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Mellors J, Carroll M. Direct enhancement of viral neutralising antibody potency by the complement system: a largely forgotten phenomenon. Cell Mol Life Sci 2024; 81:22. [PMID: 38200235 PMCID: PMC10781860 DOI: 10.1007/s00018-023-05074-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/24/2023] [Accepted: 11/29/2023] [Indexed: 01/12/2024]
Abstract
Neutralisation assays are commonly used to assess vaccine-induced and naturally acquired immune responses; identify correlates of protection; and inform important decisions on the screening, development, and use of therapeutic antibodies. Neutralisation assays are useful tools that provide the gold standard for measuring the potency of neutralising antibodies, but they are not without limitations. Common methods such as the heat-inactivation of plasma samples prior to neutralisation assays, or the use of anticoagulants such as EDTA for blood collection, can inactivate the complement system. Even in non-heat-inactivated samples, the levels of complement activity can vary between samples. This can significantly impact the conclusions regarding neutralising antibody potency. Restoration of the complement system in these samples can be achieved using an exogenous source of plasma with preserved complement activity or with purified complement proteins. This can significantly enhance the neutralisation titres for some antibodies depending on characteristics such as antibody isotype and the epitope they bind, enable neutralisation with otherwise non-neutralising antibodies, and demonstrate a better relationship between in vitro and in vivo findings. In this review, we discuss the evidence for complement-mediated enhancement of antibody neutralisation against a range of viruses, explore the potential mechanisms which underpin this enhancement, highlight current gaps in the literature, and provide a brief summary of considerations for adopting this approach in future research applications.
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Affiliation(s)
- Jack Mellors
- Centre for Human Genetics and the Pandemic Sciences Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - Miles Carroll
- Centre for Human Genetics and the Pandemic Sciences Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Krawczyk PA, Laub M, Kozik P. To Kill But Not Be Killed: Controlling the Activity of Mammalian Pore-Forming Proteins. Front Immunol 2020; 11:601405. [PMID: 33281828 PMCID: PMC7691655 DOI: 10.3389/fimmu.2020.601405] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/20/2020] [Indexed: 01/01/2023] Open
Abstract
Pore-forming proteins (PFPs) are present in all domains of life, and play an important role in host-pathogen warfare and in the elimination of cancers. They can be employed to deliver specific effectors across membranes, to disrupt membrane integrity interfering with cell homeostasis, and to lyse membranes either destroying intracellular organelles or entire cells. Considering the destructive potential of PFPs, it is perhaps not surprising that mechanisms controlling their activity are remarkably complex, especially in multicellular organisms. Mammalian PFPs discovered to date include the complement membrane attack complex (MAC), perforins, as well as gasdermins. While the primary function of perforin-1 and gasdermins is to eliminate infected or cancerous host cells, perforin-2 and MAC can target pathogens directly. Yet, all mammalian PFPs are in principle capable of generating pores in membranes of healthy host cells which-if uncontrolled-could have dire, and potentially lethal consequences. In this review, we will highlight the strategies employed to protect the host from destruction by endogenous PFPs, while enabling timely and efficient elimination of target cells.
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Affiliation(s)
- Patrycja A Krawczyk
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Marco Laub
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Patrycja Kozik
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Cambridge Biomedical Campus, Cambridge, United Kingdom
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Rendezvous at Plasma Membrane: Cellular Lipids and tRNA Set up Sites of HIV-1 Particle Assembly and Incorporation of Host Transmembrane Proteins. Viruses 2020; 12:v12080842. [PMID: 32752131 PMCID: PMC7472227 DOI: 10.3390/v12080842] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/28/2022] Open
Abstract
The HIV-1 structural polyprotein Gag drives the virus particle assembly specifically at the plasma membrane (PM). During this process, the nascent virion incorporates specific subsets of cellular lipids and host membrane proteins, in addition to viral glycoproteins and viral genomic RNA. Gag binding to the PM is regulated by cellular factors, including PM-specific phospholipid PI(4,5)P2 and tRNAs, both of which bind the highly basic region in the matrix domain of Gag. In this article, we review our current understanding of the roles played by cellular lipids and tRNAs in specific localization of HIV-1 Gag to the PM. Furthermore, we examine the effects of PM-bound Gag on the organization of the PM bilayer and discuss how the reorganization of the PM at the virus assembly site potentially contributes to the enrichment of host transmembrane proteins in the HIV-1 particle. Since some of these host transmembrane proteins alter release, attachment, or infectivity of the nascent virions, the mechanism of Gag targeting to the PM and the nature of virus assembly sites have major implications in virus spread.
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Su B, Dispinseri S, Iannone V, Zhang T, Wu H, Carapito R, Bahram S, Scarlatti G, Moog C. Update on Fc-Mediated Antibody Functions Against HIV-1 Beyond Neutralization. Front Immunol 2019; 10:2968. [PMID: 31921207 PMCID: PMC6930241 DOI: 10.3389/fimmu.2019.02968] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 12/03/2019] [Indexed: 12/31/2022] Open
Abstract
Antibodies (Abs) are the major component of the humoral immune response and a key player in vaccination. The precise Ab-mediated inhibitory mechanisms leading to in vivo protection against HIV have not been elucidated. In addition to the desired viral capture and neutralizing Ab functions, complex Ab-dependent mechanisms that involve engaging immune effector cells to clear infected host cells, immune complexes, and opsonized virus have been proposed as being relevant. These inhibitory mechanisms involve Fc-mediated effector functions leading to Ab-dependent cellular cytotoxicity, phagocytosis, cell-mediated virus inhibition, aggregation, and complement inhibition. Indeed, the decreased risk of infection observed in the RV144 HIV-1 vaccine trial was correlated with the production of non-neutralizing inhibitory Abs, highlighting the role of Ab inhibitory functions besides neutralization. Moreover, Ab isotypes and subclasses recognizing specific HIV envelope epitopes as well as pecular Fc-receptor polymorphisms have been associated with disease progression. These findings further support the need to define which Fc-mediated Ab inhibitory functions leading to protection are critical for HIV vaccine design. Herein, based on our previous review Su & Moog Front Immunol 2014, we update the different inhibitory properties of HIV-specific Abs that may potentially contribute to HIV protection.
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Affiliation(s)
- Bin Su
- Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory for HIV/AIDS Research, Beijing, China
| | - Stefania Dispinseri
- Viral Evolution and Transmission Unit, Division of Immunology, Transplantation, and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Valeria Iannone
- Viral Evolution and Transmission Unit, Division of Immunology, Transplantation, and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Tong Zhang
- Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory for HIV/AIDS Research, Beijing, China
| | - Hao Wu
- Center for Infectious Diseases, Beijing Youan Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory for HIV/AIDS Research, Beijing, China
| | - Raphael Carapito
- INSERM U1109, LabEx TRANSPLANTEX, Fédération Hospitalo-Universitaire (FHU) OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Seiamak Bahram
- INSERM U1109, LabEx TRANSPLANTEX, Fédération Hospitalo-Universitaire (FHU) OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Gabriella Scarlatti
- Viral Evolution and Transmission Unit, Division of Immunology, Transplantation, and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Christiane Moog
- INSERM U1109, LabEx TRANSPLANTEX, Fédération Hospitalo-Universitaire (FHU) OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France.,Vaccine Research Institute (VRI), Créteil, France
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Menny A, Serna M, Boyd CM, Gardner S, Joseph AP, Morgan BP, Topf M, Brooks NJ, Bubeck D. CryoEM reveals how the complement membrane attack complex ruptures lipid bilayers. Nat Commun 2018; 9:5316. [PMID: 30552328 PMCID: PMC6294249 DOI: 10.1038/s41467-018-07653-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/12/2018] [Indexed: 01/08/2023] Open
Abstract
The membrane attack complex (MAC) is one of the immune system's first responders. Complement proteins assemble on target membranes to form pores that lyse pathogens and impact tissue homeostasis of self-cells. How MAC disrupts the membrane barrier remains unclear. Here we use electron cryo-microscopy and flicker spectroscopy to show that MAC interacts with lipid bilayers in two distinct ways. Whereas C6 and C7 associate with the outer leaflet and reduce the energy for membrane bending, C8 and C9 traverse the bilayer increasing membrane rigidity. CryoEM reconstructions reveal plasticity of the MAC pore and demonstrate how C5b6 acts as a platform, directing assembly of a giant β-barrel whose structure is supported by a glycan scaffold. Our work provides a structural basis for understanding how β-pore forming proteins breach the membrane and reveals a mechanism for how MAC kills pathogens and regulates cell functions.
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Affiliation(s)
- Anaïs Menny
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Marina Serna
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
- Spanish National Cancer Research Centre, CNIO, Melchor Fernández Almagro, 3.28029, Madrid, Spain
| | - Courtney M Boyd
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Scott Gardner
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, OX11 0FA, UK
| | - B Paul Morgan
- Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Doryen Bubeck
- Department of Life Sciences, Sir Ernst Chain Building, Imperial College London, London, SW7 2AZ, UK.
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Gag induces the coalescence of clustered lipid rafts and tetraspanin-enriched microdomains at HIV-1 assembly sites on the plasma membrane. J Virol 2011; 85:9749-66. [PMID: 21813604 DOI: 10.1128/jvi.00743-11] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The HIV-1 structural protein Gag associates with two types of plasma membrane microdomains, lipid rafts and tetraspanin-enriched microdomains (TEMs), both of which have been proposed to be platforms for HIV-1 assembly. However, a variety of studies have demonstrated that lipid rafts and TEMs are distinct microdomains in the absence of HIV-1 infection. To measure the impact of Gag on microdomain behaviors, we took advantage of two assays: an antibody-mediated copatching assay and a Förster resonance energy transfer (FRET) assay that measures the clustering of microdomain markers in live cells without antibody-mediated patching. We found that lipid rafts and TEMs copatched and clustered to a greater extent in the presence of membrane-bound Gag in both assays, suggesting that Gag induces the coalescence of lipid rafts and TEMs. Substitutions in membrane binding motifs of Gag revealed that, while Gag membrane binding is necessary to induce coalescence of lipid rafts and TEMs, either acylation of Gag or binding of phosphatidylinositol-(4,5)-bisphosphate is sufficient. Finally, a Gag derivative that is defective in inducing membrane curvature appeared less able to induce lipid raft and TEM coalescence. A higher-resolution analysis of assembly sites by correlative fluorescence and scanning electron microscopy showed that coalescence of clustered lipid rafts and TEMs occurs predominantly at completed cell surface virus-like particles, whereas a transmembrane raft marker protein appeared to associate with punctate Gag fluorescence even in the absence of cell surface particles. Together, these results suggest that different membrane microdomain components are recruited in a stepwise manner during assembly.
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Graham DRM, Chertova E, Hilburn JM, Arthur LO, Hildreth JEK. Cholesterol depletion of human immunodeficiency virus type 1 and simian immunodeficiency virus with beta-cyclodextrin inactivates and permeabilizes the virions: evidence for virion-associated lipid rafts. J Virol 2003; 77:8237-48. [PMID: 12857892 PMCID: PMC165256 DOI: 10.1128/jvi.77.15.8237-8248.2003] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Recent evidence suggests that human immunodeficiency virus type 1 (HIV-1) particles assemble and bud selectively through areas in the plasma membrane of cells that are highly enriched with glycosylphosphatidylinositol-anchored proteins and cholesterol, called lipid rafts. Since cholesterol is required to maintain lipid raft structure and function, we proposed that virion-associated cholesterol removal with the compound 2-hydroxy-propyl-beta-cyclodextrin (beta-CD) might be disruptive to HIV-1 and simian immunodeficiency virus (SIV). We examined the effect of beta-CD on the structure and infectivity of cell-free virions. We found that beta-CD inactivated HIV-1 and SIV in a dose-dependent manner and permeabilized the viral membranes, resulting in the loss of mature Gag proteins (capsid, matrix, nucleocapsid, p1, and p6) without loss of the envelope glycoproteins. SIV also lost reverse transcriptase (RT), integrase (IN), and viral RNA. IN appeared to be only slightly diminished in HIV-1, and viral RNA, RT, matrix, and nucleocapsid proteins were retained in HIV-1 but to a much lesser degree. Host proteins located internally in the virus (actin, moesin, and ezrin) and membrane-associated host proteins (major histocompatibility complex classes I and II) remained associated with the treated virions. Electron microscopy revealed that under conditions that permeabilized the viruses, holes were present in the viral membranes and the viral core structure was perturbed. These data provide evidence that an intact viral membrane is required to maintain mature virion core integrity. Since the viruses were not fixed before beta-CD treatment and intact virion particles were recovered, the data suggest that virions may possess a protein scaffold that can maintain overall structure despite disruptions in membrane integrity.
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Affiliation(s)
- David R. M. Graham
- The Leukocyte Immunochemistry Laboratory, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, AIDS Vaccine Program, SAIC Frederick, NCI-Frederick, Frederick, Maryland 21702
| | - Elena Chertova
- The Leukocyte Immunochemistry Laboratory, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, AIDS Vaccine Program, SAIC Frederick, NCI-Frederick, Frederick, Maryland 21702
| | - Joanne M. Hilburn
- The Leukocyte Immunochemistry Laboratory, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, AIDS Vaccine Program, SAIC Frederick, NCI-Frederick, Frederick, Maryland 21702
| | - Larry O. Arthur
- The Leukocyte Immunochemistry Laboratory, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, AIDS Vaccine Program, SAIC Frederick, NCI-Frederick, Frederick, Maryland 21702
| | - James E. K. Hildreth
- The Leukocyte Immunochemistry Laboratory, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, AIDS Vaccine Program, SAIC Frederick, NCI-Frederick, Frederick, Maryland 21702
- Corresponding author. Mailing address: Johns Hopkins School of Medicine, Department of Pharmacology and Molecular Sciences, 725 N. Wolfe St., 320A Physiology Bldg., Baltimore, MD 21205. Phone: (410) 955-3017. Fax: (410) 955-1894. E-mail:
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