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Chen C, Sun Z, Wang Z, Shin S, Berrios A, Mellors JW, Dimitrov DS, Li W. Identification of a Fully Human Antibody VH Domain Targeting Anaplastic Lymphoma Kinase (ALK) with Applications in ALK-Positive Solid Tumor Immunotherapy. Antibodies (Basel) 2024; 13:39. [PMID: 38804307 PMCID: PMC11130946 DOI: 10.3390/antib13020039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/03/2024] [Accepted: 04/12/2024] [Indexed: 05/29/2024] Open
Abstract
The anaplastic lymphoma kinase (ALK, CD247) is a potential target for antibody-based therapy. However, no antibody-based therapeutics targeting ALK have entered clinical trials, necessitating the development of novel antibodies with unique therapeutic merits. Single-domain antibodies (sdAb) bear therapeutic advantages compared to the full-length antibody including deeper tumor penetration, cost-effective production and fast washout from normal tissues. In this study, we identified a human immunoglobulin heavy chain variable domain (VH domain) (VH20) from an in-house phage library. VH20 exhibits good developability and high specificity with no off-target binding to ~6000 human membrane proteins. VH20 efficiently bound to the glycine-rich region of ALK with an EC50 of 0.4 nM and a KD of 6.54 nM. Both VH20-based bispecific T cell engager (TCE) and chimeric antigen receptor T cells (CAR Ts) exhibited potent cytolytic activity to ALK-expressing tumor cells in an ALK-dependent manner. VH20 CAR Ts specifically secreted proinflammatory cytokines including IL-2, TNFα and IFNγ after incubation with ALK-positive cells. To our knowledge, this is the first reported human single-domain antibody against ALK. Our in vitro characterization data indicate that VH20 could be a promising ALK-targeting sdAb with potential applications in ALK-expressing tumors, including neuroblastoma (NBL) and non-small cell lung cancer.
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Affiliation(s)
- Chuan Chen
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
| | - Zehua Sun
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
| | - Zening Wang
- Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Seungmin Shin
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
| | - Abigail Berrios
- Department of Biological Sciences, University of Pittsburgh Kenneth P. Dietrich School of Arts and Sciences, Pittsburgh, PA 15260, USA;
| | - John W. Mellors
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
| | - Dimiter S. Dimitrov
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
| | - Wei Li
- Center for Antibody Therapeutics, Division of Infectious Diseases, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA 15261, USA; (C.C.); (Z.S.); (S.S.); (J.W.M.)
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2
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Screnci B, Stafford LJ, Barnes T, Shema K, Gilman S, Wright R, Al Absi S, Phillips T, Azuelos C, Slovik K, Murphy P, Harmon DB, Charpentier T, Doranz BJ, Rucker JB, Chambers R. Antibody specificity against highly conserved membrane protein Claudin 6 driven by single atomic contact point. iScience 2022; 25:105665. [PMID: 36505931 PMCID: PMC9732412 DOI: 10.1016/j.isci.2022.105665] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 09/20/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
The tight junction protein claudin 6 (CLDN6) is differentially expressed on cancer cells with almost no expression in healthy tissue. However, achieving therapeutic MAb specificity for this 4 transmembrane protein is challenging because it is nearly identical to the widely expressed CLDN9, with only 3 extracellular amino acids different. Most other CLDN6 MAbs, including those in clinical development are cross-reactive with CLDN9, and several trials have now been stopped. Here we isolated rare MAbs that bind CLDN6 with up to picomolar affinity and display minimal cross-reactivity with CLDN9, 22 other CLDN family members, or across the human membrane proteome. Amino acid-level epitope mapping distinguished the binding sites of our MAbs from existing clinical-stage MAbs. Atomic-level epitope mapping identified the structural mechanism by which our MAbs differentiate CLDN6 and CLDN9 through steric hindrance at a single molecular contact point, the γ carbon on CLDN6 residue Q156.
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Affiliation(s)
- Brad Screnci
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Lewis J. Stafford
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Trevor Barnes
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Kristen Shema
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Samantha Gilman
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Rebecca Wright
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Suzie Al Absi
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Tim Phillips
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Charles Azuelos
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Katherine Slovik
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Paige Murphy
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Daniel B. Harmon
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Tom Charpentier
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Benjamin J. Doranz
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Joseph B. Rucker
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA
| | - Ross Chambers
- Integral Molecular, 3711 Market Street, Suite 900, Philadelphia, PA 19104, USA,Corresponding author
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3
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Makowski EK, Schardt JS, Tessier PM. Improving antibody drug development using bionanotechnology. Curr Opin Biotechnol 2021; 74:137-145. [PMID: 34890875 DOI: 10.1016/j.copbio.2021.10.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/25/2021] [Accepted: 10/31/2021] [Indexed: 12/20/2022]
Abstract
Monoclonal antibodies are being used to treat a remarkable breadth of human disorders. Nevertheless, there are several key challenges at the earliest stages of antibody drug development that need to be addressed using simple and widely accessible methods, especially related to generating antibodies against membrane proteins and identifying antibody candidates with drug-like biophysical properties (high solubility and low viscosity). Here we highlight key bionanotechnologies for preparing functional and stable membrane proteins in diverse types of lipoparticles that are being used to improve antibody discovery and engineering efforts. We also highlight key bionanotechnologies for high-throughput and ultra-dilute screening of antibody biophysical properties during antibody discovery and optimization that are being used for identifying antibodies with superior combinations of in vitro (formulation) and in vivo (half-life) properties.
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Affiliation(s)
- Emily K Makowski
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - John S Schardt
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter M Tessier
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA; Departmant of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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4
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Sabapathy T, Helmerhorst E, Bottomley S, Babaeff S, Munyard K, Newsholme P, Mamotte CD. Use of virus-like particles as a native membrane model to study the interaction of insulin with the insulin receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1204-1212. [PMID: 30951702 DOI: 10.1016/j.bbamem.2019.03.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 03/15/2019] [Accepted: 03/28/2019] [Indexed: 12/15/2022]
Abstract
There is emerging evidence of the utility of virus-like particles (VLPs) as a novel model for the study of receptor-ligand interactions in a native plasma membrane environment. VLPs consist of a viral core protein encapsulated by portions of the cell membrane with membrane proteins and receptors expressed in their native conformation. VLPs can be generated in mammalian cells by transfection with the retroviral core protein (gag). In this study, we used Chinese hamster ovary (CHO T10) cells stably overexpressing the insulin receptor (IR) to generate IR bearing VLPs. The diameter and size uniformity of VLPs were estimated by dynamic light scattering and morphological features examined by scanning electron microscopy. The presence of high affinity IR on VLPs was demonstrated by competitive binding assays (KD: 2.3 ± 0.4 nM, n = 3), which was similar to that on the parental CHO T10 cells (KD: 2.1 ± 0.4 nM, n = 3). We also report that increases or decreases in membrane cholesterol content by treatment with methyl-β-cyclodextrin (MBCD) or cholesterol pre-loaded methyl-β-cyclodextrin (cMBCD), respectively, substantially decreased insulin binding (> 30%) to both VLPs and cells, and we speculate this is due to a change in receptor disposition. We suggest that this novel finding of decreases in insulin binding in response to changes in membrane cholesterol content may largely account for the unexplained decreases in insulin signalling events previously reported elsewhere. Finally, we propose VLPs as a viable membrane model for the study of insulin-IR interactions in a native membrane environment.
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Affiliation(s)
- Thiru Sabapathy
- School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia.
| | - Erik Helmerhorst
- School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia.
| | | | | | - Kylie Munyard
- School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia.
| | - Philip Newsholme
- School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia.
| | - Cyril D Mamotte
- School of Pharmacy and Biomedical Sciences, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley campus, Perth, Western Australia 6102, Australia.
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5
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Isolation of state-dependent monoclonal antibodies against the 12-transmembrane domain glucose transporter 4 using virus-like particles. Proc Natl Acad Sci U S A 2018; 115:E4990-E4999. [PMID: 29769329 DOI: 10.1073/pnas.1716788115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The insulin-responsive 12-transmembrane transporter GLUT4 changes conformation between an inward-open state and an outward-open state to actively facilitate cellular glucose uptake. Because of the difficulties of generating conformational mAbs against complex and highly conserved membrane proteins, no reliable tools exist to measure GLUT4 at the cell surface, follow its trafficking, or detect the conformational state of the protein. Here we report the isolation and characterization of conformational mAbs that recognize the extracellular and intracellular domains of GLUT4, including mAbs that are specific for the inward-open and outward-open states of GLUT4. mAbs against GLUT4 were generated using virus-like particles to present this complex membrane protein in its native conformation and using a divergent host species (chicken) for immunization to overcome immune tolerance. As a result, the isolated mAbs recognize conformational epitopes on native GLUT4 in cells, with apparent affinities as high as 1 pM and with specificity for GLUT4 across the human membrane proteome. Epitope mapping using shotgun mutagenesis alanine scanning across the 509 amino acids of GLUT4 identified the binding epitopes for mAbs specific for the states of GLUT4 and allowed the comprehensive identification of the residues that functionally control the GLUT4 inward-open and outward-open states. The mAbs identified here will be valuable molecular tools for monitoring GLUT4 structure, function, and trafficking, for differentiating GLUT4 conformational states, and for the development of novel therapeutics for the treatment of diabetes.
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6
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Kushida Y, Arai Y, Shimono K, Nagai T. Biomimetic Chemical Sensing by Fluorescence Signals Using a Virus-like Particle-Based Platform. ACS Sens 2018; 3:87-92. [PMID: 29256249 DOI: 10.1021/acssensors.7b00537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The chemical receptors present in living organisms are promising tools for developing biomimetic chemical sensors. However, these receptors require lipid membranes for functioning under physiological conditions, which prevents their utilization in the production of cell-free in vitro chemical sensing systems. Here, we report the development of a cell-free biomimetic sensing platform using virus-like particles (VLPs) with intact ligand-gated Ca2+ channels and genetically encoded Ca2+ indicator (GECI). We observed that targeting GECI to the plasma membrane was essential for efficient loading GECI in the VLPs. Although the physiological Ca2+ concentration [Ca2+] maintained in the cells was low (∼10 nM), the concentration in the VLPs was high. This prevented the detection of the increase in [Ca2+] caused by binding of the ligand to the receptor. To address this problem, we employed Lyn-R-CEPIA1, which had low affinity for Ca2+, and a membrane targeting sequence. Thus, we succeeded in monitoring the activation of cyclic nucleotide-gated channels (CNG) on the VLPs by measuring the increase in fluorescence of Lyn-R-CEPIA1. Our VLP-based sensing system can act as a fundamental platform for all kinds of ligand-gated channels.
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Affiliation(s)
- Yuki Kushida
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Advanced
Research Division, Panasonic Corporation, 3-4 Hikaridai,
Seika, Soraku, Kyoto 619-0237, Japan
| | - Yoshiyuki Arai
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Department
of Biomolecular Science and Engineering, The Institute of Scientific
and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
| | - Ken Shimono
- Advanced
Research Division, Panasonic Corporation, 3-4 Hikaridai,
Seika, Soraku, Kyoto 619-0237, Japan
| | - Takeharu Nagai
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Department
of Biomolecular Science and Engineering, The Institute of Scientific
and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
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7
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Martínez-Muñoz L, Barroso R, Paredes AG, Mellado M, Rodríguez-Frade JM. Methods to immobilize GPCR on the surface of SPR sensors. Methods Mol Biol 2015; 1272:173-188. [PMID: 25563184 DOI: 10.1007/978-1-4939-2336-6_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The G protein-coupled receptors (GPCRs) form one of the largest membrane receptor families. The nature of the ligands that interact with these receptors is highly diverse; they include light, peptides and hormones, neurotransmitters, and small molecular weight compounds. The GPCRs are involved in a wide variety of physiological processes and thus hold considerable therapeutic potential.GPCR function is usually determined in cell-based assays, whose complexity nonetheless limits their use. The use of alternative, cell-free assays is hampered by the difficulties in purifying these seven-transmembrane domain receptors without altering their functional properties. Several methods have been proposed to immobilize GPCR on biosensor surfaces which use antibodies or avidin-/biotin-based capture procedures, alone or with reconstitution of the GPCR physiological microenvironment. Here we propose a method for GPCR immobilization in their native membrane microenvironment that requires no manipulation of the target receptor and maintains the many conformations GPCR can adopt in the cell membrane.
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Affiliation(s)
- Laura Martínez-Muñoz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB/CSIC), Darwin 3, Campus de Cantoblanco, Madrid, 28049, Spain
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8
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Detection of proton movement directly across viral membranes to identify novel influenza virus M2 inhibitors. J Virol 2013; 87:10679-86. [PMID: 23885079 DOI: 10.1128/jvi.01190-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influenza virus M2 protein is a well-validated yet underexploited proton-selective ion channel essential for influenza virus infectivity. Because M2 is a toxic viral ion channel, existing M2 inhibitors have been discovered through live virus inhibition or medicinal chemistry rather than M2-targeted high-throughput screening (HTS), and direct measurement of its activity has been limited to live cells or reconstituted lipid bilayers. Here, we describe a cell-free ion channel assay in which M2 ion channels are incorporated into virus-like particles (VLPs) and proton conductance is measured directly across the viral lipid bilayer, detecting changes in membrane potential, ion permeability, and ion channel function. Using this approach in high-throughput screening of over 100,000 compounds, we identified 19 M2-specific inhibitors, including two novel chemical scaffolds that inhibit both M2 function and influenza virus infectivity. Counterscreening for nonspecific disruption of viral bilayer ion permeability also identified a broad-spectrum antiviral compound that acts by disrupting the integrity of the viral membrane. In addition to its application to M2 and potentially other ion channels, this technology enables direct measurement of the electrochemical and biophysical characteristics of viral membranes.
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9
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Maturation of the Gag core decreases the stability of retroviral lipid membranes. Virology 2012; 433:401-9. [PMID: 22995186 DOI: 10.1016/j.virol.2012.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/13/2012] [Accepted: 08/14/2012] [Indexed: 01/15/2023]
Abstract
To better understand how detergents disrupt enveloped viruses, we monitored the biophysical stability of murine leukemia virus (MLV) virus-like particles (VLPs) against a panel of commonly used detergents using real-time biosensor measurements. Although exposure to many detergents, such as Triton X-100 and Empigen, results in lysis of VLP membranes, VLPs appeared resistant to complete membrane lysis by a significant number of detergents, including Tween 20, Tween 80, Lubrol, and Saponin. VLPs maintained their structural integrity after exposure to Tween 20 at concentrations up to 500-fold above its CMC. Remarkably, VLPs containing immature cores composed of unprocessed (uncleaved) Gag polyprotein were significantly more resistant to detergent lysis than VLPs with mature cores. Although the maturity of retroviral Gag is known to influence the stability of the protein core structure itself, our studies suggest that the maturity of the Gag core also influences the stability of the lipid bilayer surrounding the core.
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10
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Arenkiel BR, Hasegawa H, Yi JJ, Larsen RS, Wallace ML, Philpot BD, Wang F, Ehlers MD. Activity-induced remodeling of olfactory bulb microcircuits revealed by monosynaptic tracing. PLoS One 2011; 6:e29423. [PMID: 22216277 PMCID: PMC3247270 DOI: 10.1371/journal.pone.0029423] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 11/28/2011] [Indexed: 12/21/2022] Open
Abstract
The continued addition of new neurons to mature olfactory circuits represents a remarkable mode of cellular and structural brain plasticity. However, the anatomical configuration of newly established circuits, the types and numbers of neurons that form new synaptic connections, and the effect of sensory experience on synaptic connectivity in the olfactory bulb remain poorly understood. Using in vivo electroporation and monosynaptic tracing, we show that postnatal-born granule cells form synaptic connections with centrifugal inputs and mitral/tufted cells in the mouse olfactory bulb. In addition, newly born granule cells receive extensive input from local inhibitory short axon cells, a poorly understood cell population. The connectivity of short axon cells shows clustered organization, and their synaptic input onto newborn granule cells dramatically and selectively expands with odor stimulation. Our findings suggest that sensory experience promotes the synaptic integration of new neurons into cell type-specific olfactory circuits.
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Affiliation(s)
- Benjamin R. Arenkiel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (BRA); (MDE)
| | - Hiroshi Hasegawa
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
| | - Jason J. Yi
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
| | - Rylan S. Larsen
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Michael L. Wallace
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Benjamin D. Philpot
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- UNC Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Neurodevelopmental Disorders Research Center, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Fan Wang
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
| | - Michael D. Ehlers
- Department of Cell Biology, Duke University, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University, Durham, North Carolina, United States of America
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut, United States of America
- * E-mail: (BRA); (MDE)
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Abstract
Enveloped viruses penetrate their cell targets following the merging of their membrane with that of the cell. This fusion process is catalyzed by one or several viral glycoproteins incorporated on the membrane of the virus. These envelope glycoproteins (EnvGP) evolved in order to combine two features. First, they acquired a domain to bind to a specific cellular protein, named "receptor." Second, they developed, with the help of cellular proteins, a function of finely controlled fusion to optimize the replication and preserve the integrity of the cell, specific to the genus of the virus. Following the activation of the EnvGP either by binding to their receptors and/or sometimes the acid pH of the endosomes, many changes of conformation permit ultimately the action of a specific hydrophobic domain, the fusion peptide, which destabilizes the cell membrane and leads to the opening of the lipidic membrane. The comprehension of these mechanisms is essential to develop medicines of the therapeutic class of entry inhibitor like enfuvirtide (Fuzeon) against human immunodeficiency virus (HIV). In this chapter, we will summarize the different envelope glycoprotein structures that viruses develop to achieve membrane fusion and the entry of the virus. We will describe the different entry pathways and cellular proteins that viruses have subverted to allow infection of the cell and the receptors that are used. Finally, we will illustrate more precisely the recent discoveries that have been made within the field of the entry process, with a focus on the use of pseudoparticles. These pseudoparticles are suitable for high-throughput screenings that help in the development of natural or artificial inhibitors as new therapeutics of the class of entry inhibitors.
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Affiliation(s)
- François-Loic Cosset
- Université de Lyon, UCB-Lyon1, IFR128, Lyon, France,INSERM, U758, Lyon, France,Ecole Normale Supérieure de Lyon, Lyon, France
| | - Dimitri Lavillette
- Université de Lyon, UCB-Lyon1, IFR128, Lyon, France,INSERM, U758, Lyon, France,Ecole Normale Supérieure de Lyon, Lyon, France
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12
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Challenges and Approaches for Assay Development of Membrane and Membrane-Associated Proteins in Drug Discovery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010. [DOI: 10.1016/s1877-1173(10)91007-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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13
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Abstract
Viruses can be engineered to efficiently deliver exogenous genes, but their natural gene delivery properties often fail to meet human therapeutic needs. Therefore, engineering viral vectors with new properties, including enhanced targeting abilities and resistance to immune responses, is a growing area of research. This review discusses protein engineering approaches to generate viral vectors with novel gene delivery capabilities. Rational design of viral vectors has yielded successful advances in vitro, and to an extent in vivo. However, there is often insufficient knowledge of viral structure-function relationships to reengineer existing functions or create new capabilities, such as virus-cell interactions, whose molecular basis is distributed throughout the primary sequence of the viral proteins. Therefore, high-throughput library and directed evolution methods offer alternative approaches to engineer viral vectors with desired properties. Parallel and integrated efforts in rational and library-based design promise to aid the translation of engineered viral vectors toward the clinic.
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Affiliation(s)
- David V Schaffer
- The Department of Chemical Engineering, the Department of Bioengineering, and The Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-3220, USA.
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14
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Nef can enhance the infectivity of receptor-pseudotyped human immunodeficiency virus type 1 particles. J Virol 2008; 82:10811-9. [PMID: 18715908 DOI: 10.1128/jvi.01150-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nef is an accessory protein of human immunodeficiency virus type 1 (HIV-1) that enhances the infectivity of progeny virions when expressed in virus-producing cells. The requirement for Nef for optimal infectivity is, at least in part, determined by the envelope (Env) glycoprotein, because it can be eliminated by pseudotyping HIV-1 particles with pH-dependent Env proteins. To investigate the role of Env in the function of Nef, we have examined the effect of Nef on the infectivity of Env-deficient HIV-1 particles pseudotyped with viral receptors for cells expressing cognate Env proteins. We found that Nef significantly enhances the infectivity of CD4-chemokine receptor pseudotypes for cells expressing HIV-1 Env. Nef also increased the infectivity of HIV-1 particles pseudotyped with Tva, the receptor for subgroup A Rous sarcoma virus (RSV-A), even though Nef had no effect if the pH-dependent Env protein of RSV-A was used for pseudotyping. However, Nef does not always enhance viral infectivity if the normal orientation of the Env-receptor interaction is reversed, because the entry of Env-deficient HIV-1 into cells expressing the vesicular stomatitis virus G protein was unaffected by Nef. Together, our results demonstrate that the presence of a viral Env protein during virus production is not required for the ability of Nef to increase viral infectivity. Furthermore, since the infectivity of Tva pseudotypes was blocked by inhibitors of endosomal acidification, we conclude that low-pH-dependent entry does not always bypass the requirement for Nef.
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15
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Willis S, Davidoff C, Schilling J, Wanless A, Doranz BJ, Rucker J. Virus-like particles as quantitative probes of membrane protein interactions. Biochemistry 2008; 47:6988-90. [PMID: 18553929 DOI: 10.1021/bi800540b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate that virus-like particles carrying conformationally complex membrane proteins ("lipoparticles") can be used as soluble probes of membrane protein interactions. To demonstrate the utility of this approach, we use lipoparticles to rapidly differentiate the relative kinetics of membrane protein interactions using optical biosensor technology. The technique is applied to diverse membrane proteins, including G protein-coupled receptors, and used to rank the relative kinetics of nearly all the commercially available monoclonal antibodies against chemokine receptor CCR5. These particles serve as versatile probes for screening crude and purified antibody preparations for receptor specificity, epitope reactivity, and relative binding kinetics.
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Affiliation(s)
- Sharon Willis
- Integral Molecular, Inc., 3701 Market Street, Suite 340, Philadelphia, Pennsylvania 19104, USA
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16
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Jones JW, Greene TA, Grygon CA, Doranz BJ, Brown MP. Cell-Free Assay of G-Protein-Coupled Receptors Using Fluorescence Polarization. ACTA ACUST UNITED AC 2008; 13:424-9. [DOI: 10.1177/1087057108318332] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A recently developed nanotechnology, the Integral Molecular lipoparticle, provides an essentially soluble cell-free system in which G-protein-coupled receptors (GPCRs) in their native conformations are concentrated within virus-like particles. As a result, the lipoparticle provides a means to overcome 2 common obstacles to the development of homogeneous, nonradioactive GPCR ligand-binding assays: membrane protein solubilization and low receptor density. The work reported here describes the first application of this nanotechnology to a fluorescence polarization (FP) molecular binding assay format. The GPCR chosen for these studies was the well-studied chemokine receptor CXCR4 for which a peptide ligand (T-22) has been previously characterized. The EC50 determined for the CXCR4-T-22 peptide interaction via FP with CXCR4 lipoparticles (15 nM) is consistent with the IC50 determined for the unlabeled T-22 peptide via competitive binding (59 nM). ( Journal of Biomolecular Screening 2008:424-429)
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Affiliation(s)
- Jessi Wildeson Jones
- Biologics and Biomolecular Sciences, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | | | - Christine A. Grygon
- Biologics and Biomolecular Sciences, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | | | - Martha P. Brown
- Biologics and Biomolecular Sciences, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut,
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17
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Deniger DC, Kolokoltsov AA, Moore AC, Albrecht TB, Davey RA. Targeting and penetration of virus receptor bearing cells by nanoparticles coated with envelope proteins of Moloney murine leukemia virus. NANO LETTERS 2006; 6:2414-21. [PMID: 17090066 DOI: 10.1021/nl061180z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
One of the most important steps in a productive viral infection is when the virus fuses to a cell membrane and delivers its genome into the cell cytosol. This dynamic event is mediated by interactions between specific virus envelope proteins with their cell-bound receptors. This process is exemplified by Moloney murine leukemia virus (Mo-MLV) where envelope protein interaction with its receptor, mCAT-1, leads to virus-cell membrane fusion and infection of cells. Here, fluorescent nanoparticles (NPs) were coated with Mo-MLV derived membranes (Mo-NPs) by extrusion. Electron microscopy and biochemical analysis showed tight association of the virus membranes and NPs. The coated NPs mimic native virus by binding and entering only cells expressing the virus receptor. Confocal microscopy revealed that the coated NPs were taken up into endocytic compartments containing receptor and were also seen associated with caveolin, a marker of caveolae. To demonstrate that the Mo-NPs could escape endosomes and deliver a protein cargo into the cell cytosol, beta-lactamase (betalac) was covalently coupled to the Mo-NP cores and incubated with cells. betalac activity was only detected in the cytosol of mCAT-1-expressing cells. This is the first time that virus proteins have been used to specifically target NPs to receptor-bearing cells as well as penetration into the cell cytosol. Extrusion provides a rapid, detergent-free method to couple virus membranes to NPs and should be readily applicable for many other virus and NP types.
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Affiliation(s)
- Drew C Deniger
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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18
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Yu JH, Schaffer DV. Advanced targeting strategies for murine retroviral and adeno-associated viral vectors. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2005; 99:147-67. [PMID: 16568891 DOI: 10.1007/10_006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Targeted gene delivery involves broadening viral tropism to infect previously nonpermissive cells, replacing viral tropism to infect a target cell exclusively, or stealthing the vector against nonspecific interactions with host cells and proteins. These approaches offer the potential advantages of enhanced therapeutic effects, reduced side effects, lowered dosages, and enhanced therapeutic economics. This review will discuss a variety of targeting strategies, both genetic and nongenetic, for re-engineering the tropism of two representative enveloped and nonenveloped viruses, murine retrovirus and adeno-associated virus. Basic advances in understanding the structural biology and virology of the parent viruses have aided rational design efforts to engineer novel properties into the viral attachment proteins. Furthermore, even in the absence of basic, mechanistic knowledge of viral function, high-throughput library and directed evolution approaches can yield significant improvements in vector function. These two complementary strategies offer the potential to gain enhanced molecular control over vector properties and overcome challenges in generating high titer, stealthy, retargeted vectors.
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Affiliation(s)
- Julie H Yu
- Department of Chemical Engineering and Helen Wills Neuroscience Institute, University of California, Berkeley 94720, USA
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19
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Ye K, Jin S, Ataai MM, Schultz JS, Ibeh J. Tagging retrovirus vectors with a metal binding peptide and one-step purification by immobilized metal affinity chromatography. J Virol 2004; 78:9820-7. [PMID: 15331716 PMCID: PMC515015 DOI: 10.1128/jvi.78.18.9820-9827.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2003] [Accepted: 04/28/2004] [Indexed: 11/20/2022] Open
Abstract
Retroviral vectors produced from packaging cells are invariably contaminated by protein, nucleic acid, and other substances introduced in the manufacturing process. Elimination of these contaminants from retroviral vector preparations is helpful to reduce unwanted side effects, and purified vector preparations are desirable to improve reproducibility of therapeutic effect. Here we report a novel approach to engineer a metal binding peptide (MBP)-tagged murine leukemia virus (MuLV), allowing for one-step purification of retroviral vectors by immobilized metal affinity chromatography (IMAC). We inserted a His6 peptide into an ecotropic envelope protein (Env) by replacing part of its hypervariable region sequence with a sequence encoding the His6 peptide. Display of the His6 tag on the surface of Env endowed the vectors with a high affinity for immobilized metal ions, such as nickel. We demonstrated that the His6-tagged MuLV could be produced to high titers and could be highly purified by one-step IMAC. The protein and DNA contaminants in the purified vector supernatants were below 7 microg/ml and 25 pg/ml, respectively, indicating a 1,229-fold reduction in protein contaminant level and a 6,800-fold reduction in DNA contaminant level. About 56% of the viral vectors were recovered in the IMAC purification. The purified vectors retained their functionality and infectivity. These results establish that an MBP can be functionally displayed on the surface of ecotropic retroviruses without interfering with their integrity, and MBP-tagged retroviral vectors can be highly purified by one-step IMAC.
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Affiliation(s)
- Kaiming Ye
- Center for Biotechnology and Bioengineering, Department of Bioengineering, University of Pittsburgh, 300 Technology Dr., Suite 410, Pittsburgh, PA 15260, USA.
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20
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Curlee KV, Hong JS, Clancy JP, King SA, Hunter E, Berdiev B, Benos D, Sommerfelt MA, Sorscher EJ, Sakalian M. Membrane transplantation to correct integral membrane protein defects. J Mol Med (Berl) 2003; 81:511-20. [PMID: 12879148 DOI: 10.1007/s00109-003-0446-7] [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: 02/04/2003] [Accepted: 05/02/2003] [Indexed: 11/29/2022]
Abstract
In this report we show that the tendency of certain viruses to carry host membrane proteins in their envelopes can be harnessed for transplantation of small patches of plasma membrane, including fully functional, polytopic ion channel proteins and their regulatory binding partners. As a stringent model we tested the topologically complex epithelial ion channel CFTR. Initially an attenuated vaccinia virus was found capable of transferring CFTR in a properly folded, functional and regulatable form to CFTR negative cells. Next we generated viruslike particles (VLPs) composed of retroviral structural proteins that assemble and bud at the host cell plasma membrane. These particles were also shown to mediate functional ion channel transfer. By testing the capacity of complex membrane proteins to incorporate into viral envelopes these experiments provide new insight into the permissiveness of viral envelopment, including the ability of incorporated proteins to retain function and repair defects at the cell surface, and serve as a platform for studies of ion channel and membrane protein biochemistry.
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Affiliation(s)
- Kimberly V Curlee
- Department of Human Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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21
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Affiliation(s)
- A Larochelle
- Internal Medicine Program, Siebens 6, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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22
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Sparacio S, Pfeiffer T, Holtkotte D, Bosch V. Inter-retroviral fusion mediated by human immunodeficiency virus or murine leukemia virus glycoproteins: independence of cellular membranes and membrane vesicles. Virology 2002; 294:305-11. [PMID: 12009872 DOI: 10.1006/viro.2001.1363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently demonstrated for the first time that inter-retroviral membrane fusion, i.e., membrane fusion between individual retroviral particle populations with incorporated HIV-1 Env and cellular receptors, respectively, can occur (Sparacio et al. 2000, Virology 271: 248-252). We have extended these analyses here and confirmed that fusion between particles can occur in the extracellular medium independent of any cellular membranes and that luciferase transduction, mediated by the fused structures, is independent of significant potential contribution by contaminating membrane vesicles. We have additionally analyzed whether membrane fusion between HIV-like particles can be mediated by amphotropic murine leukemia virus (MuLV) glycoprotein and its respective cellular receptor, PiT-2. We demonstrate that PiT-2 can be incorporated into HIV-like particles and can fuse with MuLV-Env-carrying particles. This occurs only in the situation in which the incorporated MuLV-Env protein has been activated to fusion activity by HIV protease-mediated removal of the C-terminal R-peptide and is completely inhibited when the respective particles are generated in the presence of the HIV protease inhibitor, Saquinavir.
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MESH Headings
- Animals
- CD4 Antigens/genetics
- CD4 Antigens/metabolism
- Cell Membrane/metabolism
- Gene Products, env/genetics
- Gene Products, env/metabolism
- Gene Products, gag/metabolism
- Glycoproteins/genetics
- Glycoproteins/metabolism
- HIV Protease Inhibitors/pharmacology
- HIV-1/genetics
- HIV-1/metabolism
- HIV-1/physiology
- Humans
- Leukemia Virus, Murine/genetics
- Leukemia Virus, Murine/metabolism
- Leukemia Virus, Murine/physiology
- Membrane Fusion/physiology
- Mice
- Protein Precursors/metabolism
- Receptors, CCR5/genetics
- Receptors, CCR5/metabolism
- Receptors, CXCR4/genetics
- Receptors, CXCR4/metabolism
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Saquinavir/pharmacology
- Virion/metabolism
- Virion/physiology
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Affiliation(s)
- Sandra Sparacio
- Forschungsschwerpunkt Angewandte Tumorvirologie, F0200, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, Heidelberg, D-69120, Germany
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23
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Zhou J, Aiken C. Nef enhances human immunodeficiency virus type 1 infectivity resulting from intervirion fusion: evidence supporting a role for Nef at the virion envelope. J Virol 2001; 75:5851-9. [PMID: 11390586 PMCID: PMC114300 DOI: 10.1128/jvi.75.13.5851-5859.2001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) accessory protein Nef stimulates viral infectivity by facilitating an early event in the HIV-1 life cycle. Although no structural or biochemical defects in Nef-defective HIV-1 particles have been demonstrated, the Nef protein is incorporated into HIV-1 particles. To localize the function of Nef within the virus particle, we developed a novel technology involving fusion of enveloped donor HIV-1 particles bearing core defects with envelope-defective target virions bearing HIV-1 receptors. Although neither virus alone was capable of infecting CD4(+) target cells, the incubation of donor and target virions prior to addition to target cells resulted in infection. This effect, termed "virion transcomplementation," required a functional Env protein on the donor virus and CD4 and an appropriate coreceptor on target virions. To provide evidence for intervirion fusion as the mechanism of complementation, experiments were performed using dual-enveloped HIV-1 particles bearing both HIV-1 and ecotropic murine leukemia virus (E-MLV) Env proteins as donor virions. Infection of CD4-negative target cells bearing E-MLV receptors was prevented by HIV-1 entry inhibitors when added before, but not after, incubation of donor and target virions prior to the addition to cells. When we used Nef(+) and Nef(-) donor and target virions, Nef enhanced infection when present in donor virions. In contrast, no effect of Nef was detected when present in the target virus. These results reveal a potential mechanism for enhancing HIV-1 diversity in vivo through the rescue of defective viral genomes and provide a novel genetic system for the functional analysis of virion-associated proteins in HIV-1 infection.
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Affiliation(s)
- J Zhou
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
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24
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Zeilfelder U, Bosch V. Properties of wild-type, C-terminally truncated, and chimeric maedi-visna virus glycoprotein and putative pseudotyping of retroviral vector particles. J Virol 2001; 75:548-55. [PMID: 11119626 PMCID: PMC113950 DOI: 10.1128/jvi.75.1.548-555.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have characterized the properties of the maedi-visna virus (MVV) glycoprotein, which has a long cytoplasmic C-terminal domain, and of a panel of C-terminally truncated and C-terminally chimeric MVV-Env constructs. Cells expressing wild-type MVV glycoprotein form syncytia with target cells from many different species and tissues, demonstrating that the MVV-Env cellular receptor is widely distributed. Similar to the situation with other lentiviral glycoproteins, truncation of the C-terminal domain of MVV-Env significantly increases its membrane fusion capacity. However, despite their presence in a fusogenic form at the cell surface, neither the wild-type nor any of the C-terminally modified MVV-Env constructs, these latter lacking sterically inhibitory C termini, were able to successfully pseudotype murine leukemia virus- or human immunodeficiency virus-derived vector particles.
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Affiliation(s)
- U Zeilfelder
- Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany
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25
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Hoffman TL, Canziani G, Jia L, Rucker J, Doms RW. A biosensor assay for studying ligand-membrane receptor interactions: binding of antibodies and HIV-1 Env to chemokine receptors. Proc Natl Acad Sci U S A 2000; 97:11215-20. [PMID: 11005830 PMCID: PMC17180 DOI: 10.1073/pnas.190274097] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The HIV envelope (Env) protein mediates entry into cells by binding CD4 and an appropriate coreceptor, which triggers structural changes in Env that lead to fusion between the viral and cellular membranes. The major HIV-1 coreceptors are the seven transmembrane domain chemokine receptors CCR5 and CXCR4. The type of coreceptor used by a virus strain is an important determinant of viral tropism and pathogenesis, and virus-receptor interactions can be therapeutic targets. However, Envs from many virus strains interact with CXCR4 and CCR5 with low affinity such that direct study of this important interaction is difficult if not impossible using standard cell-surface binding techniques. We have developed an approach that makes it possible to study ligand binding to membrane proteins, including Env-coreceptor interactions, using an optical biosensor. CCR5, CXCR4, and other membrane proteins were incorporated into retrovirus particles, which were purified and attached to the biosensor surface. Binding of conformationally sensitive antibodies as well as Env to these receptors was readily detected. The equilibrium dissociation constant for the interaction between an Env derived from the prototype HIV-1 strain IIIB for CXCR4 was approximately 500 nM, explaining the difficulty in measuring this interaction using standard equilibrium binding techniques. Retroviral pseudotypes represent easily produced, stable, homogenous structures that can be used to present a wide array of single and multiple membrane-spanning proteins in a native lipid environment for biosensor studies, thus avoiding the need for detergent solubilization, purification, and reconstitution. The approach should have general applicability and can be used to correlate Env-receptor binding constants to viral tropism and pathogenesis.
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Affiliation(s)
- T L Hoffman
- Departments of Pathology and Lab Medicine, Medicine, and Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
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26
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Damico R, Bates P. Soluble receptor-induced retroviral infection of receptor-deficient cells. J Virol 2000; 74:6469-75. [PMID: 10864659 PMCID: PMC112155 DOI: 10.1128/jvi.74.14.6469-6475.2000] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2000] [Accepted: 04/19/2000] [Indexed: 11/20/2022] Open
Abstract
Current models of retroviral entry hypothesize that interactions between the host cell receptor(s) and viral envelope protein induce structural changes in the envelope protein that convert it to an active conformation, allowing it to mediate fusion with the membrane. Recent evidence supporting this hypothesis is the demonstration that Tva, the receptor for subgroup A avian sarcoma and leukosis virus (ASLV-A), induces conformational changes in the viral envelope protein. These changes include conversion of the envelope protein to an active, membrane-binding state likely representing a fusogenic conformation. To determine whether binding of the soluble Tva (sTva) receptor was sufficient to activate fully the fusogenic potential of the ASLV-A envelope protein, we have evaluated the ability of ASLV-A to infect receptor-deficient cell lines in the presence of sTva. Soluble receptor efficiently mediated infection of cells devoid of endogenous Tva in a dose-dependent manner, and this infection was dependent absolutely on the addition of sTva. The infectivity of the virus was enhanced dramatically in the presence of the polycationic polymer Polybrene or when centrifugal forces were applied during inoculation, resulting in viral titers comparable to those achieved on cells expressing endogenous receptor. sTva functioned to mediate infection at low concentrations, approaching the estimated binding constant of the receptor and viral envelope protein. These results demonstrate that receptor binding can activate the ASLV-A envelope protein and convert it to a fusogenic conformation competent to mediate the fusion of the viral and cellular membranes.
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Affiliation(s)
- R Damico
- Department of Microbiology, Graduate Program in Cellular and Molecular Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6076, USA
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27
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Darling D, Hughes C, Galea-Lauri J, Gäken J, Trayner ID, Kuiper M, Farzaneh F. Low-speed centrifugation of retroviral vectors absorbed to a particulate substrate: a highly effective means of enhancing retroviral titre. Gene Ther 2000; 7:914-23. [PMID: 10849550 DOI: 10.1038/sj.gt.3301201] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
For many gene therapy applications the effective titre of retroviral vectors is a limiting factor both in vitro and in vivo. Purification and concentration of retrovirus from packaging cell supernatant can overcome this problem. To this end we have investigated a novel procedure which involves complexing retrovirus to a dense and particulate substrate followed by a short low-speed centrifugation. The study reported here uses heat-killed, formaldehyde fixed Staphylococcus aureus (Pansorbin) absorbed to PG13 derived retrovirus. This complex was then used to harvest retrovirus from packaging cell supernatant: centrifugation and washing of this complex allows the retrovirus to be both purified and concentrated. This procedure increases the effective titre of retrovirus by up to 7500-fold after an only 200-fold reduction in volume. The affinity of Pansorbin for retrovirus allows concentration regardless of its encoded genes and makes this protocol applicable to other popular packaging cells and envelope proteins. Possible explanations for the marked increase in titre of concentrated virus and the mechanism governing the complexing of retrovirus to Pansorbin are discussed.
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Affiliation(s)
- D Darling
- Immune Gene Therapy of Cancer Program, Department of Molecular Medicine, King's College School of Medicine and Dentistry, London, UK
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28
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Somia NV, Miyoshi H, Schmitt MJ, Verma IM. Retroviral vector targeting to human immunodeficiency virus type 1-infected cells by receptor pseudotyping. J Virol 2000; 74:4420-4. [PMID: 10756057 PMCID: PMC111959 DOI: 10.1128/jvi.74.9.4420-4424.2000] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the generation of retroviral vectors based on Moloney murine leukemia virus that specifically transduce cells infected with T-cell-tropic human immunodeficiency virus type 1 (HIV-1). This vector was pseudotyped with T-cell-tropic HIV-1 receptors CD4 and CXCR4. We demonstrate that transduction is contingent upon HIV-1 gp120 and gp41 expression.
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Affiliation(s)
- N V Somia
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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29
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Kazachkov Y, Long D, Wang C, Silver J. Changes in a murine leukemia virus (MLV) receptor encoded by an alphavirus vector during passage in cells expressing the MLV envelope. Virology 2000; 267:124-32. [PMID: 10648189 DOI: 10.1006/viro.1999.0114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We constructed alphavirus vectors encoding the ecotropic murine leukemia virus (MLV) receptor mCAT1. Cells electroporated with these vector RNAs expressed mCAT1 protein and fused with cells that expressed a fusogenic form of the MLV envelope on the cell surface. Electroporated cells also released submicron particles that were infectious in envelope-expressing cells. Infection resulted in giant syncytia that could be enumerated by plaque assay. Cell-free supernatants could be serially passaged and contained up to 10(4) infectious units/ml. To determine whether repeated passage would select for functional variants of the receptor, we analyzed mCAT1 amplified by RT-PCR after 12 serial passages. Several amino acid substitutions were identified that encoded functional receptor variants. In independent experiments, variants containing an isoleucine or a leucine instead of a phenylalanine at position 224 in the third extracellular domain of the receptor arose spontaneously and outgrew the parental vector, indicating that mutations at this site are highly selected in this system. This region of the receptor has previously been implicated in the envelope-receptor interaction. This alphavirus vector system provides a novel method for generating and selecting functional variants of viral receptors
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Affiliation(s)
- Y Kazachkov
- Laboratory of Molecular Microbiology, National Institutes of Health, Bethesda, Maryland, 20892, USA
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30
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Holmen SL, Salter DW, Payne WS, Dodgson JB, Hughes SH, Federspiel MJ. Soluble forms of the subgroup A avian leukosis virus [ALV(A)] receptor Tva significantly inhibit ALV(A) infection in vitro and in vivo. J Virol 1999; 73:10051-60. [PMID: 10559319 PMCID: PMC113056 DOI: 10.1128/jvi.73.12.10051-10060.1999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The interactions between the subgroup A avian leukosis virus [ALV(A)] envelope glycoproteins and soluble forms of the ALV(A) receptor Tva were analyzed both in vitro and in vivo by quantitating the ability of the soluble Tva proteins to inhibit ALV(A) entry into susceptible cells. Two soluble Tva proteins were tested: the 83-amino-acid Tva extracellular region fused to two epitope tags (sTva) or fused to the constant region of the mouse immunoglobulin G heavy chain (sTva-mIgG). Replication-competent ALV-based retroviral vectors with subgroup B or C env were used to deliver and express the two soluble tv-a (stva) genes in avian cells. In vitro, chicken embryo fibroblasts or DF-1 cells expressing sTva or sTva-mIgG proteins were much more resistant to infection by ALV(A) ( approximately 200-fold) than were control cells infected by only the vector. The antiviral effect was specific for ALV(A), which is consistent with a receptor interference mechanism. The antiviral effect of sTva-mIgG was positively correlated with the amount of sTva-mIgG protein. In vivo, the stva genes were delivered and expressed in line 0 chicken embryos by the ALV(B)-based vector RCASBP(B). Viremic chickens expressed relatively high levels of stva and stva-mIgG RNA in a broad range of tissues. High levels of sTva-mIgG protein were detected in the sera of chickens infected with RCASBP(B)stva-mIgG. Viremic chickens infected with RCASBP(B) alone, RCASBP(B)stva, or RCASBP(B)stva-mIgG were challenged separately with ALV(A) and ALV(C). Both sTva and sTva-mIgG significantly inhibited infection by ALV(A) (95 and 100% respectively) but had no measurable effect on ALV(C) infection. The results of this study indicate that a soluble receptor can effectively block infection of at least some retroviruses and demonstrates the utility of the ALV experimental system in characterizing the mechanism(s) of viral entry.
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Affiliation(s)
- S L Holmen
- Molecular Medicine Program, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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31
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Balliet JW, Berson J, D'Cruz CM, Huang J, Crane J, Gilbert JM, Bates P. Production and characterization of a soluble, active form of Tva, the subgroup A avian sarcoma and leukosis virus receptor. J Virol 1999; 73:3054-61. [PMID: 10074155 PMCID: PMC104065 DOI: 10.1128/jvi.73.4.3054-3061.1999] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The receptor for the subgroup A avian sarcoma and leukosis viruses [ASLV(A)] is the cellular glycoprotein Tva. A soluble form of Tva, sTva, was produced and purified with a baculovirus expression system. Using this system, 7 to 10 mg of purified sTva per liter of cultured Sf9 cells was obtained. Characterization of the carbohydrate modification of sTva revealed that the three N glycosylation sites in sTva were differentially utilized; however, the O glycosylation common to Tva produced in mammalian and avian cells was not observed. Purified sTva demonstrates significant biological activity, specifically blocking infection of avian cells by ASLV(A) with a 90% inhibitory concentration of approximately 25 pM. A quantitative enzyme-linked immunosorbent assay, developed to assess the binding of sTva to ASLV envelope glycoprotein, demonstrates that sTva has a high affinity for EnvA, with an apparent dissociation constant of approximately 0.3 nM. Once they are bound, a very stable complex is formed between EnvA and sTva, with an estimated complex half-life of 6 h. The soluble receptor protein described here represents a valuable tool for analysis of the receptor-envelope glycoprotein interaction and for structural analysis of Tva.
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Affiliation(s)
- J W Balliet
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Rong L, Gendron K, Strohl B, Shenoy R, Wool-Lewis RJ, Bates P. Characterization of determinants for envelope binding and infection in tva, the subgroup A avian sarcoma and leukosis virus receptor. J Virol 1998; 72:4552-9. [PMID: 9573218 PMCID: PMC109965 DOI: 10.1128/jvi.72.6.4552-4559.1998] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Tva is the cellular receptor for subgroup A avian leukosis and sarcoma virus (ALSV-A). The viral interaction domain of Tva is determined by a 40-residue, cysteine-rich module closely related to the ligand binding domain of the human low-density lipoprotein receptor (LDLR). In this report, we examined the role of the LDLR-like module of Tva in envelope binding and viral infection by mutational analysis. We found that the entire LDLR module in Tva is essential for efficient binding to the viral envelope protein. However, the 17 N-terminal residues of this module can be deleted without affecting receptor function, suggesting that the major determinants for viral entry are located at the C terminus of the module. The effect on viral infection of many amino acid substitutions and deletions in the LDLR module is context dependent, suggesting that the residues important for viral entry are dispersed throughout the LDLR module. In addition, we found that all 27 mutations at residues D46, E47, and W48 greatly reduced envelope binding. These results are discussed in relation to a recently elucidated structure for an LDLR module.
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Affiliation(s)
- L Rong
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Damico RL, Crane J, Bates P. Receptor-triggered membrane association of a model retroviral glycoprotein. Proc Natl Acad Sci U S A 1998; 95:2580-5. [PMID: 9482929 PMCID: PMC19420 DOI: 10.1073/pnas.95.5.2580] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Current models of retroviral entry hypothesize that interactions between the viral envelope protein and the host receptor(s) induce conformational changes in the envelope protein that activate the envelope protein and initiate fusion. We employed a liposome-binding assay to demonstrate directly and characterize the activation of a model retroviral envelope protein (EnvA) from Rous sarcoma virus (RSV). In the presence of purified viral receptor, the trimeric ectodomain of EnvA was converted from a water-soluble form to a membrane-associated form, consistent with conversion of the envelope protein to its fusogenic state. This activation was nonlinear with respect to receptor concentration, suggesting cooperativity within the trimeric envelope protein. The activated EnvA was stably associated with the target membrane through hydrophobic interactions, behaving like an intrinsic membrane protein. The ability of EnvA to associate with membrane was coincident with a loss of receptor-binding activity, suggesting that during viral entry activated EnvA dissociates from the receptor to facilitate membrane fusion. These results provide direct evidence that receptor binding triggers conversion of the EnvA protein to a membrane-binding form, illustrating that RSV is a useful model for the study of retroviral entry and activation of pH-independent fusion proteins.
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Affiliation(s)
- R L Damico
- Department of Microbiology, Graduate Program in Cellular and Molecular Biology, University of Pennsylvania, School of Medicine, 3610 Hamilton Walk, Philadelphia, PA 19104-6076, USA
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