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Titarenko V, Roseman AM. Optimal 3D angular sampling with applications to cryo-EM problems. J Struct Biol 2024; 216:108083. [PMID: 38490514 DOI: 10.1016/j.jsb.2024.108083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 02/07/2024] [Accepted: 03/09/2024] [Indexed: 03/17/2024]
Abstract
The goal of cryo-EM experiments in the biological sciences is to determine the atomic structure of a molecule and deduce insights into its functions and mechanisms. Despite improvements in instrumentation for data collection and new software algorithms, in most cases, individual atoms are not resolved. Model building of proteins, nucleic acids, or molecules in general, is feasible from the experimentally determined density maps at resolutions up to the range of 3-4 Angstroms. For lower-resolution maps or parts of maps, fitting smaller structures obtained by modelling or experimental techniques with higher resolution is a way to resolve the issue. In practice, we have an atomic structure, generate its density map at a given resolution, and translate/rotate the map within a region of interest in the experimental map, computing a measure-of-fit score with the corresponding areas of the experimental map. This procedure is computationally intensive since we work in 6D space. An optimal ordered list of rotations will reduce the angular error and help to find the best-fitting positions faster for a coarse global search or a local refinement. It can be used for adaptive approaches to stop fitting algorithms earlier once the desired accuracy has been achieved. We demonstrate how the performance of some fitting algorithms can be improved by grouping sets of rotations. We present an approach to generate more efficient 3D angular sampling, and provide the computer code to generate lists of optimal orientations for single and grouped rotations and the lists themselves.
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Affiliation(s)
- Valeriy Titarenko
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, The Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Alan M Roseman
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, The Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom
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2
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Chmielewski D, Su GC, Kaelber JT, Pintilie GD, Chen M, Jin J, Auguste AJ, Chiu W. Cryogenic electron microscopy and tomography reveal imperfect icosahedral symmetry in alphaviruses. PNAS NEXUS 2024; 3:pgae102. [PMID: 38525304 PMCID: PMC10959069 DOI: 10.1093/pnasnexus/pgae102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 02/15/2024] [Indexed: 03/26/2024]
Abstract
Alphaviruses are spherical, enveloped RNA viruses with two-layered icosahedral architecture. The structures of many alphaviruses have been studied using cryogenic electron microscopy (cryo-EM) reconstructions, which impose icosahedral symmetry on the viral particles. Using cryogenic electron tomography (cryo-ET), we revealed a polarized symmetry defect in the icosahedral lattice of Chikungunya virus (CHIKV) in situ, similar to the late budding particles, suggesting the inherent imperfect symmetry originates from the final pinch-off of assembled virions. We further demonstrated this imperfect symmetry is also present in in vitro purified CHIKV and Mayaro virus, another arthritogenic alphavirus. We employed a subparticle-based single-particle analysis protocol to circumvent the icosahedral imperfection and boosted the resolution of the structure of the CHIKV to ∼3 Å resolution, which revealed detailed molecular interactions between glycoprotein E1-E2 heterodimers in the transmembrane region and multiple lipid-like pocket factors located in a highly conserved hydrophobic pocket. This complementary use of in situ cryo-ET and single-particle cryo-EM approaches provides a more precise structural description of near-icosahedral viruses and valuable insights to guide the development of structure-based antiviral therapies against alphaviruses.
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Affiliation(s)
- David Chmielewski
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA
| | - Guan-Chin Su
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Grigore D Pintilie
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
| | - Muyuan Chen
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Jing Jin
- Vitalant Research Institute, San Francisco, CA 94118, USA
- Department of Laboratory Medicine, University of California, San Francisco, CA 94143, USA
| | - Albert J Auguste
- Department of Entomology, College of Agriculture and Life Sciences, Fralin Life Science Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Wah Chiu
- Biophysics Graduate Program, Stanford University, Stanford, CA 94305, USA
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA 94305, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
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3
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Chykunova Y, Plewka J, Wilk P, Torzyk K, Sienczyk M, Dubin G, Pyrc K. Autoinhibition of suicidal capsid protease from O'nyong'nyong virus. Int J Biol Macromol 2024; 262:130136. [PMID: 38354926 DOI: 10.1016/j.ijbiomac.2024.130136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/10/2024] [Accepted: 02/11/2024] [Indexed: 02/16/2024]
Abstract
Alphaviruses pose a significant threat to public health. Capsid protein encoded in the alphaviral genomes constitutes an interesting therapy target, as it also serves as a protease (CP). Remarkably, it undergoes autoproteolysis, leading to the generation of the C-terminal tryptophan that localizes to the active pocket, deactivating the enzyme. Lack of activity hampers the viral replication cycle, as the virus is not capable of producing the infectious progeny. We investigated the structure and function of the CP encoded in the genome of O'nyong'nyong virus (ONNV), which has instigated outbreaks in Africa. Our research provides a high-resolution crystal structure of the ONNV CP in its active state and evaluates the enzyme's activity. Furthermore, we demonstrated a dose-dependent reduction in ONNV CP proteolytic activity when exposed to indole, suggesting that tryptophan analogs may be a promising basis for developing small molecule inhibitors. It's noteworthy that the capsid protease plays an essential role in virus assembly, binding viral glycoproteins through its glycoprotein-binding hydrophobic pocket. We showed that non-aromatic cyclic compounds like dioxane disrupt this vital interaction. Our findings provide deeper insights into ONNV's biology, and we believe they will prove instrumental in guiding the development of antiviral strategies against arthritogenic alphaviruses.
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Affiliation(s)
- Yuliya Chykunova
- Virogenetics Laboratory of Virology, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387 Krakow, Poland; Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland
| | - Jacek Plewka
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Piotr Wilk
- Structural Biology Core Facility, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387 Krakow, Poland
| | - Karolina Torzyk
- Wroclaw University of Science and Technology, Faculty of Chemistry, Division of Medicinal Chemistry and Microbiology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Marcin Sienczyk
- Wroclaw University of Science and Technology, Faculty of Chemistry, Division of Medicinal Chemistry and Microbiology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Grzegorz Dubin
- Protein Crystallography Research Group, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387 Krakow, Poland.
| | - Krzysztof Pyrc
- Virogenetics Laboratory of Virology, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7a, 30-387 Krakow, Poland.
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4
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Zubair AS, McAlpine LS, Gobeske KT. Virology, ecology, epidemiology, pathology, and treatment of eastern equine encephalitis. J Neurol Sci 2024; 457:122886. [PMID: 38278094 DOI: 10.1016/j.jns.2024.122886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/28/2024]
Abstract
Eastern equine encephalitis (EEE) was one of the first-recognized neuroinvasive arboviral diseases in North America, and it remains the most lethal. Although EEE is known to have periodic spikes in infection rates, there is increasing evidence that it may be undergoing a change in its prevalence and its public health burden. Numerous factors shape the scope of EEE in humans, and there are important similarities with other emergent viral diseases that have surfaced or strengthened in recent years. Because environmental and ecological conditions that broadly influence the epidemiology of arboviral diseases also are changing, and the frequency, severity, and scope of outbreaks are expected to worsen, an expanded understanding of EEE will have untold importance in coming years. Here we review the factors shaping EEE transmission cycles and the conditions leading to outbreaks in humans from an updated, multidomain perspective. We also provide special consideration of factors shaping the virology, host-vector-environment relationships, and mechanisms of pathology and treatment as a reference for broadening audiences.
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Affiliation(s)
- Adeel S Zubair
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Kevin T Gobeske
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
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Ma H, Adams LJ, Raju S, Sariol A, Kafai NM, Janova H, Klimstra WB, Fremont DH, Diamond MS. The low-density lipoprotein receptor promotes infection of multiple encephalitic alphaviruses. Nat Commun 2024; 15:246. [PMID: 38172096 PMCID: PMC10764363 DOI: 10.1038/s41467-023-44624-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024] Open
Abstract
Members of the low-density lipoprotein receptor (LDLR) family, including LDLRAD3, VLDLR, and ApoER2, were recently described as entry factors for different alphaviruses. However, based on studies with gene edited cells and knockout mice, blockade or abrogation of these receptors does not fully inhibit alphavirus infection, indicating the existence of additional uncharacterized entry factors. Here, we perform a CRISPR-Cas9 genome-wide loss-of-function screen in mouse neuronal cells with a chimeric alphavirus expressing the Eastern equine encephalitis virus (EEEV) structural proteins and identify LDLR as a candidate receptor. Expression of LDLR on the surface of neuronal or non-neuronal cells facilitates binding and infection of EEEV, Western equine encephalitis virus, and Semliki Forest virus. Domain mapping and binding studies reveal a low-affinity interaction with LA domain 3 (LA3) that can be enhanced by concatenation of LA3 repeats. Soluble decoy proteins with multiple LA3 repeats inhibit EEEV infection in cell culture and in mice. Our results establish LDLR as a low-affinity receptor for multiple alphaviruses and highlight a possible path for developing inhibitors that could mitigate infection and disease.
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Affiliation(s)
- Hongming Ma
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Lucas J Adams
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Saravanan Raju
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Alan Sariol
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Natasha M Kafai
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hana Janova
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - William B Klimstra
- The Center for Vaccine Research and Department of Immunology, The University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Daved H Fremont
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Center for Vaccines and Immunity to Microbial Pathogens, Washington University School of Medicine, Saint Louis, MO, 63110, USA.
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Burkett-Cadena ND, Fish D, Weaver S, Vittor AY. Everglades virus: an underrecognized disease-causing subtype of Venezuelan equine encephalitis virus endemic to Florida, USA. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:1149-1164. [PMID: 37862065 PMCID: PMC10645373 DOI: 10.1093/jme/tjad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/04/2023] [Accepted: 06/08/2023] [Indexed: 10/21/2023]
Abstract
Everglades virus (EVEV) is subtype II of the Venezuelan equine encephalitis virus (VEEV) complex (Togaviridae: Alphavirus), endemic to Florida, USA. EVEV belongs to a clade that includes both enzootic and epizootic/epidemic VEEV subtypes. Like other enzootic VEEV subtypes, muroid rodents are important vertebrate hosts for EVEV and certain mosquitoes are important vectors. The hispid cotton rat Sigmodon hispidus and cotton mouse Peromyscus gossypinus are important EVEV hosts, based on natural infection (virus isolation and high seropositivity), host competence (experimental infections), and frequency of contact with the vector. The mosquito Culex (Melanoconion) cecedei is the only confirmed vector of EVEV based upon high natural infection rates, efficient vector competence, and frequent feeding upon muroid rodents. Human disease attributed to EVEV is considered rare. However, cases of meningitis and encephalitis are recorded from multiple sites, separated by 250 km or more. Phylogenetic analyses indicate that EVEV is evolving, possibly due to changes in the mammal community. Mutations in the EVEV genome are of concern, given that epidemic strains of VEEV (subtypes IAB and IC) are derived from enzootic subtype ID, the closest genetic relative of EVEV. Should epizootic mutations arise in EVEV, the abundance of Aedes taeniorhynchus and other epizootic VEEV vectors in southern Florida provides a conducive environment for widespread transmission. Other factors that will likely influence the distribution and frequency of EVEV transmission include the establishment of Culex panocossa in Florida, Everglades restoration, mammal community decline due to the Burmese python, land use alteration by humans, and climate change.
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Affiliation(s)
- Nathan D Burkett-Cadena
- Florida Medical Entomology Laboratory, University of Florida Institute of Food and Agricultural Sciences, 200 9th St. SE, Vero Beach, FL 32962, USA
| | - Durland Fish
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Scott Weaver
- Department of Pathology, Center for Biodefense and Emerging Infectious Disease, University of Texas Medical Branch, Galveston, TX 77555-0609, USA
| | - Amy Y Vittor
- Department of Medicine & Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA
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7
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Song D, Jia X, Gao Y, Xiao T, Dan J, Shen R, Cai J, Liang J, Zhu W, Hu J, Yan G, Zhang Q, Lin Y. STT3A-mediated viral N-glycosylation underlies the tumor selectivity of oncolytic virus M1. Oncogene 2023; 42:3575-3588. [PMID: 37864032 DOI: 10.1038/s41388-023-02872-7] [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: 08/10/2023] [Revised: 10/04/2023] [Accepted: 10/12/2023] [Indexed: 10/22/2023]
Abstract
Oncolytic viruses are emerging as promising anticancer agents. Although the essential biological function of N-glycosylation on viruses are widely accepted, roles of N-glycan and glycan-processing enzyme in oncolytic viral therapy are remain elusive. Here, via cryo-EM analysis, we identified three distinct N-glycans on the envelope of oncolytic virus M1 (OVM) as being necessary for efficient receptor binding. E1-N141-glycan has immediate impact on the binding of MXRA8 receptor, E2-N200-glycan mediates the maturation of E2 from its precursor PE2 which is unable to bind with MXRA8, and E2-N262-glycan slightly promotes receptor binding. The necessity of OVM N-glycans in receptor binding make them indispensable for oncolysis in vitro and in vivo. Further investigations identified STT3A, a key catalytic subunit of oligosaccharyltransferase (OST), as the determinant of OVM N-glycosylation, and STT3A expression in tumor cells is positively correlated with OVM-induced oncolysis. Increased STT3A expression was observed in various solid tumors, pointing to a broad-spectrum anticancer potential of OVM. Collectively, our research supports the importance of STT3A-mediated N-glycosylation in receptor binding and oncolysis of OVM, thus providing a novel predictive biomarker for OVM.
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Affiliation(s)
- Deli Song
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xudong Jia
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yuanzhu Gao
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Tong Xiao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jia Dan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Runling Shen
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jing Cai
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jiankai Liang
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Wenbo Zhu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jun Hu
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Guangmei Yan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qinfen Zhang
- State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
| | - Yuan Lin
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
- Advanced Medical Technology Center, The First Affiliated Hospital-Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
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Lata K, Charles S, Mangala Prasad V. Advances in computational approaches to structure determination of alphaviruses and flaviviruses using cryo-electron microscopy. J Struct Biol 2023; 215:107993. [PMID: 37414374 DOI: 10.1016/j.jsb.2023.107993] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/15/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Advancements in the field of cryo-electron microscopy (cryo-EM) have greatly contributed to our current understanding of virus structures and life cycles. In this review, we discuss the application of single particle cryo-electron microscopy (EM) for the structure elucidation of small enveloped icosahedral viruses, namely, alpha- and flaviviruses. We focus on technical advances in cryo-EM data collection, image processing, three-dimensional reconstruction, and refinement strategies for obtaining high-resolution structures of these viruses. Each of these developments enabled new insights into the alpha- and flavivirus architecture, leading to a better understanding of their biology, pathogenesis, immune response, immunogen design, and therapeutic development.
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Affiliation(s)
- Kiran Lata
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Sylvia Charles
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Vidya Mangala Prasad
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India; Center for Infectious Disease Research, Indian Institute of Science, Bengaluru, Karnataka 560012, India
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9
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Kafai NM, Janova H, Cain MD, Alippe Y, Muraro S, Sariol A, Elam-Noll M, Klein RS, Diamond MS. Entry receptor LDLRAD3 is required for Venezuelan equine encephalitis virus peripheral infection and neurotropism leading to pathogenesis in mice. Cell Rep 2023; 42:112946. [PMID: 37556325 PMCID: PMC10529316 DOI: 10.1016/j.celrep.2023.112946] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/03/2023] [Accepted: 07/21/2023] [Indexed: 08/11/2023] Open
Abstract
Venezuelan equine encephalitis virus (VEEV) is an encephalitic alphavirus responsible for epidemics of neurological disease across the Americas. Low-density lipoprotein receptor class A domain-containing 3 (LDLRAD3) is a recently reported entry receptor for VEEV. Here, using wild-type and Ldlrad3-deficient mice, we define a critical role for LDLRAD3 in controlling steps in VEEV infection, pathogenesis, and neurotropism. Our analysis shows that LDLRAD3 is required for efficient VEEV infection and pathogenesis prior to and after central nervous system invasion. Ldlrad3-deficient mice survive intranasal and intracranial VEEV inoculation and show reduced infection of neurons in different brain regions. As LDLRAD3 is a determinant of pathogenesis and an entry receptor required for VEEV infection of neurons of the brain, receptor-targeted therapies may hold promise as countermeasures.
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Affiliation(s)
- Natasha M Kafai
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hana Janova
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Matthew D Cain
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yael Alippe
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Stefanie Muraro
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alan Sariol
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michelle Elam-Noll
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Robyn S Klein
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA; The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO 63110, USA.
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10
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Han L, Song S, Feng H, Ma J, Wei W, Si F. A roadmap for developing Venezuelan equine encephalitis virus (VEEV) vaccines: Lessons from the past, strategies for the future. Int J Biol Macromol 2023:125514. [PMID: 37353130 DOI: 10.1016/j.ijbiomac.2023.125514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023]
Abstract
Venezuelan equine encephalitis (VEE) is a zoonotic infectious disease caused by the Venezuelan equine encephalitis virus (VEEV), which can lead to severe central nervous system infections in both humans and animals. At present, the medical community does not possess a viable means of addressing VEE, rendering the prevention of the virus a matter of paramount importance. Regarding the prevention and control of VEEV, the implementation of a vaccination program has been recognized as the most efficient strategy. Nevertheless, there are currently no licensed vaccines or drugs available for human use against VEEV. This imperative has led to a surge of interest in vaccine research, with VEEV being a prime focus for researchers in the field. In this paper, we initially present a comprehensive overview of the current taxonomic classification of VEEV and the cellular infection mechanism of the virus. Subsequently, we provide a detailed introduction of the prominent VEEV vaccine types presently available, including inactivated vaccines, live attenuated vaccines, genetic, and virus-like particle vaccines. Moreover, we emphasize the challenges that current VEEV vaccine development faces and suggest urgent measures that must be taken to overcome these obstacles. Notably, based on our latest research, we propose the feasibility of incorporation codon usage bias strategies to create the novel VEEV vaccine. Finally, we prose several areas that future VEEV vaccine development should focus on. Our objective is to encourage collaboration between the medical and veterinary communities, expedite the translation of existing vaccines from laboratory to clinical applications, while also preparing for future outbreaks of new VEEV variants.
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Affiliation(s)
- Lulu Han
- Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Agricultural Genetics and Breeding, Shanghai Engineering Research Center of Breeding Pig, Shanghai 201106, China; Huaihe Hospital of Henan University, Clinical Medical College of Henan University, Kai Feng 475000, China
| | - Shuai Song
- Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Key Laboratory of Livestock Disease Prevention of Guangdong Province, Scientific Observation and Experiment Station of Veterinary Drugs and Diagnostic Techniques of Guangdong Province, Ministry of Agriculture and Rural Affairs, Guangzhou 510640, PR China
| | - Huilin Feng
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences of Henan University, Kai Feng 475000, China
| | - Jing Ma
- Huaihe Hospital of Henan University, Clinical Medical College of Henan University, Kai Feng 475000, China
| | - Wenqiang Wei
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences of Henan University, Kai Feng 475000, China.
| | - Fusheng Si
- Institute of Animal Science and Veterinary Medicine, Shanghai Academy of Agricultural Sciences, Shanghai Key Laboratory of Agricultural Genetics and Breeding, Shanghai Engineering Research Center of Breeding Pig, Shanghai 201106, China.
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11
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Williamson LE, Bandyopadhyay A, Bailey K, Sirohi D, Klose T, Julander JG, Kuhn RJ, Crowe JE. Structural constraints link differences in neutralization potency of human anti-Eastern equine encephalitis virus monoclonal antibodies. Proc Natl Acad Sci U S A 2023; 120:e2213690120. [PMID: 36961925 PMCID: PMC10068833 DOI: 10.1073/pnas.2213690120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 02/10/2023] [Indexed: 03/26/2023] Open
Abstract
Selection and development of monoclonal antibody (mAb) therapeutics against pathogenic viruses depends on certain functional characteristics. Neutralization potency, or the half-maximal inhibitory concentration (IC50) values, is an important characteristic of candidate therapeutic antibodies. Structural insights into the bases of neutralization potency differences between antiviral neutralizing mAbs are lacking. In this report, we present cryo-electron microscopy (EM) reconstructions of three anti-Eastern equine encephalitis virus (EEEV) neutralizing human mAbs targeting overlapping epitopes on the E2 protein, with greater than 20-fold differences in their respective IC50 values. From our structural and biophysical analyses, we identify several constraints that contribute to the observed differences in the neutralization potencies. Cryo-EM reconstructions of EEEV in complex with these Fab fragments reveal structural constraints that dictate intravirion or intervirion cross-linking of glycoprotein spikes by their IgG counterparts as a mechanism of neutralization. Additionally, we describe critical features for the recognition of EEEV by these mAbs including the epitope-paratope interaction surface, occupancy, and kinetic differences in on-rate for binding to the E2 protein. Each constraint contributes to the extent of EEEV inhibition for blockade of virus entry, fusion, and/or egress. These findings provide structural and biophysical insights into the differences in mechanism and neutralization potencies of these antibodies, which help inform rational design principles for candidate vaccines and therapeutic antibodies for all icosahedral viruses.
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Affiliation(s)
- Lauren E. Williamson
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
| | - Abhishek Bandyopadhyay
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Kevin Bailey
- Institute for Antiviral Research, Utah State University, Logan, UT84335
| | - Devika Sirohi
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - Thomas Klose
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | | | - Richard J. Kuhn
- Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN47907
| | - James E. Crowe
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN37232
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN37232
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN37232
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12
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Self-assembly of dengue virus empty capsid-like particles in solution. iScience 2023; 26:106197. [PMID: 36890794 PMCID: PMC9986514 DOI: 10.1016/j.isci.2023.106197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 09/11/2022] [Accepted: 02/08/2023] [Indexed: 02/17/2023] Open
Abstract
Nucleocapsid (NC) assembly is an essential step of the virus replication cycle. It ensures genome protection and transmission among hosts. Flaviviruses are human viruses for which envelope structure is well known, whereas no information on NC organization is available. Here we designed a dengue virus capsid protein (DENVC) mutant in which a highly positive spot conferred by arginine 85 in α4-helix was replaced by a cysteine residue, simultaneously removing the positive charge and restricting the intermolecular motion through the formation of a disulfide cross-link. We showed that the mutant self-assembles into capsid-like particles (CLP) in solution without nucleic acids. Using biophysical techniques, we investigated capsid assembly thermodynamics, showing that an efficient assembly is related to an increased DENVC stability due to α4/α4' motion restriction. To our knowledge, this is the first time that flaviviruses' empty capsid assembly is obtained in solution, revealing the R85C mutant as a powerful tool to understand the NC assembly mechanism.
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13
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Toelzer C, Gupta K, Berger I, Schaffitzel C. Cryo-EM reveals binding of linoleic acid to SARS-CoV-2 spike glycoprotein, suggesting an antiviral treatment strategy. Acta Crystallogr D Struct Biol 2023; 79:111-121. [PMID: 36762857 PMCID: PMC9912919 DOI: 10.1107/s2059798323000049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/03/2023] [Indexed: 01/21/2023] Open
Abstract
The COVID-19 pandemic and concomitant lockdowns presented a global health challenge and triggered unprecedented research efforts to elucidate the molecular mechanisms and pathogenicity of SARS-CoV-2. The spike glycoprotein decorating the surface of SARS-CoV-2 virions is a prime target for vaccine development, antibody therapy and serology as it binds the host cell receptor and is central for viral cell entry. The electron cryo-microscopy structure of the spike protein revealed a hydrophobic pocket in the receptor-binding domain that is occupied by an essential fatty acid, linoleic acid (LA). The LA-bound spike protein adopts a non-infectious locked conformation which is more stable than the infectious form and shields important immunogenic epitopes. Here, the impact of LA binding on viral infectivity and replication, and the evolutionary conservation of the pocket in other highly pathogenic coronaviruses, including SARS-CoV-2 variants of concern (VOCs), are reviewed. The importance of LA metabolic products, the eicosanoids, in regulating the human immune response and inflammation is highlighted. Lipid and fatty-acid binding to a hydrophobic pocket in proteins on the virion surface appears to be a broader strategy employed by viruses, including picornaviruses and Zika virus. Ligand binding stabilizes their protein structure and assembly, and downregulates infectivity. In the case of rhinoviruses, this has been exploited to develop small-molecule antiviral drugs that bind to the hydrophobic pocket. The results suggest a COVID-19 antiviral treatment based on the LA-binding pocket.
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Affiliation(s)
- Christine Toelzer
- School of Biochemistry, University of Bristol, 1 Tankard’s Close, Bristol BS8 1TD, United Kingdom
- Bristol Synthetic Biology Centre: BrisSynBio, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
| | - Kapil Gupta
- Imophoron Ltd, St Philips Central, Albert Road, Bristol BS2 0XJ, United Kingdom
| | - Imre Berger
- School of Biochemistry, University of Bristol, 1 Tankard’s Close, Bristol BS8 1TD, United Kingdom
- Bristol Synthetic Biology Centre: BrisSynBio, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
- Max Planck Bristol Centre for Minimal Biology, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Christiane Schaffitzel
- School of Biochemistry, University of Bristol, 1 Tankard’s Close, Bristol BS8 1TD, United Kingdom
- Bristol Synthetic Biology Centre: BrisSynBio, 24 Tyndall Avenue, Bristol BS8 1TQ, United Kingdom
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14
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Zimmerman O, Holmes AC, Kafai NM, Adams LJ, Diamond MS. Entry receptors - the gateway to alphavirus infection. J Clin Invest 2023; 133:e165307. [PMID: 36647825 PMCID: PMC9843064 DOI: 10.1172/jci165307] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Alphaviruses are enveloped, insect-transmitted, positive-sense RNA viruses that infect humans and other animals and cause a range of clinical manifestations, including arthritis, musculoskeletal disease, meningitis, encephalitis, and death. Over the past four years, aided by CRISPR/Cas9-based genetic screening approaches, intensive research efforts have focused on identifying entry receptors for alphaviruses to better understand the basis for cellular and species tropism. Herein, we review approaches to alphavirus receptor identification and how these were used for discovery. The identification of new receptors advances our understanding of viral pathogenesis, tropism, and evolution and is expected to contribute to the development of novel strategies for prevention and treatment of alphavirus infection.
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Affiliation(s)
| | | | | | | | - Michael S. Diamond
- Department of Medicine
- Department of Pathology and Immunology
- Department of Molecular Microbiology, and
- The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, Missouri, USA
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15
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Skidmore AM, Bradfute SB. The life cycle of the alphaviruses: From an antiviral perspective. Antiviral Res 2023; 209:105476. [PMID: 36436722 PMCID: PMC9840710 DOI: 10.1016/j.antiviral.2022.105476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
The alphaviruses are a widely distributed group of positive-sense, single stranded, RNA viruses. These viruses are largely arthropod-borne and can be found on all populated continents. These viruses cause significant human disease, and recently have begun to spread into new populations, such as the expansion of Chikungunya virus into southern Europe and the Caribbean, where it has established itself as endemic. The study of alphaviruses is an active and expanding field, due to their impacts on human health, their effects on agriculture, and the threat that some pose as potential agents of biological warfare and terrorism. In this systematic review we will summarize both historic knowledge in the field as well as recently published data that has potential to shift current theories in how alphaviruses are able to function. This review is comprehensive, covering all parts of the alphaviral life cycle as well as a brief overview of their pathology and the current state of research in regards to vaccines and therapeutics for alphaviral disease.
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Affiliation(s)
- Andrew M Skidmore
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, 915 Camino de Salud, IDTC Room 3245, Albuquerque, NM, 87131, USA.
| | - Steven B Bradfute
- Center for Global Health, Department of Internal Medicine, University of New Mexico Health Sciences Center, 915 Camino de Salud, IDTC Room 3330A, Albuquerque, NM, 87131, USA.
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16
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Alphavirus Particles Can Assemble with an Alternate Triangulation Number. Viruses 2022; 14:v14122650. [PMID: 36560655 PMCID: PMC9780915 DOI: 10.3390/v14122650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Alphaviruses are spherical, enveloped RNA viruses primarily transmitted by mosquitoes, and cause significant arthritogenic and neurotropic disease in humans and livestock. Previous reports have shown that-in contrast to prototypical icosahedral viruses-alphaviruses incorporate frequent defects, and these may serve important functions in the viral life cycle. We confirm the genus-wide pleomorphism in live viral particles and extend our understanding of alphavirus assembly through the discovery of an alternate architecture of Eastern equine encephalitis virus (EEEV) particles. The alternate T = 3 icosahedral architecture differs in triangulation number from the classic T = 4 icosahedral organization that typifies alphaviruses, but the alternate architecture maintains the quasi-equivalence relationship of asymmetric units. The fusion spike glycoproteins are more loosely apposed in the T = 3 form with corresponding changes in the underlying capsid protein lattice. This alternate architecture could potentially be exploited in engineering alphavirus-based particles for delivery of alphaviral or other RNA.
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17
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Sengupta R, Mihelc EM, Angel S, Lanman JK, Kuhn RJ, Stahelin RV. Contribution of the Golgi apparatus in morphogenesis of a virus-induced cytopathic vacuolar system. Life Sci Alliance 2022; 5:5/10/e202000887. [PMID: 36137747 PMCID: PMC9500387 DOI: 10.26508/lsa.202000887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/24/2022] Open
Abstract
Electron tomography reveals four classes of cytopathic vesicles-II (CPV-II) stemming from the host Golgi apparatus after Venezuelan equine encephalitis virus infection. The Golgi apparatus (GA) in mammalian cells is pericentrosomally anchored and exhibits a stacked architecture. During infections by members of the alphavirus genus, the host cell GA is thought to give rise to distinct mobile pleomorphic vacuoles known as CPV-II (cytopathic vesicle-II) via unknown morphological steps. To dissect this, we adopted a phased electron tomography approach to image multiple overlapping volumes of a cell infected with Venezuelan equine encephalitis virus (VEEV) and complemented it with localization of a peroxidase-tagged Golgi marker. Analysis of the tomograms revealed a pattern of progressive cisternal bending into double-lamellar vesicles as a central process underpinning the biogenesis and the morphological complexity of this vacuolar system. Here, we propose a model for the conversion of the GA to CPV-II that reveals a unique pathway of intracellular virus envelopment. Our results have implications for alphavirus-induced displacement of Golgi cisternae to the plasma membrane to aid viral egress operating late in the infection cycle.
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Affiliation(s)
- Ranjan Sengupta
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA .,Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.,The Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
| | - Elaine M Mihelc
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Stephanie Angel
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.,Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.,The Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
| | - Jason K Lanman
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Richard J Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.,The Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
| | - Robert V Stahelin
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA .,The Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN, USA
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18
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Chikungunya virus assembly and budding visualized in situ using cryogenic electron tomography. Nat Microbiol 2022; 7:1270-1279. [PMID: 35773421 PMCID: PMC9930444 DOI: 10.1038/s41564-022-01164-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 05/26/2022] [Indexed: 01/30/2023]
Abstract
Chikungunya virus (CHIKV) is a representative alphavirus causing debilitating arthritogenic disease in humans. Alphavirus particles assemble into two icosahedral layers: the glycoprotein spike shell embedded in a lipid envelope and the inner nucleocapsid (NC) core. In contrast to matrix-driven assembly of some enveloped viruses, the assembly/budding process of two-layered icosahedral particles remains poorly understood. Here we used cryogenic electron tomography (cryo-ET) to capture snapshots of the CHIKV assembly in infected human cells. Subvolume classification of the snapshots revealed 12 intermediates representing different stages of assembly at the plasma membrane. Further subtomogram average structures ranging from subnanometre to nanometre resolutions show that immature non-icosahedral NCs function as rough scaffolds to trigger icosahedral assembly of the spike lattice, which in turn progressively transforms the underlying NCs into icosahedral cores during budding. Further, analysis of CHIKV-infected cells treated with budding-inhibiting antibodies revealed wider spaces between spikes than in icosahedral spike lattice, suggesting that spacing spikes apart to prevent their lateral interactions prevents the plasma membrane from bending around the NC, thus blocking virus budding. These findings provide the molecular mechanisms for alphavirus assembly and antibody-mediated budding inhibition that provide valuable insights for the development of broad therapeutics targeting the assembly of icosahedral enveloped viruses.
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19
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Chen CL, Klose T, Sun C, Kim AS, Buda G, Rossmann MG, Diamond MS, Klimstra WB, Kuhn RJ. Cryo-EM structures of alphavirus conformational intermediates in low pH-triggered prefusion states. Proc Natl Acad Sci U S A 2022; 119:e2114119119. [PMID: 35867819 PMCID: PMC9335222 DOI: 10.1073/pnas.2114119119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 06/03/2022] [Indexed: 01/24/2023] Open
Abstract
Alphaviruses can cause severe human arthritis and encephalitis. During virus infection, structural changes of viral glycoproteins in the acidified endosome trigger virus-host membrane fusion for delivery of the capsid core and RNA genome into the cytosol to initiate virus translation and replication. However, mechanisms by which E1 and E2 glycoproteins rearrange in this process remain unknown. Here, we investigate prefusion cryoelectron microscopy (cryo-EM) structures of eastern equine encephalitis virus (EEEV) under acidic conditions. With models fitted into the low-pH cryo-EM maps, we suggest that E2 dissociates from E1, accompanied by a rotation (∼60°) of the E2-B domain (E2-B) to expose E1 fusion loops. Cryo-EM reconstructions of EEEV bound to a protective antibody at acidic and neutral pH suggest that stabilization of E2-B prevents dissociation of E2 from E1. These findings reveal conformational changes of the glycoprotein spikes in the acidified host endosome. Stabilization of E2-B may provide a strategy for antiviral agent development.
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Affiliation(s)
- Chun-Liang Chen
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Chengqun Sun
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261
| | - Arthur S. Kim
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Geeta Buda
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Michael G. Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Michael S. Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110
| | - William B. Klimstra
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261
| | - Richard J. Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
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20
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Phylogenetic and Mutation Analysis of the Venezuelan Equine Encephalitis Virus Sequence Isolated in Costa Rica from a Mare with Encephalitis. Vet Sci 2022; 9:vetsci9060258. [PMID: 35737310 PMCID: PMC9229380 DOI: 10.3390/vetsci9060258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 12/10/2022] Open
Abstract
Venezuelan Equine Encephalitis virus (VEEV) is an arboviral pathogen in tropical America that causes lethal encephalitis in horses and humans. VEEV is classified into six subtypes (I to VI). Subtype I viruses are divided into epizootic (IAB and IC) and endemic strains (ID and IE) that can produce outbreaks or sporadic diseases, respectively. The objective of this study was to reconstruct the phylogeny and the molecular clock of sequences of VEEV subtype I complex and identify mutations within sequences belonging to epizootic or enzootic subtypes focusing on a sequence isolated from a mare in Costa Rica. Bayesian phylogeny of the VEEV subtype I complex tree with 110 VEEV complete genomes was analyzed. Evidence of positive selection was evaluated with Datamonkey server algorithms. The putative effects of mutations on the 3D protein structure in the Costa Rica sequence were evaluated. The phylogenetic analysis showed that Subtype IE-VEEV diverged earlier than other subtypes, Costa Rican VEEV-IE ancestors came from Nicaragua in 1963 and Guatemala in 1907. Among the observed non-synonymous mutations, only 17 amino acids changed lateral chain groups. Fourteen mutations located in the NSP3, E1, and E2 genes are unique in this sequence, highlighting the importance of E1-E2 genes in VEEV evolution.
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21
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Williams JA, Long SY, Zeng X, Kuehl K, Babka AM, Davis NM, Liu J, Trefry JC, Daye S, Facemire PR, Iversen PL, Bavari S, Pitt ML, Nasar F. Eastern equine encephalitis virus rapidly infects and disseminates in the brain and spinal cord of cynomolgus macaques following aerosol challenge. PLoS Negl Trop Dis 2022; 16:e0010081. [PMID: 35533188 PMCID: PMC9084534 DOI: 10.1371/journal.pntd.0010081] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 12/09/2021] [Indexed: 11/18/2022] Open
Abstract
Eastern equine encephalitis virus (EEEV) is mosquito-borne virus that produces fatal encephalitis in humans. We recently conducted a first of its kind study to investigate EEEV clinical disease course following aerosol challenge in a cynomolgus macaque model utilizing the state-of-the-art telemetry to measure critical physiological parameters. Here, we report the results of a comprehensive pathology study of NHP tissues collected at euthanasia to gain insights into EEEV pathogenesis. Viral RNA and proteins as well as microscopic lesions were absent in the visceral organs. In contrast, viral RNA and proteins were readily detected throughout the brain including autonomic nervous system (ANS) control centers and spinal cord. However, despite presence of viral RNA and proteins, majority of the brain and spinal cord tissues exhibited minimal or no microscopic lesions. The virus tropism was restricted primarily to neurons, and virus particles (~61–68 nm) were present within axons of neurons and throughout the extracellular spaces. However, active virus replication was absent or minimal in majority of the brain and was limited to regions proximal to the olfactory tract. These data suggest that EEEV initially replicates in/near the olfactory bulb following aerosol challenge and is rapidly transported to distal regions of the brain by exploiting the neuronal axonal transport system to facilitate neuron-to-neuron spread. Once within the brain, the virus gains access to the ANS control centers likely leading to disruption and/or dysregulation of critical physiological parameters to produce severe disease. Moreover, the absence of microscopic lesions strongly suggests that the underlying mechanism of EEEV pathogenesis is due to neuronal dysfunction rather than neuronal death. This study is the first comprehensive investigation into EEEV pathology in a NHP model and will provide significant insights into the evaluation of countermeasure. EEEV is an arbovirus endemic in parts of North America and is able to produce fatal encephalitis in humans and domesticated animals. Despite multiple human outbreaks during the last 80 years, there are still no therapeutic or vaccines to treat or prevent human disease. One critical obstacle in the development of effective countermeasure is the lack of insights into EEEV pathogenesis in a susceptible animal host. We recently conducted a study in cynomolgus macaques to investigate the disease course by measuring clinical parameters relevant to humans. Following infection, these parameters were rapidly and profoundly altered leading to severe disease. In this study, we examined the potential mechanisms that underlie pathogenesis to cause severe disease. The virus was present in many parts of the brain and spinal cord, however, minimal or no pathological lesions as well as active virus replication were observed. Additionally, neurons were the predominant target of EEEV infection and virus transport was facilitated via axonal transport system to spread neuron-to-neuron throughout the brain and spinal cord. These data show that EEEV likely hijacks essential transport system to rapidly spread in the brain and local/global neuronal dysfunction rather than neuronal death is the principal cause of severe disease.
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Affiliation(s)
- Janice A. Williams
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Simon Y. Long
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Xiankun Zeng
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Kathleen Kuehl
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - April M. Babka
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Neil M. Davis
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Jun Liu
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - John C. Trefry
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Sharon Daye
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Paul R. Facemire
- Pathology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Patrick L. Iversen
- Therapeutics Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Sina Bavari
- Office of the Commander, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Margaret L. Pitt
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- Office of the Commander, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- * E-mail: (MLP); , (FN)
| | - Farooq Nasar
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- * E-mail: (MLP); , (FN)
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22
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Kafai NM, Williamson LE, Binshtein E, Sukupolvi-Petty S, Gardner CL, Liu J, Mackin S, Kim AS, Kose N, Carnahan RH, Jung A, Droit L, Reed DS, Handley SA, Klimstra WB, Crowe JE, Diamond MS. Neutralizing antibodies protect mice against Venezuelan equine encephalitis virus aerosol challenge. J Exp Med 2022; 219:e20212532. [PMID: 35297953 PMCID: PMC9195047 DOI: 10.1084/jem.20212532] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 11/24/2022] Open
Abstract
Venezuelan equine encephalitis virus (VEEV) remains a risk for epidemic emergence or use as an aerosolized bioweapon. To develop possible countermeasures, we isolated VEEV-specific neutralizing monoclonal antibodies (mAbs) from mice and a human immunized with attenuated VEEV strains. Functional assays and epitope mapping established that potently inhibitory anti-VEEV mAbs bind distinct antigenic sites in the A or B domains of the E2 glycoprotein and block multiple steps in the viral replication cycle including attachment, fusion, and egress. A 3.2-Å cryo-electron microscopy reconstruction of VEEV virus-like particles bound by a human Fab suggests that antibody engagement of the B domain may result in cross-linking of neighboring spikes to prevent conformational requirements for viral fusion. Prophylaxis or postexposure therapy with these mAbs protected mice against lethal aerosol challenge with VEEV. Our study defines functional and structural mechanisms of mAb protection and suggests that multiple antigenic determinants on VEEV can be targeted for vaccine or antibody-based therapeutic development.
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Affiliation(s)
- Natasha M. Kafai
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Lauren E. Williamson
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
| | - Elad Binshtein
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN
| | | | - Christina L. Gardner
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA
- United States Army Research Institute for Infectious Diseases, Fort Detrick, MD
| | - Jaclyn Liu
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Samantha Mackin
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Arthur S. Kim
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN
| | - Robert H. Carnahan
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Ana Jung
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Lindsay Droit
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Douglas S. Reed
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA
| | - Scott A. Handley
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - William B. Klimstra
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA
| | - James E. Crowe
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Michael S. Diamond
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO
- The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St. Louis, MO
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23
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Structure of infective Getah virus at 2.8 Å resolution determined by cryo-electron microscopy. Cell Discov 2022; 8:12. [PMID: 35149682 PMCID: PMC8832435 DOI: 10.1038/s41421-022-00374-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/03/2022] [Indexed: 11/30/2022] Open
Abstract
Getah virus (GETV), a member of the genus alphavirus, is a mosquito-borne pathogen that can cause pyrexia and reproductive losses in animals. Although antibodies to GETV have been found in over 10% of healthy people, there are no reports of clinical symptoms associated with GETV. The biological and pathological properties of GETV are largely unknown and antiviral or vaccine treatments against GETV are still unavailable due to a lack of knowledge of the structure of the GETV virion. Here, we present the structure of infective GETV at a resolution of 2.8 Å with the atomic models of the capsid protein and the envelope glycoproteins E1 and E2. We have identified numerous glycosylation and S-acylation sites in E1 and E2. The surface-exposed glycans indicate a possible impact on viral immune evasion and host cell invasion. The S-acylation sites might be involved in stabilizing the transmembrane assembly of E1 and E2. In addition, a cholesterol and a phospholipid molecule are observed in a transmembrane hydrophobic pocket, together with two more cholesterols surrounding the pocket. The cholesterol and phospholipid stabilize the hydrophobic pocket in the viral envelope membrane. The structural information will assist structure-based antiviral and vaccine screening, design, and optimization.
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24
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Structural Insights into Alphavirus Assembly Revealed by the Cryo-EM Structure of Getah Virus. Viruses 2022; 14:v14020327. [PMID: 35215918 PMCID: PMC8876998 DOI: 10.3390/v14020327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 01/28/2022] [Accepted: 02/03/2022] [Indexed: 11/16/2022] Open
Abstract
Getah virus (GETV) is a member of the alphavirus genus, and it infects a variety of animal species, including horses, pigs, cattle, and foxes. Human infection with this virus has also been reported. The structure of GETV has not yet been determined. In this study, we report the cryo-EM structure of GETV at a resolution of 3.5 Å. This structure reveals conformational polymorphism of the envelope glycoproteins E1 and E2 at icosahedral 3-fold and quasi-3-fold axes, which is believed to be a necessary organization in forming a curvature surface of virions. In our density map, three extra densities are identified, one of which is believed a “pocket factor”; the other two are located by domain D of E2, and they may maintain the stability of E1/E2 heterodimers. We also identify three N-glycosylations at E1 N141, E2 N200, and E2 N262, which might be associated with receptor binding and membrane fusion. The resolving of the structure of GETV provides new insights into the structure and assembly of alphaviruses and lays a basis for studying the differences of biology and pathogenicity between arthritogenic and encephalitic alphaviruses.
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25
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Cross-Strain Neutralizing and Protective Monoclonal Antibodies against EEEV or WEEV. Viruses 2021; 13:v13112231. [PMID: 34835037 PMCID: PMC8621548 DOI: 10.3390/v13112231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/28/2021] [Accepted: 11/01/2021] [Indexed: 11/17/2022] Open
Abstract
The three encephalitic alphaviruses, namely, the Venezuelan, eastern, and western equine encephalitis viruses (VEEV, EEEV, and WEEV), are classified by the Centers for Disease Control and Prevention (CDC) as biothreat agents. Currently, no licensed medical countermeasures (MCMs) against these viruses are available for humans. Neutralizing antibodies (NAbs) are fast-acting and highly effective MCMs for use in both pre- and post-exposure settings against biothreat agents. While significant work has been done to identify anti-VEEV NAbs, less has been done to identify NAbs against EEEV and WEEV. In order to develop anti-EEEV or -WEEV NAbs, mice were immunized using complementary strategies with a variety of different EEEV or WEEV immunogens to maximize the generation of NAbs to each of these viruses. Of the hybridomas generated, three anti-EEEV and seven anti-WEEV monoclonal antibodies were identified with in vitro neutralization activity. The most potent neutralizers (two anti-EEEV NAbs and three anti-WEEV NAbs) were further evaluated for neutralization activity against additional strains of EEEV, a single strain of Madariaga virus (formerly South American EEEV), or WEEV. Of these, G1-2-H4 and G1-4-C3 neutralized all three EEEV strains and the Madariaga virus strain, whereas G8-2-H9 and 12 WA neutralized six out of eight WEEV strains. To determine the protective efficacy of these NAbs, the five most potent neutralizers were evaluated in respective mouse aerosol challenge models. All five NAbs demonstrated various levels of protection when administered at doses of 2.5 mg/kg or 10 mg/kg 24 h before the respective virus exposure via the aerosol route. Of these, anti-EEEV NAb G1-4-C3 and anti-WEEV NAb 8C2 provided 100% protection at both doses and all surviving mice were free of clinical signs throughout the study. Additionally, no virus was detected in the brain 14 days post virus exposure. Taken together, efficacious NAbs were developed that demonstrate the potential for the development of cross-strain antibody-based MCMs against EEEV and WEEV infections.
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26
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Capsid-E2 Interactions Rescue Core Assembly in Viruses That Cannot Form Cytoplasmic Nucleocapsid Cores. J Virol 2021; 95:e0106221. [PMID: 34495691 DOI: 10.1128/jvi.01062-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alphavirus capsid proteins (CPs) have two domains: the N-terminal domain (NTD), which interacts with the viral RNA, and the C-terminal domain (CTD), which forms CP-CP interactions and interacts with the cytoplasmic domain of the E2 spike protein (cdE2). In this study, we examine how mutations in the CP NTD affect CP CTD interactions with cdE2. We changed the length and/or charge of the NTD of Ross River virus CP and found that changing the charge of the NTD has a greater impact on core and virion assembly than changing the length of the NTD. The NTD CP insertion mutants are unable to form cytoplasmic cores during infection, but they do form cores or core-like structures in virions. Our results are consistent with cdE2 having a role in core maturation during virion assembly and rescuing core formation when cytoplasmic cores are not assembled. We go on to find that the isolated cores from some mutant virions are now assembly competent in that they can be disassembled and reassembled back into cores. These results show how the two domains of CP may have distinct yet coordinated roles. IMPORTANCE Structural viral proteins have multiple roles during entry and assembly. The capsid protein (CP) of alphaviruses has one domain that interacts with the viral genome and another domain that interacts with the E2 spike protein. In this work, we determined that the length and/or charge of the CP affects cytoplasmic core formation. However, defects in cytoplasmic core formation can be overcome by E2-CP interactions, thus assembling a core or core-like complex in the virion. In the absence of both cytoplasmic cores and CP-E2 interactions, CP is not even packaged in the released virions, but some infectious particles are still released, presumably as RNA packaged in a glycoprotein-containing membrane shell. This suggests that the virus has multiple mechanisms in place to ensure the viral genome is surrounded by a capsid core during its life cycle.
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27
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Structure of Venezuelan equine encephalitis virus with its receptor LDLRAD3. Nature 2021; 598:677-681. [PMID: 34646021 DOI: 10.1038/s41586-021-03909-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/13/2021] [Indexed: 11/08/2022]
Abstract
Venezuelan equine encephalitis virus (VEEV) is an enveloped RNA virus that causes encephalitis and potentially mortality in infected humans and equines1. At present, no vaccines or drugs are available that prevent or cure diseases caused by VEEV. Low-density lipoprotein receptor class A domain-containing 3 (LDLRAD3) was recently identified as a receptor for the entry of VEEV into host cells2. Here we present the cryo-electron microscopy structure of the LDLRAD3 extracellular domain 1 (LDLRAD3-D1) in complex with VEEV virus-like particles at a resolution of 3.0 Å. LDLRAD3-D1 has a cork-like structure and is inserted into clefts formed between adjacent VEEV E2-E1 heterodimers in the viral-surface trimer spikes through hydrophobic and polar contacts. Mutagenesis studies of LDLRAD3-D1 identified residues that are involved in the key interactions with VEEV. Of note, some of the LDLRAD3-D1 mutants showed a significantly increased binding affinity for VEEV, suggesting that LDLRAD3-D1 may serve as a potential scaffold for the development of inhibitors of VEEV entry. Our structures provide insights into alphavirus assembly and the binding of receptors to alphaviruses, which may guide the development of therapeutic countermeasures against alphaviruses.
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28
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Structure of Venezuelan equine encephalitis virus in complex with the LDLRAD3 receptor. Nature 2021; 598:672-676. [PMID: 34646020 PMCID: PMC8550936 DOI: 10.1038/s41586-021-03963-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/26/2021] [Indexed: 11/10/2022]
Abstract
LDLRAD3 is a recently defined attachment and entry receptor for Venezuelan equine encephalitis virus (VEEV)1, a New World alphavirus that causes severe neurological disease in humans. Here we present near-atomic-resolution cryo-electron microscopy reconstructions of VEEV virus-like particles alone and in a complex with the ectodomains of LDLRAD3. Domain 1 of LDLRAD3 is a low-density lipoprotein receptor type-A module that binds to VEEV by wedging into a cleft created by two adjacent E2–E1 heterodimers in one trimeric spike, and engages domains A and B of E2 and the fusion loop in E1. Atomic modelling of this interface is supported by mutagenesis and anti-VEEV antibody binding competition assays. Notably, VEEV engages LDLRAD3 in a manner that is similar to the way that arthritogenic alphaviruses bind to the structurally unrelated MXRA8 receptor, but with a much smaller interface. These studies further elucidate the structural basis of alphavirus–receptor interactions, which could inform the development of therapies to mitigate infection and disease against multiple members of this family. The structure of the Venezuelan equine encephalitis virus in complex with LDLRAD3 provides insights into the structural basis of alphavirus–receptor interactions.
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29
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Guerrero-Arguero I, Tellez-Freitas CM, Weber KS, Berges BK, Robison RA, Pickett BE. Alphaviruses: Host pathogenesis, immune response, and vaccine & treatment updates. J Gen Virol 2021; 102. [PMID: 34435944 DOI: 10.1099/jgv.0.001644] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Human pathogens belonging to the Alphavirus genus, in the Togaviridae family, are transmitted primarily by mosquitoes. The signs and symptoms associated with these viruses include fever and polyarthralgia, defined as joint pain and inflammation, as well as encephalitis. In the last decade, our understanding of the interactions between members of the alphavirus genus and the human host has increased due to the re-appearance of the chikungunya virus (CHIKV) in Asia and Europe, as well as its emergence in the Americas. Alphaviruses affect host immunity through cytokines and the interferon response. Understanding alphavirus interactions with both the innate immune system as well as the various cells in the adaptive immune systems is critical to developing effective therapeutics. In this review, we summarize the latest research on alphavirus-host cell interactions, underlying infection mechanisms, and possible treatments.
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Affiliation(s)
- Israel Guerrero-Arguero
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA.,Texas Biomedical Research Institute, San Antonio, TX, USA
| | | | - K Scott Weber
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Bradford K Berges
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Richard A Robison
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Brett E Pickett
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
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30
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Williamson LE, Reeder KM, Bailey K, Tran MH, Roy V, Fouch ME, Kose N, Trivette A, Nargi RS, Winkler ES, Kim AS, Gainza C, Rodriguez J, Armstrong E, Sutton RE, Reidy J, Carnahan RH, McDonald WH, Schoeder CT, Klimstra WB, Davidson E, Doranz BJ, Alter G, Meiler J, Schey KL, Julander JG, Diamond MS, Crowe JE. Therapeutic alphavirus cross-reactive E1 human antibodies inhibit viral egress. Cell 2021; 184:4430-4446.e22. [PMID: 34416147 PMCID: PMC8418820 DOI: 10.1016/j.cell.2021.07.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/11/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022]
Abstract
Alphaviruses cause severe arthritogenic or encephalitic disease. The E1 structural glycoprotein is highly conserved in these viruses and mediates viral fusion with host cells. However, the role of antibody responses to the E1 protein in immunity is poorly understood. We isolated E1-specific human monoclonal antibodies (mAbs) with diverse patterns of recognition for alphaviruses (ranging from Eastern equine encephalitis virus [EEEV]-specific to alphavirus cross-reactive) from survivors of natural EEEV infection. Antibody binding patterns and epitope mapping experiments identified differences in E1 reactivity based on exposure of epitopes on the glycoprotein through pH-dependent mechanisms or presentation on the cell surface prior to virus egress. Therapeutic efficacy in vivo of these mAbs corresponded with potency of virus egress inhibition in vitro and did not require Fc-mediated effector functions for treatment against subcutaneous EEEV challenge. These studies reveal the molecular basis for broad and protective antibody responses to alphavirus E1 proteins.
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MESH Headings
- Alphavirus/immunology
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/isolation & purification
- Antibodies, Neutralizing/immunology
- Antibodies, Viral/immunology
- Antigens, Viral/immunology
- Cell Line
- Chikungunya virus/immunology
- Cross Reactions/immunology
- Encephalitis Virus, Eastern Equine/immunology
- Encephalomyelitis, Equine/immunology
- Encephalomyelitis, Equine/virology
- Epitope Mapping
- Female
- Horses
- Humans
- Hydrogen-Ion Concentration
- Joints/pathology
- Male
- Mice, Inbred C57BL
- Models, Biological
- Protein Binding
- RNA, Viral/metabolism
- Receptors, Fc/metabolism
- Temperature
- Viral Proteins/immunology
- Virion/metabolism
- Virus Internalization
- Virus Release/physiology
- Mice
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Affiliation(s)
- Lauren E Williamson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA; The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kristen M Reeder
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kevin Bailey
- Institute for Antiviral Research, Utah State University, Logan, UT 84335, USA
| | - Minh H Tran
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA; Center of Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, USA
| | - Vicky Roy
- Ragon Institute of MGH, MIT, and Harvard University, Cambridge, MA 02139, USA
| | | | - Nurgun Kose
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Andrew Trivette
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rachel S Nargi
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Emma S Winkler
- Department of Medicine, Washington University, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Arthur S Kim
- Department of Medicine, Washington University, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Christopher Gainza
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jessica Rodriguez
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Erica Armstrong
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rachel E Sutton
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Joseph Reidy
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Robert H Carnahan
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - W Hayes McDonald
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, USA
| | - Clara T Schoeder
- Center of Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - William B Klimstra
- The Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 165261, USA; Department of Immunology, University of Pittsburgh, Pittsburgh, PA 165261, USA
| | | | | | - Galit Alter
- Ragon Institute of MGH, MIT, and Harvard University, Cambridge, MA 02139, USA
| | - Jens Meiler
- Center of Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Kevin L Schey
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, USA
| | - Justin G Julander
- Institute for Antiviral Research, Utah State University, Logan, UT 84335, USA
| | - Michael S Diamond
- Department of Medicine, Washington University, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University, St. Louis, MO 63110, USA
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA; The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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31
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Kim AS, Kafai NM, Winkler ES, Gilliland TC, Cottle EL, Earnest JT, Jethva PN, Kaplonek P, Shah AP, Fong RH, Davidson E, Malonis RJ, Quiroz JA, Williamson LE, Vang L, Mack M, Crowe JE, Doranz BJ, Lai JR, Alter G, Gross ML, Klimstra WB, Fremont DH, Diamond MS. Pan-protective anti-alphavirus human antibodies target a conserved E1 protein epitope. Cell 2021; 184:4414-4429.e19. [PMID: 34416146 PMCID: PMC8382027 DOI: 10.1016/j.cell.2021.07.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 04/01/2021] [Accepted: 07/02/2021] [Indexed: 12/13/2022]
Abstract
Alphaviruses are emerging, mosquito-transmitted pathogens that cause musculoskeletal and neurological disease in humans. Although neutralizing antibodies that inhibit individual alphaviruses have been described, broadly reactive antibodies that protect against both arthritogenic and encephalitic alphaviruses have not been reported. Here, we identify DC2.112 and DC2.315, two pan-protective yet poorly neutralizing human monoclonal antibodies (mAbs) that avidly bind to viral antigen on the surface of cells infected with arthritogenic and encephalitic alphaviruses. These mAbs engage a conserved epitope in domain II of the E1 protein proximal to and within the fusion peptide. Treatment with DC2.112 or DC2.315 protects mice against infection by both arthritogenic (chikungunya and Mayaro) and encephalitic (Venezuelan, Eastern, and Western equine encephalitis) alphaviruses through multiple mechanisms, including inhibition of viral egress and monocyte-dependent Fc effector functions. These findings define a conserved epitope recognized by weakly neutralizing yet protective antibodies that could be targeted for pan-alphavirus immunotherapy and vaccine design.
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Affiliation(s)
- Arthur S Kim
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Natasha M Kafai
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Emma S Winkler
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Theron C Gilliland
- Center for Vaccine Research and Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Emily L Cottle
- Center for Vaccine Research and Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - James T Earnest
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Prashant N Jethva
- Department of Chemistry, Washington University in St. Louis, Saint Louis, MO 63130, USA
| | - Paulina Kaplonek
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Aadit P Shah
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Rachel H Fong
- Integral Molecular, Inc., Philadelphia, PA 19104, USA
| | | | - Ryan J Malonis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jose A Quiroz
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Lauren E Williamson
- Vanderbilt Vaccine Center and Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lo Vang
- Emergent BioSolutions, Gaithersburg, MD 20879, USA
| | - Matthias Mack
- Department of Internal Medicine II, University Hospital Regensburg, Regensburg, Germany
| | - James E Crowe
- Vanderbilt Vaccine Center and Departments of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Jonathan R Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Galit Alter
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA 02139, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, Saint Louis, MO 63130, USA
| | - William B Klimstra
- Center for Vaccine Research and Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Daved H Fremont
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO 63110, USA; Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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32
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Elmasri Z, Nasal BL, Jose J. Alphavirus-Induced Membrane Rearrangements during Replication, Assembly, and Budding. Pathogens 2021; 10:984. [PMID: 34451448 PMCID: PMC8399458 DOI: 10.3390/pathogens10080984] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 01/01/2023] Open
Abstract
Alphaviruses are arthropod-borne viruses mainly transmitted by hematophagous insects that cause moderate to fatal disease in humans and other animals. Currently, there are no approved vaccines or antivirals to mitigate alphavirus infections. In this review, we summarize the current knowledge of alphavirus-induced structures and their functions in infected cells. Throughout their lifecycle, alphaviruses induce several structural modifications, including replication spherules, type I and type II cytopathic vacuoles, and filopodial extensions. Type I cytopathic vacuoles are replication-induced structures containing replication spherules that are sites of RNA replication on the endosomal and lysosomal limiting membrane. Type II cytopathic vacuoles are assembly induced structures that originate from the Golgi apparatus. Filopodial extensions are induced at the plasma membrane and are involved in budding and cell-to-cell transport of virions. This review provides an overview of the viral and host factors involved in the biogenesis and function of these virus-induced structures. Understanding virus-host interactions in infected cells will lead to the identification of new targets for antiviral discovery.
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Affiliation(s)
- Zeinab Elmasri
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Benjamin L. Nasal
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
| | - Joyce Jose
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA;
- Department of Biochemistry & Molecular Biology, Eberly College of Science, The Pennsylvania State University, University Park, PA 16802, USA;
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33
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Hasan SS, Dey D, Singh S, Martin M. The Structural Biology of Eastern Equine Encephalitis Virus, an Emerging Viral Threat. Pathogens 2021; 10:pathogens10080973. [PMID: 34451437 PMCID: PMC8400090 DOI: 10.3390/pathogens10080973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/21/2021] [Accepted: 07/28/2021] [Indexed: 11/16/2022] Open
Abstract
Alphaviruses are arboviruses that cause arthritis and encephalitis in humans. Eastern Equine Encephalitis Virus (EEEV) is a mosquito-transmitted alphavirus that is implicated in severe encephalitis in humans with high mortality. However, limited insights are available into the fundamental biology of EEEV and residue-level details of its interactions with host proteins. In recent years, outbreaks of EEEV have been reported mainly in the United States, raising concerns about public safety. This review article summarizes recent advances in the structural biology of EEEV based mainly on single-particle cryogenic electron microscopy (cryoEM) structures. Together with functional analyses of EEEV and related alphaviruses, these structural investigations provide clues to how EEEV interacts with host proteins, which may open avenues for the development of therapeutics.
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Affiliation(s)
- S. Saif Hasan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201, USA; (D.D.); (S.S.); (M.M.)
- Center for Biomolecular Therapeutics, University of Maryland School of Medicine, 9600 Gudelsky Drive, Rockville, MD 20850, USA
- University of Maryland Marlene and Stewart Greenebaum Cancer Center, University of Maryland Medical Center, 22. S. Greene St., Baltimore, MD 21201, USA
- Correspondence:
| | - Debajit Dey
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201, USA; (D.D.); (S.S.); (M.M.)
| | - Suruchi Singh
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201, USA; (D.D.); (S.S.); (M.M.)
| | - Matthew Martin
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201, USA; (D.D.); (S.S.); (M.M.)
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The utilization of advance telemetry to investigate critical physiological parameters including electroencephalography in cynomolgus macaques following aerosol challenge with eastern equine encephalitis virus. PLoS Negl Trop Dis 2021; 15:e0009424. [PMID: 34138849 PMCID: PMC8259972 DOI: 10.1371/journal.pntd.0009424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 07/06/2021] [Accepted: 04/29/2021] [Indexed: 11/19/2022] Open
Abstract
Most alphaviruses are mosquito-borne and can cause severe disease in humans and domesticated animals. In North America, eastern equine encephalitis virus (EEEV) is an important human pathogen with case fatality rates of 30–90%. Currently, there are no therapeutics or vaccines to treat and/or prevent human infection. One critical impediment in countermeasure development is the lack of insight into clinically relevant parameters in a susceptible animal model. This study examined the disease course of EEEV in a cynomolgus macaque model utilizing advanced telemetry technology to continuously and simultaneously measure temperature, respiration, activity, heart rate, blood pressure, electrocardiogram (ECG), and electroencephalography (EEG) following an aerosol challenge at 7.0 log10 PFU. Following challenge, all parameters were rapidly and substantially altered with peak alterations from baseline ranged as follows: temperature (+3.0–4.2°C), respiration rate (+56–128%), activity (-15-76% daytime and +5–22% nighttime), heart rate (+67–190%), systolic (+44–67%) and diastolic blood pressure (+45–80%). Cardiac abnormalities comprised of alterations in QRS and PR duration, QTc Bazett, T wave morphology, amplitude of the QRS complex, and sinoatrial arrest. An unexpected finding of the study was the first documented evidence of a critical cardiac event as an immediate cause of euthanasia in one NHP. All brain waves were rapidly (~12–24 hpi) and profoundly altered with increases of up to 6,800% and severe diffuse slowing of all waves with decreases of ~99%. Lastly, all NHPs exhibited disruption of the circadian rhythm, sleep, and food/fluid intake. Accordingly, all NHPs met the euthanasia criteria by ~106–140 hpi. This is the first of its kind study utilizing state of the art telemetry to investigate multiple clinical parameters relevant to human EEEV infection in a susceptible cynomolgus macaque model. The study provides critical insights into EEEV pathogenesis and the parameters identified will improve animal model development to facilitate rapid evaluation of vaccines and therapeutics. In North America, EEEV causes the most severe mosquito-borne disease in humans highlighted by fatal encephalitis and permeant debilitating neurological sequelae in survivors. The first confirmed human cases were reported more than 80 years ago and since then multiple sporadic outbreaks have occurred including one of the largest in 2019. Unfortunately, most human infections are diagnosed at the on-set of severe neurological symptoms and consequently a detailed disease course in humans is lacking. This gap in knowledge is a significant obstacle in the development of appropriate animal models to evaluate countermeasures. Here, we performed a cutting-edge study by utilizing a new telemetry technology to understand the course of EEEV infection in a susceptible macaque model by measuring multiple physiological parameters relevant to human disease. Our study demonstrates that the infection rapidly produces considerable alterations in many critical parameters including the electrical activity of the heart and the brain leading to severe disease. The study also highlights the extraordinary potential of new telemetry technology to develop the next generation of animal models to comprehensively investigate pathogenesis as well as evaluate countermeasures to treat and/or prevent EEEV disease.
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Cryo-EM structure of the mature and infective Mayaro virus at 4.4 Å resolution reveals features of arthritogenic alphaviruses. Nat Commun 2021; 12:3038. [PMID: 34031424 PMCID: PMC8144435 DOI: 10.1038/s41467-021-23400-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 04/27/2021] [Indexed: 12/19/2022] Open
Abstract
Mayaro virus (MAYV) is an emerging arbovirus of the Americas that may cause a debilitating arthritogenic disease. The biology of MAYV is not fully understood and largely inferred from related arthritogenic alphaviruses. Here, we present the structure of MAYV at 4.4 Å resolution, obtained from a preparation of mature, infective virions. MAYV presents typical alphavirus features and organization. Interactions between viral proteins that lead to particle formation are described together with a hydrophobic pocket formed between E1 and E2 spike proteins and conformational epitopes specific of MAYV. We also describe MAYV glycosylation residues in E1 and E2 that may affect MXRA8 host receptor binding, and a molecular “handshake” between MAYV spikes formed by N262 glycosylation in adjacent E2 proteins. The structure of MAYV is suggestive of structural and functional complexity among alphaviruses, which may be targeted for specificity or antiviral activity. Mayaro virus (MAYV) is an emerging arbovirus in Central and South America that is transmitted by mosquitoes and causes arthritogenic disease. Here, the authors present the 4.4 Å resolution cryo-EM structure of MAYV and describe specific features of the virus, which could be exploited for the design of MAYV-specific diagnostics and therapeutics.
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Arthritogenic Alphavirus Capsid Protein. Life (Basel) 2021; 11:life11030230. [PMID: 33799673 PMCID: PMC7999773 DOI: 10.3390/life11030230] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 01/03/2023] Open
Abstract
In the past two decades Old World and arthritogenic alphavirus have been responsible for epidemics of polyarthritis, causing high morbidity and becoming a major public health concern. The multifunctional arthritogenic alphavirus capsid protein is crucial for viral infection. Capsid protein has roles in genome encapsulation, budding and virion assembly. Its role in multiple infection processes makes capsid protein an attractive target to exploit in combating alphaviral infection. In this review, we summarize the function of arthritogenic alphavirus capsid protein, and describe studies that have used capsid protein to develop novel arthritogenic alphavirus therapeutic and diagnostic strategies.
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The Alphaviral Capsid Protein Inhibits IRAK1-Dependent TLR Signaling. Viruses 2021; 13:v13030377. [PMID: 33673546 PMCID: PMC7997285 DOI: 10.3390/v13030377] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022] Open
Abstract
Alphaviruses are arthropod-borne RNA viruses which can cause either mild to severe febrile arthritis which may persist for months, or encephalitis which can lead to death or lifelong cognitive impairments. The non-assembly molecular role(s), functions, and protein–protein interactions of the alphavirus capsid proteins have been largely overlooked. Here we detail the use of a BioID2 biotin ligase system to identify the protein–protein interactions of the Sindbis virus capsid protein. These efforts led to the discovery of a series of novel host–pathogen interactions, including the identification of an interaction between the alphaviral capsid protein and the host IRAK1 protein. Importantly, this capsid–IRAK1 interaction is conserved across multiple alphavirus species, including arthritogenic alphaviruses SINV, Ross River virus, and Chikungunya virus; and encephalitic alphaviruses Eastern Equine Encephalitis virus, and Venezuelan Equine Encephalitis virus. The impact of the capsid–IRAK1 interaction was evaluated using a robust set of cellular model systems, leading to the realization that the alphaviral capsid protein specifically inhibits IRAK1-dependent signaling. This inhibition represents a means by which alphaviruses may evade innate immune detection and activation prior to viral gene expression. Altogether, these data identify novel capsid protein–protein interactions, establish the capsid–IRAK1 interaction as a common alphavirus host–pathogen interface, and delineate the molecular consequences of the capsid–IRAK1 interaction on IRAK1-dependent signaling.
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Lehman CW, Kehn-Hall K, Aggarwal M, Bracci NR, Pan HC, Panny L, Lamb RA, Lin SC. Resveratrol Inhibits Venezuelan Equine Encephalitis Virus Infection by Interfering with the AKT/GSK Pathway. PLANTS 2021; 10:plants10020346. [PMID: 33673026 PMCID: PMC7918260 DOI: 10.3390/plants10020346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/03/2021] [Accepted: 02/07/2021] [Indexed: 12/21/2022]
Abstract
The host proteins Protein Kinase B (AKT) and glycogen synthase kinase-3 (GSK-3) are associated with multiple neurodegenerative disorders. They are also important for the replication of Venezuelan equine encephalitis virus (VEEV), thereby making the AKT/GSK-3 pathway an attractive target for developing anti-VEEV therapeutics. Resveratrol, a natural phytochemical, has been shown to substantially inhibit the AKT pathway. Therefore, we attempted to explore whether it exerts any antiviral activity against VEEV. In this study, we utilized green fluorescent protein (GFP)- and luciferase-encoding recombinant VEEV to determine the cytotoxicity and antiviral efficacy via luciferase reporter assays, flow cytometry, and immunofluorescent assays. Our results indicate that resveratrol treatment is capable of inhibiting VEEV replication, resulting in increased viability of Vero and U87MG cells as well as reduced virion production and viral RNA contents within host cells for at least 48 h with a single treatment. Furthermore, the suppression of apoptotic signaling adaptors, caspase-3, caspase-7, and annexin V may also be implicated in resveratrol-mediated antiviral activity. We found that decreased phosphorylation of the AKT/GSK-3 pathway, mediated by resveratrol, can be triggered during the early stages of VEEV infection, suggesting that resveratrol disrupts the viral replication cycle and consequently promotes cell survival. Finally, molecular docking and dynamics simulation studies revealed that resveratrol can directly bind to VEEV glycoproteins, which may interfere with virus attachment and entry. In conclusion, our results suggest that resveratrol exerts inhibitory activity against VEEV infection and upon further modification could be a useful compound to study in neuroprotective research and veterinary sciences.
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Affiliation(s)
- Caitlin W. Lehman
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA; (C.W.L.); (K.K.-H.); (N.R.B.); (L.P.)
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA; (C.W.L.); (K.K.-H.); (N.R.B.); (L.P.)
| | - Megha Aggarwal
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; (M.A.); (R.A.L.)
- Howard Hughes Medical Institute, Northwestern University, Evanston, IL 60208, USA
| | - Nicole R. Bracci
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA; (C.W.L.); (K.K.-H.); (N.R.B.); (L.P.)
| | - Han-Chi Pan
- National Center Animal Laboratory, National Applied Research Laboratories, Taipei 11599, Taiwan;
| | - Lauren Panny
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA; (C.W.L.); (K.K.-H.); (N.R.B.); (L.P.)
| | - Robert A. Lamb
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; (M.A.); (R.A.L.)
- Howard Hughes Medical Institute, Northwestern University, Evanston, IL 60208, USA
| | - Shih-Chao Lin
- Bachelor Degree Program in Marine Biotechnology, College of Life Sciences, National Taiwan Ocean University, 2 Pei-Ning Rd., Keelung 202301, Taiwan
- Correspondence:
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Visualization of the Oncolytic Alphavirus M1 Life Cycle in Cancer Cells. Virol Sin 2021; 36:655-666. [PMID: 33481190 DOI: 10.1007/s12250-020-00339-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 10/26/2020] [Indexed: 01/16/2023] Open
Abstract
Oncolytic alphavirus M1 has been shown to selectively target and kill cancer cells, but cytopathic morphologies induced by M1 virus and the life cycle of the M1 strain in cancer cells remain unclear. Here, we study the key stages of M1 virus infection and replication in the M1 virus-sensitive HepG2 liver cancer cell line by transmission electron microscopy, specifically examining viral entry, assembly, maturation and release. We found that M1 virus induces vacuolization of cancer cells during infection and ultimately nuclear marginalization, a typical indicator of apoptosis. Specifically, our results suggest that the endoplasmic reticulum participates in the assembly of nucleocapsids. In the early and late stage of infection, three kinds of special cytopathic vacuoles are formed and appear to be involved in the replication, maturation and release of the virus. Taken together, our data displayed the process of M1 virus infection of tumor cells and provide the structural basis for the study of M1 virus-host interactions.
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Williamson LE, Gilliland T, Yadav PK, Binshtein E, Bombardi R, Kose N, Nargi RS, Sutton RE, Durie CL, Armstrong E, Carnahan RH, Walker LM, Kim AS, Fox JM, Diamond MS, Ohi MD, Klimstra WB, Crowe JE. Human Antibodies Protect against Aerosolized Eastern Equine Encephalitis Virus Infection. Cell 2020; 183:1884-1900.e23. [PMID: 33301709 DOI: 10.1016/j.cell.2020.11.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/23/2020] [Accepted: 11/06/2020] [Indexed: 12/19/2022]
Abstract
Eastern equine encephalitis virus (EEEV) is one of the most virulent viruses endemic to North America. No licensed vaccines or antiviral therapeutics are available to combat this infection, which has recently shown an increase in human cases. Here, we characterize human monoclonal antibodies (mAbs) isolated from a survivor of natural EEEV infection with potent (<20 pM) inhibitory activity of EEEV. Cryo-electron microscopy reconstructions of two highly neutralizing mAbs, EEEV-33 and EEEV-143, were solved in complex with chimeric Sindbis/EEEV virions to 7.2 Å and 8.3 Å, respectively. The mAbs recognize two distinct antigenic sites that are critical for inhibiting viral entry into cells. EEEV-33 and EEEV-143 protect against disease following stringent lethal aerosol challenge of mice with highly pathogenic EEEV. These studies provide insight into the molecular basis for the neutralizing human antibody response against EEEV and can facilitate development of vaccines and candidate antibody therapeutics.
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Affiliation(s)
- Lauren E Williamson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA
| | - Theron Gilliland
- The Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 165261, USA
| | - Pramod K Yadav
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Elad Binshtein
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Robin Bombardi
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Nurgun Kose
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rachel S Nargi
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rachel E Sutton
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Clarissa L Durie
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Erica Armstrong
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Robert H Carnahan
- The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Lauren M Walker
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA
| | - Arthur S Kim
- Department of Medicine, Washington University, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Julie M Fox
- Department of Medicine, Washington University, St. Louis, MO 63110, USA
| | - Michael S Diamond
- Department of Medicine, Washington University, St. Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA; Department of Molecular Microbiology, Washington University, St. Louis, MO 63110, USA
| | - Melanie D Ohi
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - William B Klimstra
- The Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 165261, USA; Department of Immunology, University of Pittsburgh, Pittsburgh, PA 165261, USA
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA; The Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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Powell LA, Miller A, Fox JM, Kose N, Klose T, Kim AS, Bombardi R, Tennekoon RN, Dharshan de Silva A, Carnahan RH, Diamond MS, Rossmann MG, Kuhn RJ, Crowe JE. Human mAbs Broadly Protect against Arthritogenic Alphaviruses by Recognizing Conserved Elements of the Mxra8 Receptor-Binding Site. Cell Host Microbe 2020; 28:699-711.e7. [PMID: 32783883 PMCID: PMC7666055 DOI: 10.1016/j.chom.2020.07.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/25/2020] [Accepted: 07/15/2020] [Indexed: 10/23/2022]
Abstract
Mosquito inoculation of humans with arthritogenic alphaviruses results in a febrile syndrome characterized by debilitating musculoskeletal pain and arthritis. Despite an expanding global disease burden, no approved therapies or licensed vaccines exist. Here, we describe human monoclonal antibodies (mAbs) that bind to and neutralize multiple distantly related alphaviruses. These mAbs compete for an antigenic site and prevent attachment to the recently discovered Mxra8 alphavirus receptor. Three cryoelectron microscopy structures of Fab in complex with Ross River (RRV), Mayaro, or chikungunya viruses reveal a conserved footprint of the broadly neutralizing mAb RRV-12 in a region of the E2 glycoprotein B domain. This mAb neutralizes virus in vitro by preventing virus entry and spread and is protective in vivo in mouse models. Thus, the RRV-12 mAb and its defined epitope have potential as a therapeutic agent or target of vaccine design against multiple emerging arthritogenic alphavirus infections.
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Affiliation(s)
- Laura A Powell
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Andrew Miller
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Julie M Fox
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Nurgun Kose
- Vanderbilt Vaccine Center, Department of Pediatrics, Nashville, TN 37232, USA
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Arthur S Kim
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Robin Bombardi
- Vanderbilt Vaccine Center, Department of Pediatrics, Nashville, TN 37232, USA
| | - Rashika N Tennekoon
- Genetech Research Institute, Colombo, Sri Lanka; Department of Paraclinical Sciences, Faculty of Medicine, Kotelawala Defence University, Colombo, Sri Lanka
| | - A Dharshan de Silva
- Genetech Research Institute, Colombo, Sri Lanka; Department of Paraclinical Sciences, Faculty of Medicine, Kotelawala Defence University, Colombo, Sri Lanka
| | - Robert H Carnahan
- Vanderbilt Vaccine Center, Department of Pediatrics, Nashville, TN 37232, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Michael S Diamond
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Richard J Kuhn
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA; Markey Center for Structural Biology and Purdue Institute of Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
| | - James E Crowe
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Vaccine Center, Department of Pediatrics, Nashville, TN 37232, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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Abstract
Alphaviruses cause severe human illnesses including persistent arthritis and fatal encephalitis. As alphavirus entry into target cells is the first step in infection, intensive research efforts have focused on elucidating aspects of this pathway, including attachment, internalization, and fusion. Herein, we review recent developments in the molecular understanding of alphavirus entry both in vitro and in vivo and how these advances might enable the design of therapeutics targeting this critical step in the alphavirus life cycle.
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Baker WS, Negi S, Braun W, Schein CH. Producing physicochemical property consensus alphavirus protein antigens for broad spectrum vaccine design. Antiviral Res 2020; 182:104905. [PMID: 32800880 DOI: 10.1016/j.antiviral.2020.104905] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/19/2020] [Accepted: 08/01/2020] [Indexed: 12/16/2022]
Abstract
There is a pressing need for new vaccines against alphaviruses, which can cause fatal encephalitis (Venezuelan equine encephalitis virus (VEEV) and others) and severe arthralgia (e.g. Chikungunya virus, CHIKV). These positive-strand RNA viruses are diverse and evolve rapidly, meaning that the sequence of any vaccine should cover multiple strains that may be quite different from any previous isolate. Here, consensus proteins were produced to represent the common physicochemical properties (PCPs) of the epitope rich, B domain of the E2 envelope protein. PCP-consensus proteins were based on multiple strains of VEEV (VEEVcon) and CHIKV (CHIKVcon) or the conserved PCPs of 24 different alphaviruses (AllAVcon). The AllAVcon was altered to include binding sites for neutralizing antibodies of both VEEV and CHIKV strains (Mosaikcon). All four designed proteins were produced solubly in E. coli and purified. They formed the β-strand core expected from experimental structures of this region of the wild type E2 proteins as indicated by circular dichroism (CD) spectra. Furthermore, the CHIKVcon protein bound to a structure dependent, CHIKV neutralizing monoclonal antibody. The AllAVcon and Mosaikcon proteins bound to polyclonal antibodies generated during natural infection with either VEEV or CHIKV, indicating they contained epitopes of both serotypes. The Mosaikcon antigen induced antibodies in rabbit sera that recognized both the VEEVcon and CHIKVcon spike proteins. These PCP-consensus antigens are promising starting points for novel, broad-spectrum alphavirus vaccines.
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Affiliation(s)
- Wendy S Baker
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Surendra Negi
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Werner Braun
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Catherine H Schein
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA; Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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Aksnes I, Markussen T, Braaen S, Rimstad E. Mutation of N-glycosylation Sites in Salmonid Alphavirus (SAV) Envelope Proteins Attenuate the Virus in Cell Culture. Viruses 2020; 12:v12101071. [PMID: 32987930 PMCID: PMC7650630 DOI: 10.3390/v12101071] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/16/2022] Open
Abstract
Salmonid alphavirus (SAV) is the cause of pancreas disease and sleeping disease in farmed salmonid fish in Europe. The spread of these diseases has been difficult to control with biosecurity and current vaccination strategies, and increased understanding of the viral pathogenesis could be beneficial for the development of novel vaccine strategies. N-glycosylation of viral envelope proteins may be crucial for viral virulence and a possible target for its purposed attenuation. In this study, we mutated the N-glycosylation consensus motifs of the E1 and E2 glycoproteins of a SAV3 infectious clone using site-directed mutagenesis. Mutation of the glycosylation motif in E1 gave a complete inactivation of the virus as no viral replication could be detected in cell culture and infectious particles could not be rescued. In contrast, infectious virus particles could be recovered from the SAV3 E2 mutants (E2319Q, E2319A), but not if they were accompanied by lack of N-glycosylation in E1. Compared to the non-mutated infectious clone, the SAV3-E2319Q and SAV3-E2319A recombinant viruses produced less cytopathic effects in cell culture and lower amounts of infectious viral particles. In conclusion, the substitution in the N-linked glycosylation site in E2 attenuated SAV3 in cell culture. The findings could be useful for immunization strategies using live attenuated vaccines and testing in fish will be desirable to study the clone’s properties in vivo.
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Removing the Polyanionic Cargo Requirement for Assembly of Alphavirus Core-Like Particles to Make an Empty Alphavirus Core. Viruses 2020; 12:v12080846. [PMID: 32756493 PMCID: PMC7472333 DOI: 10.3390/v12080846] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022] Open
Abstract
The assembly of alphavirus nucleocapsid cores requires electrostatic interactions between the positively charged N-terminus of the capsid protein (CP) and the encapsidated polyanionic cargo. This system differs from many other viruses that can self-assemble particles in the absence of cargo, or form “empty” particles. We hypothesized that the introduction of a mutant, anionic CP could replace the need for charged cargo during assembly. In this work, we produced a CP mutant, Minus 38 (M38), where all N-terminal charged residues are negatively-charged. When wild-type (WT) and M38 CPs were mixed, they assembled into core-like particles (CLPs). These “empty” particles were of similar size and morphology to WT CLPs assembled with DNA cargo, but did not contain nucleic acid. When DNA cargo was added to the assembly mixture, the amount of M38 CP that was assembled into CLPs decreased, but was not fully excluded from the CLPs, suggesting that M38 competes with DNA to interact with WT CPs. The composition of CLPs can be tuned by altering the order of addition of M38 CP, WT CP, and DNA cargo. The ability to produce alphavirus CLPs that contain a range of amounts of encapsidated cargo, including none, introduces a new platform for packaging cargo for delivery or imaging purposes.
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Button JM, Qazi SA, Wang JCY, Mukhopadhyay S. Revisiting an old friend: new findings in alphavirus structure and assembly. Curr Opin Virol 2020; 45:25-33. [PMID: 32683295 DOI: 10.1016/j.coviro.2020.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/04/2020] [Accepted: 06/16/2020] [Indexed: 01/17/2023]
Abstract
Alphaviruses are transmitted by an arthropod vector to a vertebrate host. The disease pathologies, cellular environments, immune responses, and host factors are very different in these organisms. Yet, the virus is able to infect, replicate, and assemble into new particles in these two animals using one set of genetic instructions. The balance between conserved mechanisms and unique strategies during virus assembly is critical for fitness of the virus. In this review, we discuss new findings in receptor binding, polyprotein topology, nucleocapsid core formation, and particle budding that have emerged in the last five years and share opinions on how these new findings might answer some questions regarding alphavirus structure and assembly.
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Affiliation(s)
- Julie M Button
- Department of Molecular and Cellular Biochemistry, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States
| | - Shefah A Qazi
- Department of Biology, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States
| | - Joseph Che-Yen Wang
- Department of Microbiology and Immunology, Penn State College of Medicine, 700 HMC Crescent Road, Hershey, PA 17033, United States
| | - Suchetana Mukhopadhyay
- Department of Biology, Indiana University, 212 S. Hawthorne Drive, Bloomington, IN 47405, United States.
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Abstract
Alphaviruses are enveloped positive-sense RNA viruses that can cause serious human illnesses such as polyarthritis and encephalitis. Despite their widespread distribution and medical importance, there are no licensed vaccines or antivirals to combat alphavirus infections. Berberine chloride (BBC) is a pan-alphavirus inhibitor that was previously identified in a replicon-based small-molecule screen. This work showed that BBC inhibits alphavirus replication but also suggested that BBC might have additional effects later in the viral life cycle. Here, we show that BBC has late effects that target the virus nucleocapsid (NC) core. Infected cells treated with BBC late in infection were unable to form stable cytoplasmic NCs or assembly intermediates, as assayed by gradient sedimentation. In vitro studies with recombinant capsid protein (Cp) and purified genomic RNA (gRNA) showed that BBC perturbs core-like particle formation and potentially traps the assembly process in intermediate states. Particles produced from BBC-treated cells were less infectious, despite efficient particle production and only minor decreases in genome packaging. In addition, BBC treatment of free virus particles strongly decreased alphavirus infectivity. In contrast, the infectivity of the negative-sense RNA virus vesicular stomatitis virus was resistant to BBC treatment of infected cells or free virus. Together, our data indicate that BBC alters alphavirus Cp-gRNA interactions and oligomerization and suggest that this may cause defects in NC assembly and in disassembly during subsequent virus entry. Thus, BBC may be considered a novel alphavirus NC assembly inhibitor.IMPORTANCE The alphavirus chikungunya virus (CHIKV) is an example of an emerging human pathogen with increased and rapid global spread. Although an acute CHIKV infection is rarely fatal, many patients suffer from debilitating chronic arthralgia for years. Antivirals against chikungunya and other alphaviruses have been identified in vitro, but to date none have been shown to be efficacious and have been licensed for human use. Here, we investigated a small molecule, berberine chloride (BBC), and showed that it inhibited infectious virus production by several alphaviruses including CHIKV. BBC acted on a late step in the alphavirus exit pathway, namely the formation of the nucleocapsid containing the infectious viral RNA. Better understanding of nucleocapsid formation and its inhibition by BBC will provide important information on the mechanisms of infectious alphavirus production and may enable their future targeting in antiviral strategies.
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Barrett CT, Dutch RE. Viral Membrane Fusion and the Transmembrane Domain. Viruses 2020; 12:v12070693. [PMID: 32604992 PMCID: PMC7412173 DOI: 10.3390/v12070693] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 01/05/2023] Open
Abstract
Initiation of host cell infection by an enveloped virus requires a viral-to-host cell membrane fusion event. This event is mediated by at least one viral transmembrane glycoprotein, termed the fusion protein, which is a key therapeutic target. Viral fusion proteins have been studied for decades, and numerous critical insights into their function have been elucidated. However, the transmembrane region remains one of the most poorly understood facets of these proteins. In the past ten years, the field has made significant advances in understanding the role of the membrane-spanning region of viral fusion proteins. We summarize developments made in the past decade that have contributed to the understanding of the transmembrane region of viral fusion proteins, highlighting not only their critical role in the membrane fusion process, but further demonstrating their involvement in several aspects of the viral lifecycle.
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Alphavirus Replication: The Role of Cardiac Glycosides and Ion Concentration in Host Cells. BIOMED RESEARCH INTERNATIONAL 2020; 2020:2813253. [PMID: 32461975 PMCID: PMC7232666 DOI: 10.1155/2020/2813253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/31/2020] [Accepted: 04/15/2020] [Indexed: 01/07/2023]
Abstract
Alphaviruses are arthropod-borne viruses that can cause fever, rash, arthralgias, and encephalitis. The mosquito species Aedes aegypti and Aedes albopictus are the most frequent transmitters of alphaviruses. There are no effective vaccines or specific antivirals available for the treatment of alphavirus-related infections. Interestingly, changes in ion concentration in host cells have been characterized as critical regulators of the alphavirus life cycle, including fusion with the host cell, glycoprotein trafficking, genome translation, and viral budding. Cardiac glycosides, which are classical inhibitors of the Na+ K+ ATPase (NKA), can inhibit alphavirus replication although their mechanisms of action are poorly understood. Nonetheless, results from multiple studies suggest that inhibition of NKA may be a suitable strategy for the development of alphavirus-specific antiviral treatments. This review is aimed at exploring the role of changes in ion concentration during alphavirus replication and at considering the possibility of NKA as a potential therapeutic target for antiviral drugs.
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