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Tabler CO, Tilton JC. Mechanism and Kinetics of HIV-1 Protease Activation. Viruses 2024; 16:1826. [PMID: 39772135 PMCID: PMC11680253 DOI: 10.3390/v16121826] [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: 11/05/2024] [Revised: 11/18/2024] [Accepted: 11/22/2024] [Indexed: 01/11/2025] Open
Abstract
The HIV-1 protease is a critical enzyme for viral replication. Because protease activity is necessary to generate mature infectious virions, it is a primary target of antiretroviral treatment. Here, we provide an overview of the mechanisms regulating protease activation and the methods available to assess protease activity. Finally, we will highlight some of the key discoveries regarding the kinetics of protease activation from the last decade, including how the manipulation of activation kinetics may provide novel HIV-1 treatment strategies.
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Affiliation(s)
| | - John C. Tilton
- Center for Proteomics and Bioinformatics, Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
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2
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McGraw A, Hillmer G, Medehincu SM, Hikichi Y, Gagliardi S, Narayan K, Tibebe H, Marquez D, Mei Bose L, Keating A, Izumi C, Peese K, Joshi S, Krystal M, DeCicco-Skinner KL, Freed EO, Sardo L, Izumi T. Exploring HIV-1 Maturation: A New Frontier in Antiviral Development. Viruses 2024; 16:1423. [PMID: 39339899 PMCID: PMC11437483 DOI: 10.3390/v16091423] [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: 08/14/2024] [Revised: 09/01/2024] [Accepted: 09/03/2024] [Indexed: 09/30/2024] Open
Abstract
HIV-1 virion maturation is an essential step in the viral replication cycle to produce infectious virus particles. Gag and Gag-Pol polyproteins are assembled at the plasma membrane of the virus-producer cells and bud from it to the extracellular compartment. The newly released progeny virions are initially immature and noninfectious. However, once the Gag polyprotein is cleaved by the viral protease in progeny virions, the mature capsid proteins assemble to form the fullerene core. This core, harboring two copies of viral genomic RNA, transforms the virion morphology into infectious virus particles. This morphological transformation is referred to as maturation. Virion maturation influences the distribution of the Env glycoprotein on the virion surface and induces conformational changes necessary for the subsequent interaction with the CD4 receptor. Several host factors, including proteins like cyclophilin A, metabolites such as IP6, and lipid rafts containing sphingomyelins, have been demonstrated to have an influence on virion maturation. This review article delves into the processes of virus maturation and Env glycoprotein recruitment, with an emphasis on the role of host cell factors and environmental conditions. Additionally, we discuss microscopic technologies for assessing virion maturation and the development of current antivirals specifically targeting this critical step in viral replication, offering long-acting therapeutic options.
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Affiliation(s)
- Aidan McGraw
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Grace Hillmer
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Stefania M. Medehincu
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Yuta Hikichi
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MS 21702, USA; (Y.H.); (E.O.F.)
| | - Sophia Gagliardi
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Kedhar Narayan
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Hasset Tibebe
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Dacia Marquez
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Lilia Mei Bose
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Adleigh Keating
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Coco Izumi
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Kevin Peese
- ViiV Healthcare, 36 E. Industrial Road, Branford, CT 06405, USA; (K.P.) (S.J.); (M.K.)
| | - Samit Joshi
- ViiV Healthcare, 36 E. Industrial Road, Branford, CT 06405, USA; (K.P.) (S.J.); (M.K.)
| | - Mark Krystal
- ViiV Healthcare, 36 E. Industrial Road, Branford, CT 06405, USA; (K.P.) (S.J.); (M.K.)
| | - Kathleen L. DeCicco-Skinner
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
| | - Eric O. Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MS 21702, USA; (Y.H.); (E.O.F.)
| | - Luca Sardo
- ViiV Healthcare, 36 E. Industrial Road, Branford, CT 06405, USA; (K.P.) (S.J.); (M.K.)
| | - Taisuke Izumi
- Department Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (S.M.M.); (S.G.); (K.N.); (H.T.); (D.M.); (L.M.B.); (A.K.); (C.I.); (K.L.D.-S.)
- District of Columbia Center for AIDS Research, Washington, DC 20052, USA
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3
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Guerrero JF, Lesko SL, Evans EL, Sherer NM. Studying Retroviral Life Cycles Using Visible Viruses and Live Cell Imaging. Annu Rev Virol 2024; 11:125-146. [PMID: 38876144 PMCID: PMC11697243 DOI: 10.1146/annurev-virology-100422-012608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Viruses exploit key host cell factors to accomplish each individual stage of the viral replication cycle. To understand viral pathogenesis and speed the development of new antiviral strategies, high-resolution visualization of virus-host interactions is needed to define where and when these events occur within cells. Here, we review state-of-the-art live cell imaging techniques for tracking individual stages of viral life cycles, focusing predominantly on retroviruses and especially human immunodeficiency virus type 1, which is most extensively studied. We describe how visible viruses can be engineered for live cell imaging and how nonmodified viruses can, in some instances, be tracked and studied indirectly using cell biosensor systems. We summarize the ways in which live cell imaging has been used to dissect the retroviral life cycle. Finally, we discuss select challenges for the future including the need for better labeling strategies, increased resolution, and multivariate systems that will allow for the study of full viral replication cycles.
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Affiliation(s)
- Jorge F Guerrero
- McArdle Laboratory for Cancer Research, Department of Oncology, and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA;
| | - Sydney L Lesko
- McArdle Laboratory for Cancer Research, Department of Oncology, and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA;
| | - Edward L Evans
- Current affiliation: Department of Biomedical Engineering and Center for Quantitative Imaging, University of Wisconsin-Madison, Madison, Wisconsin, USA
- McArdle Laboratory for Cancer Research, Department of Oncology, and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA;
| | - Nathan M Sherer
- McArdle Laboratory for Cancer Research, Department of Oncology, and Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA;
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4
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Raghunath G, Abbott EH, Marin M, Wu H, Reyes Ballista JM, Brindley MA, Melikyan GB. Disruption of Transmembrane Phosphatidylserine Asymmetry by HIV-1 Incorporated SERINC5 Is Not Responsible for Virus Restriction. Biomolecules 2024; 14:570. [PMID: 38785977 PMCID: PMC11118262 DOI: 10.3390/biom14050570] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/26/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
Host restriction factor SERINC5 (SER5) incorporates into the HIV-1 membrane and inhibits infectivity by a poorly understood mechanism. Recently, SER5 was found to exhibit scramblase-like activity leading to the externalization of phosphatidylserine (PS) on the viral surface, which has been proposed to be responsible for SER5's antiviral activity. This and other reports that document modulation of HIV-1 infectivity by viral lipid composition prompted us to investigate the role of PS in regulating SER5-mediated HIV-1 restriction. First, we show that the level of SER5 incorporation into virions correlates with an increase in PS levels in the outer leaflet of the viral membrane. We developed an assay to estimate the PS distribution across the viral membrane and found that SER5, but not SER2, which lacks antiviral activity, abrogates PS asymmetry by externalizing this lipid. Second, SER5 incorporation diminished the infectivity of pseudoviruses produced from cells lacking a flippase subunit CDC50a and, therefore, exhibited a higher baseline level of surface-accessible PS. Finally, exogenous manipulation of the viral PS levels utilizing methyl-alpha-cyclodextrin revealed a lack of correlation between external PS and virion infectivity. Taken together, our study implies that the increased PS exposure to SER5-containing virions itself is not directly linked to HIV-1 restriction.
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Affiliation(s)
- Gokul Raghunath
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Elizabeth H. Abbott
- Emory College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Mariana Marin
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Hui Wu
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
| | - Judith Mary Reyes Ballista
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (J.M.R.B.); (M.A.B.)
| | - Melinda A. Brindley
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (J.M.R.B.); (M.A.B.)
- Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Gregory B. Melikyan
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
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5
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Sharma M, Marin M, Wu H, Prikryl D, Melikyan GB. Human Immunodeficiency Virus 1 Preferentially Fuses with pH-Neutral Endocytic Vesicles in Cell Lines and Human Primary CD4+ T-Cells. ACS NANO 2023; 17:17436-17450. [PMID: 37589658 PMCID: PMC10510587 DOI: 10.1021/acsnano.3c05508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/14/2023] [Indexed: 08/18/2023]
Abstract
Despite extensive efforts, the principal sites of productive HIV-1 entry in different target cells─plasma membrane (PM) vs endosomes─remain controversial. To delineate the site(s) of HIV-1 fusion, we implemented a triple labeling approach that involves tagging pseudoviruses with the fluid-phase viral content marker, iCherry, the viral membrane marker, DiD, and the extraviral pH sensor, ecliptic pHluorin. The viral content marker iCherry is released into the cytoplasm upon virus-cell fusion irrespective of the sites of fusion. In contrast, the extent of dilution of the membrane marker upon fusion with the PM (loss of signal) vs the endosomal membrane (no change in punctate DiD appearance) discriminates between the principal sites of viral fusion. Additionally, ecliptic pHluorin incorporated into the viral membrane reports whether virus fusion occurs in acidic endosomes. Real-time single virus imaging in living HeLa-derived cells, a CD4+ T-cell line, and activated primary human CD4+ T-cells revealed a strong (80-90%) HIV-1 preference for fusion with endosomes. Intriguingly, we observed HIV-1 fusion only with pH-neutral intracellular vesicles and never with acidified endosomes. These endocytic fusion events are likely culminating in productive infection since endocytic inhibitors, such as EIPA, Pitstop2, and Dynasore, as well as a dominant-negative dynamin-2 mutant, inhibited HIV-1 infection in HeLa-derived and primary CD4+ T-cells. Furthermore, the inhibition of endocytosis in HeLa-derived cells promoted hemifusion at the PM but abrogated complete fusion. Collectively, these data reveal that the primary HIV-1 entry pathway in diverse cell types is through fusion with pH-neutral intracellular vesicles.
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Affiliation(s)
- Manish Sharma
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
| | - Mariana Marin
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
| | - Hui Wu
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - David Prikryl
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Gregory B. Melikyan
- Department
of Pediatrics, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, United States
- Children’s
Healthcare of Atlanta, Atlanta, Georgia 30322, United States
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6
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Mannsverk S, Villamil Giraldo AM, Kasson PM. Influenza Virus Membrane Fusion Is Promoted by the Endosome-Resident Phospholipid Bis(monoacylglycero)phosphate. J Phys Chem B 2022; 126:10445-10451. [PMID: 36468619 PMCID: PMC9761668 DOI: 10.1021/acs.jpcb.2c06642] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The phospholipid bis(monoacylglycero)phosphate (BMP) is enriched in late endosomal and endolysosomal membranes and is believed to be involved in membrane deformation and generation of intralumenal vesicles within late endosomes. Previous studies have demonstrated that BMP promotes membrane fusion of several enveloped viruses, but a limited effect has been found on influenza virus. Here, we report the use of single-virus fusion assays to dissect BMP's effect on influenza virus fusion in greater depth. In agreement with prior reports, we found that hemifusion kinetics and efficiency were unaffected by the addition of 10-20 mol % BMP to the target membrane. However, using an assay for fusion pore formation and genome exposure, we found full fusion efficiency to be substantially enhanced by the addition of 10-20 mol % BMP to the target membrane, while the kinetics remained unaffected. By comparing BMP to other negatively charged phospholipids, we found the effect on fusion efficiency mainly attributable to headgroup charge, although we also hypothesize a role for BMP's unusual chemical structure. Our results suggest that BMP function as a permissive factor for a wider range of viruses than previously reported. We hypothesize that BMP may be a general cofactor for endosomal entry of enveloped viruses.
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Affiliation(s)
- Steinar Mannsverk
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
| | - Ana M. Villamil Giraldo
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
| | - Peter M. Kasson
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden,Departments
of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, United States,
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7
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Yoh SM, Mamede JI, Lau D, Ahn N, Sánchez-Aparicio MT, Temple J, Tuckwell A, Fuchs NV, Cianci GC, Riva L, Curry H, Yin X, Gambut S, Simons LM, Hultquist JF, König R, Xiong Y, García-Sastre A, Böcking T, Hope TJ, Chanda SK. Recognition of HIV-1 capsid by PQBP1 licenses an innate immune sensing of nascent HIV-1 DNA. Mol Cell 2022; 82:2871-2884.e6. [PMID: 35809572 PMCID: PMC9552964 DOI: 10.1016/j.molcel.2022.06.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 03/22/2022] [Accepted: 06/07/2022] [Indexed: 12/21/2022]
Abstract
We have previously described polyglutamine-binding protein 1 (PQBP1) as an adapter required for the cyclic GMP-AMP synthase (cGAS)-mediated innate response to the human immunodeficiency virus 1 (HIV-1) and other lentiviruses. Cytoplasmic HIV-1 DNA is a transient and low-abundance pathogen-associated molecular pattern (PAMP), and the mechanism for its detection and verification is not fully understood. Here, we show a two-factor authentication strategy by the innate surveillance machinery to selectively respond to the low concentration of HIV-1 DNA, while distinguishing these species from extranuclear DNA molecules. We find that, upon HIV-1 infection, PQBP1 decorates the intact viral capsid, and this serves as a primary verification step for the viral nucleic acid cargo. As reverse transcription and capsid disassembly initiate, cGAS is recruited to the capsid in a PQBP1-dependent manner. This positions cGAS at the site of PAMP generation and sanctions its response to a low-abundance DNA PAMP.
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Affiliation(s)
- Sunnie M Yoh
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA.
| | - João I Mamede
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL 60612, USA
| | - Derrick Lau
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Narae Ahn
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA
| | - Maria T Sánchez-Aparicio
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Joshua Temple
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Andrew Tuckwell
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Nina V Fuchs
- Host-Pathogen Interaction, Paul-Ehrlich-Institut, 63225 Langen, Germany
| | - Gianguido C Cianci
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Laura Riva
- Calibr, a Division of The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Heather Curry
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA
| | - Xin Yin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, P.R. China
| | - Stéphanie Gambut
- Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL 60612, USA
| | - Lacy M Simons
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pathogen Genomics and Microbial Evolution, Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Judd F Hultquist
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Center for Pathogen Genomics and Microbial Evolution, Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Renate König
- Host-Pathogen Interaction, Paul-Ehrlich-Institut, 63225 Langen, Germany
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Pathology, Molecular, and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Thomas J Hope
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sumit K Chanda
- Department of Immunology and Microbiology, Scripps Research, La Jolla, CA 92037, USA.
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8
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Bally M, Block S, Höök F, Larson G, Parveen N, Rydell GE. Physicochemical tools for studying virus interactions with targeted cell membranes in a molecular and spatiotemporally resolved context. Anal Bioanal Chem 2021; 413:7157-7178. [PMID: 34490501 PMCID: PMC8421089 DOI: 10.1007/s00216-021-03510-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/14/2022]
Abstract
The objective of this critical review is to provide an overview of how emerging bioanalytical techniques are expanding our understanding of the complex physicochemical nature of virus interactions with host cell surfaces. Herein, selected model viruses representing both non-enveloped (simian virus 40 and human norovirus) and enveloped (influenza A virus, human herpes simplex virus, and human immunodeficiency virus type 1) viruses are highlighted. The technologies covered utilize a wide range of cell membrane mimics, from supported lipid bilayers (SLBs) containing a single purified host membrane component to SLBs derived from the plasma membrane of a target cell, which can be compared with live-cell experiments to better understand the role of individual interaction pairs in virus attachment and entry. These platforms are used to quantify binding strengths, residence times, diffusion characteristics, and binding kinetics down to the single virus particle and single receptor, and even to provide assessments of multivalent interactions. The technologies covered herein are surface plasmon resonance (SPR), quartz crystal microbalance with dissipation (QCM-D), dynamic force spectroscopy (DFS), total internal reflection fluorescence (TIRF) microscopy combined with equilibrium fluctuation analysis (EFA) and single particle tracking (SPT), and finally confocal microscopy using multi-labeling techniques to visualize entry of individual virus particles in live cells. Considering the growing scientific and societal needs for untangling, and interfering with, the complex mechanisms of virus binding and entry, we hope that this review will stimulate the community to implement these emerging tools and strategies in conjunction with more traditional methods. The gained knowledge will not only contribute to a better understanding of the virus biology, but may also facilitate the design of effective inhibitors to block virus entry.
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Affiliation(s)
- Marta Bally
- Department of Clinical Microbiology & Wallenberg Centre for Molecular Medicine, Umeå University, 901 85, Umeå, Sweden
| | - Stephan Block
- Department of Chemistry and Biochemistry, Freie Universität Berlin, 14195, Berlin, Germany
| | - Fredrik Höök
- Department of Physics, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
| | - Göran Larson
- Department of Laboratory Medicine, Sahlgrenska Academy at the University of Gothenburg, Sahlgrenska University Hospital, Bruna Stråket 16, 413 45, Gothenburg, Sweden.
| | - Nagma Parveen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Gustaf E Rydell
- Department of Infectious Diseases, Sahlgrenska Academy at the University of Gothenburg, 413 46, Gothenburg, Sweden
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9
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Sarca AD, Sardo L, Fukuda H, Matsui H, Shirakawa K, Horikawa K, Takaori-Kondo A, Izumi T. FRET-Based Detection and Quantification of HIV-1 Virion Maturation. Front Microbiol 2021; 12:647452. [PMID: 33767685 PMCID: PMC7985248 DOI: 10.3389/fmicb.2021.647452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 01/18/2021] [Indexed: 01/27/2023] Open
Abstract
HIV-1 infectivity is achieved through virion maturation. Virus particles undergo structural changes via cleavage of the Gag polyprotein mediated by the viral protease, causing the transition from an uninfectious to an infectious status. The majority of proviruses in people living with HIV-1 treated with combination antiretroviral therapy are defective with large internal deletions. Defective proviral DNA frequently preserves intact sequences capable of expressing viral structural proteins to form virus-like particles whose maturation status is an important factor for chronic antigen-mediated immune stimulation and inflammation. Thus, novel methods to study the maturation capability of defective virus particles are needed to characterize their immunogenicity. To build a quantitative tool to study virion maturation in vitro, we developed a novel single virion visualization technique based on fluorescence resonance energy transfer (FRET). We inserted an optimized intramolecular CFP-YPF FRET donor-acceptor pair bridged with an HIV-1 protease cleavage sequence between the Gag MA-CA domains. This system allowed us to microscopically distinguish mature and immature virions via their FRET signal when the FRET donor and acceptor proteins were separated by the viral protease during maturation. We found that approximately 80% of the FRET labeled virus particles were mature with equivalent infectivity to wild type. The proportion of immature virions was increased by treatment of virus producer cells with a protease inhibitor in a dose-dependent manner, which corresponded to a relative decrease in infectivity. Potential areas of application for this tool are assessing maturation efficiency in different cell type settings of intact or deficient proviral DNA integrated cells. We believe that this FRET-based single-virion imaging platform will facilitate estimating the impact on the immune system of both extracellular intact and defective viruses by quantifying the Gag maturation status.
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Affiliation(s)
- Anamaria D Sarca
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Luca Sardo
- Department of Biological Sciences, University of the Sciences, Philadelphia, PA, United States
| | - Hirofumi Fukuda
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Matsui
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kotaro Shirakawa
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kazuki Horikawa
- Department of Optical Imaging, Advanced Research Promotion Center, Tokushima University, Tokushima, Japan
| | - Akifumi Takaori-Kondo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Taisuke Izumi
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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10
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Imaging Viral Infection by Fluorescence Microscopy: Focus on HIV-1 Early Stage. Viruses 2021; 13:v13020213. [PMID: 33573241 PMCID: PMC7911428 DOI: 10.3390/v13020213] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 12/15/2022] Open
Abstract
During the last two decades, progresses in bioimaging and the development of various strategies to fluorescently label the viral components opened a wide range of possibilities to visualize the early phase of Human Immunodeficiency Virus 1 (HIV-1) life cycle directly in infected cells. After fusion of the viral envelope with the cell membrane, the viral core is released into the cytoplasm and the viral RNA (vRNA) is retro-transcribed into DNA by the reverse transcriptase. During this process, the RNA-based viral complex transforms into a pre-integration complex (PIC), composed of the viral genomic DNA (vDNA) coated with viral and host cellular proteins. The protective capsid shell disassembles during a process called uncoating. The viral genome is transported into the cell nucleus and integrates into the host cell chromatin. Unlike biochemical approaches that provide global data about the whole population of viral particles, imaging techniques enable following individual viruses on a single particle level. In this context, quantitative microscopy has brought original data shedding light on the dynamics of the viral entry into the host cell, the cytoplasmic transport, the nuclear import, and the selection of the integration site. In parallel, multi-color imaging studies have elucidated the mechanism of action of host cell factors implicated in HIV-1 viral cycle progression. In this review, we describe the labeling strategies used for HIV-1 fluorescence imaging and report on the main advancements that imaging studies have brought in the understanding of the infection mechanisms from the viral entry into the host cell until the provirus integration step.
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11
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Chen YC, Sood C, Francis AC, Melikyan GB, Dickson RM. Facile autofluorescence suppression enabling tracking of single viruses in live cells. J Biol Chem 2019; 294:19111-19118. [PMID: 31694918 DOI: 10.1074/jbc.ra119.010268] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/01/2019] [Indexed: 11/06/2022] Open
Abstract
Live cell fluorescence imaging is the method of choice for studying dynamic processes, such as nuclear transport, vesicular trafficking, and virus entry and egress. However, endogenous cellular autofluorescence masks a useful fluorescence signal, limiting the ability to reliably visualize low-abundance fluorescent proteins. Here, we employed synchronously amplified fluorescence image recovery (SAFIRe), which optically alters ground versus photophysical dark state populations within fluorescent proteins to modulate and selectively detect their background-free emission. Using a photoswitchable rsFastLime fluorescent protein combined with a simple illumination and image-processing scheme, we demonstrate the utility of this approach for suppressing undesirable, unmodulatable fluorescence background. Significantly, we adapted this technique to different commercial wide-field and spinning-disk confocal microscopes, obtaining >10-fold improvements in signal to background. SAFIRe allowed visualization of rsFastLime targeted to mitochondria by efficiently suppressing endogenous autofluorescence or overexpressed cytosolic unmodulatable EGFP. Suppression of the overlapping EGFP signal provided a means to perform multiplexed imaging of rsFastLime and spectrally overlapping fluorophores. Importantly, we used SAFIRe to reliably visualize and track single rsFastLime-labeled HIV-1 particles in living cells exhibiting high and uneven autofluorescence signals. Time-lapse SAFIRe imaging can be performed for an extended period of time to visualize HIV-1 entry into cells. SAFIRe should be broadly applicable for imaging live cell dynamics with commercial microscopes, even in strongly autofluorescent cells or cells expressing spectrally overlapping fluorescent proteins.
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Affiliation(s)
- Yen-Cheng Chen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400.,Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322
| | - Chetan Sood
- Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322
| | - Ashwanth C Francis
- Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322
| | - Gregory B Melikyan
- Department of Pediatrics, Emory School of Medicine, Atlanta, Georgia 30322 .,Children's Healthcare of Atlanta, Atlanta, Georgia 30332
| | - Robert M Dickson
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400
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12
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Fluorescent Protein Inserts in between NC and SP2 are Tolerated for Assembly, Release and Maturation of HIV with Limited Infectivity. Viruses 2019; 11:v11110973. [PMID: 31652757 PMCID: PMC6893430 DOI: 10.3390/v11110973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/08/2019] [Accepted: 10/14/2019] [Indexed: 01/07/2023] Open
Abstract
We report the design of a fluorescent HIV construct that is labeled by insertion of fluorescent protein between the nucleocapsid (NC) and spacer peptide 2 (SP2) domains of Gag and further show that the fluorescent protein is released from its confines within Gag during maturation. This fluorescent HIV is capable of budding and maturation with similar efficiency to the parental virus. Virions generated using this design within the R8 HIV backbone pseudotyped with VSV-G were capable of delivering small RNA genomes encoding GFP to the target cells; however, the same design within the NL4-3 backbone has limited HIV infectivity. The virions generated by these constructs are approximately 165 ± 35 nm in size, which is significantly larger than wild type HIV. We suggest that this design has the potential to be a vehicle for protein and small guide RNA delivery.
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13
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Suddala KC, Lee CC, Meraner P, Marin M, Markosyan RM, Desai TM, Cohen FS, Brass AL, Melikyan GB. Interferon-induced transmembrane protein 3 blocks fusion of sensitive but not resistant viruses by partitioning into virus-carrying endosomes. PLoS Pathog 2019; 15:e1007532. [PMID: 30640957 PMCID: PMC6347298 DOI: 10.1371/journal.ppat.1007532] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/25/2019] [Accepted: 12/14/2018] [Indexed: 11/19/2022] Open
Abstract
Late endosome-resident interferon-induced transmembrane protein 3 (IFITM3) inhibits fusion of diverse viruses, including Influenza A virus (IAV), by a poorly understood mechanism. Despite the broad antiviral activity of IFITM3, viruses like Lassa virus (LASV), are fully resistant to its inhibitory effects. It is currently unclear whether resistance arises from a highly efficient fusion machinery that is capable of overcoming IFITM3 restriction or the ability to enter from cellular sites devoid of this factor. Here, we constructed and validated a functional IFITM3 tagged with EGFP or other fluorescent proteins. This breakthrough allowed live cell imaging of virus co-trafficking and fusion with endosomal compartments in cells expressing fluorescent IFITM3. Three-color single virus and endosome tracking revealed that sensitive (IAV), but not resistant (LASV), viruses become trapped within IFITM3-positive endosomes where they underwent hemifusion but failed to release their content into the cytoplasm. IAV fusion with IFITM3-containing compartments could be rescued by amphotericin B treatment, which has been previously shown to antagonize the antiviral activity of this protein. By comparison, virtually all LASV particles trafficked and fused with endosomes lacking detectable levels of fluorescent IFITM3, implying that this virus escapes restriction by utilizing endocytic pathways that are distinct from the IAV entry pathways. The importance of virus uptake and transport pathways is further reinforced by the observation that LASV glycoprotein-mediated cell-cell fusion is inhibited by IFITM3 and other members of the IFITM family expressed in target cells. Together, our results strongly support a model according to which IFITM3 accumulation at the sites of virus fusion is a prerequisite for its antiviral activity and that this protein traps viral fusion at a hemifusion stage by preventing the formation of fusion pores. We conclude that the ability to utilize alternative endocytic pathways for entry confers IFITM3-resistance to otherwise sensitive viruses.
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Affiliation(s)
- Krishna C Suddala
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Christine C Lee
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Paul Meraner
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Mariana Marin
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Ruben M Markosyan
- Rush University Medical Center, Department of Physiology and Biophysics, Chicago, IL, United States of America
| | - Tanay M Desai
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Fredric S Cohen
- Rush University Medical Center, Department of Physiology and Biophysics, Chicago, IL, United States of America
| | - Abraham L Brass
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, United States of America
- Gastroenterology Division, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Gregory B Melikyan
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
- Children's Healthcare of Atlanta, Atlanta, GA, United States of America
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14
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Francis AC, Melikyan GB. Single HIV-1 Imaging Reveals Progression of Infection through CA-Dependent Steps of Docking at the Nuclear Pore, Uncoating, and Nuclear Transport. Cell Host Microbe 2018; 23:536-548.e6. [PMID: 29649444 DOI: 10.1016/j.chom.2018.03.009] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/03/2018] [Accepted: 03/16/2018] [Indexed: 11/26/2022]
Abstract
The HIV-1 core consists of capsid proteins (CA) surrounding viral genomic RNA. After virus-cell fusion, the core enters the cytoplasm and the capsid shell is lost through uncoating. CA loss precedes nuclear import and HIV integration into the host genome, but the timing and location of uncoating remain unclear. By visualizing single HIV-1 infection, we find that CA is required for core docking at the nuclear envelope (NE), whereas early uncoating in the cytoplasm promotes proteasomal degradation of viral complexes. Only docked cores exhibiting accelerated loss of CA at the NE enter the nucleus. Interestingly, a CA mutation (N74D) altering virus engagement of host factors involved in nuclear transport does not alter the uncoating site at the NE but reduces the nuclear penetration depth. Thus, CA protects HIV-1 complexes from degradation, mediates docking at the nuclear pore before uncoating, and determines the depth of nuclear penetration en route to integration.
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Affiliation(s)
| | - Gregory B Melikyan
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA.
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15
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Banerjee S, Maurya S, Roy R. Single-molecule fluorescence imaging: Generating insights into molecular interactions in virology. J Biosci 2018; 43:519-540. [PMID: 30002270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Single-molecule fluorescence methods remain a challenging yet information-rich set of techniques that allow one to probe the dynamics, stoichiometry and conformation of biomolecules one molecule at a time. Viruses are small (nanometers) in size, can achieve cellular infections with a small number of virions and their lifecycle is inherently heterogeneous with a large number of structural and functional intermediates. Single-molecule measurements that reveal the complete distribution of properties rather than the average can hence reveal new insights into virus infections and biology that are inaccessible otherwise. This article highlights some of the methods and recent applications of single-molecule fluorescence in the field of virology. Here, we have focused on new findings in virus-cell interaction, virus cell entry and transport, viral membrane fusion, genome release, replication, translation, assembly, genome packaging, egress and interaction with host immune proteins that underline the advantage of single-molecule approach to the question at hand. Finally, we discuss the challenges, outlook and potential areas for improvement and future use of single-molecule fluorescence that could further aid our understanding of viruses.
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Affiliation(s)
- Sunaina Banerjee
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
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16
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Single-molecule fluorescence imaging: Generating insights into molecular interactions in virology. J Biosci 2018. [DOI: 10.1007/s12038-018-9769-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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17
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Live-Cell Imaging of Early Steps of Single HIV-1 Infection. Viruses 2018; 10:v10050275. [PMID: 29783762 PMCID: PMC5977268 DOI: 10.3390/v10050275] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/15/2018] [Accepted: 05/18/2018] [Indexed: 01/10/2023] Open
Abstract
Live-cell imaging of single HIV-1 entry offers a unique opportunity to delineate the spatio-temporal regulation of infection. Novel virus labeling and imaging approaches enable the visualization of key steps of HIV-1 entry leading to nuclear import, integration into the host genome, and viral protein expression. Here, we discuss single virus imaging strategies, focusing on live-cell imaging of single virus fusion and productive uncoating that culminates in HIV-1 infection.
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18
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Parveen N, Borrenberghs D, Rocha S, Hendrix J. Single Viruses on the Fluorescence Microscope: Imaging Molecular Mobility, Interactions and Structure Sheds New Light on Viral Replication. Viruses 2018; 10:E250. [PMID: 29748498 PMCID: PMC5977243 DOI: 10.3390/v10050250] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/24/2018] [Accepted: 05/04/2018] [Indexed: 12/13/2022] Open
Abstract
Viruses are simple agents exhibiting complex reproductive mechanisms. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious viral particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that we employ routinely to investigate viruses. We provide a brief overview of the microscopy hardware needed and discuss the different methods and their application. In particular, we review how we applied (i) single-molecule Förster resonance energy transfer (smFRET) to probe the subviral human immunodeficiency virus (HIV-1) integrase (IN) quaternary structure; (ii) single particle tracking to study interactions of the simian virus 40 with membranes; (iii) 3D confocal microscopy and smFRET to quantify the HIV-1 pre-integration complex content and quaternary structure; (iv) image correlation spectroscopy to quantify the cytosolic HIV-1 Gag assembly, and finally; (v) super-resolution microscopy to characterize the interaction of HIV-1 with tetherin during assembly. We hope this review is an incentive for setting up and applying similar single-virus imaging studies in daily virology practice.
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Affiliation(s)
- Nagma Parveen
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Doortje Borrenberghs
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Susana Rocha
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
| | - Jelle Hendrix
- Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, Chemistry Department, KU Leuven, B-3001 Leuven, Belgium.
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt University, B-3590 Diepenbeek, Belgium.
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19
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Witte R, Andriasyan V, Georgi F, Yakimovich A, Greber UF. Concepts in Light Microscopy of Viruses. Viruses 2018; 10:E202. [PMID: 29670029 PMCID: PMC5923496 DOI: 10.3390/v10040202] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/12/2018] [Accepted: 04/16/2018] [Indexed: 12/11/2022] Open
Abstract
Viruses threaten humans, livestock, and plants, and are difficult to combat. Imaging of viruses by light microscopy is key to uncover the nature of known and emerging viruses in the quest for finding new ways to treat viral disease and deepening the understanding of virus–host interactions. Here, we provide an overview of recent technology for imaging cells and viruses by light microscopy, in particular fluorescence microscopy in static and live-cell modes. The review lays out guidelines for how novel fluorescent chemical probes and proteins can be used in light microscopy to illuminate cells, and how they can be used to study virus infections. We discuss advantages and opportunities of confocal and multi-photon microscopy, selective plane illumination microscopy, and super-resolution microscopy. We emphasize the prevalent concepts in image processing and data analyses, and provide an outlook into label-free digital holographic microscopy for virus research.
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Affiliation(s)
- Robert Witte
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Vardan Andriasyan
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Fanny Georgi
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Artur Yakimovich
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK.
| | - Urs F Greber
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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