental virus shows unclear CPE in Vero cells. We generated a reverse genetics system to rescue recombinant GTOVs and found that E1497K in the L protein was responsible for the formation of clear plaques as well as enhanced viral RNA replication and transcription efficiency. This reverse genetic system will accelerate vaccine and antiviral drug developments, and the findings of this study contribute to the understanding of the function of GTOV L as an RNA polymerase.
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Affiliation(s)
- Satoshi Taniguchi
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Virology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Junki Maruyama
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Takeshi Saito
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Kirsten Littlefield
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Rachel A. Reyna
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - John T. Manning
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Cheng Huang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Masayuki Saijo
- Department of Virology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Slobodan Paessler
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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Jain S, Shrivastava-Ranjan P, Flint M, Montgomery JM, Spiropoulou CF, Albariño CG. Development of reverse genetic tools to study Chapare and Machupo viruses. Virology 2023; 588:109888. [PMID: 37774602 DOI: 10.1016/j.virol.2023.109888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
Arenaviruses are highly pathogenic viruses that pose a serious public health threat. Chapare virus (CHAV) and Machupo virus (MACV), two New World arenaviruses, cause hemorrhagic fevers with case fatality rates of up to 45%. Research on therapeutic drug targets and vaccines for these viruses is limited because biosafety level 4 containment is required for handling them. In this study, we developed reverse genetics systems, including minigenomes and recombinant viruses, that will facilitate the study of these pathogens. The minigenome system is based on the S segment of CHAV or MACV genomes expressing the fluorescent reporter gene ZsGreen (ZsG). We also generated recombinant CHAV and MACV with and without the ZsG reporter gene. As a proof-of-concept study, we used both minigenomes and recombinant viruses to test the inhibitory effects of previously reported antiviral compounds. The new reverse genetics system described here will facilitate future therapeutic studies for these two life-threatening arenaviruses.
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Affiliation(s)
- Shilpi Jain
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Punya Shrivastava-Ranjan
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Mike Flint
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Joel M Montgomery
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Christina F Spiropoulou
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - César G Albariño
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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Hamele CE, Spurrier MA, Leonard RA, Heaton NS. Segmented, Negative-Sense RNA Viruses of Humans: Genetic Systems and Experimental Uses of Reporter Strains. Annu Rev Virol 2023; 10:261-282. [PMID: 37774125 DOI: 10.1146/annurev-virology-111821-120445] [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] [Indexed: 10/01/2023]
Abstract
Negative-stranded RNA viruses are a large group of viruses that encode their genomes in RNA across multiple segments in an orientation antisense to messenger RNA. Their members infect broad ranges of hosts, and there are a number of notable human pathogens. Here, we examine the development of reverse genetic systems as applied to these virus families, emphasizing conserved approaches illustrated by some of the prominent members that cause significant human disease. We also describe the utility of their genetic systems in the development of reporter strains of the viruses and some biological insights made possible by their use. To conclude the review, we highlight some possible future uses of reporter viruses that not only will increase our basic understanding of how these viruses replicate and cause disease but also could inform the development of new approaches to therapeutically intervene.
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Affiliation(s)
- Cait E Hamele
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA;
| | - M Ariel Spurrier
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA;
| | - Rebecca A Leonard
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA;
| | - Nicholas S Heaton
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA;
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA
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5
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Wen Y, Xu H, Wan W, Shang W, Jin R, Zhou F, Mei H, Wang J, Xiao G, Chen H, Wu X, Zhang L. Visualizing lymphocytic choriomeningitis virus infection in cells and living mice. iScience 2022; 25:105090. [PMID: 36185356 PMCID: PMC9519613 DOI: 10.1016/j.isci.2022.105090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/31/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
Mammarenavirus are a large family of enveloped negative-strand RNA viruses that include several agents responsible for severe hemorrhagic fevers. Until now, no FDA-licensed drug has been admitted for treating an arenavirus infection, and only few effective anti-arenavirus drugs have been tested in vivo. In this work, we designed a recombinant reporter arenavirus lymphocytic choriomeningitis virus that stably expressed nanoluciferase (LCMV-Nluc). The LCMV-Nluc was proved to share similar biological properties with wild-type LCMV and the Nluc intensity reliably reflected viral replication both in vitro and in vivo. Replication of the Nluc-encoding virus in living mice can be visualized by real-time bioluminescent imaging, and bioluminescence can be detected in a variety of organs of infected mice. This work provides a novel approach that enables real-time study of the arenavirus infection and is a convenient and valuable tool for screening of compounds that are active against arenaviruses in vitro and in living mice. LCMV-Nluc was constructed and shared similar biological properties with LCMV-WT Replication of the LCMV-Nluc can be visualized by real-time bioluminescent imaging LCMV-Nluc is a valuable tool for screening antiviral compounds in vitro LCMV-Nluc is successfully applied for screening antiviral compounds in vivo
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Affiliation(s)
- Yuxi Wen
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Huan Xu
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Weiwei Wan
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Weijuan Shang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Runming Jin
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Fen Zhou
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Heng Mei
- Institute of Haematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Hubei Clinical and Research Centre of Thrombosis and Haemostasis, Wuhan, China
| | - Jingshi Wang
- Department of Hematology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Gengfu Xiao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongbo Chen
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiaoyan Wu
- Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Leike Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Hubei Jiangxia Laboratory,Wuhan 430000, China
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6
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Fénéant L, Leske A, Günther K, Groseth A. Generation of Reporter-Expressing New World Arenaviruses: A Systematic Comparison. Viruses 2022; 14:v14071563. [PMID: 35891543 PMCID: PMC9317149 DOI: 10.3390/v14071563] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/14/2022] [Accepted: 07/16/2022] [Indexed: 02/01/2023] Open
Abstract
Replication-competent reporter-expressing viruses are crucial tools in molecular virology with applications that range from antiviral screening to live-cell imaging of protein spatiotemporal dynamics. However, there is currently little information available regarding viable strategies to develop reporter-expressing arenaviruses. To address this, we used Tacaribe virus (TCRV), an apathogenic BSL2 arenavirus, to assess the feasibility of different reporter expression approaches. We first generated trisegmented TCRV viruses with either the glycoprotein (GP) or nucleoprotein (NP) replaced by a reporter (GFP, mCherry, or nanoluciferase). These viruses were all viable, but showed marked differences in brightness and attenuation. Next, we generated terminal fusions with each of the TCRV proteins (i.e., NP, GP, polymerase (L), matrix protein (Z)) either with or without a T2A self-cleavage site. We tested both the function of the reporter-fused proteins alone, and the viability of corresponding recombinant TCRVs. We successfully rescued viruses with both direct and cleavable reporter fusions at the C-terminus of Z, as well as cleavable N-terminal fusions with NP. These viruses all displayed detectable reporter activity, but were also moderately attenuated. Finally, reporter proteins were inserted into a flexible hinge region within L. These viruses were also viable and showed moderate attenuation; however, reporter expression was only detectable for the luminescent virus. These strategies provide an exciting range of new tools for research into the molecular biology of TCRV that can likely also be adapted to other arenaviruses.
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Gallo GL, López N, Loureiro ME. The Virus–Host Interplay in Junín Mammarenavirus Infection. Viruses 2022; 14:v14061134. [PMID: 35746604 PMCID: PMC9228484 DOI: 10.3390/v14061134] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 02/06/2023] Open
Abstract
Junín virus (JUNV) belongs to the Arenaviridae family and is the causative agent of Argentine hemorrhagic fever (AHF), a severe human disease endemic to agricultural areas in Argentina. At this moment, there are no effective antiviral therapeutics to battle pathogenic arenaviruses. Cumulative reports from recent years have widely provided information on cellular factors playing key roles during JUNV infection. In this review, we summarize research on host molecular determinants that intervene in the different stages of the viral life cycle: viral entry, replication, assembly and budding. Alongside, we describe JUNV tight interplay with the innate immune system. We also review the development of different reverse genetics systems and their use as tools to study JUNV biology and its close teamwork with the host. Elucidating relevant interactions of the virus with the host cell machinery is highly necessary to better understand the mechanistic basis beyond virus multiplication, disease pathogenesis and viral subversion of the immune response. Altogether, this knowledge becomes essential for identifying potential targets for the rational design of novel antiviral treatments to combat JUNV as well as other pathogenic arenaviruses.
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Fitzpatrick CJ, Mudhasani RR, Altamura LA, Campbell CE, Tran JP, Beitzel BF, Narayanan A, de la Fuente CL, Kehn-Hall K, Smith JM, Schmaljohn CS, Garrison AR. Junin Virus Activates p38 MAPK and HSP27 Upon Entry. Front Cell Infect Microbiol 2022; 12:798978. [PMID: 35463647 PMCID: PMC9022028 DOI: 10.3389/fcimb.2022.798978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/01/2022] [Indexed: 01/26/2023] Open
Abstract
Junín virus (JUNV), a New World arenavirus, is a rodent-borne virus and the causative agent of Argentine hemorrhagic fever. Humans become infected through exposure to rodent host secreta and excreta and the resulting infection can lead to an acute inflammatory disease with significant morbidity and mortality. Little is understood about the molecular pathogenesis of arenavirus hemorrhagic fever infections. We utilized Reverse Phase Protein Microarrays (RPPA) to compare global alterations in the host proteome following infection with an attenuated vaccine strain, Candid#1 (CD1), and the most parental virulent strain, XJ13, of JUNV in a human cell culture line. Human small airway epithelial cells were infected with CD1 or XJ13 at an MOI of 10, or mock infected. To determine proteomic changes at early timepoints (T = 1, 3, 8 and 24 h), the JUNV infected or mock infected cells were lysed in compatible buffers for RPPA. Out of 113 proteins that were examined by RPPA, 14 proteins were significantly altered following JUNV infection. Several proteins were commonly phosphorylated between the two strains and these correspond to entry and early replication events, to include p38 mitogen-activated protein kinase (MAPK), heat shock protein 27 (HSP27), and nuclear factor kappa B (NFκB). We qualitatively confirmed the alterations of these three proteins following infection by western blot analysis. We also determined that the inhibition of either p38 MAPK, with the small molecule inhibitor SB 203580 or siRNA knockdown, or HSP27, by siRNA knockdown, significantly decreases JUNV replication. Our data suggests that HSP27 phosphorylation at S82 upon virus infection is dependent on p38 MAPK activity. This work sheds light on the nuances of arenavirus replication.
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Affiliation(s)
- Collin J. Fitzpatrick
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Rajini R. Mudhasani
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Louis A. Altamura
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | | | - Julie P. Tran
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Brett F. Beitzel
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Aarthi Narayanan
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA, United States
| | - Cynthia L. de la Fuente
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA, United States
| | - Kylene Kehn-Hall
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA, United States
| | - Jeffrey M. Smith
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Connie S. Schmaljohn
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
| | - Aura R. Garrison
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, United States
- *Correspondence: Aura R. Garrison,
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Pyle JD, Whelan SPJ, Bloyet LM. Structure and function of negative-strand RNA virus polymerase complexes. Enzymes 2021; 50:21-78. [PMID: 34861938 DOI: 10.1016/bs.enz.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Viruses with negative-strand RNA genomes (NSVs) include many highly pathogenic and economically devastating disease-causing agents of humans, livestock, and plants-highlighted by recent Ebola and measles virus epidemics, and continuously circulating influenza virus. Because of their protein-coding orientation, NSVs face unique challenges for efficient gene expression and genome replication. To overcome these barriers, NSVs deliver a large and multifunctional RNA-dependent RNA polymerase into infected host cells. NSV-encoded polymerases contain all the enzymatic activities required for transcription and replication of their genome-including RNA synthesis and mRNA capping. Here, we review the structures and functions of NSV polymerases with a focus on key domains responsible for viral replication and gene expression. We highlight shared and unique features among polymerases of NSVs from the Mononegavirales, Bunyavirales, and Articulavirales orders.
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Affiliation(s)
- Jesse D Pyle
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States; Ph.D. Program in Virology, Harvard Medical School, Boston, MA, United States
| | - Sean P J Whelan
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
| | - Louis-Marie Bloyet
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, United States.
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Zhang X, Sun K, Liang Y, Wang S, Wu K, Li Z. Development of Rice Stripe Tenuivirus Minireplicon Reverse Genetics Systems Suitable for Analyses of Viral Replication and Intercellular Movement. Front Microbiol 2021; 12:655256. [PMID: 33833749 PMCID: PMC8021733 DOI: 10.3389/fmicb.2021.655256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/19/2021] [Indexed: 12/18/2022] Open
Abstract
Rice stripe virus (RSV), a tenuivirus with four negative-sense/ambisense genome segments, is one of the most devastating viral pathogens affecting rice production in many Asian countries. Despite extensive research, our understanding of RSV infection cycles and pathogenesis has been severely impaired by the lack of reverse genetics tools. In this study, we have engineered RSV minireplicon (MR)/minigenome cassettes with reporter genes substituted for the viral open reading frames in the negative-sense RNA1 or the ambisense RNA2-4 segments. After delivery to Nicotiana benthamiana leaves via agroinfiltration, MR reporter gene expression was detected only when the codon-optimized large viral RNA polymerase protein (L) was coexpressed with the nucleocapsid (N) protein. MR activity was also critically dependent on the coexpressed viral suppressors of RNA silencing, but ectopic expression of the RSV-encoded NS3 silencing suppressor drastically decreased reporter gene expression. We also developed intercellular movement-competent MR systems with the movement protein expressed either in cis from an RNA4-based MR or in trans from a binary plasmid. Finally, we generated multicomponent replicon systems by expressing the N and L proteins directly from complementary-sense RNA1 and RNA3 derivatives, which enhanced reporter gene expression, permitted autonomous replication and intercellular movement, and reduced the number of plasmids required for delivery. In summary, this work enables reverse genetics analyses of RSV replication, transcription, and cell-to-cell movement and provides a platform for engineering more complex recombinant systems.
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Affiliation(s)
- Xiaoyan Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Kai Sun
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Yan Liang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Shuo Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Kaili Wu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China.,Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect, Zhejiang University, Hangzhou, China.,Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Zhejiang University, Hangzhou, China
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11
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Hulswit RJG, Paesen GC, Bowden TA, Shi X. Recent Advances in Bunyavirus Glycoprotein Research: Precursor Processing, Receptor Binding and Structure. Viruses 2021; 13:353. [PMID: 33672327 PMCID: PMC7926653 DOI: 10.3390/v13020353] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 01/04/2023] Open
Abstract
The Bunyavirales order accommodates related viruses (bunyaviruses) with segmented, linear, single-stranded, negative- or ambi-sense RNA genomes. Their glycoproteins form capsomeric projections or spikes on the virion surface and play a crucial role in virus entry, assembly, morphogenesis. Bunyavirus glycoproteins are encoded by a single RNA segment as a polyprotein precursor that is co- and post-translationally cleaved by host cell enzymes to yield two mature glycoproteins, Gn and Gc (or GP1 and GP2 in arenaviruses). These glycoproteins undergo extensive N-linked glycosylation and despite their cleavage, remain associated to the virion to form an integral transmembrane glycoprotein complex. This review summarizes recent advances in our understanding of the molecular biology of bunyavirus glycoproteins, including their processing, structure, and known interactions with host factors that facilitate cell entry.
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Affiliation(s)
- Ruben J. G. Hulswit
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Guido C. Paesen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Thomas A. Bowden
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Xiaohong Shi
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G61 1QH, UK
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Foscaldi S, Loureiro ME, Sepúlveda C, Palacios C, Forlenza MB, López N. Development of a Reverse Genetic System to Generate Recombinant Chimeric Tacaribe Virus that Expresses Junín Virus Glycoproteins. Pathogens 2020; 9:pathogens9110948. [PMID: 33203040 PMCID: PMC7696886 DOI: 10.3390/pathogens9110948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 10/26/2020] [Accepted: 10/29/2020] [Indexed: 02/07/2023] Open
Abstract
Mammarenaviruses are enveloped and segmented negative-stranded RNA viruses that comprise several pathogenic members associated with severe human hemorrhagic fevers. Tacaribe virus (TCRV) is the prototype for the New World group of mammarenaviruses and is not only naturally attenuated but also phylogenetically and antigenically related to all South American pathogenic mammarenaviruses, particularly the Junín virus (JUNV), which is the etiological agent of Argentinian hemorrhagic fever (AHF). Moreover, since TCRV protects guinea pigs and non-human primates from lethal challenges with pathogenic strains of JUNV, it has already been considered as a potential live-attenuated virus vaccine candidate against AHF. Here, we report the development of a reverse genetic system that relies on T7 polymerase-driven intracellular expression of the complementary copy (antigenome) of both viral S and L RNA segments. Using this approach, we successfully recovered recombinant TCRV (rTCRV) that displayed growth properties resembling those of authentic TCRV. We also generated a chimeric recombinant TCRV expressing the JUNV glycoproteins, which propagated similarly to wild-type rTCRV. Moreover, a controlled modification within the S RNA 5′ non-coding terminal sequence diminished rTCRV propagation in a cell-type dependent manner, giving rise to new perspectives where the incorporation of additional attenuation markers could contribute to develop safe rTCRV-based vaccines against pathogenic mammarenaviruses.
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Affiliation(s)
- Sabrina Foscaldi
- Centro de Virología Animal (CEVAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428EGA, Argentina; (S.F.); (M.E.L.); (M.B.F.)
| | - María Eugenia Loureiro
- Centro de Virología Animal (CEVAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428EGA, Argentina; (S.F.); (M.E.L.); (M.B.F.)
| | - Claudia Sepúlveda
- Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires C1428EGA, Argentina;
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET- Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina
| | - Carlos Palacios
- Instituto de Ciencia y Tecnología Dr. César Milstein (CONICET-Fundación Pablo Cassará), Buenos Aires C1440FFX, Argentina;
| | - María Belén Forlenza
- Centro de Virología Animal (CEVAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428EGA, Argentina; (S.F.); (M.E.L.); (M.B.F.)
| | - Nora López
- Centro de Virología Animal (CEVAN), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires C1428EGA, Argentina; (S.F.); (M.E.L.); (M.B.F.)
- Correspondence:
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Abstract
Tacaribe virus (TCRV) is the prototype of the New World arenaviruses (also known as TCRV serocomplex viruses). While TCRV is not itself a human pathogen, many closely related members of this group cause hemorrhagic fever, and thus TCRV has long served as an important BSL2 system for research into diverse areas of arenavirus biology. Due to its widespread use, a coding-complete sequence for both the S and L segments of the bipartite genome has been publically available for almost 30 years. However, more recently, this sequence has been found to contain significant discrepancies compared to other samples of the same original strain (i.e., TRVL-11573). Further, it is incomplete with respect to the genome ends, which contain critical regulatory elements for RNA synthesis. In order to rectify these issues we now present the first complete genome sequence for this important prototype arenavirus. In addition to completing the S segment 5’ end, we identified an apparent error in the L segment 3’ end as well as substantial discrepancies in the S segment intergenic region likely to affect folding. Comparison of this sequence with existing partial sequences confirmed a 12-amino-acid deletion in GP, including putative glycosylation sites, and a 4-amino-acid exchange flanking the exonuclease domain of NP. Accounting for these corrections, the TRVL-11573 strain appears to be nearly identical to that isolated in Florida in 2012. The availability of this information provides a solid basis for future molecular and genetic work on this important prototype arenavirus.
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Klitting R, Mehta SB, Oguzie JU, Oluniyi PE, Pauthner MG, Siddle KJ, Andersen KG, Happi CT, Sabeti PC. Lassa Virus Genetics. Curr Top Microbiol Immunol 2020. [PMID: 32418034 DOI: 10.1007/82_2020_212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In a pattern repeated across a range of ecological niches, arenaviruses have evolved a compact four-gene genome to orchestrate a complex life cycle in a narrow range of susceptible hosts. A number of mammalian arenaviruses cross-infect humans, often causing a life-threatening viral hemorrhagic fever. Among this group of geographically bound zoonoses, Lassa virus has evolved a unique niche that leads to significant and sustained human morbidity and mortality. As a biosafety level 4 pathogen, direct study of the pathogenesis of Lassa virus is limited by the sparse availability, high operating costs, and technical restrictions of the high-level biocontainment laboratories required for safe experimentation. In this chapter, we introduce the relationship between genome structure and the life cycle of Lassa virus and outline reverse genetic approaches used to probe and describe functional elements of the Lassa virus genome. We then review the tools used to obtain viral genomic sequences used for phylogeny and molecular diagnostics, before shifting to a population perspective to assess the contributions of phylogenetic analysis in understanding the evolution and ecology of Lassa virus in West Africa. We finally consider the future outlook and clinical applications for genetic study of Lassa virus.
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Affiliation(s)
- Raphaëlle Klitting
- Department of Immunology and Microbiology, The Scripps Research Institute , La Jolla, CA, USA
| | - Samar B Mehta
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Judith U Oguzie
- African Center of Excellence for Genomics of Infectious Diseases (ACEGID), Redeemer's University, Ede, Osun State, Nigeria
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemers University, Ede, Osun State, Nigeria
| | - Paul E Oluniyi
- African Center of Excellence for Genomics of Infectious Diseases (ACEGID), Redeemer's University, Ede, Osun State, Nigeria
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemers University, Ede, Osun State, Nigeria
| | - Matthias G Pauthner
- Department of Immunology and Microbiology, The Scripps Research Institute , La Jolla, CA, USA
| | | | - Kristian G Andersen
- Department of Immunology and Microbiology, The Scripps Research Institute , La Jolla, CA, USA.
| | - Christian T Happi
- African Center of Excellence for Genomics of Infectious Diseases (ACEGID), Redeemer's University, Ede, Osun State, Nigeria
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemers University, Ede, Osun State, Nigeria
| | - Pardis C Sabeti
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Center for Systems Biology, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
- Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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15
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The Glycoprotein of the Live-Attenuated Junin Virus Vaccine Strain Induces Endoplasmic Reticulum Stress and Forms Aggregates prior to Degradation in the Lysosome. J Virol 2020; 94:JVI.01693-19. [PMID: 31996435 DOI: 10.1128/jvi.01693-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/24/2020] [Indexed: 01/10/2023] Open
Abstract
Argentine hemorrhagic fever is a potentially lethal disease that is caused by Junin virus (JUNV). There are currently around 5 million individuals at risk of infection within regions of endemicity in Argentina. The live attenuated vaccine strain Candid #1 (Can) is approved for use in regions of endemicity and has substantially decreased the number of annual Argentine hemorrhagic fever (AHF) cases. The glycoprotein (GPC) gene is primarily responsible for attenuation of the Can strain, and we have shown that the absence of an N-linked glycosylation motif in the subunit G1 of the glycoprotein complex of Can, which is otherwise present in the wild-type pathogenic JUNV, causes GPC retention in the endoplasmic reticulum (ER). Here, we show that Can GPC aggregates in the ER of infected cells, forming incorrect cross-chain disulfide bonds, which results in impaired GPC processing into G1 and G2. The GPC fails to cleave into its G1 and G2 subunits and is targeted for degradation within lysosomes. Cells infected with the wild-type Romero (Rom) strain do not produce aggregates that are observed in Can infection, and the stress on the ER remains minimal. While the mutation of the N-linked glycosylation motif (T168A) is primarily responsible for the formation of aggregates, other mutations within G1 that occurred earlier in the passage history of the Can strain also contribute to aggregation of the GPC within the ER.IMPORTANCE The development of vaccines and therapeutics to combat viral hemorrhagic fevers remains a top priority within the Implementation Plan of the U.S. Department of Health and Human Services Public Health Emergency Medical Countermeasures Enterprise. The Can strain, derived from the pathogenic XJ strain of JUNV, has been demonstrated to be both safe and protective against AHF. While the vaccine strain is approved for use in regions of endemicity within Argentina, the mechanisms of Can attenuation have not been elucidated. A better understanding of the viral genetic determinants of attenuation will improve our understanding of the mechanisms contributing to disease pathogenesis and provide critical information for the rational design of live attenuated vaccine candidates for other viral hemorrhagic fevers.
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Beitzel B, Hulseberg CE, Palacios G. Reverse genetics systems as tools to overcome the genetic diversity of Lassa virus. Curr Opin Virol 2019; 37:91-96. [PMID: 31357141 DOI: 10.1016/j.coviro.2019.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 11/17/2022]
Abstract
Lassa virus is endemic in a large area of sub-Saharan Africa, and exhibits a large amount of genetic diversity. Of the four currently recognized lineages, lineages I-III circulate in Nigeria, and lineage IV circulates in Sierra Leone, Guinea, and Liberia. However, several newly detected lineages have been proposed. LASV genetic diversity may result in differences in pathogenicity or response to medical countermeasures, necessitating the testing of multiple lineages during the development of countermeasures and diagnostics. Logistical and biosafety concerns can make it difficult to obtain representative collections of divergent LASV clades for comparison studies. For example, lack of a cold chain in remote areas, or shipping restrictions on live viruses can prevent the dissemination of natural virus isolates to researchers. Reverse genetics systems that have been developed for LASV can facilitate acquisition of hard-to-obtain LASV strains and enable comprehensive development of medical countermeasures.
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Affiliation(s)
- Brett Beitzel
- Center for Genome Sciences, The United States Army Medical Research Institute for Infectious Disease, 1425 Porter St., Ft. Detrick, MD 21702, United States
| | - Christine E Hulseberg
- Center for Genome Sciences, The United States Army Medical Research Institute for Infectious Disease, 1425 Porter St., Ft. Detrick, MD 21702, United States
| | - Gustavo Palacios
- Center for Genome Sciences, The United States Army Medical Research Institute for Infectious Disease, 1425 Porter St., Ft. Detrick, MD 21702, United States.
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Wendt L, Bostedt L, Hoenen T, Groseth A. High-throughput screening for negative-stranded hemorrhagic fever viruses using reverse genetics. Antiviral Res 2019; 170:104569. [PMID: 31356830 DOI: 10.1016/j.antiviral.2019.104569] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/28/2019] [Accepted: 07/25/2019] [Indexed: 02/06/2023]
Abstract
Viral hemorrhagic fevers (VHFs) cause thousands of fatalities every year, but the treatment options for their management remain very limited. In particular, the development of therapeutic interventions is restricted by the lack of commercial viability of drugs targeting individual VHF agents. This makes approaches like drug repurposing and/or the identification of broad range therapies (i.e. those directed at host responses or common proviral factors) highly attractive. However, the identification of candidates for such antiviral repurposing or of host factors/pathways important for the virus life cycle is reliant on high-throughput screening (HTS). Recently, such screening work has been increasingly facilitated by the availability of reverse genetics-based approaches, including tools such as full-length clone (FLC) systems to generate reporter-expressing viruses or various life cycle modelling (LCM) systems, many of which have been developed and/or greatly improved during the last years. In particular, since LCM systems are capable of modelling specific steps in the life cycle, they are a valuable tool for both targeted screening (i.e. for inhibitors of a specific pathway) and mechanism of action studies. This review seeks to summarize the currently available reverse genetics systems for negative-sense VHF causing viruses (i.e. arenaviruses, bunyaviruses and filoviruses), and to highlight the recent advancements made in applying these systems for HTS to identify either antivirals or new virus-host interactions that might hold promise for the development of future treatments for the infections caused by these deadly but neglected virus groups.
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Affiliation(s)
- Lisa Wendt
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Linus Bostedt
- Junior Research Group - Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany
| | - Thomas Hoenen
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
| | - Allison Groseth
- Junior Research Group - Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
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Dunham EC, Leske A, Shifflett K, Watt A, Feldmann H, Hoenen T, Groseth A. Lifecycle modelling systems support inosine monophosphate dehydrogenase (IMPDH) as a pro-viral factor and antiviral target for New World arenaviruses. Antiviral Res 2018; 157:140-150. [PMID: 30031760 PMCID: PMC11099991 DOI: 10.1016/j.antiviral.2018.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/14/2018] [Accepted: 07/16/2018] [Indexed: 12/24/2022]
Abstract
Infection with Junín virus (JUNV) is currently being effectively managed in the endemic region using a combination of targeted vaccination and plasma therapy. However, the long-term sustainability of plasma therapy is unclear and similar resources are not available for other New World arenaviruses. As a result, there has been renewed interest regarding the potential of drug-based therapies. To facilitate work on this issue, we present the establishment and subsequent optimization of a JUNV minigenome system to a degree suitable for high-throughput miniaturization, thereby providing a screening platform focused solely on factors affecting RNA synthesis. Using this tool, we conducted a limited drug library screen and identified AVN-944, a non-competitive inosine monophosphate dehydrogenase (IMPDH) inhibitor, as an inhibitor of arenavirus RNA synthesis. We further developed a transcription and replication competent virus-like particle (trVLP) system based on these minigenomes and used it to screen siRNAs against IMPDH, verifying its role in supporting arenavirus RNA synthesis. The antiviral effect of AVN-944, as well as siRNA inhibition, on JUNV RNA synthesis supports that, despite playing only a minor role in the activity of ribavirin, exclusive IMPDH inhibitors may indeed have significant therapeutic potential for use against New World arenaviruses. Finally, we confirmed that AVN-944 is also active against arenavirus infection in cell culture, supporting the suitability of arenavirus lifecycle modelling systems as tools for the screening and identification, as well as the mechanistic characterization, of novel antiviral compounds.
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Affiliation(s)
- Eric C Dunham
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA.
| | - Anne Leske
- Junior Research Group Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
| | - Kyle Shifflett
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA.
| | - Ari Watt
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA.
| | - Heinz Feldmann
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA.
| | - Thomas Hoenen
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA; Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
| | - Allison Groseth
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Hamilton, MT, USA; Junior Research Group Arenavirus Biology, Friedrich-Loeffler-Institut, Greifswald, Insel Riems, Germany.
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Dukhovny A, Shlomai A, Sklan EH. The antiviral protein Viperin suppresses T7 promoter dependent RNA synthesis-possible implications for its antiviral activity. Sci Rep 2018; 8:8100. [PMID: 29802323 PMCID: PMC5970183 DOI: 10.1038/s41598-018-26516-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/11/2018] [Indexed: 12/28/2022] Open
Abstract
Viperin is a multifunctional interferon-inducible broad-spectrum antiviral protein. Viperin belongs to the S-Adenosylmethionine (SAM) superfamily of enzymes known to catalyze a wide variety of radical-mediated reactions. However, the exact mechanism by which viperin exerts its functions is still unclear. Interestingly, for many RNA viruses viperin was shown to inhibit viral RNA accumulation by interacting with different viral non-structural proteins. Here, we show that viperin inhibits RNA synthesis by bacteriophage T7 polymerase in mammalian cells. This inhibition is specific and occurs at the RNA level. Viperin expression significantly reduced T7-mediated cytoplasmic RNA levels. The data showing that viperin inhibits the bacteriophage T7 polymerase supports the conservation of viperin’s antiviral activity between species. These results highlight the possibility that viperin might utilize a broader mechanism of inhibition. Accordingly, our results suggest a novel mechanism involving polymerase inhibition and provides a tractable system for future mechanistic studies of viperin.
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Affiliation(s)
- Anna Dukhovny
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Amir Shlomai
- Department of Medicine D and the Liver Institute, Rabin Medical Center, Beilinson Hospital, Petach-Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ella H Sklan
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
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Abstract
Among the members of the Arenaviridae family, Junín virus and Lassa virus represent important human health threats generating annual outbreaks of severe human hemorrhagic fever (HF) in endemic areas of Argentina and Western Africa, respectively. Given the lack of a specific and safe chemotherapy, the search for effective antiviral compounds is a continuous demanding effort. During the last two decades, academic research studies originated important results identifying novel molecules to be considered for further in vivo characterization. This chapter summarizes experimental in vitro approaches used to determine the possible mechanism of action of these antiviral agents.
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Epistastic Interactions within the Junín Virus Envelope Glycoprotein Complex Provide an Evolutionary Barrier to Reversion in the Live-Attenuated Candid#1 Vaccine. J Virol 2017; 92:JVI.01682-17. [PMID: 29070682 DOI: 10.1128/jvi.01682-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/16/2017] [Indexed: 01/24/2023] Open
Abstract
The Candid#1 strain of Junín virus was developed using a conventional attenuation strategy of serial passage in nonhost animals and cultured cells. The live-attenuated Candid#1 vaccine is used in Argentina to protect at-risk individuals against Argentine hemorrhagic fever, but it has not been licensed in the United States. Recent studies have revealed that Candid#1 attenuation is entirely dependent on a phenylalanine-to-isoleucine substitution at position 427 in the fusion subunit (GP2) of the viral envelope glycoprotein complex (GPC), thereby raising concerns regarding the potential for reversion to virulence. In this study, we report the identification and characterization of an intragenic epistatic interaction between the attenuating F427I mutation in GP2 and a lysine-to-serine mutation at position 33 in the stable signal peptide (SSP) subunit of GPC, and we demonstrate the utility of this interaction in creating an evolutionary barrier against reversion to the pathogenic genotype. In the presence of the wild-type F427 residue, the K33S mutation abrogates the ability of ectopically expressed GPC to mediate membrane fusion at endosomal pH. This defect is rescued by the attenuating F427I mutation. We show that the recombinant Candid#1 (rCan) virus bearing K33S GPC is viable and retains its attenuated genotype under cell culture conditions that readily select for reversion in the parental rCan virus. If back-mutation to F427 offers an accessible pathway to increase fitness in rCan, reversion in K33S-GPC rCan is likely to be lethal. The epistatic interaction between K33S and F427I thus may minimize the likelihood of reversion and enhance safety in a second-generation Candid#1 vaccine.IMPORTANCE The live-attenuated Candid#1 vaccine strain of Junín virus is used to protect against Argentine hemorrhagic fever. Recent findings that a single missense mutation in the viral envelope glycoprotein complex (GPC) is responsible for attenuation raise the prospect of facile reversion to pathogenicity. Here, we characterize a genetic interaction between GPC subunits that evolutionarily forces retention of the attenuating mutation. By incorporating this secondary mutation into Candid#1 GPC, we hope to minimize the likelihood of reversion and enhance safety in a second-generation Candid#1 vaccine. A similar approach may guide the design of live-attenuated vaccines against Lassa and other arenaviral hemorrhagic fevers.
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22
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Qian S, Chen X, Sun K, Zhang Y, Li Z. Capped antigenomic RNA transcript facilitates rescue of a plant rhabdovirus. Virol J 2017; 14:113. [PMID: 28610585 PMCID: PMC5470278 DOI: 10.1186/s12985-017-0776-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 06/06/2017] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Recovery of recombinant negative-stranded RNA viruses from cloned cDNAs is an inefficient process as multiple viral components need to be delivered into cells for reconstitution of infectious entities. Previously studies have shown that authentic viral RNA termini are essential for efficient virus rescue. However, little is known about the activity of viral RNAs processed by different strategies in supporting recovery of plant negative-stranded RNA virus. METHODS In this study, we used several versions of hammerhead ribozymes and a truncated cauliflower mosaic virus 35S promoter to generate precise 5' termini of sonchus yellow net rhabdovirus (SYNV) antigenomic RNA (agRNA) derivatives. These agRNAs were co-expressed with the SYNV core proteins in Nicotiana benthamiana leaves to evaluate their efficiency in supporting fluorescent reporter gene expression from an SYNV minireplicon (MR) and rescue of full-length virus. RESULTS Optimization of hammerhead ribozyme cleavage activities led to improved SYNV MR reporter gene expression. Although the MR agRNA processed by the most active hammerhead variants is comparable to the capped, precisely transcribed agRNA in supporting MR activity, efficient recovery of recombinant SYNV was only achieved with capped agRNA. Further studies showed that the capped SYNV agRNA permitted transient expression of the nucleocapsid (N) protein, and an agRNA derivatives unable to express the N protein in cis exhibited dramatically reduced rescue efficiency. CONCLUSION Our study reveals superior activity of precisely transcribed, capped SYNV agRNAs to uncapped, hammerhead ribozyme-processed agRNAs, and suggests a cis-acting function for the N protein expressed from the capped agRNA during recovery of SYNV from plasmids.
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Affiliation(s)
- Shasha Qian
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058 China
| | - Xiaolan Chen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058 China
| | - Kai Sun
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058 China
| | - Yang Zhang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058 China
| | - Zhenghe Li
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058 China
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Manning JT, Seregin AV, Yun NE, Koma T, Huang C, Barral J, de la Torre JC, Paessler S. Absence of an N-Linked Glycosylation Motif in the Glycoprotein of the Live-Attenuated Argentine Hemorrhagic Fever Vaccine, Candid #1, Results in Its Improper Processing, and Reduced Surface Expression. Front Cell Infect Microbiol 2017; 7:20. [PMID: 28220142 PMCID: PMC5292626 DOI: 10.3389/fcimb.2017.00020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 01/16/2017] [Indexed: 11/27/2022] Open
Abstract
Junin virus (JUNV), a highly pathogenic New World arenavirus, is the causative agent of Argentine hemorrhagic fever (AHF). The live-attenuated Candid #1 (Can) strain currently serves as a vaccine for at-risk populations. We have previously shown that the Can glycoprotein (GPC) gene is the primary gene responsible for attenuation in a guinea pig model of AHF. However, the mechanisms through which the GPC contributes to the attenuation of the Can strain remain unknown. A more complete understanding of the mechanisms underlying the attenuation and immunogenicity of the Can strain will potentially allow for the rational design of additional safe and novel vaccines. Here, we provide a detailed comparison of both RNA and protein expression profiles between both inter- and intra-segment chimeric JUNV recombinant clones expressing combinations of genes from the Can strain and the pathogenic Romero (Rom) strain. The recombinant viruses that express Can GPC, which were shown to be attenuated in guinea pigs, displayed different RNA levels and GPC processing patterns as determined by Northern and Western blot analyses, respectively. Analysis of recombinant viruses containing amino acid substitutions selected at different mouse brain passages during the generation of Can revealed that altered Can GPC processing was primarily due to the T168A substitution within G1, which eliminates an N-linked glycosylation motif. Incorporation of the T168A substitution in the Rom GPC resulted in a Can-like processing pattern of Rom GPC. In addition, JUNV GPCs containing T168A substitution were retained within the endoplasmic reticulum (ER) and displayed significantly lower cell surface expression than wild-type Rom GPC. Interestingly, the reversion A168T in Can GPC significantly increased GPC expression at the cell surface. Our results demonstrate that recombinant JUNV (rJUNV) expressing Can GPC display markedly different protein expression and elevated genomic RNA expression when compared to viruses expressing Rom GPC. Additionally, our findings indicate that the N-linked glycosylation motif at amino acid positions 166–168 is important for trafficking of JUNV GPC to the cell surface, and the elimination of this motif interferes with the GPC release from the ER.
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Affiliation(s)
- John T Manning
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Alexey V Seregin
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Nadezhda E Yun
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Takaaki Koma
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Cheng Huang
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - José Barral
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Juan C de la Torre
- Department of Immunology and Microbial Science, Scripps Research Institute La Jolla, CA, USA
| | - Slobodan Paessler
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
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24
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Abstract
Lassa virus (LASV) infection is a major public health concern due to high fatality rates and limited effective treatment. The interferon-stimulated gene cholesterol 25-hydroxylase (CH25H) encodes an enzyme that catalyzes the production of 25-hydroxycholesterol (25HC). 25HC is involved in regulating cholesterol biosynthesis and has recently been identified as a potent antiviral targeting enveloped virus entry. Here, we show a previously unrecognized role of CH25H in inhibiting LASV glycoprotein glycosylation and the production of infectious virus. Overexpression of CH25H or treatment with 25HC decreased LASV G1 glycoprotein N-glycan maturation and reduced the production of infectious LASV. Depletion of endogenous CH25H using small interfering RNA (siRNA) enhanced the levels of fully glycosylated G1 and increased infectious LASV production. Finally, LASV particles produced from 25HC-treated cells were found to be less infectious, to incorporate aberrantly glycosylated GP1 species, and to be defective in binding alpha-dystroglycan, an attachment and entry receptor. Our findings identify a novel role for CH25H in controlling LASV propagation and indicate that manipulation of the expression of CH25H or the administration of 25HC may be a useful anti-LASV therapy. Lassa fever is an acute viral hemorrhagic fever in humans caused by Lassa virus (LASV). No vaccine for LASV is currently available. Treatment is limited to the administration of ribavirin, which is only effective when given early in the course of illness. Cholesterol 25-hydroxylase (CH25H) is a recently identified interferon-stimulated gene (ISG); it encodes an enzyme that catalyzes the production of 25-hydroxycholesterol (25HC), which inhibits several viruses. Here, we identify a novel antiviral mechanism of 25HC that is dependent on inhibiting the glycosylation of Lassa virus (LASV) glycoprotein and reducing the infectivity of LASV as a means of suppressing viral replication. Since N-linked glycosylation is a critical feature of other enveloped-virus glycoproteins, 25HC may be a broad inhibitor of virus infectivity.
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Reporter-Expressing, Replicating-Competent Recombinant Arenaviruses. Viruses 2016; 8:v8070197. [PMID: 27447662 PMCID: PMC4974532 DOI: 10.3390/v8070197] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/28/2016] [Accepted: 07/08/2016] [Indexed: 02/07/2023] Open
Abstract
Several arenaviruses cause hemorrhagic fever (HF) disease in humans and pose an important public health problem in their endemic regions. To date, no Food and Drug Administration (FDA)-licensed vaccines are available to combat human arenavirus infections, and current anti-arenaviral drug therapy is limited to an off-label use of ribavirin that is only partially effective. The development of arenavirus reverse genetic approaches has provided investigators with a novel and powerful approach for the study of arenavirus biology including virus–host interactions underlying arenavirus induced disease. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in arenavirus replication and transcription, as well as particle assembly and budding. Likewise, it is now feasible to rescue infectious arenaviruses containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of pathogenesis. The use of reverse genetics approaches has also allowed the generation of recombinant arenaviruses expressing additional genes of interest. These advances in arenavirus molecular genetics have also facilitated the implementation of novel screens to identify anti-arenaviral drugs, and the development of novel strategies for the generation of arenavirus live-attenuated vaccines. In this review, we will summarize the current knowledge on reporter-expressing, replicating-competent arenaviruses harboring reporter genes in different locations of the viral genome and their use for studying and understanding arenavirus biology and the identification of anti-arenaviral drugs to combat these important human pathogens.
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Martinez-Sobrido L, de la Torre JC. Novel strategies for development of hemorrhagic fever arenavirus live-attenuated vaccines. Expert Rev Vaccines 2016; 15:1113-21. [PMID: 27118328 DOI: 10.1080/14760584.2016.1182024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Several arenaviruses, chiefly Lassa virus (LASV), cause hemorrhagic fever (HF) disease in humans and pose significant public health problems in their endemic regions. Moreover, HF arenaviruses represent credible biodefense threats. There are not FDA-approved arenavirus vaccines and current anti-arenaviral therapy is limited to an off-label use of ribavirin that is only partially effective. AREAS COVERED Live-attenuated vaccines (LAV) represent the most feasible approach to control HF arenaviruses within their endemic regions. Different platforms, including recombinant viral vectors expressing LASV antigens, and the use of attenuated reassortant arenaviruses, have been used to develop LAV candidates against LASV with promising results in animal models of LASV infection, but none of them has entered a clinical trial. These vaccine efforts have been the subject of recent reviews and will not be examined in this review, which is focused on new avenues for the development of safe and effective LAV to combat HF arenaviruses. Expert commentary: The development of arenavirus reverse genetics has provided investigators with a novel powerful approach to manipulate the genomes of HF arenaviruses, which has opened new avenues for the rapid development of safe and effective LAV to combat these human pathogens.
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Affiliation(s)
- Luis Martinez-Sobrido
- a Department of Microbiology and Immunology , University of Rochester Medical Center Ringgold standard institution , Rochester , NY , USA
| | - Juan Carlos de la Torre
- b Department of Immunology and Microbial Science , The Scripps Research Institute , La Jolla , CA , USA
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Pasquato A, Kunz S. Novel drug discovery approaches for treating arenavirus infections. Expert Opin Drug Discov 2016; 11:383-93. [PMID: 26882218 DOI: 10.1517/17460441.2016.1153626] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Arenaviruses are enveloped negative stranded viruses endemic in Africa, Europe and the Americas. Several arenaviruses cause severe viral hemorrhagic fever with high mortality in humans and pose serious public health threats. So far, there are no FDA-approved vaccines and therapeutic options are restricted to the off-label use of ribavirin. The major human pathogenic arenaviruses are classified as Category A agents and require biosafety level (BSL)-4 containment. AREAS COVERED Herein, the authors cover the recent progress in the development of BSL2 surrogate systems that recapitulate the entire or specific steps of the arenavirus life cycle and are serving as powerful platforms for drug discovery. Furthermore, they highlight the identification of selected novel drugs that target individual steps of arenavirus multiplication describing their discovery, their targets, and mode of action. EXPERT OPINION The lack of effective drugs against arenaviruses is an unmatched challenge in current medical virology. Novel technologies have provided important insights into the basic biology of arenaviruses and the mechanisms underlying virus-host cell interaction. Significant progress of our understanding of how the virus invades the host cell paved the way to develop powerful novel screening platforms. Recent efforts have provided a range of promising drug candidates currently under evaluation for therapeutic intervention in vivo.
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Affiliation(s)
- Antonella Pasquato
- a Institute of Microbiology , University Hospital Center and University of Lausanne , Lausanne , Switzerland
| | - Stefan Kunz
- a Institute of Microbiology , University Hospital Center and University of Lausanne , Lausanne , Switzerland
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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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Abstract
The family Arenaviridae currently comprises over 20 viral species, each of them associated with a main rodent species as the natural reservoir and in one case possibly phyllostomid bats. Moreover, recent findings have documented a divergent group of arenaviruses in captive alethinophidian snakes. Human infections occur through mucosal exposure to aerosols or by direct contact of abraded skin with infectious materials. Arenaviruses merit interest both as highly tractable experimental model systems to study acute and persistent infections and as clinically important human pathogens including Lassa (LASV) and Junin (JUNV) viruses, the causative agents of Lassa and Argentine hemorrhagic fevers (AHFs), respectively, for which there are no FDA-licensed vaccines, and current therapy is limited to an off-label use of ribavirin (Rib) that has significant limitations. Arenaviruses are enveloped viruses with a bi-segmented negative strand (NS) RNA genome. Each genome segment, L (ca 7.3 kb) and S (ca 3.5 kb), uses an ambisense coding strategy to direct the synthesis of two polypeptides in opposite orientation, separated by a noncoding intergenic region (IGR). The S genomic RNA encodes the virus nucleoprotein (NP) and the precursor (GPC) of the virus surface glycoprotein that mediates virus receptor recognition and cell entry via endocytosis. The L genome RNA encodes the viral RNA-dependent RNA polymerase (RdRp, or L polymerase) and the small (ca 11 kDa) RING finger protein Z that has functions of a bona fide matrix protein including directing virus budding. Arenaviruses were thought to be relatively stable genetically with intra- and interspecies amino acid sequence identities of 90-95 % and 44-63 %, respectively. However, recent evidence has documented extensive arenavirus genetic variability in the field. Moreover, dramatic phenotypic differences have been documented among closely related LCMV isolates. These data provide strong evidence of viral quasispecies involvement in arenavirus adaptability and pathogenesis. Here, we will review several aspects of the molecular biology of arenaviruses, phylogeny and evolution, and quasispecies dynamics of arenavirus populations for a better understanding of arenavirus pathogenesis, as well as for the development of novel antiviral strategies to combat arenavirus infections.
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Affiliation(s)
- Esteban Domingo
- Campus de Cantoblanco, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Peter Schuster
- The Santa Fe Institute, Santa Fe, NM, USA and Institut f. Theoretische Chemie, Universität Wien, Vienna, Austria
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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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Bergeron É, Zivcec M, Chakrabarti AK, Nichol ST, Albariño CG, Spiropoulou CF. Recovery of Recombinant Crimean Congo Hemorrhagic Fever Virus Reveals a Function for Non-structural Glycoproteins Cleavage by Furin. PLoS Pathog 2015; 11:e1004879. [PMID: 25933376 PMCID: PMC4416775 DOI: 10.1371/journal.ppat.1004879] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 04/13/2015] [Indexed: 01/01/2023] Open
Abstract
Crimean Congo hemorrhagic fever virus (CCHFV) is a negative-strand RNA virus of the family Bunyaviridae (genus: Nairovirus). In humans, CCHFV causes fever, hemorrhage, severe thrombocytopenia, and high fatality. A major impediment in precisely determining the basis of CCHFV’s high pathogenicity has been the lack of methodology to produce recombinant CCHFV. We developed a reverse genetics system based on transfecting plasmids into BSR-T7/5 and Huh7 cells. In our system, bacteriophage T7 RNA polymerase produced complementary RNA copies of the viral S, M, and L segments that were encapsidated with the support, in trans, of CCHFV nucleoprotein and L polymerase. The system was optimized to systematically recover high yields of infectious CCHFV. Additionally, we tested the ability of the system to produce specifically designed CCHFV mutants. The M segment encodes a polyprotein that is processed by host proprotein convertases (PCs), including the site-1 protease (S1P) and furin-like PCs. S1P and furin cleavages are necessary for producing the non-structural glycoprotein GP38, while S1P cleavage yields structural Gn. We studied the role of furin cleavage by rescuing a recombinant CCHFV encoding a virus glycoprotein precursor lacking a functional furin cleavage motif (RSKR mutated to ASKA). The ASKA mutation blocked glycoprotein precursor’s maturation to GP38, and Gn precursor’s maturation to Gn was slightly diminished. Furin cleavage was not essential for replication, as blocking furin cleavage resulted only in transient reduction of CCHFV titers, suggesting that either GP38 and/or decreased Gn maturation accounted for the reduced virion production. Our data demonstrate that nairoviruses can be produced by reverse genetics, and the utility of our system uncovered a function for furin cleavage. This viral rescue system could be further used to study the CCHFV replication cycle and facilitate the development of efficacious vaccines to counter this biological and public health threat. Crimean Congo hemorrhagic fever (CCHF) is a severe viral disease characterized by rapid-onset fever, hemorrhage, and high case fatality rates. CCHF virus (CCHFV), the causative agent of CCHF, is a negative-strand RNA virus of the family Bunyaviridae (genus Nairovirus). No specific treatments or efficacious vaccines exist to combat CCHF. To investigate molecular determinants of nairovirus pathogenesis and biology, we developed a reverse genetics system capable of generating CCHFV variants with genome sequences defined by the plasmids transfected into cells for virus recovery. Our system is the first to demonstrate that a nairovirus can be efficiently recovered from the simple transfection of plasmid DNA, paving the way for specifically editing genomes of CCHFV and other nairoviruses. Using this system, we engineered mutations blocking the cleavage of CCHFV’s non-structural glycoproteins at a motif recognized by the host protease furin. Using this furin-resistant CCHFV variant, we demonstrate that direct cleavage of the viral glycoprotein by furin results in a lag in virion production, revealing a function of these glycoproteins in efficient CCHFV replication. Our experiments highlight the utility of a reverse genetics system for developing viral variants for investigating CCHFV protein function and for rationally designing vaccine strains.
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Affiliation(s)
- Éric Bergeron
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
| | - Marko Zivcec
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ayan K. Chakrabarti
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Stuart T. Nichol
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - César G. Albariño
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Christina F. Spiropoulou
- Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Kell AM, Gale M. RIG-I in RNA virus recognition. Virology 2015; 479-480:110-21. [PMID: 25749629 PMCID: PMC4424084 DOI: 10.1016/j.virol.2015.02.017] [Citation(s) in RCA: 299] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 01/16/2015] [Accepted: 02/10/2015] [Indexed: 02/07/2023]
Abstract
Antiviral immunity is initiated upon host recognition of viral products via non-self molecular patterns known as pathogen-associated molecular patterns (PAMPs). Such recognition initiates signaling cascades that induce intracellular innate immune defenses and an inflammatory response that facilitates development of the acquired immune response. The retinoic acid-inducible gene I (RIG-I) and the RIG-I-like receptor (RLR) protein family are key cytoplasmic pathogen recognition receptors that are implicated in the recognition of viruses across genera and virus families, including functioning as major sensors of RNA viruses, and promoting recognition of some DNA viruses. RIG-I, the charter member of the RLR family, is activated upon binding to PAMP RNA. Activated RIG-I signals by interacting with the adapter protein MAVS leading to a signaling cascade that activates the transcription factors IRF3 and NF-κB. These actions induce the expression of antiviral gene products and the production of type I and III interferons that lead to an antiviral state in the infected cell and surrounding tissue. RIG-I signaling is essential for the control of infection by many RNA viruses. Recently, RIG-I crosstalk with other pathogen recognition receptors and components of the inflammasome has been described. In this review, we discuss the current knowledge regarding the role of RIG-I in recognition of a variety of virus families and its role in programming the adaptive immune response through cross-talk with parallel arms of the innate immune system, including how RIG-I can be leveraged for antiviral therapy. RIG-I is a cytosolic pathogen recognition receptor. RIG-I binds to PAMP RNA. RIG-I initiates the immune response to RNA virus infection.
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Affiliation(s)
- Alison M Kell
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington School of Medicine, Seattle, WA, USA
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington School of Medicine, Seattle, WA, USA.
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Weber M, Weber F. RIG-I-like receptors and negative-strand RNA viruses: RLRly bird catches some worms. Cytokine Growth Factor Rev 2014; 25:621-8. [PMID: 24894317 PMCID: PMC7108359 DOI: 10.1016/j.cytogfr.2014.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/12/2014] [Indexed: 12/16/2022]
Abstract
Negative strand RNA viruses with a nonsegmented genome (ns-NSVs) or a segmented genome (s-NSVs) are an important source of human and animal diseases. Survival of the host from those infections is critically dependent on rapidly reacting innate immune responses. Two cytoplasmic RNA helicases, RIG-I and MDA5 (collectively termed RIG-I-like receptors, RLRs), are essential for recognizing virus-specific RNA structures to initiate a signalling cascade, resulting in the production of the antiviral type I interferons. Here, we will review the current knowledge and views on RLR agonists, RLR signalling, and the wide variety of countermeasures ns-NSVs and s-NSVs have evolved. Specific aspects include the consequences of genome segmentation for RLR activation and a discussion on the physiological ligands of RLRs.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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Weber M, Weber F. Segmented negative-strand RNA viruses and RIG-I: divide (your genome) and rule. Curr Opin Microbiol 2014; 20:96-102. [PMID: 24930021 DOI: 10.1016/j.mib.2014.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/02/2014] [Accepted: 05/11/2014] [Indexed: 11/18/2022]
Abstract
The group of negative-stranded RNA viruses (NSVs) with a segmented genome comprises pathogens like influenza virus (eight segments), Rift Valley fever virus and Hantavirus (three segments), or Lassa virus (two segments). Partitioning the genome allows rapid evolution of new strains by reassortment. Each segment carries a short double-stranded (ds) 'panhandle' structure which serves as promoter. Similar dsRNA structures, however, represent the optimal ligand for RIG-I, a cytoplasmic pathogen sensor of the antiviral interferon response. Thus, segmenting a virus genome can entail an increased RIG-I sensitivity. Here, we outline the astonishingly diverse and efficient strategies by which segmented NSVs are compensating for the elevated number of RIG-I ligands in their genome.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany.
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Abstract
UNLABELLED Several arenaviruses are known to cause viral hemorrhagic fever (VHF) in sub-Saharan Africa and South America, where VHF is a major public health and medical concern. The biosafety level 4 categorization of these arenaviruses restricts their use and has impeded biological studies, including therapeutic drug and/or vaccine development. Due to difficulties associated with handling live viruses, pseudotype viruses, which transiently bear arenavirus envelope proteins based on vesicular stomatitis virus (VSV) or retrovirus, have been developed as surrogate virus systems. Here, we report the development of a pseudotype VSV bearing each envelope protein of various species of arenaviruses (AREpv), including the newly identified Lujo virus (LUJV) and Chapare virus. Pseudotype arenaviruses generated in 293T cells exhibited high infectivity in various mammalian cell lines. The infections by New World and Old World AREpv were dependent on their receptors (human transferrin receptor 1 [hTfR1] and α-dystroglycan [αDG], respectively). However, infection by pseudotype VSV bearing the LUJV envelope protein (LUJpv) occurred independently of hTfR1 and αDG, indicating that LUJpv utilizes an unidentified receptor. The pH-dependent endocytosis of AREpv was confirmed by the use of lysosomotropic agents. The fusion of cells expressing these envelope proteins, except for those expressing the LUJV envelope protein, was induced by transient treatment at low pH values. LUJpv infectivity was inhibited by U18666A, a cholesterol transport inhibitor. Furthermore, the infectivity of LUJpv was significantly decreased in the Niemann-Pick C1 (NPC1)-deficient cell line, suggesting the necessity for NPC1 activity for efficient LUJpv infection. IMPORTANCE LUJV is a newly identified arenavirus associated with a VHF outbreak in southern Africa. Although cell entry for many arenaviruses has been studied, cell entry for LUJV has not been characterized. In this study, we found that LUJpv utilizes neither αDG nor hTfR1 as a receptor and found unique characteristics of LUJV glycoprotein in membrane fusion and cell entry. Proper exclusion of cholesterol or some kinds of lipids may play important roles in LUJpv cell entry.
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Patterson M, Seregin A, Huang C, Kolokoltsova O, Smith J, Miller M, Smith J, Yun N, Poussard A, Grant A, Tigabu B, Walker A, Paessler S. Rescue of a recombinant Machupo virus from cloned cDNAs and in vivo characterization in interferon (αβ/γ) receptor double knockout mice. J Virol 2014; 88:1914-23. [PMID: 24284323 PMCID: PMC3911560 DOI: 10.1128/jvi.02925-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/20/2013] [Indexed: 11/20/2022] Open
Abstract
Machupo virus (MACV) is the etiological agent of Bolivian hemorrhagic fever (BHF), a reemerging and neglected tropical disease associated with high mortality. The prototypical strain of MACV, Carvallo, was isolated from a human patient in 1963, but minimal in vitro and in vivo characterization has been reported. To this end, we utilized reverse genetics to rescue a pathogenic MACV from cloned cDNAs. The recombinant MACV (rMACV) had in vitro growth properties similar to those of the parental MACV. Both viruses caused similar disease development in alpha/beta and gamma interferon receptor knockout mice, including neurological disease development and high mortality. In addition, we have identified a novel murine model with mortality and neurological disease similar to BHF disease reported in humans and nonhuman primates.
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MESH Headings
- Analysis of Variance
- Animals
- Arenaviruses, New World/genetics
- Base Sequence
- Cell Line
- Chlorocebus aethiops
- Cricetinae
- DNA Primers/genetics
- DNA, Complementary/genetics
- Disease Models, Animal
- Hemorrhagic Fever, American/genetics
- Histological Techniques
- Mice
- Mice, Knockout
- Molecular Sequence Data
- Plasmids/genetics
- Receptor, Interferon alpha-beta/deficiency
- Receptor, Interferon alpha-beta/genetics
- Receptors, Interferon/deficiency
- Receptors, Interferon/genetics
- Reverse Genetics/methods
- Sequence Analysis, RNA
- Vero Cells
- Interferon gamma Receptor
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Affiliation(s)
- Michael Patterson
- Galveston National Laboratory, Department of Pathology, Sealy Vaccine Center, University of Texas Medical Branch, Galveston, Texas, USA
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Albariño CG, Uebelhoer LS, Vincent JP, Khristova ML, Chakrabarti AK, McElroy A, Nichol ST, Towner JS. Development of a reverse genetics system to generate recombinant Marburg virus derived from a bat isolate. Virology 2013; 446:230-7. [PMID: 24074586 DOI: 10.1016/j.virol.2013.07.038] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 07/24/2013] [Accepted: 07/30/2013] [Indexed: 11/30/2022]
Abstract
Recent investigations have shown the Egyptian fruit bat (Rousettus aegyptiacus) to be a natural reservoir for marburgviruses. To better understand the life cycle of these viruses in the natural host, a new reverse genetics system was developed for the reliable rescue of a Marburg virus (MARV) originally isolated directly from a R. aegyptiacus bat (371Bat). To develop this system, the exact terminal sequences were first determined by 5' and 3' RACE, followed by the cloning of viral proteins NP, VP35, VP30 and L into expression plasmids. Novel conditions were then developed to efficiently replicate virus mini-genomes followed by the construction of full-length genomic clones from which recombinant wild type and GFP-containing MARVs were rescued. Surprisingly, when these recombinant MARVs were propagated in primary human macrophages, a dramatic difference was found in their ability to grow and to elicit anti-viral cytokine responses.
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Affiliation(s)
- César G Albariño
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
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Pasquato A, Burri DJ, Kunz S. Current drug discovery strategies against arenavirus infections. Expert Rev Anti Infect Ther 2013; 10:1297-309. [PMID: 23241187 DOI: 10.1586/eri.12.117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Arenaviruses are a large group of emerging viruses including several causative agents of severe hemorrhagic fevers with high mortality in man. Considering the number of people affected and the currently limited therapeutic options, novel efficacious therapeutics against arenaviruses are urgently needed. Over the past decade, significant advances in knowledge about the basic virology of arenaviruses have been accompanied by the development of novel therapeutics targeting different steps of the arenaviral life cycle. High-throughput, small-molecule screens identified potent and broadly active inhibitors of arenavirus entry that were instrumental for the dissection of unique features of arenavirus fusion. Novel inhibitors of arenavirus replication have been successfully tested in animal models and hold promise for application in humans. Late in the arenavirus life cycle, the proteolytic processing of the arenavirus envelope glycoprotein precursor and cellular factors critically involved virion assembly and budding provide further promising 'druggable' targets for novel therapeutics to combat human arenavirus infection.
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Affiliation(s)
- Antonella Pasquato
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland
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Arenavirus budding: a common pathway with mechanistic differences. Viruses 2013; 5:528-49. [PMID: 23435234 PMCID: PMC3640512 DOI: 10.3390/v5020528] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 01/17/2013] [Accepted: 01/18/2013] [Indexed: 11/17/2022] Open
Abstract
The Arenaviridae is a diverse and growing family of viruses that includes several agents responsible for important human diseases. Despite the importance of this family for public health, particularly in Africa and South America, much of its biology remains poorly understood. However, in recent years significant progress has been made in this regard, particularly relating to the formation and release of new enveloped virions, which is an essential step in the viral lifecycle. While this process is mediated chiefly by the viral matrix protein Z, recent evidence suggests that for some viruses the nucleoprotein (NP) is also required to enhance the budding process. Here we highlight and compare the distinct budding mechanisms of different arenaviruses, concentrating on the role of the matrix protein Z, its known late domain sequences, and the involvement of cellular endosomal sorting complex required for transport (ESCRT) pathway components. Finally we address the recently described roles for the nucleoprotein NP in budding and ribonucleoprotein complex (RNP) incorporation, as well as discussing possible mechanisms related to its involvement.
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Ortiz-Riaño E, Cheng BYH, Carlos de la Torre J, Martínez-Sobrido L. Arenavirus reverse genetics for vaccine development. J Gen Virol 2013; 94:1175-1188. [PMID: 23364194 DOI: 10.1099/vir.0.051102-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Arenaviruses are important human pathogens with no Food and Drug Administration (FDA)-licensed vaccines available and current antiviral therapy being limited to an off-label use of the nucleoside analogue ribavirin of limited prophylactic efficacy. The development of reverse genetics systems represented a major breakthrough in arenavirus research. However, rescue of recombinant arenaviruses using current reverse genetics systems has been restricted to rodent cells. In this study, we describe the rescue of recombinant arenaviruses from human 293T cells and Vero cells, an FDA-approved line for vaccine development. We also describe the generation of novel vectors that mediate synthesis of both negative-sense genome RNA and positive-sense mRNA species of lymphocytic choriomeningitis virus (LCMV) directed by the human RNA polymerases I and II, respectively, within the same plasmid. This approach reduces by half the number of vectors required for arenavirus rescue, which could facilitate virus rescue in cell lines approved for human vaccine production but that cannot be transfected at high efficiencies. We have shown the feasibility of this approach by rescuing both the Old World prototypic arenavirus LCMV and the live-attenuated vaccine Candid#1 strain of the New World arenavirus Junín. Moreover, we show the feasibility of using these novel strategies for efficient rescue of recombinant tri-segmented both LCMV and Candid#1.
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Affiliation(s)
- Emilio Ortiz-Riaño
- Department of Microbiology and Immunology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Benson Yee Hin Cheng
- Department of Microbiology and Immunology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Juan Carlos de la Torre
- Department of Immunology and Microbial Science, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Biochemical reconstitution of hemorrhagic-fever arenavirus envelope glycoprotein-mediated membrane fusion. PLoS One 2012; 7:e51114. [PMID: 23226473 PMCID: PMC3511403 DOI: 10.1371/journal.pone.0051114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 10/16/2012] [Indexed: 11/19/2022] Open
Abstract
The membrane-anchored proteins of enveloped viruses form labile spikes on the virion surface, primed to undergo large-scale conformational changes culminating in virus-cell membrane fusion and viral entry. The prefusion form of these envelope glycoproteins thus represents an important molecular target for antiviral intervention. A critical roadblock to this endeavor has been our inability to produce the prefusion envelope glycoprotein trimer for biochemical and structural analysis. Through our studies of the GPC envelope glycoprotein of the hemorrhagic fever arenaviruses, we have shown that GPC is unique among class I viral fusion proteins in that the mature complex retains a stable signal peptide (SSP) in addition to the conventional receptor-binding and transmembrane fusion subunits. In this report we show that the recombinant GPC precursor can be produced as a discrete native-like trimer and that its proteolytic cleavage generates the mature glycoprotein. Proteoliposomes containing the cleaved GPC mediate pH-dependent membrane fusion, a characteristic feature of arenavirus entry. This reaction is inhibited by arenavirus-specific monoclonal antibodies and small-molecule fusion inhibitors. The in vitro reconstitution of GPC-mediated membrane-fusion activity offers unprecedented opportunities for biochemical and structural studies of arenavirus entry and its inhibition. To our knowledge, this report is the first to demonstrate functional reconstitution of membrane fusion by a viral envelope glycoprotein.
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Zhou X, Ramachandran S, Mann M, Popkin DL. Role of lymphocytic choriomeningitis virus (LCMV) in understanding viral immunology: past, present and future. Viruses 2012; 4:2650-69. [PMID: 23202498 PMCID: PMC3509666 DOI: 10.3390/v4112650] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 10/18/2012] [Accepted: 10/24/2012] [Indexed: 11/16/2022] Open
Abstract
Lymphocytic choriomeningitis virus (LCMV) is a common infection of rodents first identified over eighty years ago in St. Louis, MO, U.S.A. It is best known for its application in immunological studies. The history of LCMV closely correlates with the development of modern immunology. With the use of LCMV as a model pathogen several key concepts have emerged: Major Histocompatibility Complex (MHC) restriction, T cell memory, persistent infections, T cell exhaustion and the key role of immune pathology in disease. Given the phenomenal infrastructure within this field (e.g., defined immunodominant and subdominant epitopes to all T cell receptor specificities as well as the cognate tetramers for enumeration in vivo) the study of LCMV remains an active and productive platform for biological research across the globe to this day. Here we present a historical primer that highlights several breakthroughs since the discovery of LCMV. Next, we highlight current research in the field and conclude with our predictions for future directions in the remarkable field of LCMV research.
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Affiliation(s)
- Xin Zhou
- Department of Dermatology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; (X.Z.); (S.R.); (M.M.)
| | - Srividya Ramachandran
- Department of Dermatology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; (X.Z.); (S.R.); (M.M.)
| | - Margaret Mann
- Department of Dermatology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; (X.Z.); (S.R.); (M.M.)
| | - Daniel L. Popkin
- Department of Dermatology, Pathology, Microbiology & Molecular Biology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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Cleavage of the Junin virus nucleoprotein serves a decoy function to inhibit the induction of apoptosis during infection. J Virol 2012; 87:224-33. [PMID: 23077297 DOI: 10.1128/jvi.01929-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The regulation of apoptosis during infection is an important factor for host survival and, in some cases, also for the virus life cycle. At the same time, mechanisms to prevent the induction of apoptosis have been observed in numerous viral pathogens, but until now the role of apoptosis during arenavirus infection has not been investigated. Junin virus (JUNV) belongs to the New World arenavirus serogroup of the Arenaviridae and is the causative agent of Argentine hemorrhagic fever. We have demonstrated that infection with JUNV in cell culture does not induce apoptosis but leads to cleavage of the nucleoprotein (NP) into discrete products resembling caspase cleavage events. Similar specific NP degradation patterns were also observed in NP-transfected cell lines, and a closer examination of the sequence of NP showed several putative caspase cleavage motifs. Point mutations that abolished these cleavage motifs were consistent with the loss of certain cleavage products. Consistent with these data, further studies showed that treatment with a caspase inhibitor also reduced NP cleavage, indicating that the observed cleavage events were occurring as a result of caspase activity with NP as a substrate. Finally, we showed that expression of NP suppresses the cleavage of caspase 3 in cells treated with an apoptosis activator. Based on these findings, we propose that NP functions as a decoy substrate for caspase cleavage in order to inhibit the induction of apoptosis in JUNV-infected cells.
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Loureiro ME, D’Antuono A, Levingston Macleod JM, López N. Uncovering viral protein-protein interactions and their role in arenavirus life cycle. Viruses 2012; 4:1651-67. [PMID: 23170177 PMCID: PMC3499824 DOI: 10.3390/v4091651] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 09/04/2012] [Accepted: 09/10/2012] [Indexed: 11/16/2022] Open
Abstract
The Arenaviridae family includes widely distributed pathogens that cause severe hemorrhagic fever in humans. Replication and packaging of their single-stranded RNA genome involve RNA recognition by viral proteins and a number of key protein-protein interactions. Viral RNA synthesis is directed by the virus-encoded RNA dependent-RNA polymerase (L protein) and requires viral RNA encapsidation by the Nucleoprotein. In addition to the role that the interaction between L and the Nucleoprotein may have in the replication process, polymerase activity appears to be modulated by the association between L and the small multifunctional Z protein. Z is also a structural component of the virions that plays an essential role in viral morphogenesis. Indeed, interaction of the Z protein with the Nucleoprotein is critical for genome packaging. Furthermore, current evidence suggests that binding between Z and the viral envelope glycoprotein complex is required for virion infectivity, and that Z homo-oligomerization is an essential step for particle assembly and budding. Efforts to understand the molecular basis of arenavirus life cycle have revealed important details on these viral protein-protein interactions that will be reviewed in this article.
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Affiliation(s)
- Maria Eugenia Loureiro
- Centro de Virología Animal (CEVAN), Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Consejo Nacional de Ciencia y Tecnología (CONICET), Saladillo 2468, Buenos Aires C1440FFX, Argentina. (M.E.L.); (A.D.A.)
| | - Alejandra D’Antuono
- Centro de Virología Animal (CEVAN), Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Consejo Nacional de Ciencia y Tecnología (CONICET), Saladillo 2468, Buenos Aires C1440FFX, Argentina. (M.E.L.); (A.D.A.)
| | - Jesica M. Levingston Macleod
- Department of Microbiology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. (J.M.L.M.)
| | - Nora López
- Author to whom correspondence should be addressed; (N.L.); Tel/Fax: +54-11-4687-8735
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Linero FN, Sepúlveda CS, Giovannoni F, Castilla V, García CC, Scolaro LA, Damonte EB. Host cell factors as antiviral targets in arenavirus infection. Viruses 2012; 4:1569-91. [PMID: 23170173 PMCID: PMC3499820 DOI: 10.3390/v4091569] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 08/31/2012] [Accepted: 09/04/2012] [Indexed: 12/11/2022] Open
Abstract
Among the members of the Arenaviridae family, Lassa virus and Junin virus generate periodic annual outbreaks of severe human hemorrhagic fever (HF) in endemic areas of West Africa and Argentina, respectively. Given the human health threat that arenaviruses represent and the lack of a specific and safe chemotherapy, the search for effective antiviral compounds is a continuous demanding effort. Since diverse host cell pathways and enzymes are used by RNA viruses to fulfill their replicative cycle, the targeting of a host process has turned an attractive antiviral approach in the last years for many unrelated virus types. This strategy has the additional benefit to reduce the serious challenge for therapy of RNA viruses to escape from drug effects through selection of resistant variants triggered by their high mutation rate. This article focuses on novel strategies to identify inhibitors for arenavirus therapy, analyzing the potential for antiviral developments of diverse host factors essential for virus infection.
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Affiliation(s)
- Florencia N Linero
- Laboratorio de Virología, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires/IQUIBICEN (CONICET), Ciudad Universitaria, Pabellón 2, Piso 4, Buenos Aires 1428, Argentina.
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Reverse genetics recovery of Lujo virus and role of virus RNA secondary structures in efficient virus growth. J Virol 2012; 86:10759-65. [PMID: 22837210 DOI: 10.1128/jvi.01144-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arenaviruses are rodent-borne viruses with a bisegmented RNA genome. A genetically unique arenavirus, Lujo virus, was recently discovered as the causal agent of a nosocomial outbreak of acute febrile illness with hemorrhagic manifestations in Zambia and South Africa. The outbreak had a case fatality rate of 80%. A reverse genetics system to rescue infectious Lujo virus from cDNA was established to investigate the biological properties of this virus. Sequencing the genomic termini showed unique nucleotides at the 3' terminus of the S segment promoter element. While developing this system, we discovered that reconstructing infectious Lujo virus using the previously reported L segment intergenic region (IGR), comprising the arenaviral transcription termination signal, yielded an attenuated Lujo virus. Resequencing revealed that the correct L segment IGR was 36 nucleotides longer, and incorporating it into the reconstructed Lujo virus restored the growth rate to that of the authentic clinical virus isolate. These additional nucleotides were predicted to more than double the free energy of the IGR main stem-loop structure. In addition, incorporating the newly determined L-IGR into a replicon reporter system enhanced the expression of a luciferase reporter L segment. Overall, these results imply that an extremely stable secondary structure within the L-IGR is critical for Lujo virus propagation and viral protein production. The technology for producing recombinant Lujo virus now provides a method to precisely investigate the molecular determinants of virulence of this newly identified pathogen.
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Radoshitzky SR, Kuhn JH, de Kok-Mercado F, Jahrling PB, Bavari S. Drug discovery technologies and strategies for Machupo virus and other New World arenaviruses. Expert Opin Drug Discov 2012; 7:613-32. [PMID: 22607481 DOI: 10.1517/17460441.2012.687719] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Seven arenaviruses cause viral hemorrhagic fever in humans: the Old World arenaviruses Lassa and Lujo, and the New World Clade B arenaviruses Machupo (MACV), Junín (JUNV), Guanarito (GTOV), Sabiá (SABV), and Chapare (CHPV). All of these viruses are Risk Group 4 biosafety pathogens. MACV causes human disease outbreak with high case-fatality rates. To date, at least 1,200 cases with ≈200 fatalities have been recorded. AREAS COVERED This review summarizes available systems and technologies for the identification of antivirals against MACV. Furthermore, the article summarizes animal models that have been used for the in vivo evaluation of novel inhibitors. The article highlights present treatments for arenaviral diseases and provides an overview of efficacious small molecules and other therapeutics reported to date. Finally, the article summarizes strategies to identify novel inhibitors for anti-arenaviral therapy. EXPERT OPINION New high-throughput approaches to quantitate infection rates of arenaviruses, as well as viruses modified to carry reporter genes, will accelerate compound screens and drug discovery efforts. RNAi, gene expression profiling and proteomics studies will identify host targets for therapeutic intervention. New discoveries in the cell entry mechanism of MACV and other arenaviruses as well as extensive structural studies of arenaviral L and NP could facilitate the rational design of antivirals effective against all pathogenic New World arenaviruses.
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Affiliation(s)
- Sheli R Radoshitzky
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD 21702, USA
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The curious case of arenavirus entry, and its inhibition. Viruses 2012; 4:83-101. [PMID: 22355453 PMCID: PMC3280523 DOI: 10.3390/v4010083] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/07/2011] [Accepted: 01/05/2012] [Indexed: 11/17/2022] Open
Abstract
Arenaviruses comprise a diverse family of enveloped negative-strand RNA viruses that are endemic to specific rodent hosts worldwide. Several arenaviruses cause severe hemorrhagic fevers in humans, including Junín and Machupo viruses in South America and Lassa fever virus in western Africa. Arenavirus entry into the host cell is mediated by the envelope glycoprotein complex, GPC. The virion is endocytosed on binding to a cell-surface receptor, and membrane fusion is initiated in response to physiological acidification of the endosome. As with other class I virus fusion proteins, GPC-mediated membrane fusion is promoted through a regulated sequence of conformational changes leading to formation of the classical postfusion trimer-of-hairpins structure. GPC is, however, unique among the class I fusion proteins in that the mature complex retains a stable signal peptide (SSP) as a third subunit, in addition to the canonical receptor-binding and fusion proteins. We will review the curious properties of the tripartite GPC complex and describe evidence that SSP interacts with the fusion subunit to modulate pH-induced activation of membrane fusion. This unusual solution to maintaining the metastable prefusion state of GPC on the virion and activating the class I fusion cascade at acidic pH provides novel targets for antiviral intervention.
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Substitutions in the glycoprotein (GP) of the Candid#1 vaccine strain of Junin virus increase dependence on human transferrin receptor 1 for entry and destabilize the metastable conformation of GP. J Virol 2011; 85:13457-62. [PMID: 21976641 DOI: 10.1128/jvi.05616-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Candid#1 (Cd1) is an attenuated vaccine strain of Junin virus, the causative agent of Argentine hemorrhagic fever. Although several substitutions are present in Cd1, their importance for attenuation has not been established. We functionally characterized the substitutions present in the Cd1 glycoprotein (GP) and identified F427I in the transmembrane domain of the GP2 subunit as reducing infectivity in a reconstituted viral system. We further showed that this phenotype derives from the destabilization of the GP metastable conformation. Lastly, we identified an increased dependence of Cd1 GP on human transferrin receptor type 1 (hTfR-1) for entry, which may affect the tropism of the attenuated strain in vivo.
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Abstract
Junín virus is the causative agent for Argentine hemorrhagic fever, and its natural host is the New World rodent Calomys musculinus. The virus is transmitted to humans by aerosolization, and it is believed that many of the clinical symptoms are caused by cytokines produced by sentinel cells of the immune system. Here we used the Junín virus vaccine strain Candid 1 to determine whether mouse cells could be used to study virus entry and antiviral innate immune responses. We show that Candid 1 can infect and propagate in different mouse-derived cell lines through a low-pH-dependent, transferrin receptor 1-independent mechanism, suggesting that there is a second entry receptor. In addition, Candid 1 induced expression of the antiviral cytokines tumor necrosis factor alpha and beta interferon in macrophages, and this induction was independent of viral replication. Using Candid 1, as well as virus-like particles bearing the viral glycoprotein, to infect different primary cells and established macrophage cell lines with deletions in the Toll-like receptor (TLR) pathway, we show that TLR2 is a cellular sensor of both the Parodi and Candid 1 viral glycoproteins. Because Junín virus is highly lethal in humans, the use of an experimentally tractable model system, such as the mouse, could provide a better understanding of the antiviral innate cellular responses to Junín virus and the role of these responses in pathogenesis.
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