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Jain A, Govindan R, Berkman AR, Luban J, Díaz-Salinas MA, Durham ND, Munro JB. Regulation of Ebola GP conformation and membrane binding by the chemical environment of the late endosome. PLoS Pathog 2023; 19:e1011848. [PMID: 38055723 PMCID: PMC10727438 DOI: 10.1371/journal.ppat.1011848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/18/2023] [Accepted: 11/20/2023] [Indexed: 12/08/2023] Open
Abstract
Interaction between the Ebola virus envelope glycoprotein (GP) and the endosomal membrane is an essential step during virus entry into the cell. Acidic pH and Ca2+ have been implicated in mediating the GP-membrane interaction. However, the molecular mechanism by which these environmental factors regulate the conformational changes that enable engagement of GP with the target membrane is unknown. Here, we apply fluorescence correlation spectroscopy (FCS) and single-molecule Förster resonance energy transfer (smFRET) imaging to elucidate how the acidic pH, Ca2+ and anionic phospholipids in the late endosome promote GP-membrane interaction, thereby facilitating virus entry. We find that bis(monoacylglycero)phosphate (BMP), which is specific to the late endosome, is especially critical in determining the Ca2+-dependence of the GP-membrane interaction. Molecular dynamics (MD) simulations suggested residues in GP that sense pH and induce conformational changes that make the fusion loop available for insertion into the membrane. We similarly confirm residues in the fusion loop that mediate GP's interaction with Ca2+, which likely promotes local conformational changes in the fusion loop and mediates electrostatic interactions with the anionic phospholipids. Collectively, our results provide a mechanistic understanding of how the environment of the late endosome regulates the timing and efficiency of virus entry.
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Affiliation(s)
- Aastha Jain
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Ramesh Govindan
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Medical Scientist Training Program, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Alex R. Berkman
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Jeremy Luban
- Program in Molecular Medicine, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Marco A. Díaz-Salinas
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Natasha D. Durham
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - James B. Munro
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, Massachusetts, United States of America
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Durham ND, Howard AR, Govindan R, Senjobe F, Fels JM, Diehl WE, Luban J, Chandran K, Munro JB. Real-Time Analysis of Individual Ebola Virus Glycoproteins Reveals Pre-Fusion, Entry-Relevant Conformational Dynamics. Viruses 2020; 12:v12010103. [PMID: 31952255 PMCID: PMC7019799 DOI: 10.3390/v12010103] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/21/2022] Open
Abstract
The Ebola virus (EBOV) envelope glycoprotein (GP) mediates the fusion of the virion membrane with the membrane of susceptible target cells during infection. While proteolytic cleavage of GP by endosomal cathepsins and binding of the cellular receptor Niemann-Pick C1 protein (NPC1) are essential steps for virus entry, the detailed mechanisms by which these events promote membrane fusion remain unknown. Here, we applied single-molecule Förster resonance energy transfer (smFRET) imaging to investigate the structural dynamics of the EBOV GP trimeric ectodomain, and the functional transmembrane protein on the surface of pseudovirions. We show that in both contexts, pre-fusion GP is dynamic and samples multiple conformations. Removal of the glycan cap and NPC1 binding shift the conformational equilibrium, suggesting stabilization of conformations relevant to viral fusion. Furthermore, several neutralizing antibodies enrich alternative conformational states. This suggests that these antibodies neutralize EBOV by restricting access to GP conformations relevant to fusion. This work demonstrates previously unobserved dynamics of pre-fusion EBOV GP and presents a platform with heightened sensitivity to conformational changes for the study of GP function and antibody-mediated neutralization.
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Affiliation(s)
- Natasha D. Durham
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605, USA;
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA; (A.R.H.); (F.S.)
- Correspondence: (N.D.D.); (J.B.M.)
| | - Angela R. Howard
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA; (A.R.H.); (F.S.)
| | - Ramesh Govindan
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605, USA;
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA; (A.R.H.); (F.S.)
| | - Fernando Senjobe
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA; (A.R.H.); (F.S.)
| | - J. Maximilian Fels
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; (J.M.F.); (K.C.)
| | - William E. Diehl
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA; (W.E.D.); (J.L.)
| | - Jeremy Luban
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA; (W.E.D.); (J.L.)
| | - Kartik Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; (J.M.F.); (K.C.)
| | - James B. Munro
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605, USA;
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine and Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA; (A.R.H.); (F.S.)
- Correspondence: (N.D.D.); (J.B.M.)
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Zang F, Su Z, Zhou L, Konduru K, Kaplan G, Chou SY. Ultrasensitive Ebola Virus Antigen Sensing via 3D Nanoantenna Arrays. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1902331. [PMID: 31168856 DOI: 10.1002/adma.201902331] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/15/2019] [Indexed: 05/29/2023]
Abstract
Sensitive detection of pathogens is crucial for early disease diagnosis and quarantine, which is of tremendous need in controlling severe and fatal illness epidemics such as of Ebola virus (EBOV) disease. Serology assays can detect EBOV-specific antigens and antibodies cost-effectively without sophisticated equipment; however, they are less sensitive than reverse transcriptase polymerase chain reaction (RT-PCR) tests. Herein, a 3D plasmonic nanoantenna assay sensor is developed as an on-chip immunoassay platform for ultrasensitive detection of Ebola virus (EBOV) antigens. The EBOV sensor exhibits substantial fluorescence intensity enhancement in immunoassays compared to flat gold substrate. The nanoantenna-based biosensor successfully detects EBOV soluble glycoprotein (sGP) in human plasma down to 220 fg mL-1 , a significant 240 000-fold sensitivity improvement compared to the 53 ng mL-1 EBOV antigen detection limit of the existing rapid EBOV immunoassay. In a mock clinical trial, the sensor detects sGP-spiked human plasma samples at two times the limit of detection with 95.8% sensitivity. The results combined highlight the nanosensor's extraordinary capability of detecting EBOV antigen at ultralow concentration compared to existing immunoassay methods. It is a promising next-generation bioassay platform for early-stage disease diagnosis and pathogen detection for both public health and national security applications.
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Affiliation(s)
- Faheng Zang
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Zhijuan Su
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Liangcheng Zhou
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Krishnamurthy Konduru
- Laboratory of Emerging Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Gerardo Kaplan
- Laboratory of Emerging Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Stephen Y Chou
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
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First Evidence of Antibodies Against Lloviu Virus in Schreiber's Bent-Winged Insectivorous Bats Demonstrate a Wide Circulation of the Virus in Spain. Viruses 2019; 11:v11040360. [PMID: 31010201 PMCID: PMC6521100 DOI: 10.3390/v11040360] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/16/2019] [Accepted: 04/17/2019] [Indexed: 11/16/2022] Open
Abstract
Although Lloviu virus (LLOV) was discovered in the carcasses of insectivorous Schreiber’s Bent-winged bats in the caves of Northern Spain in 2002, its infectivity and pathogenicity remain unclear. We examined the seroprevalence of LLOV in potentially exposed Schreiber’s Bent-winged bats (n = 60), common serotine bats (n = 10) as controls, and humans (n = 22) using an immunoblot assay. We found antibodies against LLOV GP2 in all of Schreiber’s Bent-winged bats serum pools, but not in any of the common serotine bats and human pools tested. To confirm this seroreactivity, 52 serums were individually tested using Domain Programmable Arrays (DPA), a phage display based-system serology technique for profiling filovirus epitopes. A serological signature against different LLOV proteins was obtained in 19/52 samples tested (36.5%). The immunodominant response was in the majority specific to LLOV-unique epitopes, confirming that the serological response detected was to LLOV. To our knowledge, this is the first serological evidence of LLOV exposure in live captured Schreiber’s Bent-winged bats, dissociating LLOV circulation as the cause of the previously reported die-offs.
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Walper SA, Lasarte Aragonés G, Sapsford KE, Brown CW, Rowland CE, Breger JC, Medintz IL. Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies. ACS Sens 2018; 3:1894-2024. [PMID: 30080029 DOI: 10.1021/acssensors.8b00420] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.
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Affiliation(s)
- Scott A. Walper
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Guillermo Lasarte Aragonés
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
- College of Science, George Mason University Fairfax, Virginia 22030, United States
| | - Kim E. Sapsford
- OMPT/CDRH/OIR/DMD Bacterial Respiratory and Medical Countermeasures Branch, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | - Carl W. Brown
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
- College of Science, George Mason University Fairfax, Virginia 22030, United States
| | - Clare E. Rowland
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
- National Research Council, Washington, D.C. 20036, United States
| | - Joyce C. Breger
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Igor L. Medintz
- Center for Bio/Molecular Science and Engineering, Code 6900, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
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Gai W, Zheng X, Wang C, Wang H, Zhao Y, Wang Q, Wong G, Zhang W, Feng N, Qiu B, Chi H, Li N, Wang T, Gao Y, Shan J, Yang S, Xia X. Marburg virus-like particles by co-expression of glycoprotein and matrix protein in insect cells induces immune responses in mice. Virol J 2017; 14:204. [PMID: 29070075 PMCID: PMC5657058 DOI: 10.1186/s12985-017-0869-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/12/2017] [Indexed: 06/14/2023] Open
Abstract
Background Marburg virus (MARV) causes severe haemorrhagic fever in humans and nonhuman primates and has a high mortality rate. However, effective drugs or licensed vaccines are not currently available to control the outbreak and spread of this disease. Methods In this study, we generated MARV virus-like particles (VLPs) by co-expressing the glycoprotein (GP) and matrix protein (VP40) using the baculovirus expression system. MARV VLPs and three adjuvants, Poria cocos polysaccharide (PCP-II), poly(I:C) and aluminium hydroxide, were evaluated after intramuscular vaccination in mice. Results Murine studies demonstrated that vaccination with the MARV VLPs induce neutralizing antibodies and cellar immune responses. MARV VLPs and the PCP-II adjuvant group resulted in high titres of MARV-specific antibodies, activated relatively higher numbers of B cells and T cells in peripheral blood mononuclear cells (PBMCs), and induced greater cytokine secretion from splenocytes than the other adjuvants. Conclusion MARV VLPs with the PCP-II adjuvant may constitute an effective vaccination and PCP-II should be further investigated as a novel adjuvant.
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Affiliation(s)
- Weiwei Gai
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, China.,Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Xuexing Zheng
- School of Public Health, Shandong University, Jinan, China
| | - Chong Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Hualei Wang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Yongkun Zhao
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Qi Wang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China.,College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Gary Wong
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Weijiao Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, China.,Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Na Feng
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Boning Qiu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, China.,Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Hang Chi
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Nan Li
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Tiecheng Wang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Yuwei Gao
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China
| | - Junjie Shan
- Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, China. .,Department of Virology, Institute of Military Veterinary, Academy of Military Medical Sciences, 666 Liuying West Road, Changchun, Jilin, 130012, People's Republic of China.
| | - Songtao Yang
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China. .,Department of Virology, Institute of Military Veterinary, Academy of Military Medical Sciences, 666 Liuying West Road, Changchun, Jilin, 130012, People's Republic of China.
| | - Xianzhu Xia
- Key Laboratory of Jilin Province for Zoonosis Prevention and Control, Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China. .,Department of Virology, Institute of Military Veterinary, Academy of Military Medical Sciences, 666 Liuying West Road, Changchun, Jilin, 130012, People's Republic of China.
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Development of a liquid chromatography high resolution mass spectrometry method for the quantitation of viral envelope glycoprotein in Ebola virus-like particle vaccine preparations. Clin Proteomics 2016; 13:18. [PMID: 27597813 PMCID: PMC5011338 DOI: 10.1186/s12014-016-9119-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 07/13/2016] [Indexed: 01/30/2023] Open
Abstract
Background Ebola virus like particles (EBOV VLPs, eVLPs), are produced by expressing the viral transmembrane glycoprotein (GP) and structural matrix protein VP40 in mammalian cells. When expressed, these proteins self-assemble and bud from ‘host’ cells displaying morphology similar to infectious virions. Several studies have shown that rodents and non-human primates vaccinated with eVLPs are protected from lethal EBOV challenge. The mucin-like domain of envelope glycoprotein GP1 serves as the major target for a productive humoral immune response. Therefore GP1 concentration is a critical quality attribute of EBOV vaccines and accurate measurement of the amount of GP1 present in eVLP lots is crucial to understanding variability in vaccine efficacy. Methods After production, eVLPs are characterized by determining total protein concentration and by western blotting, which only provides semi-quantitative information for GP1. Therefore, a liquid chromatography high resolution mass spectrometry (LC-HRMS) approach for accurately measuring GP1 concentration in eVLPs was developed. The method employs an isotope dilution strategy using four target peptides from two regions of the GP1 protein. Purified recombinant GP1 was generated to serve as an assay standard. GP1 quantitation in 5 eVLP lots was performed on an LTQ-Orbitrap Elite and the final quantitation was derived by comparing the relative response of 200 fmol AQUA peptide standards to the analyte response at 4 ppm. Results Conditions were optimized to ensure complete tryptic digestion of eVLP, however, persistent missed cleavages were observed in target peptides. Additionally, N-terminal truncated forms of the GP1 protein were observed in all eVLP lots, making peptide selection crucial. The LC-HRMS strategy resulted in quantitation of GP1 with a lower limit of quantitation of 1 fmol and an average percent coefficient of variation (CV) of 7.6 %. Unlike western blot values, the LC-HRMS quantitation of GP1 in 5 eVLP vaccine lots exhibited a strong linear relationship (positive correlation) with survival (after EBOV challenge) in mice. Conclusions This method provides a means to rapidly determine eVLP batch quality based upon quantitation of antigenic GP1. By monitoring variability in GP1 content, the eVLP production process can be optimized, and the total amount of GP1 needed to confer protection accurately determined. Electronic supplementary material The online version of this article (doi:10.1186/s12014-016-9119-8) contains supplementary material, which is available to authorized users.
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Mapping of Ebolavirus Neutralization by Monoclonal Antibodies in the ZMapp Cocktail Using Cryo-Electron Tomography and Studies of Cellular Entry. J Virol 2016; 90:7618-27. [PMID: 27279622 DOI: 10.1128/jvi.00406-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/30/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED ZMapp, a cocktail of three monoclonal antibodies (MAbs; c2G4, c4G7, and c13C6) against the ebolavirus (EBOV) glycoprotein (GP), shows promise for combatting outbreaks of EBOV, as occurred in West Africa in 2014. Prior studies showed that Fabs from these MAbs bind a soluble EBOV GP ectodomain and that MAbs c2G4 and c4G7, but not c13C6, neutralize infections in cell cultures. Using cryo-electron tomography, we extended these findings by characterizing the structures of c2G4, c4G7, and c13C6 IgGs bound to native, full-length GP from the West African 2014 isolate embedded in filamentous viruslike particles (VLPs). As with the isolated ectodomain, c13C6 bound to the glycan cap, whereas c2G4 and c4G7 bound to the base region of membrane-bound GP. The tomographic data suggest that all three MAbs bind with high occupancy and that the base-binding antibodies can potentially bridge neighboring GP spikes. Functional studies indicated that c2G4 and c4G7, but not c13C6, competitively inhibit entry of VLPs bearing EBOV GP into the host cell cytoplasm, without blocking trafficking of VLPs to NPC1(+) endolysosomes, where EBOV fuses. Moreover, c2G4 and c4G7 bind to and can block entry mediated by the primed (19-kDa) form of GP without impeding binding of the C-loop of NPC1, the endolysosomal receptor for EBOV. The most likely mode of action of c2G4 and c4G7 is therefore by inhibiting conformational changes in primed, NPC1-bound GP that initiate fusion between the viral and target membranes, similar to the action of certain broadly neutralizing antibodies against influenza hemagglutinin and HIV Env. IMPORTANCE The recent West African outbreak of ebolavirus caused the deaths of more than 11,000 individuals. Hence, there is an urgent need to be prepared with vaccines and therapeutics for similar future disasters. ZMapp, a cocktail of three MAbs directed against the ebolavirus glycoprotein, is a promising anti-ebolavirus therapeutic. Using cryo-electron tomography, we provide structural information on how each of the MAbs in this cocktail binds to the ebolavirus glycoprotein as it is displayed-embedded in the membrane and present at high density-on filamentous viruslike particles that recapitulate the surface structure and entry functions of ebolavirus. Moreover, after confirming that two of the MAbs bind to the same region in the base of the glycoprotein, we show that they competitively block the entry function of the glycoprotein and that they can do so after the glycoprotein is proteolytically primed and bound to its intracellular receptor, Niemann-Pick C1. These findings should inform future developments of ebolavirus therapeutics.
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Burk R, Bollinger L, Johnson JC, Wada J, Radoshitzky SR, Palacios G, Bavari S, Jahrling PB, Kuhn JH. Neglected filoviruses. FEMS Microbiol Rev 2016; 40:494-519. [PMID: 27268907 PMCID: PMC4931228 DOI: 10.1093/femsre/fuw010] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/06/2016] [Accepted: 05/04/2016] [Indexed: 12/22/2022] Open
Abstract
Eight viruses are currently assigned to the family Filoviridae Marburg virus, Sudan virus and, in particular, Ebola virus have received the most attention both by researchers and the public from 1967 to 2013. During this period, natural human filovirus disease outbreaks occurred sporadically in Equatorial Africa and, despite high case-fatality rates, never included more than several dozen to a few hundred infections per outbreak. Research emphasis shifted almost exclusively to Ebola virus in 2014, when this virus was identified as the cause of an outbreak that has thus far involved more than 28 646 people and caused more than 11 323 deaths in Western Africa. Consequently, major efforts are currently underway to develop licensed medical countermeasures against Ebola virus infection. However, the ecology of and mechanisms behind Ebola virus emergence are as little understood as they are for all other filoviruses. Consequently, the possibility of the future occurrence of a large disease outbreak caused by other less characterized filoviruses (i.e. Bundibugyo virus, Lloviu virus, Ravn virus, Reston virus and Taï Forest virus) is impossible to rule out. Yet, for many of these viruses, not even rudimentary research tools are available, let alone medical countermeasures. This review summarizes the current knowledge on these less well-characterized filoviruses.
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Affiliation(s)
- Robin Burk
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
- Department of Infectious Diseases, Virology, University of Heidelberg, 69120 Heidelberg, Baden-Württemberg, Germany
| | - Laura Bollinger
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
| | - Joshua C. Johnson
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
| | - Jiro Wada
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
| | - Sheli R. Radoshitzky
- United States Army Medical Research Institute of Infectious Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Gustavo Palacios
- United States Army Medical Research Institute of Infectious Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Sina Bavari
- United States Army Medical Research Institute of Infectious Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Frederick, MD 21702, USA
| | - Peter B. Jahrling
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
| | - Jens H. Kuhn
- Integrated Research Facility at Fort Detrick (IRF-Frederick), Division of Clinical Research (DCR), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), B-8200 Research Plaza, Fort Detrick, Frederick, MD 21702, USA
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Nucleoprotein-based indirect enzyme-linked immunosorbent assay (indirect ELISA) for detecting antibodies specific to Ebola virus and Marbug virus. Virol Sin 2014; 29:372-80. [PMID: 25547682 DOI: 10.1007/s12250-014-3512-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/06/2014] [Indexed: 10/24/2022] Open
Abstract
Full-length nucleoproteins from Ebola and Marburg viruses were expressed as His-tagged recombinant proteins in Escherichia coli and nucleoprotein-based enzyme-linked immunosorbent assays (ELISAs) were established for the detection of antibodies specific to Ebola and Marburg viruses. The ELISAs were evaluated by testing antisera collected from rabbit immunized with Ebola and Marburg virus nucleoproteins. Although little cross-reactivity of antibodies was observed in anti-Ebola virus nucleoprotein rabbit antisera, the highest reactions to immunoglobulin G (IgG) were uniformly detected against the nucleoprotein antigens of homologous viruses. We further evaluated the ELISA's ability to detect antibodies to Ebola and Marburg viruses using human sera samples collected from individuals passing through the Guangdong port of entry. With a threshold set at the mean plus three standard deviations of average optical densities of sera tested, the ELISA systems using these two recombinant nucleoproteins have good sensitivity and specificity. These results demonstrate the usefulness of ELISA for diagnostics as well as ecological and serosurvey studies of Ebola and Marburg virus infection.
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Ou W, Delisle J, Jacques J, Shih J, Price G, Kuhn JH, Wang V, Verthelyi D, Kaplan G, Wilson CA. Induction of ebolavirus cross-species immunity using retrovirus-like particles bearing the Ebola virus glycoprotein lacking the mucin-like domain. Virol J 2012; 9:32. [PMID: 22273269 PMCID: PMC3284443 DOI: 10.1186/1743-422x-9-32] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 01/25/2012] [Indexed: 11/21/2022] Open
Abstract
Background The genus Ebolavirus includes five distinct viruses. Four of these viruses cause hemorrhagic fever in humans. Currently there are no licensed vaccines for any of them; however, several vaccines are under development. Ebola virus envelope glycoprotein (GP1,2) is highly immunogenic, but antibodies frequently arise against its least conserved mucin-like domain (MLD). We hypothesized that immunization with MLD-deleted GP1,2 (GPΔMLD) would induce cross-species immunity by making more conserved regions accessible to the immune system. Methods To test this hypothesis, mice were immunized with retrovirus-like particles (retroVLPs) bearing Ebola virus GPΔMLD, DNA plasmids (plasmo-retroVLP) that can produce such retroVLPs in vivo, or plasmo-retroVLP followed by retroVLPs. Results Cross-species neutralizing antibody and GP1,2-specific cellular immune responses were successfully induced. Conclusion Our findings suggest that GPΔMLD presented through retroVLPs may provide a strategy for development of a vaccine against multiple ebolaviruses. Similar vaccination strategies may be adopted for other viruses whose envelope proteins contain highly variable regions that may mask more conserved domains from the immune system.
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Affiliation(s)
- Wu Ou
- Division of Cellular and Gene Therapies, Center for Biologics Evaluation and Research, Bldg, 29B, Room 5NN22, 8800 Rockville Pike, Bethesda, MD 20892, USA
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Production and characterization of peptide antibodies. Methods 2011; 56:136-44. [PMID: 22178691 DOI: 10.1016/j.ymeth.2011.12.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 11/30/2011] [Accepted: 12/02/2011] [Indexed: 12/18/2022] Open
Abstract
Proteins are effective immunogens for generation of antibodies. However, occasionally the native protein is known but not available for antibody production. In such cases synthetic peptides derived from the native protein are good alternatives for antibody production. These peptide antibodies are powerful tools in experimental biology and are easily produced to any peptide of choice. A widely used approach for production of peptide antibodies is to immunize animals with a synthetic peptide coupled to a carrier protein. Very important is the selection of the synthetic peptide, where factors such as structure, accessibility and amino acid composition are crucial. Since small peptides tend not to be immunogenic, it may be necessary to conjugate them to carrier proteins in order to enhance immune presentation. Several strategies for conjugation of peptide-carriers applied for immunization exist, including solid-phase peptide-carrier conjugation and peptide-carrier conjugation in solution. Upon immunization, adjuvants such as Al(OH)(3) are added together with the immunogenic peptide-carrier conjugate, which usually leads to high-titred antisera. Following immunization and peptide antibody purification, the antibodies are characterized based on their affinity or specificity. An efficient approach for characterization of peptide antibodies is epitope mapping using peptide based assays. This review describes standard solid-phase approaches for generation of peptide antibodies with special emphasis on peptide selection, generation of peptide conjugates for immunization and characterization of the resulting peptide antibodies.
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