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Liu B, Zhu J, He T, Zhang Z. Genetic variants of Dabie bandavirus: classification and biological/clinical implications. Virol J 2023; 20:68. [PMID: 37060090 PMCID: PMC10103499 DOI: 10.1186/s12985-023-02033-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/07/2023] [Indexed: 04/16/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by Dabie bandavirus (DBV), a novel Bandavirus in the family Phenuiviridae. The first case of SFTS was reported in China, followed by cases in Japan, South Korea, Taiwan and Vietnam. With clinical manifestations including fever, leukopenia, thrombocytopenia, and gastrointestinal symptoms, SFTS has a fatality rate of approximately 10%. In recent years, an increasing number of viral strains have been isolated and sequenced, and several research groups have attempted to classify the different genotypes of DBV. Additionally, accumulating evidence indicates certain correlations between the genetic makeup and biological/clinical manifestations of the virus. Here, we attempted to evaluate the genetic classification of different groups, align the genotypic nomenclature in different studies, summarize the distribution of different genotypes, and review the biological and clinical implications of DBV genetic variations.
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Affiliation(s)
- Bingyan Liu
- Institute of Clinical Virology, Department of Infectious Diseases, The Second Affiliated Hospital of Anhui Medical University, Furong Road 678, Hefei, 230601, China
| | - Jie Zhu
- Institute of Clinical Virology, Department of Infectious Diseases, The Second Affiliated Hospital of Anhui Medical University, Furong Road 678, Hefei, 230601, China
| | - Tengfei He
- Institute of Clinical Virology, Department of Infectious Diseases, The Second Affiliated Hospital of Anhui Medical University, Furong Road 678, Hefei, 230601, China
| | - Zhenhua Zhang
- Institute of Clinical Virology, Department of Infectious Diseases, The Second Affiliated Hospital of Anhui Medical University, Furong Road 678, Hefei, 230601, China.
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2
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Moetlhoa B, Naicker L, Hayeshi R, Grobler A, Mokoena NB, Mawadza C. Application of a real-time cell analysis system in the process development and quantification of Rift Valley fever virus clone 13. Access Microbiol 2021; 3:000191. [PMID: 34151150 PMCID: PMC8209705 DOI: 10.1099/acmi.0.000191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/17/2020] [Indexed: 11/18/2022] Open
Abstract
Conventional cell-culture viral quantification methods, namely viral plaque and 50 % tissue culture infective dose assays, are time-consuming, subjective and are not suitable for routine testing. The viral plaque formation assay is the main method utilized for Rift Valley fever virus (RVFV) clone 13 quantification. The RVFV is a mosquito-borne RNA Phlebovirus belonging to the family Bunyaviridae. The virus comprises a single serotype and causes the zoonotic Rift Valley fever disease. The real-time cell analysis (RTCA) system has been developed for the monitoring of cell growth, cell adhesion, cell viability and mortality using electronic impedance technology. In this study, Vero cell growth kinetics and RVFV clone 13 replication kinetics were investigated in a roller bottle and RTCA systems. In roller bottles, Vero cell growth was measured by cell counts through trypan blue staining, whilst impedance expressed as the cell index (CI) was used for Vero growth measurement in the RTCA system. Similar growth patterns were observed in both roller bottle and RTCA systems. Exponential growth phase was observed between 48 and 100 h, followed by a stationary phase from 100 to 120 h, before cell death was observed. Viral plaque assay quantification of RVFV clone 13 in the roller bottle system and the time required for the CI to decrease 50 % after virus infection (CIT50) in the RTCA system were comparable. The highest RVFV clone 13 titre was obtained at 120 h in both roller bottle and RTCA systems. An increase in time for cytopathic effect (CPE) formation was observed with a decrease in the concentration of the virus used to infect the RTCA plates. A positive correlation was observed between the viral concentration and the time for a CPE and was used to calculate CIT50. A similar correlation was observed between the viral concentration and the time for a CPE in the roller bottle system. This study shows that the RTCA system can be used as an alternative method for conducting cell culture kinetics and viral quantification.
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Affiliation(s)
- Boitumelo Moetlhoa
- Onderstepoort Biological Products (OBP) SOC Ltd, 100 Old Soutpan Road, Onderstepoort 0110, South Africa
- DST-NWU Preclinical Drug Development Platform (PCDDP), North-West University, Potchefstroom 2520, South Africa
| | - Leeann Naicker
- Onderstepoort Biological Products (OBP) SOC Ltd, 100 Old Soutpan Road, Onderstepoort 0110, South Africa
| | - Rose Hayeshi
- DST-NWU Preclinical Drug Development Platform (PCDDP), North-West University, Potchefstroom 2520, South Africa
| | - Anne Grobler
- DST-NWU Preclinical Drug Development Platform (PCDDP), North-West University, Potchefstroom 2520, South Africa
| | - Nobalanda B. Mokoena
- Onderstepoort Biological Products (OBP) SOC Ltd, 100 Old Soutpan Road, Onderstepoort 0110, South Africa
| | - Crispen Mawadza
- Onderstepoort Biological Products (OBP) SOC Ltd, 100 Old Soutpan Road, Onderstepoort 0110, South Africa
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Rius-Rocabert S, García-Romero N, García A, Ayuso-Sacido A, Nistal-Villan E. Oncolytic Virotherapy in Glioma Tumors. Int J Mol Sci 2020; 21:ijms21207604. [PMID: 33066689 PMCID: PMC7589679 DOI: 10.3390/ijms21207604] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/08/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
Glioma tumors are one of the most devastating cancer types. Glioblastoma is the most advanced stage with the worst prognosis. Current therapies are still unable to provide an effective cure. Recent advances in oncolytic immunotherapy have generated great expectations in the cancer therapy field. The use of oncolytic viruses (OVs) in cancer treatment is one such immune-related therapeutic alternative. OVs have a double oncolytic action by both directly destroying the cancer cells and stimulating a tumor specific immune response to return the ability of tumors to escape the control of the immune system. OVs are one promising alternative to conventional therapies in glioma tumor treatment. Several clinical trials have proven the feasibility of using some viruses to specifically infect tumors, eluding undesired toxic effects in the patient. Here, we revisited the literature to describe the main OVs proposed up to the present moment as therapeutic alternatives in order to destroy glioma cells in vitro and trigger tumor destruction in vivo. Oncolytic viruses were divided with respect to the genome in DNA and RNA viruses. Here, we highlight the results obtained in various clinical trials, which are exploring the use of these agents as an alternative where other approaches provide limited hope.
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Affiliation(s)
- Sergio Rius-Rocabert
- Microbiology Section, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad San Pablo-CEU, 28668 Madrid, Spain;
- Facultad de Medicina, Instituto de Medicina Molecular Aplicada (IMMA), Universidad San Pablo-CEU, 28668 Madrid, Spain
- Centre for Metabolomics and Bioanalysis (CEMBIO), Facultad de Farmacia, Universidad San Pablo-CEU, 28668 Madrid, Spain;
| | - Noemí García-Romero
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, 28223 Madrid, Spain;
| | - Antonia García
- Centre for Metabolomics and Bioanalysis (CEMBIO), Facultad de Farmacia, Universidad San Pablo-CEU, 28668 Madrid, Spain;
| | - Angel Ayuso-Sacido
- Faculty of Experimental Sciences, Universidad Francisco de Vitoria, 28223 Madrid, Spain;
- Brain Tumor Laboratory, Fundación Vithas, Grupo Hospitales Vithas, 28043 Madrid, Spain
- Correspondence: (A.A.-S.); (E.N.-V.); Tel.: +34-913-724-714 (E.N.-V.)
| | - Estanislao Nistal-Villan
- Microbiology Section, Departamento de Ciencias Farmacéuticas y de la Salud, Facultad de Farmacia, Universidad San Pablo-CEU, 28668 Madrid, Spain;
- Facultad de Medicina, Instituto de Medicina Molecular Aplicada (IMMA), Universidad San Pablo-CEU, 28668 Madrid, Spain
- Correspondence: (A.A.-S.); (E.N.-V.); Tel.: +34-913-724-714 (E.N.-V.)
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4
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Smith MR, Schirtzinger EE, Wilson WC, Davis AS. Rift Valley Fever Virus: Propagation, Quantification, and Storage. ACTA ACUST UNITED AC 2020; 55:e92. [PMID: 31763765 DOI: 10.1002/cpmc.92] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rift Valley fever virus (RVFV) is an arthropod-borne, zoonotic disease endemic to sub-Saharan Africa and the Arabian Peninsula. Outbreaks of Rift Valley fever have had up to 100% mortality rates in fetal and neonatal sheep. Upon infection of ruminant and human hosts alike, RVFV infection causes an at times severe hepatitis and pathology in many other organs. The enveloped virion contains a tripartite, predominantly negative-sense, single-stranded RNA genome, which codes for the proteins the virus needs to replicate both in mammalian hosts and insect vectors. Endemic countries often use attenuated RVFV strains for vaccination of livestock but there are no commercially licensed vaccines for humans or livestock in non-endemic areas. In the laboratory, RVFV can be readily propagated and manipulated in vitro using cell culture systems. Presented in this article are techniques routinely used in RVFV research that have proven successful in our laboratories. © 2019 by John Wiley & Sons, Inc. Basic Protocol 1: Propagation of Rift Valley fever virus in mammalian cells Basic Protocol 2: Quantification of Rift Valley fever virus by plaque assay Basic Protocol 3: Quantification of Rift Valley fever virus by 50% tissue culture infectious dose (TCID50 ) assay Basic Protocol 4: Quantification of Rift Valley fever virus by focus-forming assay Basic Protocol 5: Storage and disinfection Alternate Protocol 1: Propagation of Rift Valley fever virus in MRC-5 cells Alternate Protocol 2: Propagation of RVFV in mosquito-derived cells Alternate Protocol 3: TCID50 detection using fluorescence visualization Support Protocol 1: Calculation of the amount of virus needed to infect a flask at a chosen multiplicity of infection Support Protocol 2: Calculation of the virus titer by plaque assay or focus-forming assay Support Protocol 3: Calculation of the TCID50 titer by the method of Reed and Muench Support Protocol 4: Calculation of the antibody volume for the focus-forming assay.
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Affiliation(s)
- MaRyka R Smith
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
| | - Erin E Schirtzinger
- Arthropod-Borne Animal Diseases Research Unit, Agricultural Research Service, United States Department of Agriculture, Manhattan, Kansas
| | - William C Wilson
- Arthropod-Borne Animal Diseases Research Unit, Agricultural Research Service, United States Department of Agriculture, Manhattan, Kansas
| | - A Sally Davis
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas
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Tsuda Y, Igarashi M, Ito R, Nishio S, Shimizu K, Yoshimatsu K, Arikawa J. The amino acid at position 624 in the glycoprotein of SFTSV (severe fever with thrombocytopenia virus) plays a critical role in low-pH-dependent cell fusion activity. Biomed Res 2018; 38:89-97. [PMID: 28442665 DOI: 10.2220/biomedres.38.89] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel phlebovirus responsible for causing an emerging zoonotic disease. We previously established subclones from SFTSV strain YG1 based on differences in low-pH-dependent cell fusion activities and found two amino acid substitutions, Y328H and R624W, in the envelope glycoprotein (GP) of high fusion subclones. In this study, we show that transiently expressed GP with the R624W mutation, but not the Y328H mutation, induced cell fusion under acidic conditions. GP possessing either tryptophan, serine, glycine or aspartic acid at position 624 induced cell fusion, whereas GP possessing basic amino acids such as arginine or lysine did not induce cell fusion. These results indicated that the amino acid at position 624 has an important role for inducing low-pH-dependent cell fusion.
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Affiliation(s)
- Yoshimi Tsuda
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
| | - Manabu Igarashi
- Division of Global Epidemiology, Research Center for Zoonosis Control, Hokkaido University.,Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education, Hokkaido University
| | - Ryo Ito
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
| | - Sanae Nishio
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
| | - Kenta Shimizu
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
| | - Kumiko Yoshimatsu
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
| | - Jiro Arikawa
- Department of Microbiology, Graduate School of Medicine, Hokkaido University
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6
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Discovery of Novel Small-Molecule Inhibitors of LIM Domain Kinase for Inhibiting HIV-1. J Virol 2017; 91:JVI.02418-16. [PMID: 28381571 PMCID: PMC5469273 DOI: 10.1128/jvi.02418-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/28/2017] [Indexed: 01/22/2023] Open
Abstract
A dynamic actin cytoskeleton is necessary for viral entry, intracellular migration, and virion release. For HIV-1 infection, during entry, the virus triggers early actin activity by hijacking chemokine coreceptor signaling, which activates a host dependency factor, cofilin, and its kinase, the LIM domain kinase (LIMK). Although knockdown of human LIM domain kinase 1 (LIMK1) with short hairpin RNA (shRNA) inhibits HIV infection, no specific small-molecule inhibitor of LIMK has been available. Here, we describe the design and discovery of novel classes of small-molecule inhibitors of LIMK for inhibiting HIV infection. We identified R10015 as a lead compound that blocks LIMK activity by binding to the ATP-binding pocket. R10015 specifically blocks viral DNA synthesis, nuclear migration, and virion release. In addition, R10015 inhibits multiple viruses, including Zaire ebolavirus (EBOV), Rift Valley fever virus (RVFV), Venezuelan equine encephalitis virus (VEEV), and herpes simplex virus 1 (HSV-1), suggesting that LIMK inhibitors could be developed as a new class of broad-spectrum antiviral drugs. IMPORTANCE The actin cytoskeleton is a structure that gives the cell shape and the ability to migrate. Viruses frequently rely on actin dynamics for entry and intracellular migration. In cells, actin dynamics are regulated by kinases, such as the LIM domain kinase (LIMK), which regulates actin activity through phosphorylation of cofilin, an actin-depolymerizing factor. Recent studies have found that LIMK/cofilin are targeted by viruses such as HIV-1 for propelling viral intracellular migration. Although inhibiting LIMK1 expression blocks HIV-1 infection, no highly specific LIMK inhibitor is available. This study describes the design, medicinal synthesis, and discovery of small-molecule LIMK inhibitors for blocking HIV-1 and several other viruses and emphasizes the feasibility of developing LIMK inhibitors as broad-spectrum antiviral drugs.
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7
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Nishio S, Tsuda Y, Ito R, Shimizu K, Yoshimatsu K, Arikawa J. Establishment of Subclones of the Severe Fever with Thrombocytopenia Syndrome Virus YG1 Strain Selected Using Low pH-Dependent Cell Fusion Activity. Jpn J Infect Dis 2016; 70:388-393. [PMID: 28003599 DOI: 10.7883/yoken.jjid.2016.357] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The first clinical case of the YG1 strain of the severe fever with thrombocytopenia syndrome virus (SFTSV) has been isolated in Japan. We found that only some of the cells underwent low pH-dependent cell fusion, although all of the cells were confirmed to have been infected with the virus. This suggested that the YG1 strain consists of a heterogeneous mixture of related viruses. Here, we established 3 subclones (termed E3, A4, and B7) from the YG1 strain, using the limiting dilution method with the pH-dependent cell fusion activity. Subclone E3 showed weak fusion activity and cytopathic effects (CPE) in Vero E6 cells. The amino acid sequence of E3 was identical to the published sequence for the YG1 strain, and it likely comprises a subpopulation of the YG1 strain. Subclone A4 displayed strong fusion activity under acidic conditions. In contrast, subclone B7 showed strong fusion activity and CPE under neutral and acidic conditions. Two amino acid differences shared between B7 and A4 were found in the envelope glycoproteins. In addition, an amino acid variant of the RNA-dependent RNA polymerase was found only in B7. These subclones will be valuable tools to elucidate cell fusion mechanisms of SFTSV and the relationship between viral proteins and their functions.
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Affiliation(s)
- Sanae Nishio
- Department of Microbiology, Hokkaido University Graduate School of Medicine
| | - Yoshimi Tsuda
- Department of Microbiology, Hokkaido University Graduate School of Medicine
| | - Ryo Ito
- Department of Microbiology, Hokkaido University Graduate School of Medicine
| | - Kenta Shimizu
- Department of Microbiology, Hokkaido University Graduate School of Medicine
| | - Kumiko Yoshimatsu
- Department of Microbiology, Hokkaido University Graduate School of Medicine
| | - Jiro Arikawa
- Department of Microbiology, Hokkaido University Graduate School of Medicine
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A Genome-Wide RNA Interference Screen Identifies a Role for Wnt/β-Catenin Signaling during Rift Valley Fever Virus Infection. J Virol 2016; 90:7084-7097. [PMID: 27226375 PMCID: PMC4984662 DOI: 10.1128/jvi.00543-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/14/2016] [Indexed: 01/18/2023] Open
Abstract
Rift Valley fever virus (RVFV) is an arbovirus within the Bunyaviridae family capable of causing serious morbidity and mortality in humans and livestock. To identify host factors involved in bunyavirus replication, we employed genome-wide RNA interference (RNAi) screening and identified 381 genes whose knockdown reduced infection. The Wnt pathway was the most represented pathway when gene hits were functionally clustered. With further investigation, we found that RVFV infection activated Wnt signaling, was enhanced when Wnt signaling was preactivated, was reduced with knockdown of β-catenin, and was blocked using Wnt signaling inhibitors. Similar results were found using distantly related bunyaviruses La Crosse virus and California encephalitis virus, suggesting a conserved role for Wnt signaling in bunyaviral infection. We propose a model where bunyaviruses activate Wnt-responsive genes to regulate optimal cell cycle conditions needed to promote efficient viral replication. The findings in this study should aid in the design of efficacious host-directed antiviral therapeutics. IMPORTANCE RVFV is a mosquito-borne bunyavirus that is endemic to Africa but has demonstrated a capacity for emergence in new territories (e.g., the Arabian Peninsula). As a zoonotic pathogen that primarily affects livestock, RVFV can also cause lethal hemorrhagic fever and encephalitis in humans. Currently, there are no treatments or fully licensed vaccines for this virus. Using high-throughput RNAi screening, we identified canonical Wnt signaling as an important host pathway regulating RVFV infection. The beneficial role of Wnt signaling was observed for RVFV, along with other disparate bunyaviruses, indicating a conserved bunyaviral replication mechanism involving Wnt signaling. These studies supplement our knowledge of the fundamental mechanisms of bunyavirus infection and provide new avenues for countermeasure development against pathogenic bunyaviruses.
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The Role of Phlebovirus Glycoproteins in Viral Entry, Assembly and Release. Viruses 2016; 8:v8070202. [PMID: 27455305 PMCID: PMC4974537 DOI: 10.3390/v8070202] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 01/08/2023] Open
Abstract
Bunyaviruses are enveloped viruses with a tripartite RNA genome that can pose a serious threat to animal and human health. Members of the Phlebovirus genus of the family Bunyaviridae are transmitted by mosquitos and ticks to humans and include highly pathogenic agents like Rift Valley fever virus (RVFV) and severe fever with thrombocytopenia syndrome virus (SFTSV) as well as viruses that do not cause disease in humans, like Uukuniemi virus (UUKV). Phleboviruses and other bunyaviruses use their envelope proteins, Gn and Gc, for entry into target cells and for assembly of progeny particles in infected cells. Thus, binding of Gn and Gc to cell surface factors promotes viral attachment and uptake into cells and exposure to endosomal low pH induces Gc-driven fusion of the viral and the vesicle membranes. Moreover, Gn and Gc facilitate virion incorporation of the viral genome via their intracellular domains and Gn and Gc interactions allow the formation of a highly ordered glycoprotein lattice on the virion surface. Studies conducted in the last decade provided important insights into the configuration of phlebovirus Gn and Gc proteins in the viral membrane, the cellular factors used by phleboviruses for entry and the mechanisms employed by phlebovirus Gc proteins for membrane fusion. Here, we will review our knowledge on the glycoprotein biogenesis and the role of Gn and Gc proteins in the phlebovirus replication cycle.
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Characterization of Glycoprotein-Mediated Entry of Severe Fever with Thrombocytopenia Syndrome Virus. J Virol 2016; 90:5292-5301. [PMID: 26984731 DOI: 10.1128/jvi.00110-16] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 03/14/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Severe fever with thrombocytopenia syndrome (SFTS) is an emerging hemorrhagic fever with a high case fatality rate caused by SFTS virus (SFTSV). Effective vaccines and specific therapies for SFTS are urgently sought, and investigation into virus-host cell interactions is expected to contribute to the development of antiviral strategies. In this study, we have developed a pseudotype vesicular stomatitis virus (VSV) bearing the unmodified Gn/Gc glycoproteins (GPs) of SFTSV (SFTSVpv). We have analyzed the host cell entry of this pseudotype virus and native SFTSV. Both SFTSVpv and SFTSV exhibited high infectivity in various mammalian cell lines. The use of lysosomotropic agents indicated that virus entry occurred via pH-dependent endocytosis. SFTSVpv and SFTSV infectivity was neutralized by serial dilutions of convalescent-phase patient sera. Entry of SFTSVpv and growth of SFTSV were increased in Raji cells expressing not only the C-type lectin dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) but also DC-SIGN-related (DC-SIGNR) and liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin). 25-Hydroxycholesterol (25HC), a soluble oxysterol metabolite, inhibited the cell entry of SFTSVpv and the membrane fusion of SFTSV. These results indicate that pH-dependent endocytosis of SFTSVpv and SFTSV is enhanced by attachment to certain C-type lectins. SFTSVpv is an appropriate model for the investigation of SFTSV-GP-mediated cell entry and virus neutralization at lower biosafety levels. Furthermore, 25HC may represent a potential antiviral agent against SFTS. IMPORTANCE SFTSV is a recently discovered bunyavirus associated with SFTS, a viral hemorrhagic fever with a high case fatality rate endemic to China, South Korea, and Japan. Because little is known about the characteristics of the envelope protein and entry mechanisms of SFTSV, further studies will be required for the development of a vaccine or effective therapies. In this study, we investigated the mechanism of SFTSV cell entry using SFTSVpv and the native virus. SFTSV can grow in nonsusceptible cell lines in the presence of certain C-type lectins. Moreover, 25HC, an oxysterol metabolite, may represent a potential therapeutic inhibitor of SFTSV infection.
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Ndiaye EH, Fall G, Gaye A, Bob NS, Talla C, Diagne CT, Diallo D, B A Y, Dia I, Kohl A, Sall AA, Diallo M. Vector competence of Aedes vexans (Meigen), Culex poicilipes (Theobald) and Cx. quinquefasciatus Say from Senegal for West and East African lineages of Rift Valley fever virus. Parasit Vectors 2016; 9:94. [PMID: 26897521 PMCID: PMC4761212 DOI: 10.1186/s13071-016-1383-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is a mosquito-borne, zoonotic pathogen. In Senegal, RVFV was first isolated in 1974 from Aedes dalzieli (Theobald) and thereafter from Ae. fowleri (de Charmoy), Ae. ochraceus Theobald, Ae. vexans (Meigen), Culex poicilipes (Theobald), Mansonia africana (Theobald) and Ma. uniformis (Theobald). However, the vector competence of these local species has never been demonstrated making hypothetical the transmission cycle proposed for West Africa based on serological data and mosquito isolates. METHODS Aedes vexans and Cx. poicilipes, two common mosquito species most frequently associated with RVFV in Senegal, and Cx. quinquefasciatus, the most common domestic species, were assessed after oral feeding with three RVFV strains of the West and East/central African lineages. Fully engorged mosquitoes (420 Ae. vexans, 563 Cx. quinquefasciatus and 380 Cx. poicilipes) were maintained at 27 ± 1 °C and 70-80% relative humidity. The saliva, legs/wings and bodies were tested individually for the RVFV genome using real-time RT-PCR at 5, 10, 15 and 20 days post exposure (dpe) to estimate the infection, dissemination, and transmission rates. Genotypic characterisation of the 3 strains used were performed to identify factors underlying the different patterns of transmission. RESULTS The infection rates varied between 30.0-85.0% for Ae. vexans, 3.3-27% for Cx. quinquefasciatus and 8.3-46.7% for Cx. poicilipes, and the dissemination rates varied between 10.5-37% for Ae. vexans, 9.5-28.6% for Cx. quinquefasciatus and 3.0-40.9% for Cx. poicilipes. However only the East African lineage was transmitted, with transmission rates varying between 13.3-33.3% in Ae. vexans, 50% in Cx. quinquefasciatus and 11.1% in Cx. poicilipes. Culex mosquitoes were less susceptible to infection than Ae. vexans. Compared to other strains, amino acid variation in the NSs M segment proteins of the East African RVFV lineage human-derived strain SH172805, might explain the differences in transmission potential. CONCLUSION Our findings revealed that all the species tested were competent for RVFV with a significant more important role of Ae. vexans compared to Culex species and a highest potential of the East African lineage to be transmitted.
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Affiliation(s)
- El Hadji Ndiaye
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Gamou Fall
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Alioune Gaye
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Ndeye Sakha Bob
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Cheikh Talla
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Cheikh Tidiane Diagne
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal. .,Université Cheikh Anta Diop de Dakar, Département de Biologie Animale, Faculté des Sciences et Techniques, Dakar, Senegal.
| | - Diawo Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Yamar B A
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Ibrahima Dia
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, G61 1QH, Scotland, UK.
| | - Amadou Alpha Sall
- Institut Pasteur de Dakar, Unité des Arbovirus et Virus de Fièvres hémorragiques, Dakar, Senegal.
| | - Mawlouth Diallo
- Unité d'Entomologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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12
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A Haploid Genetic Screen Identifies Heparan Sulfate Proteoglycans Supporting Rift Valley Fever Virus Infection. J Virol 2015; 90:1414-23. [PMID: 26581979 DOI: 10.1128/jvi.02055-15] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/10/2015] [Indexed: 01/13/2023] Open
Abstract
UNLABELLED Rift Valley fever virus (RVFV) causes recurrent insect-borne epizootics throughout the African continent, and infection of humans can lead to a lethal hemorrhagic fever syndrome. Deep mutagenesis of haploid human cells was used to identify host factors required for RVFV infection. This screen identified a suite of enzymes involved in glycosaminoglycan (GAG) biogenesis and transport, including several components of the cis-oligomeric Golgi (COG) complex, one of the central components of Golgi complex trafficking. In addition, disruption of PTAR1 led to RVFV resistance as well as reduced heparan sulfate surface levels, consistent with recent observations that PTAR1-deficient cells exhibit altered Golgi complex morphology and glycosylation defects. A variety of biochemical and genetic approaches were utilized to show that both pathogenic and attenuated RVFV strains require GAGs for efficient infection on some, but not all, cell types, with the block to infection being at the level of virion attachment. Examination of other members of the Bunyaviridae family for GAG-dependent infection suggested that the interaction with GAGs is not universal among bunyaviruses, indicating that these viruses, as well as RVFV on certain cell types, employ additional unidentified virion attachment factors and/or receptors. IMPORTANCE Rift Valley fever virus (RVFV) is an emerging pathogen that can cause severe disease in humans and animals. Epizootics among livestock populations lead to high mortality rates and can be economically devastating. Human epidemics of Rift Valley fever, often initiated by contact with infected animals, are characterized by a febrile disease that sometimes leads to encephalitis or hemorrhagic fever. The global burden of the pathogen is increasing because it has recently disseminated beyond Africa, which is of particular concern because the virus can be transmitted by widely distributed mosquito species. There are no FDA-licensed vaccines or antiviral agents with activity against RVFV, and details of its life cycle and interaction with host cells are not well characterized. We used the power of genetic screening in human cells and found that RVFV utilizes glycosaminoglycans to attach to host cells. This furthers our understanding of the virus and informs the development of antiviral therapeutics.
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Terasaki K, Tercero BR, Makino S. Single-cycle replicable Rift Valley fever virus mutants as safe vaccine candidates. Virus Res 2015; 216:55-65. [PMID: 26022573 DOI: 10.1016/j.virusres.2015.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/05/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
Abstract
Rift Valley fever virus (RVFV) is an arbovirus circulating between ruminants and mosquitoes to maintain its enzootic cycle. Humans are infected with RVFV through mosquito bites or direct contact with materials of infected animals. The virus causes Rift Valley fever (RVF), which was first recognized in the Great Rift Valley of Kenya in 1931. RVF is characterized by a febrile illness resulting in a high rate of abortions in ruminants and an acute febrile illness, followed by fatal hemorrhagic fever and encephalitis in humans. Initially, the virus was restricted to the eastern region of Africa, but the disease has now spread to southern and western Africa, as well as outside of the African continent, e.g., Madagascar, Saudi Arabia and Yemen. There is a serious concern that the virus may spread to other areas, such as North America and Europe. As vaccination is an effective tool to control RVFV epidemics, formalin-inactivated vaccines and live-attenuated RVFV vaccines have been used in endemic areas. The formalin-inactivated vaccines require boosters for effective protection, whereas the live-attenuated vaccines enable the induction of protective immunity by a single vaccination. However, the use of live-attenuated RVFV vaccines for large human populations having a varied health status is of concern, because of these vaccines' residual neuro-invasiveness and neurovirulence. Recently, novel vaccine candidates have been developed using replication-defective RVFV that can undergo only a single round of replication in infected cells. The single-cycle replicable RVFV does not cause systemic infection in immunized hosts, but enables the conferring of protective immunity. This review summarizes the properties of various RVFV vaccines and recent progress on the development of the single-cycle replicable RVFV vaccines.
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Affiliation(s)
- Kaori Terasaki
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA.
| | - Breanna R Tercero
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA
| | - Shinji Makino
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA; Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA; UTMB Center for Tropical Diseases, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA; Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA; Institute for Human Infections and Immunity, The University of Texas Medical Branch, Galveston, TX 77555-1019, USA
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14
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Meier R, Franceschini A, Horvath P, Tetard M, Mancini R, von Mering C, Helenius A, Lozach PY. Genome-wide small interfering RNA screens reveal VAMP3 as a novel host factor required for Uukuniemi virus late penetration. J Virol 2014; 88:8565-78. [PMID: 24850728 PMCID: PMC4135934 DOI: 10.1128/jvi.00388-14] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 05/12/2014] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The Bunyaviridae constitute a large family of enveloped animal viruses, many of which are important emerging pathogens. How bunyaviruses enter and infect mammalian cells remains largely uncharacterized. We used two genome-wide silencing screens with distinct small interfering RNA (siRNA) libraries to investigate host proteins required during infection of human cells by the bunyavirus Uukuniemi virus (UUKV), a late-penetrating virus. Sequence analysis of the libraries revealed that many siRNAs in the screens inhibited infection by silencing not only the intended targets but additional genes in a microRNA (miRNA)-like manner. That the 7-nucleotide seed regions in the siRNAs can cause a perturbation in infection was confirmed by using synthetic miRNAs (miRs). One of the miRs tested, miR-142-3p, was shown to interfere with the intracellular trafficking of incoming viruses by regulating the v-SNARE VAMP3, a strong hit shared by both siRNA screens. Inactivation of VAMP3 by the tetanus toxin led to a block in infection. Using fluorescence-based techniques in fixed and live cells, we found that the viruses enter VAMP3(+) endosomal vesicles 5 min after internalization and that colocalization was maximal 15 min thereafter. At this time, LAMP1 was associated with the VAMP3(+) virus-containing endosomes. In cells depleted of VAMP3, viruses were mainly trapped in LAMP1-negative compartments. Together, our results indicated that UUKV relies on VAMP3 for penetration, providing an indication of added complexity in the trafficking of viruses through the endocytic network. IMPORTANCE Bunyaviruses represent a growing threat to humans and livestock globally. Unfortunately, relatively little is known about these emerging pathogens. We report here the first human genome-wide siRNA screens for a bunyavirus. The screens resulted in the identification of 562 host cell factors with a potential role in cell entry and virus replication. To demonstrate the robustness of our approach, we confirmed and analyzed the role of the v-SNARE VAMP3 in Uukuniemi virus entry and infection. The information gained lays the basis for future research into the cell biology of bunyavirus infection and new antiviral strategies. In addition, by shedding light on serious caveats in large-scale siRNA screening, our experimental and bioinformatics procedures will be valuable in the comprehensive analysis of past and future high-content screening data.
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Affiliation(s)
- Roger Meier
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Andrea Franceschini
- Institute of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Peter Horvath
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland Light Microscopy and Screening Center, ETH Zurich, Zurich, Switzerland
| | - Marilou Tetard
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
| | | | - Christian von Mering
- Institute of Molecular Life Sciences and Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland
| | - Ari Helenius
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Pierre-Yves Lozach
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada
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15
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Murakami S, Terasaki K, Ramirez SI, Morrill JC, Makino S. Development of a novel, single-cycle replicable rift valley Fever vaccine. PLoS Negl Trop Dis 2014; 8:e2746. [PMID: 24651859 PMCID: PMC3961198 DOI: 10.1371/journal.pntd.0002746] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/30/2014] [Indexed: 12/25/2022] Open
Abstract
Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) is an arbovirus that causes severe disease in humans and livestock in sub-Saharan African countries. Although the MP-12 strain of RVFV is a live attenuated vaccine candidate, neuroinvasiveness and neurovirulence of MP-12 in mice may be a concern when vaccinating certain individuals, especially those that are immunocompromised. We have developed a novel, single-cycle replicable MP-12 (scMP-12), which carries an L RNA, M RNA mutant encoding a mutant envelope protein lacking an endoplasmic reticulum retrieval signal and defective for membrane fusion function, and S RNA encoding N protein and green fluorescent protein. The scMP-12 underwent efficient amplification, then formed plaques and retained the introduced mutation after serial passages in a cell line stably expressing viral envelope proteins. However, inoculation of the scMP-12 into naïve cells resulted in a single round of viral replication, and production of low levels of noninfectious virus-like particles. Intracranial inoculation of scMP-12 into suckling mice did not cause clinical signs or death, a finding which demonstrated that the scMP-12 lacked neurovirulence. Mice immunized with a single dose of scMP-12 produced neutralizing antibodies, whose titers were higher than in mice immunized with replicon particles carrying L RNA and S RNA encoding N protein and green fluorescent protein. Moreover, 90% of the scMP-12-immunized mice were protected from wild-type RVFV challenge by efficiently suppressing viremia and replication of the challenge virus in the liver and the spleen. These data demonstrated that scMP-12 is a safe and immunogenic RVFV vaccine candidate.
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MESH Headings
- Animals
- Antibodies, Neutralizing/blood
- Antibodies, Viral/blood
- Disease Models, Animal
- Female
- Mice
- Mutant Proteins/genetics
- Mutant Proteins/metabolism
- Rift Valley Fever/prevention & control
- Rift Valley fever virus/genetics
- Rift Valley fever virus/immunology
- Rift Valley fever virus/physiology
- Survival Analysis
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/adverse effects
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/adverse effects
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/immunology
- Viral Proteins/genetics
- Viral Proteins/immunology
- Viral Vaccines/administration & dosage
- Viral Vaccines/adverse effects
- Viral Vaccines/genetics
- Viral Vaccines/immunology
- Virus Internalization
- Virus Replication
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Affiliation(s)
- Shin Murakami
- Department of Microbiology and Immunology, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Kaori Terasaki
- Department of Microbiology and Immunology, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Sydney I. Ramirez
- Department of Pathology, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - John C. Morrill
- Department of Microbiology and Immunology, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Shinji Makino
- Department of Microbiology and Immunology, the University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, the University of Texas Medical Branch, Galveston, Texas, United States of America
- UTMB Center for Tropical Diseases, the University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Vaccine Development, the University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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16
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Koehler JW, Smith JM, Ripoll DR, Spik KW, Taylor SL, Badger CV, Grant RJ, Ogg MM, Wallqvist A, Guttieri MC, Garry RF, Schmaljohn CS. A fusion-inhibiting peptide against Rift Valley fever virus inhibits multiple, diverse viruses. PLoS Negl Trop Dis 2013; 7:e2430. [PMID: 24069485 PMCID: PMC3772029 DOI: 10.1371/journal.pntd.0002430] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 08/02/2013] [Indexed: 12/22/2022] Open
Abstract
For enveloped viruses, fusion of the viral envelope with a cellular membrane is critical for a productive infection to occur. This fusion process is mediated by at least three classes of fusion proteins (Class I, II, and III) based on the protein sequence and structure. For Rift Valley fever virus (RVFV), the glycoprotein Gc (Class II fusion protein) mediates this fusion event following entry into the endocytic pathway, allowing the viral genome access to the cell cytoplasm. Here, we show that peptides analogous to the RVFV Gc stem region inhibited RVFV infectivity in cell culture by inhibiting the fusion process. Further, we show that infectivity can be inhibited for diverse, unrelated RNA viruses that have Class I (Ebola virus), Class II (Andes virus), or Class III (vesicular stomatitis virus) fusion proteins using this single peptide. Our findings are consistent with an inhibition mechanism similar to that proposed for stem peptide fusion inhibitors of dengue virus in which the RVFV inhibitory peptide first binds to both the virion and cell membranes, allowing it to traffic with the virus into the endocytic pathway. Upon acidification and rearrangement of Gc, the peptide is then able to specifically bind to Gc and prevent fusion of the viral and endocytic membranes, thus inhibiting viral infection. These results could provide novel insights into conserved features among the three classes of viral fusion proteins and offer direction for the future development of broadly active fusion inhibitors. Entry into a cell is an essential stage of the viral replication cycle. Enveloped viruses require fusion of viral and cellular membranes for the viral genome to enter the cell cytoplasm. This entry is mediated by a viral fusion protein. Here, we synthesized peptides based on the Rift Valley fever virus (RVFV) fusion protein stem region and tested the peptides for their ability to prevent RVFV infection of cell cultures. We found that one of these peptides was able to inhibit RVFV infectivity by preventing the fusion process and that this peptide had broad activity against other RNA viruses including Ebola, Andes, and vesicular stomatitis viruses.
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Affiliation(s)
- Jeffrey W. Koehler
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Jeffrey M. Smith
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Daniel R. Ripoll
- DoD Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, Maryland, United States of America
| | - Kristin W. Spik
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Shannon L. Taylor
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Catherine V. Badger
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Rebecca J. Grant
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Monica M. Ogg
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Anders Wallqvist
- DoD Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, Maryland, United States of America
| | - Mary C. Guttieri
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
| | - Robert F. Garry
- Tulane University, Department of Microbiology and Immunology, New Orleans, Louisiana, United States of America
| | - Connie S. Schmaljohn
- United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America
- * E-mail:
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17
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Faburay B, Wilson W, McVey DS, Drolet BS, Weingartl H, Madden D, Young A, Ma W, Richt JA. Rift Valley fever virus structural and nonstructural proteins: recombinant protein expression and immunoreactivity against antisera from sheep. Vector Borne Zoonotic Dis 2013; 13:619-29. [PMID: 23962238 DOI: 10.1089/vbz.2012.1285] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The Rift Valley fever virus (RVFV) encodes the structural proteins nucleoprotein (N), aminoterminal glycoprotein (Gn), carboxyterminal glycoprotein (Gc), and L protein, 78-kD, and the nonstructural proteins NSm and NSs. Using the baculovirus system, we expressed the full-length coding sequence of N, NSs, NSm, Gc, and the ectodomain of the coding sequence of the Gn glycoprotein derived from the virulent strain of RVFV ZH548. Western blot analysis using anti-His antibodies and monoclonal antibodies against Gn and N confirmed expression of the recombinant proteins, and in vitro biochemical analysis showed that the two glycoproteins, Gn and Gc, were expressed in glycosylated form. Immunoreactivity profiles of the recombinant proteins in western blot and in indirect enzyme-linked immunosorbent assay against a panel of antisera obtained from vaccinated or wild type (RVFV)-challenged sheep confirmed the results obtained with anti-His antibodies and demonstrated the suitability of the baculo-expressed antigens for diagnostic assays. In addition, these recombinant proteins could be valuable for the development of diagnostic methods that differentiate infected from vaccinated animals (DIVA).
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Affiliation(s)
- Bonto Faburay
- 1 Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University , Manhattan, Kansas
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18
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Garrison AR, Radoshitzky SR, Kota KP, Pegoraro G, Ruthel G, Kuhn JH, Altamura LA, Kwilas SA, Bavari S, Haucke V, Schmaljohn CS. Crimean-Congo hemorrhagic fever virus utilizes a clathrin- and early endosome-dependent entry pathway. Virology 2013; 444:45-54. [PMID: 23791227 DOI: 10.1016/j.virol.2013.05.030] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 02/21/2013] [Accepted: 05/21/2013] [Indexed: 11/17/2022]
Abstract
The early events in Crimean-Congo hemorrhagic fever virus (CCHFV) have not been completely characterized. Earlier work indicated that CCHFV likely enters cells by clathrin-mediated endocytosis (CME). Here we provide confirmatory evidence for CME entry by showing that CCHFV infection is inhibited in cells treated with Pitstop 2, a drug that specifically and reversibly interferes with the dynamics of clathrin-coated pits. Additionally, we show that CCHFV infection is inhibited by siRNA depletion of the clathrin pit associated protein AP-2. Following CME entry, we show that CCHFV has a pH-dependent entry step, with virus inactivation occurring at pH 6.0 and below. To more precisely define the endosomal trafficking of CCHFV, we show for the first time that overexpression of the dominant negative forms of Rab5 protein but not Rab7 protein inhibits CCHFV infection. These results indicate that CCHFV likely enters cells through the early endosomal compartment.
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Affiliation(s)
- Aura R Garrison
- United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Maryland, USA
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19
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Abstract
We show that interferon-induced transmembrane protein 1 (IFITM-1), IFITM-2, and IFITM-3 exhibit a broad spectrum of antiviral activity against several members of the Bunyaviridae family, including Rift Valley fever virus (RVFV), La Crosse virus, Andes virus, and Hantaan virus, all of which can cause severe disease in humans and animals. We found that RVFV was restricted by IFITM-2 and -3 but not by IFITM-1, whereas the remaining viruses were equally restricted by all IFITMs. Indeed, at low doses of alpha interferon (IFN-α), IFITM-2 and -3 mediated more than half of the antiviral activity of IFN-α against RVFV. IFITM-2 and -3 restricted RVFV infection mostly by preventing virus membrane fusion with endosomes, while they had no effect on virion attachment to cells, endocytosis, or viral replication kinetics. We found that large fractions of IFITM-2 and IFITM-3 occupy vesicular compartments that are distinct from the vesicles coated by IFITM-1. In addition, although overexpression of all IFITMs expanded vesicular and acidified compartments within cells, there were marked phenotypic differences among the vesicular compartments occupied by IFITMs. Collectively, our data provide new insights into the possible mechanisms by which the IFITM family members restrict distinct viruses.
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20
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Zhou Y, Simmons G. Development of novel entry inhibitors targeting emerging viruses. Expert Rev Anti Infect Ther 2013. [PMID: 23199399 DOI: 10.1586/eri.12.104] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Emerging viral diseases pose a unique risk to public health, and thus there is a need to develop therapies. A current focus of funding agencies, and hence research, is the development of broad-spectrum antivirals, and in particular, those targeting common cellular pathways. The scope of this article is to review screening strategies and recent advances in this area, with a particular emphasis on antivirals targeting the step of viral entry for emerging lipid-enveloped viruses such as Ebola virus and SARS-coronavirus.
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Affiliation(s)
- Yanchen Zhou
- Blood Systems Research Institute and Department of Laboratory Medicine, University of California, San Francisco, 270 Masonic Avenue, San Francisco, CA 94118, USA
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21
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Weber M, Gawanbacht A, Habjan M, Rang A, Borner C, Schmidt AM, Veitinger S, Jacob R, Devignot S, Kochs G, García-Sastre A, Weber F. Incoming RNA virus nucleocapsids containing a 5'-triphosphorylated genome activate RIG-I and antiviral signaling. Cell Host Microbe 2013; 13:336-46. [PMID: 23498958 PMCID: PMC5515363 DOI: 10.1016/j.chom.2013.01.012] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 10/12/2012] [Accepted: 01/25/2013] [Indexed: 12/24/2022]
Abstract
Host defense to RNA viruses depends on rapid intracellular recognition of viral RNA by two cytoplasmic RNA helicases: RIG-I and MDA5. RNA transfection experiments indicate that RIG-I responds to naked double-stranded RNAs (dsRNAs) with a triphosphorylated 5' (5'ppp) terminus. However, the identity of the RIG-I stimulating viral structures in an authentic infection context remains unresolved. We show that incoming viral nucleocapsids containing a 5'ppp dsRNA "panhandle" structure trigger antiviral signaling that commences with RIG-I, is mediated through the adaptor protein MAVS, and terminates with transcription factor IRF-3. Independent of mammalian cofactors or viral polymerase activity, RIG-I bound to viral nucleocapsids, underwent a conformational switch, and homo-oligomerized. Enzymatic probing and superresolution microscopy suggest that RIG-I interacts with the panhandle structure of the viral nucleocapsids. These results define cytoplasmic entry of nucleocapsids as the proximal RIG-I-sensitive step during infection and establish viral nucleocapsids with a 5'ppp dsRNA panhandle as a RIG-I activator.
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Affiliation(s)
- Michaela Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Ali Gawanbacht
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Matthias Habjan
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Andreas Rang
- Institute of Virology, Helmut-Ruska-Haus, University Hospital Charité, Charité Campus Mitte, Berlin, Germany
| | - Christoph Borner
- Institute of Molecular Medicine, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
| | - Anna Mareike Schmidt
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
| | - Sophie Veitinger
- Department of Cell Biology and Cell Pathology, Philipps-University Marburg, Marburg, Germany
| | - Ralf Jacob
- Department of Cell Biology and Cell Pathology, Philipps-University Marburg, Marburg, Germany
| | - Stéphanie Devignot
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Georg Kochs
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
| | - Adolfo García-Sastre
- Department of Microbiology, Mount Sinai School of Medicine, New York, NY-10029, USA
- Department of Medicine, Division of Infectious Diseases, Mount Sinai School of Medicine, New York, NY-10029, USA
- Global Health and Emerging Pathogens Institute, Mount Sinai School of Medicine, New York, NY-10029, USA
| | - Friedemann Weber
- Institute for Virology, Philipps-University Marburg, D-35043 Marburg, Germany
- Department of Virology, University Freiburg, Hermann-Herder-Strasse 11, D-79008 Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs University Freiburg, Germany
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22
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Acid-activated structural reorganization of the Rift Valley fever virus Gc fusion protein. J Virol 2012; 86:13642-52. [PMID: 23035232 DOI: 10.1128/jvi.01973-12] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The entry of the enveloped Rift Valley fever virus (RVFV) into its host cell is mediated by the viral glycoproteins Gn and Gc. We investigated the RVFV entry process and, in particular, its pH-dependent activation mechanism using our recently developed nonspreading-RVFV-particle system. Entry of the virus into the host cell was efficiently inhibited by lysosomotropic agents that prevent endosomal acidification and by compounds that interfere with dynamin- and clathrin-dependent endocytosis. Exposure of plasma membrane-bound virions to an acidic pH (<pH 6) equivalent to the pH of late endolysosomal compartments allowed the virus to bypass the endosomal route of infection. Acid exposure of virions in the absence of target membranes triggered the class II-like Gc fusion protein to form extremely stable oligomers that were resistant to SDS and temperature dissociation and concomitantly compromised virus infectivity. By targeted mutagenesis of conserved histidines in Gn and Gc, we demonstrated that mutation of a single histidine (H857) in Gc completely abrogated virus entry, as well as acid-induced Gc oligomerization. In conclusion, our data suggest that after endocytic uptake, RVFV traffics to the acidic late endolysosomal compartments, where histidine protonation drives the reorganization of the Gc fusion protein that leads to membrane fusion.
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23
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Rift Valley fever virus strain MP-12 enters mammalian host cells via caveola-mediated endocytosis. J Virol 2012; 86:12954-70. [PMID: 22993156 DOI: 10.1128/jvi.02242-12] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a zoonotic pathogen capable of causing serious morbidity and mortality in both humans and livestock. The lack of efficient countermeasure strategies, the potential for dispersion into new regions, and the pathogenesis in humans and livestock make RVFV a serious public health concern. The receptors, cellular factors, and entry pathways used by RVFV and other members of the family Bunyaviridae remain largely uncharacterized. Here we provide evidence that RVFV strain MP-12 uses dynamin-dependent caveola-mediated endocytosis for cell entry. Caveolae are lipid raft domains composed of caveolin (the main structural component), cholesterol, and sphingolipids. Caveola-mediated endocytosis is responsible for the uptake of a wide variety of host ligands, as well as bacteria, bacterial toxins, and a number of viruses. To determine the cellular entry mechanism of RVFV, we used small-molecule inhibitors, RNA interference (RNAi), and dominant negative (DN) protein expression to inhibit the major mammalian cell endocytic pathways. Inhibitors and RNAi specific for macropinocytosis and clathrin-mediated endocytosis had no effect on RVFV infection. In contrast, inhibitors of caveola-mediated endocytosis, and RNAi targeted to caveolin-1 and dynamin, drastically reduced RVFV infection in multiple cell lines. Expression of DN caveolin-1 also reduced RVFV infection significantly, while expression of DN EPS15, a protein required for the assembly of clathrin-coated pits, and DN PAK-1, an obligate mediator of macropinocytosis, had no significant impact on RVFV infection. These results together suggest that the primary mechanism of RVFV MP-12 uptake is dynamin-dependent, caveolin-1-mediated endocytosis.
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Zhao SL, Dai XJ, Liang JS, Liang CY. Surface display of rice stripe virus NSvc2 and analysis of its membrane fusion activity. Virol Sin 2012; 27:100-8. [PMID: 22492001 DOI: 10.1007/s12250-012-3237-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/08/2012] [Indexed: 11/25/2022] Open
Abstract
Rice stripe virus (RSV) infects rice and is transmitted in a propagative manner by the small brown planthopper. How RSV enters an insect cell to initiate the infection cycle is poorly understood. Sequence analysis revealed that the RSV NSvc2 protein was similar to the membrane glycoproteins of several members in the family Bunyaviridae and might induce cell membrane fusion. To conveniently study the membrane fusion activity of NSvc2, we constructed cell surface display vectors for expressing Nsvc2 on the insect cell surface as the membrane glycoproteins of the enveloped viruses. Our results showed that NSvc2 was successfully expressed and displayed on the surface of insect Sf9 cells. When induced by low pH, the membrane fusion was not observed in the cells that expressed NSvc2. Additionally, the membrane fusion was also not detected when co-expressing Nsvc2 and the viral capsid protein on insect cell surface. Thus, RSV NSvc2 is probably different from the phlebovirus counterparts, which could suggest different functions. RSV might enter insect cells other than by fusion with plasma or endosome membrane.
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Affiliation(s)
- Shu-ling Zhao
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, China
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Abstract
Rift Valley fever (RVF) is an emerging zoonotic disease distributed in sub-Saharan African countries and the Arabian Peninsula. The disease is caused by the Rift Valley fever virus (RVFV) of the family Bunyaviridae and the genus Phlebovirus. The virus is transmitted by mosquitoes, and virus replication in domestic ruminant results in high rates of mortality and abortion. RVFV infection in humans usually causes a self-limiting, acute and febrile illness; however, a small number of cases progress to neurological disorders, partial or complete blindness, hemorrhagic fever, or thrombosis. This review describes the pathology of RVF in human patients and several animal models, and summarizes the role of viral virulence factors and host factors that affect RVFV pathogenesis.
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Abstract
Rift Valley fever virus (RVFV) is a zoonotic pathogen that primarily affects ruminants but can also be lethal in humans. A negative-stranded RNA virus of the family Bunyaviridae, this pathogen is transmitted mainly via mosquito vectors. RVFV has shown the ability to inflict significant damage to livestock and is also a threat to public health. While outbreaks have traditionally occurred in sub-Saharan Africa, recent outbreaks in the Middle East have raised awareness of the potential of this virus to spread to Europe, Asia, and the Americas. Although the virus was initially characterized almost 80 years ago, the only vaccine approved for widespread veterinary use is an attenuated strain that has been associated with significant pathogenic side effects. However, increased understanding of the molecular biology of the virus over the last few years has led to recent advances in vaccine design and has enabled the development of more-potent prophylactic measures to combat infection. In this review, we discuss several aspects of RVFV, with particular emphasis on the molecular components of the virus and their respective roles in pathogenesis and an overview of current vaccine candidates. Progress in understanding the epidemiology of Rift Valley fever has also enabled prediction of potential outbreaks well in advance, thus providing another tool to combat the physical and economic impact of this disease.
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Pepin M, Bouloy M, Bird BH, Kemp A, Paweska J. Rift Valley fever virus(Bunyaviridae: Phlebovirus): an update on pathogenesis, molecular epidemiology, vectors, diagnostics and prevention. Vet Res 2010; 41:61. [PMID: 21188836 PMCID: PMC2896810 DOI: 10.1051/vetres/2010033] [Citation(s) in RCA: 417] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Accepted: 05/21/2010] [Indexed: 12/24/2022] Open
Abstract
Rift Valley fever(RVF) virus is an arbovirus in the Bunyaviridae family that, from phylogenetic analysis, appears to have first emerged in the mid-19th century and was only identified at the beginning of the 1930's in the Rift Valley region of Kenya. Despite being an arbovirus with a relatively simple but temporally and geographically stable genome, this zoonotic virus has already demonstrated a real capacity for emerging in new territories, as exemplified by the outbreaks in Egypt (1977), Western Africa (1988) and the Arabian Peninsula (2000), or for re-emerging after long periods of silence as observed very recently in Kenya and South Africa. The presence of competent vectors in countries previously free of RVF, the high viral titres in viraemic animals and the global changes in climate, travel and trade all contribute to make this virus a threat that must not be neglected as the consequences of RVF are dramatic, both for human and animal health. In this review, we present the latest advances in RVF virus research. In spite of this renewed interest, aspects of the epidemiology of RVF virus are still not fully understood and safe, effective vaccines are still not freely available for protecting humans and livestock against the dramatic consequences of this virus.
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Lozach PY, Mancini R, Bitto D, Meier R, Oestereich L, Overby AK, Pettersson RF, Helenius A. Entry of bunyaviruses into mammalian cells. Cell Host Microbe 2010; 7:488-99. [PMID: 20542252 PMCID: PMC7172475 DOI: 10.1016/j.chom.2010.05.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2009] [Revised: 03/16/2010] [Accepted: 04/28/2010] [Indexed: 01/31/2023]
Abstract
The Bunyaviridae constitute a large family of enveloped animal viruses, many members of which cause serious diseases. However, early bunyavirus-host cell interactions and entry mechanisms remain largely uncharacterized. Investigating Uukuniemi virus, a bunyavirus of the genus Phlebovirus, we found that virus attachment to the cell surface was specific but inefficient, with 25% of bound viruses being endocytosed within 10 min, mainly via noncoated vesicles. The viruses entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomes. Acid-activated penetration, occurring 20-40 min after internalization, required maturation of early to late endosomes. The pH threshold for viral membrane fusion was 5.4, and entry was sensitive to temperatures below 25 degrees C. Together, our results indicate that Uukuniemi virus penetrates host cells by acid-activated membrane fusion from late endosomal compartments. This study also highlights the importance of the degradative branch of the endocytic pathway in facilitating entry of late-penetrating viruses.
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Affiliation(s)
- Pierre-Yves Lozach
- ETH Zurich, Institute of Biochemistry, Schafmattstrasse 18, CH-8093 Zurich, Switzerland
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Bouloy M, Weber F. Molecular biology of rift valley Fever virus. Open Virol J 2010; 4:8-14. [PMID: 20517489 PMCID: PMC2878978 DOI: 10.2174/1874357901004020008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 11/25/2009] [Accepted: 11/25/2009] [Indexed: 12/25/2022] Open
Abstract
Rift Valley fever virus (RVFV) causes large outbreaks of acute febrile and often fatal illness among humans and domesticated animals in sub-saharan Africa and the Arabian peninsula. RVFV is a member of the family Bunyaviridae, genus Phlebovirus. Like all members of this large virus family, it contains a three-segmented genome of negative/ambisense strand RNA, packaged into viral nucleocapsid protein, and enveloped by a lipid bilayer containing two viral glycoproteins. During the past years, there was an increased interest in RVFV epidemiology, molecular biology, and virulence mechanisms. Here, we will try to provide an overview over the basic features of this significant pathogen, and review the latest developments in this highly active research field.
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Affiliation(s)
- Michele Bouloy
- Unite de Genetique Moleculaire des Bunyavirus, Institut Pasteur, Paris, France
| | - Friedemann Weber
- Department of Virology, University of Freiburg, D-79008 Freiburg, Germany
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Piper ME, Gerrard SR. A novel system for identification of inhibitors of rift valley Fever virus replication. Viruses 2010; 2:731-747. [PMID: 21994655 PMCID: PMC3185646 DOI: 10.3390/v2030731] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/07/2010] [Accepted: 03/09/2010] [Indexed: 12/24/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a human and livestock pathogen endemic to sub-Saharan Africa. We have developed a T7-dependent system for the efficient production of RVFV-like particles (RVF-VLPs) based on the virulent ZH-501 strain of RVFV. The RVF-VLPs are capable of performing a single round of infection, allowing for the study of viral replication, assembly, and infectivity. We demonstrate that these RVF-VLPs are antigenically indistinguishable from authentic RVFV and respond similarly to a wide array of known and previously unknown chemical inhibitors. This system should be useful for screening for small molecule inhibitors of RVFV replication.
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Affiliation(s)
- Mary E. Piper
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA; E-Mail: (M.E.P.)
| | - Sonja R. Gerrard
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA; E-Mail: (M.E.P.)
- Department of Epidemiology, University of Michigan, Ann Arbor, MI, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-734-615-8491; Fax: +1-734-764-3192
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Mandell RB, Koukuntla R, Mogler LJ, Carzoli AK, Freiberg AN, Holbrook MR, Martin BK, Staplin WR, Vahanian NN, Link CJ, Flick R. A replication-incompetent Rift Valley fever vaccine: chimeric virus-like particles protect mice and rats against lethal challenge. Virology 2010; 397:187-98. [PMID: 19932911 PMCID: PMC2813982 DOI: 10.1016/j.virol.2009.11.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 10/27/2009] [Accepted: 11/02/2009] [Indexed: 11/09/2022]
Abstract
Virus-like particles (VLPs) present viral antigens in a native conformation and are effectively recognized by the immune system and therefore are considered as suitable and safe vaccine candidates against many viral diseases. Here we demonstrate that chimeric VLPs containing Rift Valley fever virus (RVFV) glycoproteins G(N) and G(C), nucleoprotein N and the gag protein of Moloney murine leukemia virus represent an effective vaccine candidate against Rift Valley fever, a deadly disease in humans and livestock. Long-lasting humoral and cellular immune responses are demonstrated in a mouse model by the analysis of neutralizing antibody titers and cytokine secretion profiles. Vaccine efficacy studies were performed in mouse and rat lethal challenge models resulting in high protection rates. Taken together, these results demonstrate that replication-incompetent chimeric RVF VLPs are an efficient RVFV vaccine candidate.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Nicholas N. Vahanian
- BioProtection Systems Corporation, Ames, IA, USA,NewLink Genetics Corporation, Ames, IA, USA
| | - Charles J. Link
- BioProtection Systems Corporation, Ames, IA, USA,NewLink Genetics Corporation, Ames, IA, USA
| | - Ramon Flick
- BioProtection Systems Corporation, Ames, IA, USA,Corresponding author. Fax: +1 515 296 3820
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Kortekaas J, Dekker A, de Boer SM, Weerdmeester K, Vloet RPM, de Wit AAC, Peeters BPH, Moormann RJM. Intramuscular inoculation of calves with an experimental Newcastle disease virus-based vector vaccine elicits neutralizing antibodies against Rift Valley fever virus. Vaccine 2010; 28:2271-6. [PMID: 20079874 DOI: 10.1016/j.vaccine.2010.01.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 01/04/2010] [Accepted: 01/06/2010] [Indexed: 12/01/2022]
Abstract
In the past decade, the use of Newcastle disease virus (NDV) as a vaccine vector for the prevention of economically important livestock diseases as well as for human diseases has been extensively explored. In this study, we have constructed a recombinant NDV vaccine virus, named NDFL-Gn, that produces the Rift Valley fever virus (RVFV) Gn glycoprotein. Calves were immunized via either the intranasal route or the intramuscular route. Delivery via the intranasal route elicited no detectable antibody responses, whereas delivery via the intramuscular route elicited antibodies against both NDV and the Gn protein. The RVFV-neutralizing activity of the antisera from intramuscularly vaccinated calves was demonstrated, suggesting that NDV is a promising vaccine vector for the prevention of RVF in calves.
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Affiliation(s)
- J Kortekaas
- Virology Division, Cluster of Mammalian Virology, Central Veterinary Institute of Wageningen University Research Centre, P.O. Box 65, 8200 AB Lelystad, The Netherlands.
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de Boer SM, Kortekaas J, Antonis AF, Kant J, van Oploo JL, Rottier PJM, Moormann RJM, Bosch BJ. Rift Valley fever virus subunit vaccines confer complete protection against a lethal virus challenge. Vaccine 2010; 28:2330-9. [PMID: 20056185 DOI: 10.1016/j.vaccine.2009.12.062] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 12/08/2009] [Accepted: 12/23/2009] [Indexed: 11/15/2022]
Abstract
Rift Valley fever virus (RVFV) is an emerging mosquito-borne virus causing significant morbidity and mortality in livestock and humans. Rift Valley fever is endemic in Africa, but also outside this continent outbreaks have been reported. Here we report the evaluation of two vaccine candidates based on the viral Gn and Gc envelope glycoproteins, both produced in a Drosophila insect cell expression system. Virus-like particles (VLPs) were generated by merely expressing the Gn and Gc glycoproteins. In addition, a soluble form of the Gn ectodomain was expressed and affinity-purified from the insect cell culture supernatant. Both vaccine candidates fully protected mice from a lethal challenge with RVFV. Importantly, absence of the nucleocapsid protein in either vaccine candidate facilitates the differentiation between infected and vaccinated animals using a commercial recombinant nucleocapsid protein-based indirect ELISA.
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Affiliation(s)
- S M de Boer
- Central Veterinary Institute of Wageningen University and Research Centre, Cluster of Mammalian Virology, Edelhertweg 15, 8219 PH, Lelystad, The Netherlands.
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Shi X, Goli J, Clark G, Brauburger K, Elliott RM. Functional analysis of the Bunyamwera orthobunyavirus Gc glycoprotein. J Gen Virol 2009; 90:2483-2492. [PMID: 19570952 PMCID: PMC2885756 DOI: 10.1099/vir.0.013540-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The virion glycoproteins Gn and Gc of Bunyamwera orthobunyavirus (family Bunyaviridae) are encoded by the M RNA genome segment and have roles in both viral attachment and membrane fusion. To investigate further the structure and function of the Gc protein in viral replication, we generated 12 mutants that contain truncations from the N terminus. The effects of these deletions were analysed with regard to Golgi targeting, low pH-dependent membrane fusion, infectious virus-like particle (VLP) formation and virus infectivity. Our results show that the N-terminal half (453 residues) of the Gc ectodomain (909 residues in total) is dispensable for Golgi trafficking and cell fusion. However, deletions in this region resulted in a significant reduction in VLP formation. Four mutant viruses that contained N-terminal deletions in their Gc proteins were rescued, and found to be attenuated to different degrees in BHK-21 cells. Taken together, our data indicate that the N-terminal half of the Gc ectodomain is dispensable for replication in cell culture, whereas the C-terminal half is required to mediate cell fusion. A model for the domain structure of the Gc ectodomain is proposed.
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Affiliation(s)
- Xiaohong Shi
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland, UK
| | - Josthna Goli
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland, UK
| | - Gordon Clark
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland, UK
| | - Kristina Brauburger
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland, UK
| | - Richard M Elliott
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland, UK
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An alphavirus replicon-derived candidate vaccine against Rift Valley fever virus. Epidemiol Infect 2009; 137:1309-18. [PMID: 19171081 DOI: 10.1017/s0950268808001696] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rift Valley fever virus (RVFV) is a mosquito-transmitted bunyavirus (genus Phlebovirus) associated with severe disease in livestock and fatal encephalitis or haemorrhagic fever in a proportion of infected humans. Although live attenuated and inactivated vaccines have been used in livestock, and on a limited scale in humans, there is a need for improved anti-RVFV vaccines. Towards this goal, Sindbis virus replicon vectors expressing the RVFV Gn and Gc glycoproteins, as well as the non-structural nsM protein, were constructed and evaluated for their ability to induce protective immune responses against RVFV. These replicon vectors were shown to produce the RVFV glycoproteins to high levels in vitro and to induce systemic anti-RVFV antibody responses in immunized mice, as determined by RVFV-specific ELISA, fluorescent antibody tests, and demonstration of a neutralizing antibody response. Replicon vaccination also provided 100% protection against lethal RVFV challenge by either the intraperitoneal or intranasal route. Furthermore, preliminary results indicate that the replicon vectors elicit RVFV-specific neutralizing antibody responses in vaccinated sheep. These results suggest that alphavirus-based replicon vectors can induce protective immunity against RVFV, and that this approach merits further investigation into its potential utility as a RVFV vaccine.
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Liu L, Celma CCP, Roy P. Rift Valley fever virus structural proteins: expression, characterization and assembly of recombinant proteins. Virol J 2008; 5:82. [PMID: 18638365 PMCID: PMC2488336 DOI: 10.1186/1743-422x-5-82] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 07/18/2008] [Indexed: 01/24/2023] Open
Abstract
Background Studies on Rift Valley Fever Virus (RVFV) infection process and morphogenesis have been hampered due to the biosafety conditions required to handle this virus, making alternative systems such as recombinant virus-like particles, that may facilitate understanding of these processes are highly desirable. In this report we present the expression and characterization of RVFV structural proteins N, Gn and Gc and demonstrate the efficient generation of RVFV virus-like particles (VLPs) using a baculovirus expression system. Results A recombinant baculovirus, expressing nucleocapsid (N) protein of RVFV at high level under the control of the polyhedrin promoter was generated. Gel filtration analysis indicated that expressed N protein could form complex multimers. Further, N protein complex when visualized by electron microscopy (EM) exhibited particulate, nucleocapsid like-particles (NLPs). Subsequently, a single recombinant virus was generated that expressed the RVFV glycoproteins (Gn/Gc) together with the N protein using a dual baculovirus vector. Both the Gn and Gc glycoproteins were detected not only in the cytoplasm but also on the cell surface of infected cells. Moreover, expression of the Gn/Gc in insect cells was able to induce cell-cell fusion after a low pH shift indicating the retention of their functional characteristics. In addition, assembly of these three structural proteins into VLPs was identified by purification of cells' supernatant through potassium tartrate-glycerol gradient centrifugation followed by EM analysis. The purified particles exhibited enveloped structures that were similar to the structures of the wild-type RVFV virion particle. In parallel, a second recombinant virus was constructed that expressed only Gc protein together with N protein. This dual recombinant virus also generated VLPs with clear spiky structures, but appeared to be more pleomorphic than the VLPs with both glycoproteins, suggesting that Gc and probably also Gn interacts with N protein complex independent of each other. Conclusion Our results suggest that baculovirus expression system has enormous potential to produce large amount of VLPs that may be used both for fundamental and applied research of RVFV.
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Affiliation(s)
- Li Liu
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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