1
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Gu F, Boisjoli M, Naghavi MH. HIV-1 promotes ubiquitination of the amyloidogenic C-terminal fragment of APP to support viral replication. Nat Commun 2023; 14:4227. [PMID: 37454116 PMCID: PMC10349857 DOI: 10.1038/s41467-023-40000-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/07/2023] [Indexed: 07/18/2023] Open
Abstract
HIV-1 replication in macrophages and microglia involves intracellular assembly and budding into modified subsets of multivesicular bodies (MVBs), which support both viral persistence and spread. However, the cellular factors that regulate HIV-1's vesicular replication remain poorly understood. Recently, amyloid precursor protein (APP) was identified as an inhibitor of HIV-1 replication in macrophages and microglia via an unknown mechanism. Here, we show that entry of HIV-1 Gag into MVBs is blocked by the amyloidogenic C-terminal fragment of APP, "C99", but not by the non-amyloidogenic product, "C83". To counter this, Gag promotes multi-site ubiquitination of C99 which controls both exocytic sorting of MVBs and further processing of C99 into toxic amyloids. Processing of C99, entry of Gag into MVBs and release of infectious virus could be suppressed by expressing ubiquitination-defective C99 or by γ-secretase inhibitor treatment, suggesting that APP's amyloidogenic pathway functions to sense and suppress HIV-1 replication in macrophages and microglia.
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Affiliation(s)
- Feng Gu
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Marie Boisjoli
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Mojgan H Naghavi
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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2
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Urokinase plasminogen activator surface receptor restricts HIV-1 replication by blocking virion release from the cell membrane. Proc Natl Acad Sci U S A 2023; 120:e2212991120. [PMID: 36638209 PMCID: PMC9934069 DOI: 10.1073/pnas.2212991120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The urokinase-type plasminogen activator (uPA) system consists of the proteinase uPA, its receptor (PLAUR/uPAR). Under physiological conditions, uPA and PLAUR are predominantly expressed by blood cells, including neutrophils, monocytes, and macrophages, and play important roles in cell activation, adhesion, migration, and extravasation. Here, we report that PLAUR, which is highly expressed in macrophages and dendritic cells (DCs) but hardly expressed in CD4+ T cells, inhibits the release of HIV-1 progeny virions from the cell membrane. Silencing PLAUR markedly enhanced the transmission of HIV-1 in macrophages and DCs. We further demonstrated that PLAUR is localized at the cell membrane to block the release of HIV-1 virions. Interestingly, we found that uPA compromises the PLAUR-mediated inhibition to slightly enhance HIV-1 production in primary macrophages and DCs. In the absence of PLAUR, this enhanced effect induced by uPA is abrogated. In conclusion, PLAUR is a new anti-HIV-1 protein produced in both macrophages and DCs where it inhibits HIV-1 transmission. This discovery may provide a novel therapeutic target for combating HIV.
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3
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Nickoloff-Bybel EA, Festa L, Meucci O, Gaskill PJ. Co-receptor signaling in the pathogenesis of neuroHIV. Retrovirology 2021; 18:24. [PMID: 34429135 PMCID: PMC8385912 DOI: 10.1186/s12977-021-00569-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/11/2021] [Indexed: 12/13/2022] Open
Abstract
The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development. ![]()
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Affiliation(s)
- E A Nickoloff-Bybel
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA
| | - L Festa
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA, 19104, USA
| | - O Meucci
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.,Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - P J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.
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4
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Cilliers K, Muller CJF. Effect of Human Immunodeficiency Virus on Trace Elements in the Brain. Biol Trace Elem Res 2021; 199:41-52. [PMID: 32239375 DOI: 10.1007/s12011-020-02129-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/23/2020] [Indexed: 11/27/2022]
Abstract
Comorbidities of human immunodeficiency virus (HIV) include HIV-associated neurocognitive disorder (HAND). Changes in the brain due to HIV include atrophy, hyperintensities, and diffusion changes. However, no research has focused on trace elements concentration changes in the brain due to HIV, as seen in other neurodegenerative diseases. Therefore, the aim of this study was to determine the concentration of several trace elements in the brains of individuals with and without HIV infection. Prior to formalin embalming, blood was drawn and tested in triplicate with Determine HIV-1/2 rapid tests and confirmed with a SD HIV Device 1/2 3.0 rapid HIV Kit. After embalming, tissue was sampled from the caudate nucleus and analyzed using inductively coupled plasma mass spectrometry. A Kruskal-Wallis test was used to determine statistically significant differences between the two groups (p < 0.05). Fifteen HIV-positive and 14 HIV-negative male cadavers were included (mean age 44, range 22 to 61). Cadmium was marginally decreased, possibly due to malnutrition or utilization by the HIV nucleocapsid. Nickel was marginally increased, perhaps due to a reduced capability to remove metals from the body. In conclusion, this article provides the first information on trace element levels in the brains from HIV-infected individuals and postulates that cadmium and nickel may play a role in the pathophysiology of HAND. This information can contribute to finding a treatment for HAND, other than the use of antiretroviral drugs. Future studies should asses the levels of cadmium and nickel in a larger cohort of HIV-infected individuals.
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Affiliation(s)
- Karen Cilliers
- Division of Clinical Anatomy, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Western Cape, South Africa.
| | - Christo J F Muller
- Biomedical Research and Innovation Platform (BRIP), South African Medical Research Council, Tygerberg, Western Cape, South Africa
- Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Western Cape, South Africa
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5
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How HIV-1 Gag Manipulates Its Host Cell Proteins: A Focus on Interactors of the Nucleocapsid Domain. Viruses 2020; 12:v12080888. [PMID: 32823718 PMCID: PMC7471995 DOI: 10.3390/v12080888] [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: 07/13/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) polyprotein Gag (Group-specific antigen) plays a central role in controlling the late phase of the viral lifecycle. Considered to be only a scaffolding protein for a long time, the structural protein Gag plays determinate and specific roles in HIV-1 replication. Indeed, via its different domains, Gag orchestrates the specific encapsidation of the genomic RNA, drives the formation of the viral particle by its auto-assembly (multimerization), binds multiple viral proteins, and interacts with a large number of cellular proteins that are needed for its functions from its translation location to the plasma membrane, where newly formed virions are released. Here, we review the interactions between HIV-1 Gag and 66 cellular proteins. Notably, we describe the techniques used to evidence these interactions, the different domains of Gag involved, and the implications of these interactions in the HIV-1 replication cycle. In the final part, we focus on the interactions involving the highly conserved nucleocapsid (NC) domain of Gag and detail the functions of the NC interactants along the viral lifecycle.
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6
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Bauer A, Frascaroli G, Walther P. Megapinosome: Morphological description of a novel organelle. J Struct Biol 2020; 210:107505. [DOI: 10.1016/j.jsb.2020.107505] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/19/2020] [Accepted: 03/30/2020] [Indexed: 01/08/2023]
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7
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Dupont M, Sattentau QJ. Macrophage Cell-Cell Interactions Promoting HIV-1 Infection. Viruses 2020; 12:E492. [PMID: 32354203 PMCID: PMC7290394 DOI: 10.3390/v12050492] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023] Open
Abstract
Many pathogens infect macrophages as part of their intracellular life cycle. This is particularly true for viruses, of which HIV-1 is one of the best studied. HIV-1 infection of macrophages has important consequences for viral persistence and pathogenesis, but the mechanisms of macrophage infection remain to be fully elucidated. Despite expressing viral entry receptors, macrophages are inefficiently infected by cell-free HIV-1 virions, whereas direct cell-cell spread is more efficient. Different modes of cell-cell spread have been described, including the uptake by macrophages of infected T cells and the fusion of infected T cells with macrophages, both leading to macrophage infection. Cell-cell spread can also transmit HIV-1 between macrophages and from macrophages to T cells. Here, we describe the current state of the field concerning the cell-cell spread of HIV-1 to and from macrophages, discuss mechanisms, and highlight potential in vivo relevance.
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Affiliation(s)
- Maeva Dupont
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford OX13RE, UK
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8
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Contribution of the Cytoplasmic Determinants of Vpu to the Expansion of Virus-Containing Compartments in HIV-1-Infected Macrophages. J Virol 2019; 93:JVI.00020-19. [PMID: 30867316 DOI: 10.1128/jvi.00020-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/09/2019] [Indexed: 12/30/2022] Open
Abstract
HIV-1 infection of macrophages leads to the sequestration of newly formed viruses in intracellular plasma membrane-connected structures termed virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The cellular restriction factor bone marrow stromal cell antigen 2 (BST2), which prevents HIV-1 dissemination by tethering budding viral particles at the plasma membrane, can be found in VCCs. The HIV-1 accessory protein Vpu counteracts the restriction factor BST2 by downregulating its expression and removing it from viral budding sites. Numerous studies described these Vpu countermeasures in CD4+ T cells or model cell lines, but the interplay between Vpu and BST2 in VCC formation and HIV-1 production in macrophages is less explored. Here, we show that Vpu expression in HIV-1-infected macrophages enhances viral release. This effect is related to Vpu's ability to circumvent BST2 antiviral activity. We show that in absence of Vpu, BST2 is enriched in VCCs and colocalizes with capsid p24, whereas Vpu expression significantly reduces the presence of BST2 in these compartments. Furthermore, our data reveal that BST2 is dispensable for the formation of VCCs and that Vpu expression impacts the volume of these compartments. This Vpu activity partly depends on BST2 expression and requires the integrity of the Vpu transmembrane domain, the dileucine-like motif E59XXXLV64 and phosphoserines 52 and 56 of Vpu. Altogether, these results highlight that Vpu controls the volume of VCCs and promotes HIV-1 release from infected macrophages.IMPORTANCE HIV-1 infection of macrophages leads to the sequestration of newly formed viruses in virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The restriction factor BST2, which prevents HIV-1 dissemination by tethering budding viral particles, can be found in VCCs. The HIV-1 Vpu protein counteracts BST2. This study explores the interplay between Vpu and BST2 in the viral protein functions on HIV-1 release and viral particle sequestration in VCCs in macrophages. The results show that Vpu controls the volume of VCCs and favors viral particle release. These Vpu functions partly depend on Vpu's ability to antagonize BST2. This study highlights that the transmembrane domain of Vpu and two motifs of the Vpu cytoplasmic domain are required for these functions. These motifs were notably involved in the control of the volume of VCCs by Vpu but were dispensable for the prevention of the specific accumulation of BST2 in these structures.
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Cellular Determinants of HIV Persistence on Antiretroviral Therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1075:213-239. [PMID: 30030795 DOI: 10.1007/978-981-13-0484-2_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The era of antiretroviral therapy has made HIV-1 infection a manageable chronic disease for those with access to treatment. Despite treatment, virus persists in tissue reservoirs seeded with long-lived infected cells that are resistant to cell death and immune recognition. Which cells contribute to this reservoir and which factors determine their persistence are central questions that need to be answered to achieve viral eradication. In this chapter, we describe how cell susceptibility to infection, resistance to cell death, and immune-mediated killing as well as natural cell life span and turnover potential are central components that allow persistence of different lymphoid and myeloid cell subsets that were recently identified as key players in harboring latent and actively replicating virus. The relative contribution of these subsets to persistence of viral reservoir is described, and the open questions are highlighted.
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10
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Rodrigues V, Ruffin N, San-Roman M, Benaroch P. Myeloid Cell Interaction with HIV: A Complex Relationship. Front Immunol 2017; 8:1698. [PMID: 29250073 PMCID: PMC5714857 DOI: 10.3389/fimmu.2017.01698] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/17/2017] [Indexed: 12/19/2022] Open
Abstract
Cells of the myeloid lineage, particularly macrophages, serve as primary hosts for HIV in vivo, along with CD4 T lymphocytes. Macrophages are present in virtually every tissue of the organism, including locations with negligible T cell colonization, such as the brain, where HIV-mediated inflammation may lead to pathological sequelae. Moreover, infected macrophages are present in multiple other tissues. Recent evidence obtained in humanized mice and macaque models highlighted the capacity of macrophages to sustain HIV replication in vivo in the absence of T cells. Combined with the known resistance of the macrophage to the cytopathic effects of HIV infection, such data bring a renewed interest in this cell type both as a vehicle for viral spread as well as a viral reservoir. While our understanding of key processes of HIV infection of macrophages is far from complete, recent years have nevertheless brought important insight into the uniqueness of the macrophage infection. Productive infection of macrophages by HIV can occur by different routes including from phagocytosis of infected T cells. In macrophages, HIV assembles and buds into a peculiar plasma membrane-connected compartment that preexists to the infection. While the function of such compartment remains elusive, it supposedly allows for the persistence of infectious viral particles over extended periods of time and may play a role on viral transmission. As cells of the innate immune system, macrophages have the capacity to detect and respond to viral components. Recent data suggest that such sensing may occur at multiple steps of the viral cycle and impact subsequent viral spread. We aim to provide an overview of the HIV-macrophage interaction along the multiple stages of the viral life cycle, extending when pertinent such observations to additional myeloid cell types such as dendritic cells or blood monocytes.
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Affiliation(s)
- Vasco Rodrigues
- Institut Curie, PSL Research University, INSERM U932, Paris, France
| | - Nicolas Ruffin
- Institut Curie, PSL Research University, INSERM U932, Paris, France
| | - Mabel San-Roman
- Institut Curie, PSL Research University, UMR3216, Paris, France
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11
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Rizkallah G, Alais S, Futsch N, Tanaka Y, Journo C, Mahieux R, Dutartre H. Dendritic cell maturation, but not type I interferon exposure, restricts infection by HTLV-1, and viral transmission to T-cells. PLoS Pathog 2017; 13:e1006353. [PMID: 28426803 PMCID: PMC5413061 DOI: 10.1371/journal.ppat.1006353] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 05/02/2017] [Accepted: 04/13/2017] [Indexed: 12/21/2022] Open
Abstract
Human T lymphotropic Virus type 1 (HTLV-1) is the etiological agent of Adult T cell Leukemia/Lymphoma (ATLL) and HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). Both CD4+ T-cells and dendritic cells (DCs) infected with HTLV-1 are found in peripheral blood from HTLV-1 carriers. We previously demonstrated that monocyte-derived IL-4 DCs are more susceptible to HTLV-1 infection than autologous primary T-cells, suggesting that DC infection precedes T-cell infection. However, during blood transmission, breast-feeding or sexual transmission, HTLV-1 may encounter different DC subsets present in the blood, the intestinal or genital mucosa respectively. These different contacts may impact HTLV-1 ability to infect DCs and its subsequent transfer to T-cells. Using in vitro monocyte-derived IL-4 DCs, TGF-β DCs and IFN-α DCs that mimic DCs contacting HTLV-1 in vivo, we show here that despite their increased ability to capture HTLV-1 virions, IFN-α DCs restrict HTLV-1 productive infection. Surprisingly, we then demonstrate that it is not due to the antiviral activity of type-I interferon produced by IFN-α DCs, but that it is likely to be linked to a distinct trafficking route of HTLV-1 in IL-4 DCs vs. IFN-α DCs. Finally, we demonstrate that, in contrast to IL-4 DCs, IFN-α DCs are impaired in their capacity to transfer HTLV-1 to CD4 T-cells, both after viral capture and trans-infection and after their productive infection. In conclusion, the nature of the DCs encountered by HTLV-1 upon primo-infection and the viral trafficking route through the vesicular pathway of these cells determine the efficiency of viral transmission to T-cells, which may condition the fate of infection.
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Affiliation(s)
- Gergès Rizkallah
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
| | - Sandrine Alais
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
| | - Nicolas Futsch
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, Uehara 207, Nishihara-cho, Okinawa, Japan
| | - Chloé Journo
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
| | - Renaud Mahieux
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
| | - Hélène Dutartre
- International Center for Research in Infectiology, Retroviral Oncogenesis laboratory, INSERM U1111 –Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Lyon, Lyon, France
- Equipe labellisée “Ligue Nationale Contre le Cancer”, Lyon, France
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12
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The sleeping beauty kissed awake: new methods in electron microscopy to study cellular membranes. Biochem J 2017; 474:1041-1053. [DOI: 10.1042/bcj20160990] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/03/2017] [Accepted: 01/23/2017] [Indexed: 01/12/2023]
Abstract
Electron microscopy (EM) for biological samples, developed in the 1940–1950s, changed our conception about the architecture of eukaryotic cells. It was followed by a period where EM applied to cell biology had seemingly fallen asleep, even though new methods with important implications for modern EM were developed. Among these was the discovery that samples can be preserved by chemical fixation and most importantly by rapid freezing without the formation of crystalline ice, giving birth to the world of cryo-EM. The past 15–20 years are hallmarked by a tremendous interest in EM, driven by important technological advances. Cryo-EM, in particular, is now capable of revealing structures of proteins at a near-atomic resolution owing to improved sample preparation methods, microscopes and cameras. In this review, we focus on the challenges associated with the imaging of membranes by EM and give examples from the field of host–pathogen interactions, in particular of virus-infected cells. Despite the advantages of imaging membranes under native conditions in cryo-EM, conventional EM will remain an important complementary method, in particular if large volumes need to be imaged.
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13
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Russell MRG, Lerner TR, Burden JJ, Nkwe DO, Pelchen-Matthews A, Domart MC, Durgan J, Weston A, Jones ML, Peddie CJ, Carzaniga R, Florey O, Marsh M, Gutierrez MG, Collinson LM. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy. J Cell Sci 2017; 130:278-291. [PMID: 27445312 PMCID: PMC5394779 DOI: 10.1242/jcs.188433] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 07/14/2016] [Indexed: 12/12/2022] Open
Abstract
The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research.
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Affiliation(s)
- Matthew R G Russell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Thomas R Lerner
- Host-pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Jemima J Burden
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - David O Nkwe
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Annegret Pelchen-Matthews
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Marie-Charlotte Domart
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | | | - Anne Weston
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Martin L Jones
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Christopher J Peddie
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Raffaella Carzaniga
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | | | - Mark Marsh
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Maximiliano G Gutierrez
- Host-pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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14
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Inlora J, Chukkapalli V, Bedi S, Ono A. Molecular Determinants Directing HIV-1 Gag Assembly to Virus-Containing Compartments in Primary Macrophages. J Virol 2016; 90:8509-19. [PMID: 27440886 PMCID: PMC5021390 DOI: 10.1128/jvi.01004-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/11/2016] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED The subcellular sites of HIV-1 assembly, determined by the localization of the structural protein Gag, vary in a cell-type-dependent manner. In T cells and transformed cell lines used as model systems, HIV-1 assembles at the plasma membrane (PM). The binding and localization of HIV-1 Gag to the PM are mediated by the interaction between the matrix (MA) domain, specifically the highly basic region, and a PM-specific acidic phospholipid, phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. In primary macrophages, prominent accumulation of assembling or assembled particles is found in the virus-containing compartments (VCCs), which largely consist of convoluted invaginations of the PM. To elucidate the molecular mechanism of HIV-1 Gag targeting to the VCCs, we examined the impact of overexpression of polyphosphoinositide 5-phosphatase IV (5ptaseIV), which depletes cellular PI(4,5)P2, in primary macrophages. We found that the VCC localization and virus release of HIV-1 are severely impaired upon 5ptaseIV overexpression, suggesting an important role for the MA-PI(4,5)P2 interaction in HIV-1 assembly in primary macrophages. However, our analysis of HIV-1 Gag derivatives with MA changes showed that this interaction contributes to Gag membrane binding but is dispensable for specific targeting of Gag to the VCCs per se We further determined that deletion of the NC domain abolishes VCC-specific localization of HIV-1 Gag. Notably, HIV-1 Gag localized efficiently to the VCCs when the NC domain was replaced with a leucine zipper dimerization motif that promotes Gag multimerization. Altogether, our data revealed that targeting of HIV-1 Gag to the VCCs requires NC-dependent multimerization. IMPORTANCE In T cells and model cell lines, HIV-1 Gag localizes to the PM in a manner dependent on the MA-PI(4,5)P2 interaction. On the other hand, in primary macrophages, HIV-1 Gag localizes to convoluted intracellular membrane structures termed virus-containing compartments (VCCs). Although these compartments have been known for decades, and despite the implication of viruses in VCCs being involved in virus reservoir maintenance and spread, the viral determinant(s) that promotes Gag targeting to VCCs is unknown. In this study, we found that the MA-PI(4,5)P2 interaction facilitates efficient Gag membrane binding in macrophages but is not essential for Gag targeting to VCCs. Rather, our results revealed that NC-dependent multimerization promotes VCC targeting. Our findings highlight the differential roles played by MA and NC in HIV-1 Gag membrane binding and targeting and suggest a multimerization-dependent mechanism for Gag trafficking in primary macrophages similar to that for Gag localization to uropods in polarized T cells.
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Affiliation(s)
- Jingga Inlora
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Vineela Chukkapalli
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sukhmani Bedi
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Cell-Free versus Cell-to-Cell Infection by Human Immunodeficiency Virus Type 1 and Human T-Lymphotropic Virus Type 1: Exploring the Link among Viral Source, Viral Trafficking, and Viral Replication. J Virol 2016; 90:7607-17. [PMID: 27334587 DOI: 10.1128/jvi.00407-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) and human T-lymphotropic virus type 1 (HTLV-1) are complex retroviruses mainly infecting CD4(+) T lymphocytes. In addition, antigen-presenting cells such as dendritic cells (DCs) are targeted in vivo by both viruses, although to a lesser extent. Interaction of HIV-1 with DCs plays a key role in viral dissemination from the mucosa to CD4(+) T lymphocytes present in lymphoid organs. While similar mechanisms may occur for HTLV-1 as well, most HTLV-1 data were obtained from T-cell studies, and little is known regarding the trafficking of this virus in DCs. We first compared the efficiency of cell-free versus cell-associated viral sources of both retroviruses at infecting DCs. We showed that both HIV-1 and HTLV-1 cell-free particles are poorly efficient at productively infecting DCs, except when DC-SIGN has been engaged. Furthermore, while SAMHD-1 accounts for restriction of cell-free HIV-1 infection, it is not involved in HTLV-1 restriction. In addition, cell-free viruses lead mainly to a nonproductive DC infection, leading to trans-infection of T-cells, a process important for HIV-1 spread but not for that of HTLV-1. Finally, we show that T-DC cell-to-cell transfer implies viral trafficking in vesicles that may both increase productive infection of DCs ("cis-infection") and allow viral escape from immune surveillance. Altogether, these observations allowed us to draw a model of HTLV-1 and HIV-1 trafficking in DCs.
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Nkwe DO, Pelchen-Matthews A, Burden JJ, Collinson LM, Marsh M. The intracellular plasma membrane-connected compartment in the assembly of HIV-1 in human macrophages. BMC Biol 2016; 14:50. [PMID: 27338237 PMCID: PMC4919869 DOI: 10.1186/s12915-016-0272-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 06/09/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In HIV-infected macrophages, newly formed progeny virus particles accumulate in intracellular plasma membrane-connected compartments (IPMCs). Although the virus is usually seen in these compartments, it is unclear whether HIV assembly is specifically targeted to IPMCs or whether some viruses may also form at the cell surface but are not detected, as particles budding from the latter site will be released into the medium. RESULTS To investigate the fidelity of HIV-1 targeting to IPMCs compared to the cell surface directly, we generated mutants defective in recruitment of the Endosomal Sorting Complexes Required for Transport (ESCRT) proteins required for virus scission. For mutants unable to bind the ESCRT-I component Tsg101, HIV release was inhibited and light and electron microscopy revealed that budding was arrested. When expressed in human monocyte-derived macrophages (MDM), these mutants formed budding-arrested, immature particles at their assembly sites, allowing us to capture virtually all of the virus budding events. A detailed morphological analysis of the distribution of the arrested viruses by immunofluorescence staining and confocal microscopy, and by electron microscopy, demonstrated that HIV assembly in MDMs is targeted primarily to IPMCs, with fewer than 5 % of budding events seen at the cell surface. Morphometric analysis of the relative membrane areas at the cell surface and IPMCs confirmed a large enrichment of virus assembly events in IPMCs. Serial block-face scanning electron microscopy of macrophages infected with a budding-defective HIV mutant revealed high-resolution 3D views of the complex organisation of IPMCs, with in excess of 15,000 associated HIV budding sites, and multiple connections between IPMCs and the cell surface. CONCLUSIONS Using detailed quantitative analysis, we demonstrate that HIV assembly in MDMs is specifically targeted to IPMCs. Furthermore, 3D analysis shows, for the first time, the detailed ultrastructure of an IPMC within a large cell volume, at a resolution that allowed identification of individual virus assembly events, and potential portals through which virus may be released during cell-cell transfer. These studies provide new insights to the organisation of the HIV assembly compartments in macrophages, and show how HIV particles accumulating in these protected sites may function as a virus reservoir.
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Affiliation(s)
- David O. Nkwe
- />MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT UK
- />Present Address: Department of Biology and Biotechnological Sciences, College of Science, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana
| | - Annegret Pelchen-Matthews
- />MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT UK
| | - Jemima J. Burden
- />MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT UK
| | - Lucy M. Collinson
- />The Francis Crick Institute, Lincoln’s Inn Fields Laboratories, 44 Lincoln’s Inn Fields, London, WC2A 3LY UK
| | - Mark Marsh
- />MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT UK
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Araínga M, Guo D, Wiederin J, Ciborowski P, McMillan J, Gendelman HE. Opposing regulation of endolysosomal pathways by long-acting nanoformulated antiretroviral therapy and HIV-1 in human macrophages. Retrovirology 2015; 12:5. [PMID: 25608975 PMCID: PMC4307176 DOI: 10.1186/s12977-014-0133-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 12/19/2014] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Long-acting nanoformulated antiretroviral therapy (nanoART) is designed to improve patient regimen adherence, reduce systemic drug toxicities, and facilitate clearance of human immunodeficiency virus type one (HIV-1) infection. While nanoART establishes drug depots within recycling and late monocyte-macrophage endosomes, whether or not this provides a strategic advantage towards viral elimination has not been elucidated. RESULTS We applied quantitative SWATH-MS proteomics and cell profiling to nanoparticle atazanavir (nanoATV)-treated and HIV-1 infected human monocyte-derived macrophages (MDM). Native ATV and uninfected cells served as controls. Both HIV-1 and nanoATV engaged endolysosomal trafficking for assembly and depot formation, respectively. Notably, the pathways were deregulated in opposing manners by the virus and the nanoATV, likely by viral clearance. Paired-sample z-scores, of the proteomic data sets, showed up- and down- regulation of Rab-linked endolysosomal proteins. NanoART and native ATV treated uninfected cells showed limited effects. The data was confirmed by Western blot. DAVID and KEGG bioinformatics analyses of proteomic data showed relationships between secretory, mobility and phagocytic cell functions and virus and particle trafficking. CONCLUSIONS We posit that modulation of endolysosomal pathways by antiretroviral nanoparticles provides a strategic path to combat HIV infection.
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Affiliation(s)
- Mariluz Araínga
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
| | - Dongwei Guo
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
- />Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198-5880 USA
| | - Jayme Wiederin
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
| | - Pawel Ciborowski
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
| | - JoEllyn McMillan
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
| | - Howard E Gendelman
- />Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, 985880 Nebraska Medical Center, Omaha, NE 68198-5880 USA
- />Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198-5880 USA
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Placental Hofbauer cells assemble and sequester HIV-1 in tetraspanin-positive compartments that are accessible to broadly neutralizing antibodies. J Int AIDS Soc 2015; 18:19385. [PMID: 25623930 PMCID: PMC4308659 DOI: 10.7448/ias.18.1.19385] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/11/2014] [Accepted: 12/16/2014] [Indexed: 12/23/2022] Open
Abstract
Introduction Within monocyte-derived macrophages, HIV-1 accumulates in intracellular virus-containing compartments (VCCs) that are inaccessible to the external environment, which implicate these cells as latently infected HIV-1 reservoirs. During mother-to-child transmission of HIV-1, human placental macrophages (Hofbauer cells (HCs)) are viral targets, and have been shown to be infected in vivo and sustain low levels of viral replication in vitro; however, the risk of in utero transmission is less than 7%. The role of these primary macrophages as viral reservoirs is largely undefined. The objective of this study is to define potential sites of viral assembly, accumulation and neutralization in HCs given the pivotal role of the placenta in preventing HIV-1 infection in the mother-infant dyad. Methods Term placentae from 20 HIV-1 seronegative women were obtained following caesarian section. VCCs were evaluated by 3D confocal and electron microscopy. Colocalization R values (Pearson's correlation) were quantified with colocalization module of Volocity 5.2.1. Replication kinetics and neutralization studies were evaluated using p24 ELISA. Results We demonstrate that primary HCs assemble and sequester HIV-1BaL in intracellular VCCs, which are enriched in endosomal/lysosomal markers, including CD9, CD81, CD63 and LAMP-1. Following infection, we observed HIV-1 accumulation in potentially acidic compartments, which stained intensely with Lysotracker-Red. Remarkably, these compartments are readily accessible via the cell surface and can be targeted by exogenously applied small molecules and HIV-1-specific broadly neutralizing antibodies. In addition, broadly neutralizing antibodies (4E10 and VRC01) limited viral replication by HIV-1-infected HCs, which may be mediated by FcγRI. Conclusions These findings suggest that placental HCs possess intrinsic adaptations facilitating unique sequestration of HIV-1, and may serve as a protective viral reservoir to permit viral neutralization and/or antiretroviral drug entry in utero.
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Risco C, de Castro IF, Sanz-Sánchez L, Narayan K, Grandinetti G, Subramaniam S. Three-Dimensional Imaging of Viral Infections. Annu Rev Virol 2014; 1:453-73. [PMID: 26958730 DOI: 10.1146/annurev-virology-031413-085351] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Three-dimensional (3D) imaging technologies are beginning to have significant impact in the field of virology, as they are helping us understand how viruses take control of cells. In this article we review several methodologies for 3D imaging of cells and show how these technologies are contributing to the study of viral infections and the characterization of specialized structures formed in virus-infected cells. We include 3D reconstruction by transmission electron microscopy (TEM) using serial sections, electron tomography, and focused ion beam scanning electron microscopy (FIB-SEM). We summarize from these methods selected contributions to our understanding of viral entry, replication, morphogenesis, egress and propagation, and changes in the spatial architecture of virus-infected cells. In combination with live-cell imaging, correlative microscopy, and new techniques for molecular mapping in situ, the availability of these methods for 3D imaging is expected to provide deeper insights into understanding the structural and dynamic aspects of viral infection.
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Affiliation(s)
- Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | | | - Laura Sanz-Sánchez
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | - Kedar Narayan
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Giovanna Grandinetti
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Sriram Subramaniam
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
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Giese S, Marsh M. Tetherin can restrict cell-free and cell-cell transmission of HIV from primary macrophages to T cells. PLoS Pathog 2014; 10:e1004189. [PMID: 24991932 PMCID: PMC4081785 DOI: 10.1371/journal.ppat.1004189] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 05/02/2014] [Indexed: 11/19/2022] Open
Abstract
Bst-2/Tetherin inhibits the release of HIV by tethering newly formed virus particles to the plasma membrane of infected cells. Although the mechanisms of Tetherin-mediated restriction are increasingly well understood, the biological relevance of this restriction in the natural target cells of HIV is unclear. Moreover, whether Tetherin exerts any restriction on the direct cell-cell spread of HIV across intercellular contacts remains controversial. Here we analyse the restriction endogenous Tetherin imposes on HIV transmission from primary human macrophages, one of the main targets of HIV in vivo. We find that the mRNA and protein levels of Tetherin in macrophages are comparable to those in T cells from the same donors, and are highly upregulated by type I interferons. Improved immunocytochemistry protocols enable us to demonstrate that Tetherin localises to the cell surface, the trans-Golgi network, and the macrophage HIV assembly compartments. Tetherin retains budded virions in the assembly compartments, thereby impeding the release and cell-free spread of HIV, but it is not required for the maintenance of these compartments per se. Notably, using a novel assay to quantify cell-cell spread, we show that Tetherin promotes the transfer of virus clusters from macrophages to T cells and thereby restricts the direct transmission of a dual-tropic HIV-1. Kinetic analyses provide support for the notion that this direct macrophage-T cell spread is mediated, at least in part, by so-called virological synapses. Finally, we demonstrate that the viral Vpu protein efficiently downregulates the cell surface and overall levels of Tetherin, and thereby abrogates this HIV restriction in macrophages. Together, our study shows that Tetherin, one of the most potent HIV restriction factors identified to date, can inhibit virus spread from primary macrophages, regardless of the mode of transmission.
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Affiliation(s)
- Sebastian Giese
- MRC/UCL Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Mark Marsh
- MRC/UCL Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
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Virus particle release from glycosphingolipid-enriched microdomains is essential for dendritic cell-mediated capture and transfer of HIV-1 and henipavirus. J Virol 2014; 88:8813-25. [PMID: 24872578 DOI: 10.1128/jvi.00992-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) exploits dendritic cells (DCs) to promote its transmission to T cells. We recently reported that the capture of HIV-1 by mature dendritic cells (MDCs) is mediated by an interaction between the glycosphingolipid (GSL) GM3 on virus particles and CD169/Siglec-1 on MDCs. Since HIV-1 preferentially buds from GSL-enriched lipid microdomains on the plasma membrane, we hypothesized that the virus assembly and budding site determines the ability of HIV-1 to interact with MDCs. In support of this hypothesis, mutations in the N-terminal basic domain (29/31KE) or deletion of the membrane-targeting domain of the HIV-1 matrix (MA) protein that altered the virus assembly and budding site to CD63(+)/Lamp-1-positive intracellular compartments resulted in lower levels of virion incorporation of GM3 and attenuation of virus capture by MDCs. Furthermore, MDC-mediated capture and transmission of MA mutant viruses to T cells were decreased, suggesting that HIV-1 acquires GSLs via budding from the plasma membrane to access the MDC-dependent trans infection pathway. Interestingly, MDC-mediated capture of Nipah and Hendra virus (recently emerged zoonotic paramyxoviruses) M (matrix) protein-derived virus-like particles that bud from GSL-enriched plasma membrane microdomains was also dependent on interactions between virion-incorporated GSLs and CD169. Moreover, capture and transfer of Nipah virus envelope glycoprotein-pseudotyped lentivirus particles by MDCs were severely attenuated upon depletion of GSLs from virus particles. These results suggest that GSL incorporation into virions is critical for the interaction of diverse enveloped RNA viruses with DCs and that the GSL-CD169 recognition nexus might be a conserved viral mechanism of parasitization of DC functions for systemic virus dissemination. IMPORTANCE Dendritic cells (DCs) can capture HIV-1 particles and transfer captured virus particles to T cells without establishing productive infection in DCs, a mechanism of HIV-1 trans infection. We have recently identified CD169-mediated recognition of GM3, a host-derived glycosphingolipid (GSL) incorporated into the virus particle membrane, as the receptor and ligand for the DC-HIV trans infection pathway. In this study, we have identified the matrix (MA) domain of Gag to be the viral determinant that governs incorporation of GM3 into HIV-1 particles, a previously unappreciated function of the HIV-1 MA. In addition, we demonstrate that the GSL-CD169-dependent trans infection pathway is also utilized as a dissemination mechanism by henipaviruses. GSL incorporation in henipaviruses was also dependent on the viral capsid (M) protein-directed assembly and budding from GSL-enriched lipid microdomains. These findings provide evidence of a conserved mechanism of retrovirus and henipavirus parasitization of cell-to-cell recognition pathways for systemic virus dissemination.
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Kumar A, Abbas W, Herbein G. HIV-1 latency in monocytes/macrophages. Viruses 2014; 6:1837-60. [PMID: 24759213 PMCID: PMC4014723 DOI: 10.3390/v6041837] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/11/2014] [Accepted: 03/28/2014] [Indexed: 12/24/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) targets CD4+ T cells and cells of the monocyte/macrophage lineage. HIV pathogenesis is characterized by the depletion of T lymphocytes and by the presence of a population of cells in which latency has been established called the HIV-1 reservoir. Highly active antiretroviral therapy (HAART) has significantly improved the life of HIV-1 infected patients. However, complete eradication of HIV-1 from infected individuals is not possible without targeting latent sources of infection. HIV-1 establishes latent infection in resting CD4+ T cells and findings indicate that latency can also be established in the cells of monocyte/macrophage lineage. Monocyte/macrophage lineage includes among others, monocytes, macrophages and brain resident macrophages. These cells are relatively more resistant to apoptosis induced by HIV-1, thus are important stable hideouts of the virus. Much effort has been made in the direction of eliminating HIV-1 resting CD4+ T-cell reservoirs. However, it is impossible to achieve a cure for HIV-1 without considering these neglected latent reservoirs, the cells of monocyte/macrophage lineage. In this review we will describe our current understanding of the mechanism of latency in monocyte/macrophage lineage and how such cells can be specifically eliminated from the infected host.
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Affiliation(s)
- Amit Kumar
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
| | - Wasim Abbas
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
| | - Georges Herbein
- UPRES EA4266, SFR FED 4234, Pathogens and Inflammation Laboratory, Department of Virology, CHRU Besançon, University of Franche-Comte, F-25030 Besançon, France.
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Kumar A, Herbein G. The macrophage: a therapeutic target in HIV-1 infection. MOLECULAR AND CELLULAR THERAPIES 2014; 2:10. [PMID: 26056579 PMCID: PMC4452058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 01/27/2014] [Indexed: 11/21/2023]
Abstract
Human immunodeficiency virus (HIV) is still a serious global health concern responsible for more than 25 million deaths in last three decades. More than 34 million people are living with HIV infection. Macrophages and CD4+ T cells are the principal targets of HIV-1. The pathogenesis of HIV-1 takes different routes in macrophages and CD4+ T cells. Macrophages are resistant to the cytopathic effect of HIV-1 and produce virus for longer periods of time. In addition, macrophages being present in every organ system thus can disseminate virus to the different anatomical sites leading to the formation of viral sanctuaries. Complete cure of HIV-1 needs better understanding of viral pathogenesis in these reservoirs and implementation of knowledge into robust therapeutic products. In this review we will focus on the unique relationship between HIV-1 and macrophages. Furthermore, we will describe how successful antiretroviral therapy (ART) is in suppressing HIV and novel molecular and cellular strategies against HIV-1 in macrophages.
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Affiliation(s)
- Amit Kumar
- />Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
| | - Georges Herbein
- />Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
- />Department of Virology, Hôpital Saint-Jacques, CHRU Besançon, 2 place Saint-Jacques, F-25030 Besançon cedex, France
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Kumar A, Herbein G. The macrophage: a therapeutic target in HIV-1 infection. MOLECULAR AND CELLULAR THERAPIES 2014; 2:10. [PMID: 26056579 PMCID: PMC4452058 DOI: 10.1186/2052-8426-2-10] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 01/27/2014] [Indexed: 12/21/2022]
Abstract
Human immunodeficiency virus (HIV) is still a serious global health concern responsible for more than 25 million deaths in last three decades. More than 34 million people are living with HIV infection. Macrophages and CD4+ T cells are the principal targets of HIV-1. The pathogenesis of HIV-1 takes different routes in macrophages and CD4+ T cells. Macrophages are resistant to the cytopathic effect of HIV-1 and produce virus for longer periods of time. In addition, macrophages being present in every organ system thus can disseminate virus to the different anatomical sites leading to the formation of viral sanctuaries. Complete cure of HIV-1 needs better understanding of viral pathogenesis in these reservoirs and implementation of knowledge into robust therapeutic products. In this review we will focus on the unique relationship between HIV-1 and macrophages. Furthermore, we will describe how successful antiretroviral therapy (ART) is in suppressing HIV and novel molecular and cellular strategies against HIV-1 in macrophages.
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Affiliation(s)
- Amit Kumar
- Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France
| | - Georges Herbein
- Department of Virology, UPRES EA4266 Pathogens & Inflammation, University of Franche-Comte, SFR FED 4234, F-25030 Besançon, France ; Department of Virology, Hôpital Saint-Jacques, CHRU Besançon, 2 place Saint-Jacques, F-25030 Besançon cedex, France
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Revie D, Salahuddin SZ. Role of macrophages and monocytes in hepatitis C virus infections. World J Gastroenterol 2014; 20:2777-2784. [PMID: 24659871 PMCID: PMC3961986 DOI: 10.3748/wjg.v20.i11.2777] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/27/2013] [Accepted: 01/06/2014] [Indexed: 02/06/2023] Open
Abstract
A number of studies conducted over many years have shown that hepatitis C virus (HCV) can infect a variety of cell types. In vivo infection of monocytes, macrophages, and dendritic cells by HCV has been frequently shown by a number of researchers. These studies have demonstrated replication of HCV by detecting the presence of both negative genomic strands and a variety of non-structural HCV proteins in infected cells. In addition, analyses of genome sequences have also shown that different cell types can harbor different HCV variants. Investigators have also done preliminary studies of which cellular genes are affected by HCV infection, but there have not yet been a sufficient number of these studies to understand the effects of infection on these cells. Analyses of in vitro HCV replication have shown that monocytes, macrophages and dendritic cells can be infected by HCV from patient sera or plasma. These studies suggest that entry and cellular locations may vary between different cell types. Some studies suggest that macrophages may preferentially allow HCV genotype 1 to replicate, but macrophages do not appear to select particular hypervariable regions. Overall, these studies agree with a model where monocytes and macrophages act as an amplification system, in which these cells are infected and show few cytopathic effects, but continuously produce HCV. This allows them to produce virus over an extended time and allows its spread to other cell types.
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Efficient transfer of HIV-1 in trans and in cis from Langerhans dendritic cells and macrophages to autologous T lymphocytes. AIDS 2014; 28:667-77. [PMID: 24451159 DOI: 10.1097/qad.0000000000000193] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The chronology of HIV infection in mucosal tissue after sexual transmission is unknown. Several potential HIV target cells are present at these sites, including dendritic cells, macrophages, and CD4(+) T lymphocytes. Dendritic cells and macrophages are antigen-presenting cells (APCs) and are thus involved in cross-talk with T cells. This close contact may favor efficient HIV-1 transfer to T lymphocytes, resulting in rapid HIV-1 dissemination. DESIGN We investigated the role of APCs in HIV transfer to T cells by incubating Langerhans cells and interstitial dendritic cells (IDCs) or monocyte-derived macrophages (MDMs) with HIV for 2 h before addition of uninfected autologous CD4(+) T lymphocytes. METHODS HIV infection was recorded after different time points. Following staining, the measurement of intracellular p24 in the different cell populations was analyzed by flow cytometry. RESULTS We showed that Langerhans cells/IDCs and macrophages efficiently transferred HIV to CD4(+) T cells. Interestingly, a rapid HIV transfer in trans predominated in MDMs, whereas cis transfer mainly occurred in Langerhans cells/IDC cocultures. Neutralizing antibody 2G12, added to HIV-loaded APCs, efficiently blocked both the trans and the cis infection of T cells. CONCLUSION These findings highlight the major contributions of various mucosal cells in HIV dissemination and suggest that HIV hijacks the different properties of APCs to favor its dissemination through the body. They emphasize the role of macrophages in the rapid transmission of HIV to T lymphocytes at mucosal sites, dendritic cells being prone to migration to lymphoid organ for subsequent dissemination by cis transfer.
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High-multiplicity HIV-1 infection and neutralizing antibody evasion mediated by the macrophage-T cell virological synapse. J Virol 2013; 88:2025-34. [PMID: 24307588 DOI: 10.1128/jvi.03245-13] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Macrophage infection is considered to play an important role in HIV-1 pathogenesis and persistence. Using a primary cell-based coculture model, we show that monocyte-derived macrophages (MDM) efficiently transmit a high-multiplicity HIV-1 infection to autologous CD4(+) T cells through a viral envelope glycoprotein (Env) receptor- and actin-dependent virological synapse (VS), facilitated by interactions between ICAM-1 and LFA-1. Virological synapse (VS)-mediated transmission by MDM results in high levels of T cell HIV-1 integration and is 1 to 2 orders of magnitude more efficient than cell-free infection. This mode of cell-to-cell transmission is broadly susceptible to the activity of CD4 binding site (CD4bs) and glycan or glycopeptide epitope-specific broadly neutralizing monoclonal antibodies (bNMAbs) but shows resistance to bNMAbs targeting the Env gp41 subunit membrane-proximal external region (MPER). These data define for the first time the structure and function of the macrophage-to-T cell VS and have important implications for bNMAb activity in HIV-1 prophylaxis and therapy. IMPORTANCE The ability of HIV-1 to move directly between contacting immune cells allows efficient viral dissemination with the potential to evade antibody attack. Here, we show that HIV-1 spreads from infected macrophages to T cells via a structure called a virological synapse that maintains extended contact between the two cell types, allowing transfer of multiple infectious events to the T cell. This process allows the virus to avoid neutralization by a class of antibody targeting the gp41 subunit of the envelope glycoproteins. These results have implications for viral spread in vivo and the specificities of neutralizing antibody elicited by antibody-based vaccines.
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Berre S, Gaudin R, Cunha de Alencar B, Desdouits M, Chabaud M, Naffakh N, Rabaza-Gairi M, Gobert FX, Jouve M, Benaroch P. CD36-specific antibodies block release of HIV-1 from infected primary macrophages and its transmission to T cells. ACTA ACUST UNITED AC 2013; 210:2523-38. [PMID: 24145510 PMCID: PMC3832921 DOI: 10.1084/jem.20130566] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
HIV-1-infected macrophages likely represent viral reservoirs, as they accumulate newly formed virions in internal virus-containing compartments (VCCs). However, the nature and biogenesis of VCCs remain poorly defined. We show that upon HIV-1 infection of primary human macrophages, Gag is recruited to preexisting compartments containing the scavenger receptor CD36, which then become VCCs. Silencing of CD36 in HIV-1-infected macrophages decreases the amount of virions released. Strikingly, soluble anti-CD36 antibodies, but not the natural ligands of CD36, inhibit release of virions from HIV-1-infected macrophages and the transmission of virus to CD4(+) T cells. The effect of the antibodies is potent, rapid, and induces the retention of virions within VCCs. Ectopic expression of CD36 in HeLa cells renders them susceptible to the inhibitory effect of the anti-CD36 mAb upon HIV-1 infection. We show that the anti-CD36 mAb inhibits HIV-1 release by clustering newly formed virions at their site of budding, and that signaling via CD36 is not required. Thus, HIV-1 reservoirs in macrophages may be tackled therapeutically using anti-CD36 antibodies to prevent viral dissemination.
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Affiliation(s)
- Stefano Berre
- Institut Curie, Centre de Recherche, F-75248 Paris, France
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Schiffner T, Sattentau QJ, Duncan CJA. Cell-to-cell spread of HIV-1 and evasion of neutralizing antibodies. Vaccine 2013; 31:5789-97. [PMID: 24140477 DOI: 10.1016/j.vaccine.2013.10.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/29/2013] [Accepted: 10/04/2013] [Indexed: 01/13/2023]
Abstract
Cell-to-cell spread of human immunodeficiency virus (HIV-1) between immune cells was first observed over 20 years ago. During this time, the question of whether this infection route favours viral evasion of neutralizing antibodies (NAbs) targeting the virus envelope glycoprotein (Env) has been repeatedly investigated, but with conflicting results. A clearer picture has formed in the last few years as more broadly neutralizing antibodies have been isolated and we gain further insight into the mechanisms of HIV-1 transmission at virological and infectious synapses. Nevertheless consensus is still lacking, a situation which may be at least partly explained by variability in the experimental approaches used to study the activity of NAbs in the cell-to-cell context. In this review we focus on the most critical question concerning the activity of NAbs against cell-to-cell transmission: is NAb inhibition of cell-to-cell HIV-1 quantitatively or qualitatively different from cell-free infection? Overall, data consistently show that NAbs are capable of blocking HIV-1 infection at synapses, supporting the concept that cell-to-cell infection occurs through directed transfer of virions accessible to the external environment. However, more recent findings suggest that higher concentrations of certain NAbs might be needed to inhibit synaptic infection, with important potential implications for prophylactic vaccine development. We discuss several mechanistic explanations for this relative and selective loss of activity, and highlight gaps in knowledge that are still to be explored.
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Affiliation(s)
- Torben Schiffner
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom
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30
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Mlcochova P, Pelchen-Matthews A, Marsh M. Organization and regulation of intracellular plasma membrane-connected HIV-1 assembly compartments in macrophages. BMC Biol 2013; 11:89. [PMID: 23915020 PMCID: PMC3751737 DOI: 10.1186/1741-7007-11-89] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/26/2013] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND In HIV-1-infected human monocyte-derived macrophages (MDMs), virus particles assemble primarily on intracellularly sequestered plasma membrane domains termed intracellular plasma membrane-connected compartments (IPMCs). Despite their clear role in virus formation, little is known of the organization, composition, dynamics or function of these compartments. RESULTS We have used amphipathic membrane dyes to reveal the complex three-dimensional structure of IPMCs in whole MDMs and to visualize connections between IPMCs and the cell surface. The observation of similar IPMC structures in both infected and uninfected cells indicates that these compartments are not induced by virus infection, but are present constitutively in MDMs. By expressing a phospholipase Cδ pleckstrin homology domain linked to green fluorescent protein, we demonstrate that IPMCs contain phosphatidylinositol 4,5-bisphosphate. Live cell imaging of cells expressing this probe shows that IPMCs are dynamic, but relatively stable, sub-domains of the plasma membrane. As recent electron microscopy studies indicated that portions of IPMCs are coated with β2 integrin-containing focal adhesion-like complexes linked to actin, we investigated whether the actin cytoskeleton is required for the organization of IPMCs. In MDMs treated with the actin polymerization inhibitor latrunculin, the normally compact IPMCs dispersed into smaller structures that remained connected to the plasma membrane. Moreover, latrunculin enhanced the release of preformed, mature HIV-1 particles from infected MDMs. CONCLUSIONS IPMCs are constitutive features of MDMs that are continuous with the plasma membrane and are used as unique sites for the assembly of new virions following infection by HIV-1. A functionally intact actin cytoskeleton is required to maintain the organization of the IPMCs and, in HIV-1-infected cells, perturbation of the actin cytoskeleton influences both the organization of the compartment and the release of sequestered virus.
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Affiliation(s)
- Petra Mlcochova
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Annegret Pelchen-Matthews
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
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31
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Dynamics of HIV-containing compartments in macrophages reveal sequestration of virions and transient surface connections. PLoS One 2013; 8:e69450. [PMID: 23922713 PMCID: PMC3726685 DOI: 10.1371/journal.pone.0069450] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 06/09/2013] [Indexed: 11/19/2022] Open
Abstract
During HIV pathogenesis, infected macrophages behave as “viral reservoirs” that accumulate and retain virions within dedicated internal Virus-Containing Compartments (VCCs). The nature of VCCs remains ill characterized and controversial. Using wild-type HIV-1 and a replication-competent HIV-1 carrying GFP internal to the Gag precursor, we analyzed the biogenesis and evolution of VCCs in primary human macrophages. VCCs appear roughly 14 hours after viral protein synthesis is detected, initially contain few motile viral particles, and then mature to fill up with virions that become packed and immobile. The amount of intracellular Gag, the proportion of dense VCCs, and the density of viral particles in their lumen increased with time post-infection. In contrast, the secretion of virions, their infectivity and their transmission to T cells decreased overtime, suggesting that HIV-infected macrophages tend to pack and retain newly formed virions into dense compartments. A minor proportion of VCCs remains connected to the plasma membrane overtime. Surprisingly, live cell imaging combined with correlative light and electron microscopy revealed that such connections can be transient, highlighting their dynamic nature. Together, our results shed light on the late phases of the HIV-1 cycle and reveal some of its macrophage specific features.
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32
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Tan J, Sattentau QJ. The HIV-1-containing macrophage compartment: a perfect cellular niche? Trends Microbiol 2013; 21:405-12. [PMID: 23735804 DOI: 10.1016/j.tim.2013.05.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/29/2013] [Accepted: 05/06/2013] [Indexed: 12/15/2022]
Abstract
Macrophages are a major target of HIV-1 infection and are believed to act as viral reservoirs and mediators of HIV-1-associated neurological damage. These pathological roles may be associated with the ability of the virus to assemble and accumulate in apparently intracellular compartments in macrophages. These so-called virus-containing compartments were initially thought to be late endosomes or multivesicular bodies, but it has since been shown that they are distinct structures that have complex three-dimensional morphology, a unique set of protein markers, and features such as a near-neutral pH and frequent connections to the extracellular milieu. These features appear to protect HIV-1 from hostile elements both within and outside the cell. This review discusses the cellular and molecular characteristics of HIV-1-containing compartments in macrophages and how they offer a safe haven for the virus, with important consequences for pathogenesis.
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Affiliation(s)
- Joshua Tan
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford OX13RE, UK
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33
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Hütter S, Zurnic I, Lindemann D. Foamy virus budding and release. Viruses 2013; 5:1075-98. [PMID: 23575110 PMCID: PMC3705266 DOI: 10.3390/v5041075] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 12/21/2022] Open
Abstract
Like all other viruses, a successful egress of functional particles from infected cells is a prerequisite for foamy virus (FV) spread within the host. The budding process of FVs involves steps, which are shared by other retroviruses, such as interaction of the capsid protein with components of cellular vacuolar protein sorting (Vps) machinery via late domains identified in some FV capsid proteins. Additionally, there are features of the FV budding strategy quite unique to the spumaretroviruses. This includes secretion of non-infectious subviral particles and a strict dependence on capsid-glycoprotein interaction for release of infectious virions from the cells. Virus-like particle release is not possible since FV capsid proteins lack a membrane-targeting signal. It is noteworthy that in experimental systems, the important capsid-glycoprotein interaction could be bypassed by fusing heterologous membrane-targeting signals to the capsid protein, thus enabling glycoprotein-independent egress. Aside from that, other systems have been developed to enable envelopment of FV capsids by heterologous Env proteins. In this review article, we will summarize the current knowledge on FV budding, the viral components and their domains involved as well as alternative and artificial ways to promote budding of FV particle structures, a feature important for alteration of target tissue tropism of FV-based gene transfer systems.
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Affiliation(s)
- Sylvia Hütter
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Irena Zurnic
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
| | - Dirk Lindemann
- Institute of Virology, Medical Faculty "Carl Gustav Carus", Technische Universität Dresden, Fetscherstr. 74, Dresden 01307, Germany; E-Mails: (S.H); (I.Z.)
- DFG-Center for Regenerative Therapies Dresden (CRTD)—Cluster of Excellence, Technische Universität Dresden, Fetscherstr. 105, Dresden 01307, Germany
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-351458-6210; Fax: +49-351-458-6310
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Hogue IB, Llewellyn GN, Ono A. Dynamic Association between HIV-1 Gag and Membrane Domains. Mol Biol Int 2012; 2012:979765. [PMID: 22830021 PMCID: PMC3399408 DOI: 10.1155/2012/979765] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Accepted: 06/01/2012] [Indexed: 12/18/2022] Open
Abstract
HIV-1 particle assembly is driven by the structural protein Gag. Gag binds to and multimerizes on the inner leaflet of the plasma membrane, eventually resulting in formation of spherical particles. During virus spread among T cells, Gag accumulates to the plasma membrane domain that, together with target cell membrane, forms a cell junction known as the virological synapse. While Gag association with plasma membrane microdomains has been implicated in virus assembly and cell-to-cell transmission, recent studies suggest that, rather than merely accumulating to pre-existing microdomains, Gag plays an active role in reorganizing the microdomains via its multimerization activity. In this paper, we will discuss this emerging view of Gag microdomain interactions. Relationships between Gag multimerization and microdomain association will be further discussed in the context of Gag localization to T-cell uropods and virological synapses.
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Affiliation(s)
- Ian B. Hogue
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - G. Nicholas Llewellyn
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Molecular Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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35
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Kyere SK, Mercredi PY, Dong X, Spearman P, Summers MF. The HIV-1 matrix protein does not interact directly with the protein interactive domain of AP-3δ. Virus Res 2012; 169:411-4. [PMID: 22705971 DOI: 10.1016/j.virusres.2012.06.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/06/2012] [Accepted: 06/06/2012] [Indexed: 11/19/2022]
Abstract
During the late phase of the Human Immunodeficiency Virus Type-1 (HIV-1) replication cycle, viral Gag proteins and the intact RNA genome are trafficked to specific sub-cellular membranes where virus assembly and budding occurs. Targeting to the plasma membranes of T cells and macrophages is mediated by interactions between the N-terminal matrix (MA) domain of Gag and cellular phosphatidylinositol-4,5-bisphosphate [PI(4,5)P(2)] molecules. However, in macrophages and dendritic cells, a subset of Gag proteins appears to be targeted to tetraspanin enriched viral compartments, a process that appears to be mediated by MA interactions with the Delta subunit of the cellular Adaptor Protein AP-3 (AP-3δ). We cloned, overexpressed and purified the protein interactive domain of AP-3δ and probed for MA binding by NMR. Unexpectedly, no evidence of binding was observed in these in vitro experiments, even at relatively high protein concentrations (200μM), suggesting that AP-3δ plays an alternative role in HIV-1 assembly.
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Affiliation(s)
- Sampson K Kyere
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
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Chu H, Wang JJ, Qi M, Yoon JJ, Wen X, Chen X, Ding L, Spearman P. The intracellular virus-containing compartments in primary human macrophages are largely inaccessible to antibodies and small molecules. PLoS One 2012; 7:e35297. [PMID: 22567100 PMCID: PMC3342280 DOI: 10.1371/journal.pone.0035297] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 03/14/2012] [Indexed: 12/29/2022] Open
Abstract
HIV-1 assembly and release occurs at the plasma membrane of human T lymphocytes and model epithelial cell lines, whereas in macrophages intracellular sites of virus assembly or accumulation predominate. The origin of the intracellular virus-containing compartment (VCC) has been controversial. This compartment is enriched in markers of the multivesicular body, and has been described as a modified endosomal compartment. Several studies of this compartment have revealed the presence of small channels connecting to the plasma membrane, suggesting that instead of an endosomal origin the compartment is a modified plasma membrane compartment. If the compartment is accessible to the external environment, this would have important implications for antiviral immune responses and antiviral therapy. We performed a series of experiments designed to determine if the VCC in macrophages was open to the external environment and accessible to antibodies and small molecules. The majority of VCCs were found to be inaccessible to exogenously-applied antibodies to tetraspanins in the absence of membrane permeabilization, while tetraspanin staining was readily observed following membrane permeabilization. Cationized ferritin was utilized to stain the plasma membrane, and revealed that the majority of virus-containing compartments were inaccessible to ferritin. Low molecular weight dextrans could access only a very small percentage of VCCs, and these tended to be more peripheral compartments. We conclude that the VCCs in monocyte-derived human macrophages are heterogeneous, but the majority of VCCs are closed to the external environment.
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Affiliation(s)
- Hin Chu
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Jaang-Jiun Wang
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Mingli Qi
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Jeong-Joong Yoon
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Xiaoyun Wen
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Xuemin Chen
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Lingmei Ding
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
| | - Paul Spearman
- Department of Pediatrics, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, United States of America
- * E-mail:
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Dordor A, Poudevigne E, Göttlinger H, Weissenhorn W. Essential and supporting host cell factors for HIV-1 budding. Future Microbiol 2012; 6:1159-70. [PMID: 22004035 DOI: 10.2217/fmb.11.100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
HIV-1 employs its structural proteins to orchestrate assembly and budding at the plasma membrane of host cells. The Gag polyprotein is sufficient to form virus-like particles in the absence of other viral proteins and provides a platform to interact with numerous cellular factors that regulate Gag trafficking to the site of assembly and budding. Notably endosomal sorting complexes required for transport have attained much attention over the last decade because of their essential role in virion release. Here we review recent advances in understanding the role of host cell factors recruited by Gag during HIV-1 assembly and budding.
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Affiliation(s)
- Aurelien Dordor
- Unit of Virus Host Cell Interactions UMI 3265 Université Joseph Fourier-EMBL-CNRS, 6 rue Jules Horowitz 38042 Grenoble Cedex 9, France
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Abstract
In macrophages, HIV-1 accumulates in intracellular vesicles designated virus-containing compartments (VCCs). These might play an important role in the constitution of macrophages as viral reservoirs and allow HIV-1 to evade the immune system by sequestration in an internal niche, which is difficult to access from the exterior. However, until now, evidence of whether internal virus accumulations are protected from the host's humoral immune response is still lacking. In order to be able to study the formation and antibody accessibility of VCCs, we generated HIV-1 with green fluorescent protein (GFP)-tagged Gag replicating in primary macrophages. Live-cell observations revealed faint initial cytosolic Gag expression and subsequent large intracellular Gag accumulations which stayed stable over days. Taking advantage of the opportunity to study the accessibility of intracellular VCCs via the cell surface, we demonstrate that macrophage internal HIV-1-containing compartments cannot be targeted by neutralizing antibodies. Furthermore, HIV-1 was efficiently transferred from antibody-treated macrophages to T cells. Three-dimensional reconstruction of electron microscopic slices revealed that Gag accumulations correspond to viral particles within enclosed compartments and convoluted membranes. Thus, although some VCCs were connected to the plasma membrane, the complex membrane architecture of the HIV-1-containing compartment might shield viral particles from neutralizing antibodies. In sum, our study provides evidence that HIV-1 is sequestered into a macrophage internal membranous web, posing an obstacle for the elimination of this viral reservoir.
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39
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Pelchen-Matthews A, Giese S, Mlčochová P, Turner J, Marsh M. β2 integrin adhesion complexes maintain the integrity of HIV-1 assembly compartments in primary macrophages. Traffic 2011; 13:273-91. [PMID: 22017400 DOI: 10.1111/j.1600-0854.2011.01306.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 11/30/2022]
Abstract
In human monocyte-derived macrophages (MDM), human immunodeficiency virus type 1 (HIV-1) assembly takes place primarily on complex intracellular plasma membrane domains connected to the cell surface by closely apposed membrane sheets or narrow channels. Some of the membranes associated with these compartments are decorated by thick (≈30 nm), electron-dense, cytoplasmic coats. Here we show by immunolabelling of ultrathin cryosections that the β2 integrin CD18, together with the αM and αX integrins (CD11b and CD11c), is clustered at these coated domains, and that the coats themselves contain the cytoskeletal linker proteins talin, vinculin and paxillin that connect the integrin complexes to the actin cytoskeleton. Intracellular plasma membrane-connected compartments (IPMC) with CD18-containing focal adhesion-like coats are also present in uninfected MDM. These compartments become more prominent as the cells mature in tissue culture and their appearance correlates with increased expression of CD18, CD11b/c and paxillin. Depletion of CD18 by RNA interference leads to parallel down-regulation of CD11b and CD11c, as well as of paxillin, and the disappearance of the adhesion-like coats. In addition, CD18 knockdown alters the appearance of virus-containing IPMC in HIV-infected MDM, indicating that the β2 integrin/focal adhesion-like coat structures are involved in the organization of these compartments.
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Affiliation(s)
- Annegret Pelchen-Matthews
- Cell Biology Unit, Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, WC1E 6BT, UK
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40
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Inhibition or deficiency of cathepsin B leads defects in HIV-1 Gag pseudoparticle release in macrophages and HEK293T cells. Antiviral Res 2011; 93:175-84. [PMID: 22138708 DOI: 10.1016/j.antiviral.2011.11.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 10/11/2011] [Accepted: 11/17/2011] [Indexed: 11/23/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) egresses from infected cells through utilizing the host membrane budding mechanisms. Assembly of HIV-1 Gag particles occurs on membranes where the Gag multimers subsequently bud off and form enveloped viral particles. In certain cell types such as macrophages, HIV-1 Gag particles have shown to be released into intracellular virus containing compartments (VCC) such as late endosomes, multivesicular bodies (MVBs) or invaginated plasma membrane pockets. Here, we showed that macrophages or HEK293T cells treated with the cathepsin B (CTSB)-specific inhibitor CA-074Me or cells deficient in CTSB failed to release HIV-1 Gag pseudoparticles into the extracellular environment. Based on immunofluorescence and electron microscopy, these cells retained the pseudoparticles in heterogeneous intracellular VCC. CA-074Me was also able to inhibit propagation of two enveloped viruses, herpes simplex virus and influenza A virus, but not non-enveloped enterovirus. These results suggest that CTSB is required for the efficient release of HIV-1 Gag pseudoparticles and targeting CTSB can be a new therapeutic strategy for inhibiting egress of HIV-1 and other enveloped viruses.
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Duncan CJA, Sattentau QJ. Viral determinants of HIV-1 macrophage tropism. Viruses 2011; 3:2255-79. [PMID: 22163344 PMCID: PMC3230851 DOI: 10.3390/v3112255] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 01/23/2023] Open
Abstract
Macrophages are important target cells for HIV-1 infection that play significant roles in the maintenance of viral reservoirs and other aspects of pathogenesis. Understanding the determinants of HIV-1 tropism for macrophages will inform HIV-1 control and eradication strategies. Tropism for macrophages is both qualitative (infection or not) and quantitative (replication capacity). For example many R5 HIV-1 isolates cannot infect macrophages, but for those that can the macrophage replication capacity can vary by up to 1000-fold. Some X4 viruses are also capable of replication in macrophages, indicating that cellular tropism is partially independent of co-receptor preference. Preliminary data obtained with a small number of transmitted/founder viruses indicate inefficient macrophage infection, whereas isolates from later in disease are more frequently tropic for macrophages. Thus tropism may evolve over time, and more macrophage tropic viruses may be implicated in the pathogenesis of advanced HIV-1 infection. Compartmentalization of macrophage-tropic brain-derived envelope glycoproteins (Envs), and non-macrophage tropic non-neural tissue-derived Envs points to adaptation of HIV-1 quasi-species in distinct tissue microenvironments. Mutations within and adjacent to the Env-CD4 binding site have been identified that determine macrophage tropism at the entry level, but post-entry molecular determinants of macrophage replication capacity involving HIV-1 accessory proteins need further definition.
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