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Yu X, Zhu Y, Yin G, Wang Y, Shi X, Cheng G. Exploiting hosts and vectors: viral strategies for facilitating transmission. EMBO Rep 2024:10.1038/s44319-024-00214-6. [PMID: 39048750 DOI: 10.1038/s44319-024-00214-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 04/17/2024] [Accepted: 06/25/2024] [Indexed: 07/27/2024] Open
Abstract
Viruses have developed various strategies to ensure their survival and transmission. One intriguing strategy involves manipulating the behavior of infected arthropod vectors and hosts. Through intricate interactions, viruses can modify vector behavior, aiding in crossing barriers and improving transmission to new hosts. This manipulation may include altering vector feeding preferences, thus promoting virus transmission to susceptible individuals. In addition, viruses employ diverse dissemination methods, including cell-to-cell and intercellular transmission via extracellular vesicles. These strategies allow viruses to establish themselves in favorable environments, optimize replication, and increase the likelihood of spreading to other individuals. Understanding these complex viral strategies offers valuable insights into their biology, transmission dynamics, and potential interventions for controlling infections. Unraveling interactions between viruses, hosts, and vectors enables the development of targeted approaches to effectively mitigate viral diseases and prevent transmission.
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Affiliation(s)
- Xi Yu
- New Cornerstone Science Laboratory, Tsinghua-Peking Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, Guangdong, 518000, China
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, Guangdong, 518055, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yibin Zhu
- New Cornerstone Science Laboratory, Tsinghua-Peking Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, Guangdong, 518055, China
| | - Gang Yin
- Department of Parasitology, School of Basic Medical Sciences, Central South University, Changsha, Hunan, 410013, China
| | - Yibaina Wang
- China National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Xiaolu Shi
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, Guangdong, 518055, China
| | - Gong Cheng
- New Cornerstone Science Laboratory, Tsinghua-Peking Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China.
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, Guangdong, 518000, China.
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, Guangdong, 518055, China.
- Southwest United Graduate School, Kunming, 650092, China.
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2
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Heparan Sulfate Proteoglycans in Viral Infection and Treatment: A Special Focus on SARS-CoV-2. Int J Mol Sci 2021; 22:ijms22126574. [PMID: 34207476 PMCID: PMC8235362 DOI: 10.3390/ijms22126574] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 01/27/2023] Open
Abstract
Heparan sulfate proteoglycans (HSPGs) encompass a group of glycoproteins composed of unbranched negatively charged heparan sulfate (HS) chains covalently attached to a core protein. The complex HSPG biosynthetic machinery generates an extraordinary structural variety of HS chains that enable them to bind a plethora of ligands, including growth factors, morphogens, cytokines, chemokines, enzymes, matrix proteins, and bacterial and viral pathogens. These interactions translate into key regulatory activity of HSPGs on a wide range of cellular processes such as receptor activation and signaling, cytoskeleton assembly, extracellular matrix remodeling, endocytosis, cell-cell crosstalk, and others. Due to their ubiquitous expression within tissues and their large functional repertoire, HSPGs are involved in many physiopathological processes; thus, they have emerged as valuable targets for the therapy of many human diseases. Among their functions, HSPGs assist many viruses in invading host cells at various steps of their life cycle. Viruses utilize HSPGs for the attachment to the host cell, internalization, intracellular trafficking, egress, and spread. Recently, HSPG involvement in the pathogenesis of SARS-CoV-2 infection has been established. Here, we summarize the current knowledge on the molecular mechanisms underlying HSPG/SARS-CoV-2 interaction and downstream effects, and we provide an overview of the HSPG-based therapeutic strategies that could be used to combat such a fearsome virus.
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3
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Primary HIV-1 and Infectious Molecular Clones Are Differentially Susceptible to Broadly Neutralizing Antibodies. Vaccines (Basel) 2020; 8:vaccines8040782. [PMID: 33371189 PMCID: PMC7767270 DOI: 10.3390/vaccines8040782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/19/2020] [Accepted: 12/20/2020] [Indexed: 11/16/2022] Open
Abstract
To prevent the spread of HIV-1, a vaccine should elicit antibodies that block viral entry for all cell types. Recently, we have developed a virus capture assay to quantitatively examine early time points of infection. Here we present data on the ability of bNAbs to inhibit capture (1 h) or replication (48 h) of purified primary acute or chronic HIV or infectious molecular clones (IMCs) in human peripheral blood mononuclear cells (PBMCs) as quantified by qRT-PCR. Although bNAbs significantly inhibited HIV-1 replication in PBMCs in a virus subtype and in a PBMC-donor specific manner, they did not inhibit virus capture of primary viruses. In contrast, IMC capture and replication in PBMCs and purified CD4+ T cells were significantly inhibited by bNAbs, thus indicating that unlike IMCs, primary HIV-1 may initially bind to other cell surface molecules, which leads to virus capture even in the presence of bNAbs. Our results demonstrate that the initial interactions and some aspects of infectivity of primary HIV-1 and IMCs are inherently different, which underscores the importance of studying virus transmission using primary viruses in in vitro studies, an issue that could impact HIV-1 vaccine design strategies.
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Llorente García I, Marsh M. A biophysical perspective on receptor-mediated virus entry with a focus on HIV. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183158. [PMID: 31863725 PMCID: PMC7156917 DOI: 10.1016/j.bbamem.2019.183158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry.
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Affiliation(s)
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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5
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HIV-1-Infected CD4+ T Cells Facilitate Latent Infection of Resting CD4+ T Cells through Cell-Cell Contact. Cell Rep 2020; 24:2088-2100. [PMID: 30134170 DOI: 10.1016/j.celrep.2018.07.079] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/01/2018] [Accepted: 07/22/2018] [Indexed: 02/07/2023] Open
Abstract
HIV-1 is transmitted between T cells through the release of cell-free particles and through cell-cell contact. Cell-to-cell transmission is more efficient than cell-free virus transmission, mediates resistance to immune responses, and facilitates the spread of virus among T cells. However, whether HIV cell-to-cell transmission influences the establishment of HIV-1 latency has not been carefully explored. We developed an HIV-1 latency model based on the transmission of HIV-1 directly to resting CD4+ T cells by cell-cell contact. This model recapitulates the spread of HIV-1 in T-cell-dense anatomical compartments. We demonstrate that productively infected activated CD4+ T cells transmit HIV-1 to resting CD4+ T cells in a cell-contact-dependent manner. However, proviruses generated in this fashion are more difficult to induce compared to proviruses generated by cell-free infection, suggesting that cell-to-cell transmission influences the establishment and maintenance of latent infection in resting CD4+ T cells.
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Rumlová M, Ruml T. In vitro methods for testing antiviral drugs. Biotechnol Adv 2018; 36:557-576. [PMID: 29292156 PMCID: PMC7127693 DOI: 10.1016/j.biotechadv.2017.12.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 12/22/2017] [Accepted: 12/27/2017] [Indexed: 12/24/2022]
Abstract
Despite successful vaccination programs and effective treatments for some viral infections, humans are still losing the battle with viruses. Persisting human pandemics, emerging and re-emerging viruses, and evolution of drug-resistant strains impose continuous search for new antiviral drugs. A combination of detailed information about the molecular organization of viruses and progress in molecular biology and computer technologies has enabled rational antivirals design. Initial step in establishing efficacy of new antivirals is based on simple methods assessing inhibition of the intended target. We provide here an overview of biochemical and cell-based assays evaluating the activity of inhibitors of clinically important viruses.
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Affiliation(s)
- Michaela Rumlová
- Department of Biotechnology, University of Chemistry and Technology, Prague 166 28, Czech Republic.
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 166 28, Czech Republic.
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Xiao S, Tian Z, Wang Y, Si L, Zhang L, Zhou D. Recent progress in the antiviral activity and mechanism study of pentacyclic triterpenoids and their derivatives. Med Res Rev 2018; 38:951-976. [PMID: 29350407 PMCID: PMC7168445 DOI: 10.1002/med.21484] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 12/14/2017] [Accepted: 12/16/2017] [Indexed: 12/20/2022]
Abstract
Viral infections cause many serious human diseases with high mortality rates. New drug‐resistant strains are continually emerging due to the high viral mutation rate, which makes it necessary to develop new antiviral agents. Compounds of plant origin are particularly interesting. The pentacyclic triterpenoids (PTs) are a diverse class of natural products from plants composed of three terpene units. They exhibit antitumor, anti‐inflammatory, and antiviral activities. Oleanolic, betulinic, and ursolic acids are representative PTs widely present in nature with a broad antiviral spectrum. This review focuses on the recent literatures in the antiviral efficacy of this class of phytochemicals and their derivatives. In addition, their modes of action are also summarized.
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Affiliation(s)
- Sulong Xiao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Zhenyu Tian
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Yufei Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Longlong Si
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Lihe Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Demin Zhou
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China
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8
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Mulato A, Hansen D, Thielen A, Porter D, Stepan G, White K, Daeumer M, Cihlar T, Yant SR. Rapid In Vitro Evaluation of Antiretroviral Barrier to Resistance at Therapeutic Drug Levels. AIDS Res Hum Retroviruses 2016; 32:1237-1247. [PMID: 27356854 DOI: 10.1089/aid.2016.0071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Failure of combination antiretroviral (ARV) therapy in HIV-infected patients is often associated with the emergence of drug resistance-associated mutations (RAMs). To facilitate analysis of the barrier to resistance at therapeutically relevant ARV concentrations, we performed fixed-dose in vitro HIV-1 drug resistance selection assays using the immortalized MT-2 T-cell line and primary human CD4+ T cells with a panel of FDA-approved ARVs, each at their respective cell culture equivalent clinical trough concentration (CCE Cmin). At high multiples of its CCE Cmin, emtricitabine (FTC) selected for the rapid emergence of M184I/V, a result consistent with resistance emergence in vivo. While the rate of viral breakthrough in the presence of rilpivirine or efavirenz was delayed relative to FTC, both inhibitors selected for virus with known clinically relevant RAMs. No viral breakthrough was observed for the protease inhibitor atazanavir even at subtherapeutic drug concentrations, which is consistent with its previously characterized high in vivo barrier to resistance. Depending on assay conditions, treatment with integrase inhibitors elvitegravir and raltegravir resulted in breakthrough of both resistant and wild-type virus. The RAMs observed in drug selections were not detected above a 2% threshold by deep sequencing in the in vitro virus inoculum, and only rarely in isolates from treatment-naive HIV+ patients. These new viral breakthrough assays facilitate the analysis of multiple experimental replicates and conditions in parallel and provide a rapid quantitative means to evaluate drug resistance emergence at therapeutically relevant drug concentrations, which should facilitate the identification of new ARVs with a high barrier to resistance.
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HIV Cell-to-Cell Spread Results in Earlier Onset of Viral Gene Expression by Multiple Infections per Cell. PLoS Pathog 2016; 12:e1005964. [PMID: 27812216 PMCID: PMC5094736 DOI: 10.1371/journal.ppat.1005964] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/29/2016] [Indexed: 02/07/2023] Open
Abstract
Cell-to-cell spread of HIV, a directed mode of viral transmission, has been observed to be more rapid than cell-free infection. However, a mechanism for earlier onset of viral gene expression in cell-to-cell spread was previously uncharacterized. Here we used time-lapse microscopy combined with automated image analysis to quantify the timing of the onset of HIV gene expression in a fluorescent reporter cell line, as well as single cell staining for infection over time in primary cells. We compared cell-to-cell spread of HIV to cell-free infection, and limited both types of transmission to a two-hour window to minimize differences due to virus transit time to the cell. The mean time to detectable onset of viral gene expression in cell-to-cell spread was accelerated by 19% in the reporter cell line and by 35% in peripheral blood mononuclear cells relative to cell-free HIV infection. Neither factors secreted by infected cells, nor contact with infected cells in the absence of transmission, detectably changed onset. We recapitulated the earlier onset by infecting with multiple cell-free viruses per cell. Surprisingly, the acceleration in onset of viral gene expression was not explained by cooperativity between infecting virions. Instead, more rapid onset was consistent with a model where the fastest expressing virus out of the infecting virus pool sets the time for infection independently of the other co-infecting viruses. How quickly infection occurs should be an important determinant of viral fitness, but mechanisms which could accelerate the onset of viral gene expression were previously undefined. In this work we use time-lapse microscopy to quantify the timing of the HIV viral cycle and show that onset of viral gene expression can be substantially accelerated. This occurs during cell-to-cell spread of HIV, a mode of directed viral infection where multiple virions are transmitted between cells. Surprisingly, we found that neither cooperativity between infecting viruses, nor trans-acting factors from already infected cells, influence the timing of infection. Rather, we show experimentally that a more rapid onset of infection is explained by a first-past-the-post mechanism, where the fastest expressing virus out of the infecting virus pool sets the time for the onset of viral gene expression of an individual cell independently of other infections of the same cell. Fast onset of viral gene expression in cell-to-cell spread may play an important role in seeding the HIV reservoir, which rapidly makes infection irreversible.
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10
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Becerra JC, Bildstein LS, Gach JS. Recent Insights into the HIV/AIDS Pandemic. MICROBIAL CELL (GRAZ, AUSTRIA) 2016; 3:451-475. [PMID: 28357381 PMCID: PMC5354571 DOI: 10.15698/mic2016.09.529] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/27/2016] [Indexed: 12/21/2022]
Abstract
Etiology, transmission and protection: Transmission of HIV, the causative agent of AIDS, occurs predominantly through bodily fluids. Factors that significantly alter the risk of HIV transmission include male circumcision, condom use, high viral load, and the presence of other sexually transmitted diseases. Pathology/Symptomatology: HIV infects preferentially CD4+ T lymphocytes, and Monocytes. Because of their central role in regulating the immune response, depletion of CD4+ T cells renders the infected individual incapable of adequately responding to microorganisms otherwise inconsequential. Epidemiology, incidence and prevalence: New HIV infections affect predominantly young heterosexual women and homosexual men. While the mortality rates of AIDS related causes have decreased globally in recent years due to the use of highly active antiretroviral therapy (HAART) treatment, a vaccine remains an elusive goal. Treatment and curability: For those afflicted HIV infection remains a serious illness. Nonetheless, the use of advanced therapeutics have transformed a dire scenario into a chronic condition with near average life spans. When to apply those remedies appears to be as important as the remedies themselves. The high rate of HIV replication and the ability to generate variants are central to the viral survival strategy and major barriers to be overcome. Molecular mechanisms of infection: In this review, we assemble new details on the molecular events from the attachment of the virus, to the assembly and release of the viral progeny. Yet, much remains to be learned as understanding of the molecular mechanisms used in viral replication and the measures engaged in the evasion of immune surveillance will be important to develop effective interventions to address the global HIV pandemic.
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Affiliation(s)
- Juan C. Becerra
- Department of Medicine, Division of Infectious Diseases, University
of California, Irvine, Irvine, CA 92697, USA
| | | | - Johannes S. Gach
- Department of Medicine, Division of Infectious Diseases, University
of California, Irvine, Irvine, CA 92697, USA
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11
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Cohen M. Notable Aspects of Glycan-Protein Interactions. Biomolecules 2015; 5:2056-72. [PMID: 26340640 PMCID: PMC4598788 DOI: 10.3390/biom5032056] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 08/27/2015] [Accepted: 08/27/2015] [Indexed: 01/01/2023] Open
Abstract
This mini review highlights several interesting aspects of glycan-mediated interactions that are common between cells, bacteria, and viruses. Glycans are ubiquitously found on all living cells, and in the extracellular milieu of multicellular organisms. They are known to mediate initial binding and recognition events of both immune cells and pathogens with their target cells or tissues. The host target tissues are hidden under a layer of secreted glycosylated decoy targets. In addition, pathogens can utilize and display host glycans to prevent identification as foreign by the host’s immune system (molecular mimicry). Both the host and pathogens continually evolve. The host evolves to prevent infection and the pathogens evolve to evade host defenses. Many pathogens express both glycan-binding proteins and glycosidases. Interestingly, these proteins are often located at the tip of elongated protrusions in bacteria, or in the leading edge of the cell. Glycan-protein interactions have low affinity and, as a result, multivalent interactions are often required to achieve biologically relevant binding. These enable dynamic forms of adhesion mechanisms, reviewed here, and include rolling (cells), stick and roll (bacteria) or surfacing (viruses).
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Affiliation(s)
- Miriam Cohen
- Depatment of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, BRF2 MC 0687, La Jolla, CA 92093-0687, USA.
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12
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Determining the involvement and therapeutic implications of host cellular factors in hepatitis C virus cell-to-cell spread. J Virol 2014; 88:5050-61. [PMID: 24554660 DOI: 10.1128/jvi.03241-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infects 180 million people worldwide and is a leading cause of liver diseases such as fibrosis, cirrhosis, and hepatocellular carcinoma. It has been shown that HCV can spread to naive cells using two distinct entry mechanisms, "cell-free" entry of infectious extracellular virions that have been released by infected cells and direct "cell-to-cell" transmission. Here, we examined host cell requirements for HCV spread and found that the cholesterol uptake receptor NPC1L1, which we recently identified as being an antiviral target involved in HCV cell-free entry/spread, is also required for the cell-to-cell spread. In contrast, the very low density lipoprotein (VLDL) pathway, which is required for the secretion of cell-free infectious virus and thus has been identified as an antiviral target for blocking cell-free virus secretion/spread, is not required for cell-to-cell spread. Noting that HCV cell-free and cell-to-cell spread share some common factors but not others, we tested the therapeutic implications of these observations and demonstrate that inhibitors that target cell factors required for both forms of HCV spread exhibit synergy when used in combination with interferon (a representative inhibitor of intracellular HCV production), while inhibitors that block only cell-free spread do not. This provides insight into the mechanistic basis of synergy between interferon and HCV entry inhibitors and highlights the broader, previously unappreciated impact blocking HCV cell-to-cell spread can have on the efficacy of HCV combination therapies. IMPORTANCE HCV can spread to naive cells using distinct mechanisms: "cell-free" entry of extracellular virus and direct "cell-to-cell" transmission. Herein, we identify the host cell HCV entry factor NPC1L1 as also being required for HCV cell-to-cell spread, while showing that the VLDL pathway, which is required for the secretion of cell-free infectious virus, is not required for cell-to-cell spread. While both these host factors are considered viable antiviral targets, we demonstrate that only inhibitors that block factors required for both forms of HCV entry/spread (i.e., NPC1L1) exhibit synergy when used in combination with interferon, while inhibitors that block factors required only for cell-free spread (i.e., VLDL pathway components) do not. Thus, this study advances our understanding of HCV cell-to-cell spread, provides mechanistic insight into the basis of drug synergy, and highlights inhibition of HCV spread as a previously unappreciated consideration in HCV therapy design.
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Connell BJ, Lortat-Jacob H. Human immunodeficiency virus and heparan sulfate: from attachment to entry inhibition. Front Immunol 2013; 4:385. [PMID: 24312095 PMCID: PMC3834540 DOI: 10.3389/fimmu.2013.00385] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/05/2013] [Indexed: 11/13/2022] Open
Abstract
By targeting cells that provide protection against infection, HIV-1 causes acquired immunodeficiency syndrome. Infection starts when gp120, the viral envelope glycoprotein, binds to CD4 and to a chemokine receptor usually CCR5 or CXCR4. As many microorganisms, HIV-1 also interacts with heparan sulfate (HS), a complex group of cell surface associated anionic polysaccharides. It has been thought that this binding, occurring at a step prior to CD4 recognition, increases infectivity by pre-concentrating the virion particles at the cell surface. Early work, dating from before the identification of CCR5 and CXCR4, showed that a variety of HS mimetics bind to the gp120 V3 loop through electrostatic interactions, compete with cell surface associated HS to bind the virus and consequently, neutralize the infectivity of a number of T-cell line-adapted HIV-1 strains. However, progress made to better understand HIV-1 attachment and entry, coupled with the recent identification of additional gp120 regions mediating HS recognition, have considerably modified this view. Firstly, the V3 loop from CXCR4-using viruses is much more positively charged compared to those using CCR5. HS inhibition of cell attachment is thus restricted to CXCR4-using viruses (such as T-cell line-adapted HIV-1). Secondly, studies aiming at characterizing the gp120/HS complex revealed that HS binding was far more complex than previously thought: in addition to the V3 loop of CXCR4 tropic gp120, HS interacts with several other cryptic areas of the protein, which can be induced upon CD4 binding, and are conserved amongst CCR5 and CXCR4 viruses. In view of these data, this review will detail the present knowledge on HS binding to HIV-1, with regards to attachment and entry processes. It will discuss the perspective of targeting the gp120 co-receptor binding site with HS mimetic compounds, a strategy that recently gave rise to entry inhibitors that work in the low nanomolar range, independently of co-receptor usage.
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Affiliation(s)
- Bridgette J Connell
- University of Grenoble Alpes, Institut de Biologie Structurale , Grenoble , France ; Centre National de la Recherche Scientifique, Institut de Biologie Structurale , Grenoble , France ; Commissariat à l'Énergie Atomique, Direction des Sciences du Vivant, Institut de Biologie Structurale , Grenoble , France
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14
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Skinner AM, Chakkaramakkil Verghese S, Kurre P. Cell-cell transmission of VSV-G pseudotyped lentivector particles. PLoS One 2013; 8:e74925. [PMID: 24040363 PMCID: PMC3769293 DOI: 10.1371/journal.pone.0074925] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 08/07/2013] [Indexed: 12/22/2022] Open
Abstract
Many replicating viruses, including HIV-1 and HTLV-1, are efficiently transmitted from the cell surface of actively infected cells upon contact with bystander cells. In a previous study, we reported the prolonged cell surface retention of VSV-G replication-deficient pseudotyped lentivector prior to endocytic entry. However, the competing kinetics of cell surface versus dissociation, neutralization or direct transfer to other cells have received comparatively little attention. Here we demonstrate that the relative efficiency of cell-cell surface transmission can outpace "cell-free" transduction at limiting vector input. This coincides with the prolonged half-life of cell bound vector but occurs, unlike HTLV-1, without evidence for particle aggregation. These studies suggest that cell-surface attachment stabilizes particles and alters neutralization kinetics. Our experiments provide novel insight into the underexplored cell-cell transmission of pseudotyped particles.
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Affiliation(s)
- Amy M. Skinner
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Santhosh Chakkaramakkil Verghese
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Peter Kurre
- Departments of Pediatrics, Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Cell & Developmental Biology, Oregon Health & Science University, Portland, Oregon, United States of America
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15
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Chen CC, Liu HP, Chao M, Liang Y, Tsang NM, Huang HY, Wu CC, Chang YS. NF-κB-mediated transcriptional upregulation of TNFAIP2 by the Epstein-Barr virus oncoprotein, LMP1, promotes cell motility in nasopharyngeal carcinoma. Oncogene 2013; 33:3648-59. [PMID: 23975427 DOI: 10.1038/onc.2013.345] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/01/2013] [Accepted: 07/22/2013] [Indexed: 12/21/2022]
Abstract
Nasopharyngeal carcinoma (NPC), which is closely associated with Epstein-Barr virus (EBV), is a metastasis-prone epithelial cancer. We previously showed that tumor necrosis factor α-induced protein 2 (TNFAIP2) is highly expressed in NPC tumor tissues and is correlated with metastasis and poor survival in NPC patients. However, the underlying mechanism remains unclear. In this study, we demonstrate that the EBV oncoprotein, latent membrane protein 1 (LMP1), can transcriptionally induce TNFAIP2 expression via NF-κB. Quantitative RT-PCR and western blotting revealed that LMP1 induces TNFAIP2 expression through its C-terminal-activating region (CTAR2) domain, which is required for transduction of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) signaling. Inhibition of NF-κB activation or depletion of p65 (a component of NF-κB) by RNA interference abolished the LMP1-induced expression of TNFAIP2, whereas ectopic expression of p65 was sufficient to induce TNFAIP2 expression. Luciferase reporter assays showed that LMP1 transcriptionally induces TNFAIP2 expression through a newly identified NF-κB-binding site within the TNFAIP2 promoter (-3,869 to -3,860 bp). Immunohistochemical analysis of NPC biopsy specimens further revealed a significant correlation between the protein levels of TNFAIP2 and activated p65 (R=0.689, P<0.001), indicating that our findings are clinically relevant. Immunofluorescence microscopy and co-immunoprecipitation assays showed that TNFAIP2 associates with actin and is involved in the formation of actin-based membrane protrusions. Furthermore, transwell migration assays demonstrated that TNFAIP2 contributes to LMP1-induced cell motility. Collectively, these findings provide novel insights into the regulation of TNFAIP2 and its role in promoting NPC tumor progression.
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Affiliation(s)
- C-C Chen
- Chang Gung Molecular Medicine Research Center, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
| | - H-P Liu
- Chang Gung Molecular Medicine Research Center, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
| | - M Chao
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
| | - Y Liang
- Chang Gung Molecular Medicine Research Center, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
| | - N-M Tsang
- Departments of Radiation Oncology, Chang Gung Memorial Hospital at Lin-Kou, Kwei-Shan, Taiwan
| | - H-Y Huang
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
| | - C-C Wu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kwei-Shan, Taiwan
| | - Y-S Chang
- Chang Gung Molecular Medicine Research Center, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-Shan, Taiwan
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16
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Sewald X, Gonzalez DG, Haberman AM, Mothes W. In vivo imaging of virological synapses. Nat Commun 2013; 3:1320. [PMID: 23271654 DOI: 10.1038/ncomms2338] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 11/23/2012] [Indexed: 11/09/2022] Open
Abstract
Retroviruses such as the human immunodeficiency virus, human T-cell lymphotropic virus and murine leukaemia virus are believed to spread via sites of cell-cell contact designated virological synapses. Support for this model is based on in vitro evidence in which infected cells are observed to specifically establish long-lived cell-cell contact with uninfected cells. Whether virological synapses exist in vivo is unknown. Here we apply intravital microscopy to identify a subpopulation of B cells infected with the Friend murine leukaemia virus that form virological synapses with uninfected leucocytes in the lymph node of living mice. In vivo virological synapses are, like their in vitro counterpart, dependent on the expression of the viral envelope glycoprotein and are characterized by a prolonged polarization of viral capsid to the cell-cell interface. Our results validate the concept of virological synapses and introduce intravital imaging as a tool to visualize retroviral spreading directly in living mice.
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Affiliation(s)
- Xaver Sewald
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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17
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HIV-1 Gag associates with specific uropod-directed microdomains in a manner dependent on its MA highly basic region. J Virol 2013; 87:6441-54. [PMID: 23536680 DOI: 10.1128/jvi.00040-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In polarized T cells, HIV-1 Gag localizes to a rear-end protrusion known as the uropod in a multimerization-dependent manner. Gag-laden uropods participate in formation of virological synapses, intercellular contact structures that play a key role in cell-to-cell HIV-1 transmission. Our previous observations suggest that Gag associates with uropod-directed microdomains (UDMs) that eventually comigrate with Gag to the uropod over the cell surface. However, the nature of Gag multimerization required for this movement, the composition of the UDMs, and the molecular determinants for Gag association with these microdomains remain unknown. In this study, we found that Gag multimerization prior to budding but beyond dimerization is necessary for Gag localization to the uropods, indicating that uropod localization occurs early in the assembly process. We also found that prior to membrane curvature, Gag multimers associate with a specific subset of UDMs containing PSGL-1, CD43, and CD44 but not ICAM-1, ICAM-3, or CD59. Notably, upon association, Gag excludes ICAM-3 from this subset of UDMs, revealing an active and selective reorganization of these microdomains by Gag. This specific association between Gag and UDMs is dependent on the highly basic region (HBR) in the Gag matrix (MA) domain. The overall positive charge of the HBR was needed for the interaction with the specific UDM subset, while the exact HBR sequence was not, unlike that seen for MA binding to the plasma membrane phospholipid phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. Taken together, these findings revealed that HIV-1 Gag associates with specific microdomains present in polarized T cells in an MA-dependent manner, which results in modification of the microdomain constituents.
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18
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Zhong P, Agosto LM, Munro JB, Mothes W. Cell-to-cell transmission of viruses. Curr Opin Virol 2012; 3:44-50. [PMID: 23219376 DOI: 10.1016/j.coviro.2012.11.004] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 10/28/2012] [Accepted: 11/13/2012] [Indexed: 01/08/2023]
Abstract
The life cycle of most viruses involves the release of particles into the extracellular space. Consequently, the study of virus egress as well as virus entry has focused almost exclusively on the biology of cell-free virus. However, cell-free virus spread is often very inefficient. Specific barriers, either located in the donor cell or in the target cell, prevent efficient spread by the cell-free mode. In contrast, viral spread by direct cell-cell contact is largely unaffected by most of these barriers resulting in preferential spread by cell-to-cell transmission. Virus cell-to-cell transmission allows an efficient coordination of several steps of the viral life cycle. It often involves complex inter-cellular adhesion, cellular polarity and intra-cellular trafficking. Because virus cell-to-cell transmission can involve transmission through zones of tight cell-cell contact that are resistant to neutralizing antibodies and reach a high local particle concentration, cell-to-cell transmission can contribute to the pathogenesis of viral infections.
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Affiliation(s)
- Peng Zhong
- Department of Microbial Pathogenesis, Yale University School of Medicine, 295 Congress Ave., New Haven, CT 06536, USA
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19
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O’Flynn NJ, Patel A, Kadlec J, Jones I. Improving promiscuous mammalian cell entry by the baculovirus Autographa californica multiple nuclear polyhedrosis virus. Biosci Rep 2012; 33:23-36. [PMID: 23035899 PMCID: PMC3522474 DOI: 10.1042/bsr20120093] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 09/25/2012] [Accepted: 10/02/2012] [Indexed: 02/08/2023] Open
Abstract
The insect baculovirus AcMNPV (Autographa californica multiple nuclear polyhedrosis virus) enters many mammalian cell lines, prompting its application as a general eukaryotic gene delivery agent, but the basis of entry is poorly understood. For adherent mammalian cells, we show that entry is favoured by low pH and by increasing the available cell-surface area through a transient release from the substratum. Low pH also stimulated baculovirus entry into mammalian cells grown in suspension which, optimally, could reach 90% of the transduced population. The basic loop, residues 268-281, of the viral surface glycoprotein gp64 was required for entry and a tetra mutant with increasing basicity increased entry into a range of mammalian cells. The same mutant failed to plaque in Sf9 cells, instead showing individual cell entry and minimal cell-to-cell spread, consistent with an altered fusion phenotype. Viruses grown in different insect cells showed different mammalian cell entry efficiencies, suggesting that additional factors also govern entry.
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Key Words
- baculovirus
- fusion
- gene transduction
- gp64
- mammalian cell
- virus entry
- acmnpv, autographa californica multiple nuclear polyhedrosis virus
- atcp, amorphous tricalcium phosphate
- cf, carboxyfluorescein
- cho, chinese-hamster ovary
- dmem, dulbecco’s modified eagle’s medium
- egfp, enhanced green fluorescent protein
- fcs, fetal calf serum
- hek-293t, hek-293 cells expressing the large t-antigen of sv40 (simian virus 40)
- ie1, immediate early 1
- moi, multiplicity of infection
- mab, monoclonal antibody
- npv, nucleopolyhedrosis virus
- pc, phosphatidylcholine
- pbs-t, pbs containing 0.1% tween 20
- pe, phosphatidylethanolamine
- pi, phosphatidylinositol
- popc, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- popg, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol
- qpcr, quantitative pcr
- rmsd, root mean square deviation
- vsv g, vesicular-stomatitis virus glycoprotein g
- wt, wild-type
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Affiliation(s)
- Neil M. J. O’Flynn
- *School of Biological Sciences, University of Reading, Reading RG6 6AJ, U.K
| | - Avnish Patel
- *School of Biological Sciences, University of Reading, Reading RG6 6AJ, U.K
| | - Jan Kadlec
- †European Molecular Biology Laboratory, BP 181, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
| | - Ian M. Jones
- *School of Biological Sciences, University of Reading, Reading RG6 6AJ, U.K
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20
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Pique C, Jones KS. Pathways of cell-cell transmission of HTLV-1. Front Microbiol 2012; 3:378. [PMID: 23109932 PMCID: PMC3479854 DOI: 10.3389/fmicb.2012.00378] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/03/2012] [Indexed: 01/23/2023] Open
Abstract
The deltaretroviruses human T cell lymphotropic virus type 1 (HTLV-1) and human T cell lymphotropic virus type 2 (HTLV-2) have long been believed to differ from retroviruses in other genera by their mode of transmission. While other retroviruses were thought to primarily spread by producing cell-free particles that diffuse through extracellular fluids prior to binding to and infecting target cells, HTLV-1 and HTLV-2 were believed to transmit the virus solely by cell–cell interactions. This difference in transmission was believed to reflect the fact that, relative to other retroviruses, the cell-free virions produced by HTLV-infected cells are very poorly infectious. Since HTLV-1 and HTLV-2 are primarily found in T cells in the peripheral blood, spread of these viruses was believed to occur between infected and uninfected, T cells, although little was known about the cellular and viral proteins involved in this interaction. Recent studies have revealed that the method of transmission of HTLV is not unique: other retroviruses including human immunodeficiency virus (HIV) are also transmitted from cell-to-cell, and this method is dramatically more efficient than cell-free transmission. Moreover, cell–cell transmission of HTLV-1, as well as HIV, can occur following interactions between dendritic cells and T cells, as well as between T cells. Conversely, other studies have shown that cell-free HTLV-1 is not as poorly infectious as previously thought, since it is capable of infecting certain cell types. Here we summarize the recent insights about the mechanisms of cell–cell transmission of HTLV-1 and other retroviruses. We also review in vitro and in vivo studies of infection and discuss how these finding may relate to the spread of HTLV-1 between individuals.
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Affiliation(s)
- Claudine Pique
- CNRS UMR 8104, INSERM U567, Université Paris-Descartes, Institut Cochin Paris, France
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21
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Wilen CB, Tilton JC, Doms RW. HIV: cell binding and entry. Cold Spring Harb Perspect Med 2012; 2:cshperspect.a006866. [PMID: 22908191 DOI: 10.1101/cshperspect.a006866] [Citation(s) in RCA: 373] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The first step of the human immunodeficiency virus (HIV) replication cycle-binding and entry into the host cell-plays a major role in determining viral tropism and the ability of HIV to degrade the human immune system. HIV uses a complex series of steps to deliver its genome into the host cell cytoplasm while simultaneously evading the host immune response. To infect cells, the HIV protein envelope (Env) binds to the primary cellular receptor CD4 and then to a cellular coreceptor. This sequential binding triggers fusion of the viral and host cell membranes, initiating infection. Revealing the mechanism of HIV entry has profound implications for viral tropism, transmission, pathogenesis, and therapeutic intervention. Here, we provide an overview into the mechanism of HIV entry, provide historical context to key discoveries, discuss recent advances, and speculate on future directions in the field.
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Affiliation(s)
- Craig B Wilen
- Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
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22
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Retroviral env glycoprotein trafficking and incorporation into virions. Mol Biol Int 2012; 2012:682850. [PMID: 22811910 PMCID: PMC3395148 DOI: 10.1155/2012/682850] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/08/2012] [Accepted: 05/31/2012] [Indexed: 11/17/2022] Open
Abstract
Together with the Gag protein, the Env glycoprotein is a major retroviral structural protein and is essential for forming infectious virus particles. Env is synthesized, processed, and transported to certain microdomains at the plasma membrane and takes advantage of the same host machinery for its trafficking as that used by cellular glycoproteins. Incorporation of Env into progeny virions is probably mediated by the interaction between Env and Gag, in some cases with the additional involvement of certain host factors. Although several general models have been proposed to explain the incorporation of retroviral Env glycoproteins into virions, the actual mechanism for this process is still unclear, partly because structural data on the Env protein cytoplasmic tail is lacking. This paper presents the current understanding of the synthesis, trafficking, and virion incorporation of retroviral Env proteins.
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23
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Liu M, Eiden MV. A mutant retroviral receptor restricts virus superinfection interference and productive infection. Retrovirology 2012; 9:51. [PMID: 22691439 PMCID: PMC3418563 DOI: 10.1186/1742-4690-9-51] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/12/2012] [Indexed: 11/13/2022] Open
Abstract
Background Both cell-free and cell-associated infection routes are important for retroviral dissemination. Regardless of the mechanism, the driving force of retroviral entry is the interaction between the viral envelope and its receptor. To date it remains unclear how decreased affinity of viruses for their receptors affects viral cell-free infection, cell-cell transmission, and spreading kinetics. We have previously characterized a mutant form of the amphotropic murine retrovirus receptor human phosphate transporter 2 (PiT2) wherein the single substitution of a glutamic acid for the lysine residue at position 522 of this receptor is sufficient to render it to function as a gibbon ape leukemia virus (GALV) receptor. Results In this study we analyzed the binding affinity of the mutant receptor PiT2K522E and determined that it has a 1000 fold decreased GALV envelope binding affinity compared to the GALV wild type receptor. The decreased affinity does not restrict the initiation of cell-free GALV infection. The diminished binding affinity does, however, correlate with a decrease in the ability of GALV to spread in cells expressing this mutant receptor. Conclusions The reduced ability of GALV to subsequently spread among cells expressing PiT2K522E is likely resulted from reduced cell-cell transmission, the decreased ability of PiT2K522E-expressing cells to establish superinfection interference, and attendant cytopathic affects.
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Affiliation(s)
- Meihong Liu
- Section on Directed Gene Transfer, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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24
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Sattentau QJ. The direct passage of animal viruses between cells. Curr Opin Virol 2011; 1:396-402. [PMID: 22440841 DOI: 10.1016/j.coviro.2011.09.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 09/20/2011] [Indexed: 11/28/2022]
Abstract
The paradigm that viruses can move directly, and in some cases covertly, between contacting target cells is now well established for several virus families. The underlying mechanisms of cell-to-cell spread, however, remain to be fully elucidated and may differ substantially depending on the viral exit/entry route and the cellular tropism. Here, two divergent cell-to-cell spread mechanisms are exemplified: firstly by human retroviruses, which rely upon transient adhesive structures that form between polarized immune cells termed virological synapses, and secondly by herpesviruses that depend predominantly on pre-existing stable cellular contacts, but may also form virological synapses. Plant viruses can also spread directly between contacting cells, but are obliged by the rigid host cell wall to move across pore structures termed plasmodesmata. This review will focus primarily on recent advances in our understanding of animal virus cell-to-cell spread using examples from these two virus families, and will conclude by comparing and contrasting the cell-to-cell spread of animal and plant viruses.
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Affiliation(s)
- Quentin J Sattentau
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford OX13RE, UK.
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25
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Checkley MA, Luttge BG, Freed EO. HIV-1 envelope glycoprotein biosynthesis, trafficking, and incorporation. J Mol Biol 2011; 410:582-608. [PMID: 21762802 PMCID: PMC3139147 DOI: 10.1016/j.jmb.2011.04.042] [Citation(s) in RCA: 328] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/14/2011] [Accepted: 04/15/2011] [Indexed: 12/13/2022]
Abstract
The HIV-1 envelope (Env) glycoproteins play an essential role in the virus replication cycle by mediating the fusion between viral and cellular membranes during the entry process. The Env glycoproteins are synthesized as a polyprotein precursor (gp160) that is cleaved by cellular proteases to the mature surface glycoprotein gp120 and the transmembrane glycoprotein gp41. During virus assembly, the gp120/gp41 complex is incorporated as heterotrimeric spikes into the lipid bilayer of nascent virions. These gp120/gp41 complexes then initiate the infection process by binding receptor and coreceptor on the surface of target cells. Much is currently known about the HIV-1 Env glycoprotein trafficking pathway and the structure of gp120 and the extracellular domain of gp41. However, the mechanism by which the Env glycoprotein complex is incorporated into virus particles remains incompletely understood. Genetic data support a major role for the cytoplasmic tail of gp41 and the matrix domain of Gag in Env glycoprotein incorporation. Still to be defined are the identities of host cell factors that may promote Env incorporation and the role of specific membrane microdomains in this process. Here, we review our current understanding of HIV-1 Env glycoprotein trafficking and incorporation into virions.
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Affiliation(s)
- Mary Ann Checkley
- Virus-Cell Interaction Section, HIV Drug Resistance Program National Cancer Institute Frederick, MD 21702
| | - Benjamin G. Luttge
- Virus-Cell Interaction Section, HIV Drug Resistance Program National Cancer Institute Frederick, MD 21702
| | - Eric O. Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program National Cancer Institute Frederick, MD 21702
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26
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Liu M, Eiden MV. The receptors for gibbon ape leukemia virus and amphotropic murine leukemia virus are not downregulated in productively infected cells. Retrovirology 2011; 8:53. [PMID: 21729311 PMCID: PMC3136417 DOI: 10.1186/1742-4690-8-53] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 07/05/2011] [Indexed: 11/12/2022] Open
Abstract
Background Over the last several decades it has been noted, using a variety of different methods, that cells infected by a specific gammaretrovirus are resistant to infection by other retroviruses that employ the same receptor; a phenomenon termed receptor interference. Receptor masking is thought to provide an earlier means of blocking superinfection, whereas receptor down regulation is generally considered to occur in chronically infected cells. Results We used replication-competent GFP-expressing viruses containing either an amphotropic murine leukemia virus (A-MLV) or the gibbon ape leukemia virus (GALV) envelope. We also constructed similar viruses containing fluorescence-labeled Gag proteins for the detection of viral particles. Using this repertoire of reagents together with a wide range of antibodies, we were able to determine the presence and availability of viral receptors, and detect viral envelope proteins and particles presence on the cell surface of chronically infected cells. Conclusions A-MLV or GALV receptors remain on the surface of chronically infected cells and are detectable by respective antibodies, indicating that these receptors are not downregulated in these infected cells as previously proposed. We were also able to detect viral envelope proteins on the infected cell surface and infected cells are unable to bind soluble A-MLV or GALV envelopes indicating that receptor binding sites are masked by endogenously expressed A-MLV or GALV viral envelope. However, receptor masking does not completely prevent A-MLV or GALV superinfection.
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Affiliation(s)
- Meihong Liu
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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27
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Abstract
Retrovirus transmission via direct cell-cell contact is more efficient than diffusion through the extracellular milieu. This is believed to be due to the ability of viruses to efficiently coordinate several steps of the retroviral life cycle at cell-cell contact sites (D. C. Johnson et al., J. Virol. 76:1-8, 2002; D. M. Phillips, AIDS 8:719-731, 1994; Q. Sattenau, Nat. Rev. Microbiol. 6:815-826, 2008). Using the murine leukemia virus (MLV) as a model retrovirus, we have previously shown that interaction between viral envelope (Env) and receptor directs viral assembly to cell-cell contact sites to promote efficient viral spreading (J. Jin et al., PLoS Biol. 7:e1000163, 2009). In addressing the underlying mechanism, we observed that Env cytoplasmic tail directs this contact-induced polarized assembly. We present here the viral determinants in the Env cytoplasmic tail and Gag that are important in this process. A tyrosine residue within the cytoplasmic tail of Env was identified, which directs polarized assembly. MLV matrix-mediated membrane targeting is required for Gag recruitment to sites of cell-cell contact. Our results suggest that MLV polarized assembly is mediated by a direct or indirect interaction between both domains, thereby coupling Gag recruitment and virus assembly to Env accumulation at the cell-cell interface. In contrast, HIV Gag that assembles outside of cell-cell interfaces can subsequently be drawn into contact zones mediated by MLV Env and receptor, a finding that is consistent with the previously observed lateral movement of HIV into the virological synapse (W. Hubner et al., Science 323:1743-1747, 2009; D. Rudnicka et al., J. Virol. 83:6234-6246, 2009). As such, we observed two distinct modes of virus cell-to-cell transmission that involve either polarized or nonpolarized assembly, but both result in virus transmission.
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28
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Jolly C. Cell-to-cell transmission of retroviruses: Innate immunity and interferon-induced restriction factors. Virology 2011; 411:251-9. [PMID: 21247613 PMCID: PMC3053447 DOI: 10.1016/j.virol.2010.12.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 12/13/2010] [Accepted: 12/17/2010] [Indexed: 01/02/2023]
Abstract
It has been known for some time that retroviruses can disseminate between immune cells either by conventional cell-free transmission or by directed cell-to-cell spread. Over the past few years there has been increasing interest in how retroviruses may use cell-to-cell spread to promote more rapid infection kinetics and circumvent humoral immunity. Effective humoral immune responses are intimately linked with innate immunity and the interplay between retroviruses and innate immunity is a rapidly expanding area of research that has been advanced considerably by the identification of cellular restriction factors that provide barriers to retroviral infection. The effect of innate immunity and restriction factors on retroviral cell-to-cell spread has been comparatively little studied; however recent work suggests this maybe changing. Here I will review some recent advances in what is a budding area of retroviral research.
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Affiliation(s)
- Clare Jolly
- MRC Centre for Medical Molecular Virology, University College London, W1T 4JF, UK.
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29
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Brimacombe CL, Grove J, Meredith LW, Hu K, Syder AJ, Flores MV, Timpe JM, Krieger SE, Baumert TF, Tellinghuisen TL, Wong-Staal F, Balfe P, McKeating JA. Neutralizing antibody-resistant hepatitis C virus cell-to-cell transmission. J Virol 2011; 85:596-605. [PMID: 20962076 PMCID: PMC3014195 DOI: 10.1128/jvi.01592-10] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 10/04/2010] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) can initiate infection by cell-free particle and cell-cell contact-dependent transmission. In this study we use a novel infectious coculture system to examine these alternative modes of infection. Cell-to-cell transmission is relatively resistant to anti-HCV glycoprotein monoclonal antibodies and polyclonal immunoglobulin isolated from infected individuals, providing an effective strategy for escaping host humoral immune responses. Chimeric viruses expressing the structural proteins representing the seven major HCV genotypes demonstrate neutralizing antibody-resistant cell-to-cell transmission. HCV entry is a multistep process involving numerous receptors. In this study we demonstrate that, in contrast to earlier reports, CD81 and the tight-junction components claudin-1 and occludin are all essential for both cell-free and cell-to-cell viral transmission. However, scavenger receptor BI (SR-BI) has a more prominent role in cell-to-cell transmission of the virus, with SR-BI-specific antibodies and small-molecule inhibitors showing preferential inhibition of this infection route. These observations highlight the importance of targeting host cell receptors, in particular SR-BI, to control viral infection and spread in the liver.
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Affiliation(s)
- Claire L. Brimacombe
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Joe Grove
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Luke W. Meredith
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Ke Hu
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Andrew J. Syder
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Maria Victoria Flores
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Jennifer M. Timpe
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Sophie E. Krieger
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Thomas F. Baumert
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Timothy L. Tellinghuisen
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Flossie Wong-Staal
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Peter Balfe
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
| | - Jane A. McKeating
- Hepatitis C Research Group, Institute For Biomedical Research, University of Birmingham, Birmingham B15 2TT, United Kingdom, iTherX Pharmaceuticals, Inc., P.O. Box 910530, San Diego, California 92191-0530, Pfizer Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom, Inserm U748, Université de Strasbourg and Pôle Hépato-Digestif, Hôpitaux Universitaires de Strasbourg, F-67000 Strasbourg, France, Department of Infectology, The Scripps Research Institute, Jupiter, Florida 33458
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Cell-cell spread of human immunodeficiency virus type 1 overcomes tetherin/BST-2-mediated restriction in T cells. J Virol 2010; 84:12185-99. [PMID: 20861257 DOI: 10.1128/jvi.01447-10] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Direct cell-to-cell spread of human immunodeficiency virus type 1 (HIV-1) between T cells at the virological synapse (VS) is an efficient mechanism of viral dissemination. Tetherin (BST-2/CD317) is an interferon-induced, antiretroviral restriction factor that inhibits nascent cell-free particle release. The HIV-1 Vpu protein antagonizes tetherin activity; however, whether tetherin also restricts cell-cell spread is unclear. We performed quantitative cell-to-cell transfer analysis of wild-type (WT) or Vpu-defective HIV-1 in Jurkat and primary CD4(+) T cells, both of which express endogenous levels of tetherin. We found that Vpu-defective HIV-1 appeared to disseminate more efficiently by cell-to-cell contact between Jurkat cells under conditions where tetherin restricted cell-free virion release. In T cells infected with Vpu-defective HIV-1, tetherin was enriched at the VS, and VS formation was increased compared to the WT, correlating with an accumulation of virus envelope proteins on the cell surface. Increasing tetherin expression with type I interferon had only minor effects on cell-to-cell transmission. Furthermore, small interfering RNA (siRNA)-mediated depletion of tetherin decreased VS formation and cell-to-cell transmission of both Vpu-defective and WT HIV-1. Taken together, these data demonstrate that tetherin does not restrict VS-mediated T cell-to-T cell transfer of Vpu-defective HIV-1 and suggest that under some circumstances tetherin might promote cell-to-cell transfer, either by mediating the accumulation of virions on the cell surface or by regulating integrity of the VS. If so, inhibition of tetherin activity by Vpu may balance requirements for efficient cell-free virion production and cell-to-cell transfer of HIV-1 in the face of antiviral immune responses.
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The HTLV-1 Virological Synapse. Viruses 2010; 2:1427-1447. [PMID: 21994688 PMCID: PMC3185711 DOI: 10.3390/v2071427] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 06/04/2010] [Accepted: 06/29/2010] [Indexed: 01/05/2023] Open
Abstract
Human T-lymphotropic virus-1 (HTLV-1) spreads efficiently between T-cells via a tight and highly organized cell-cell contact known as the virological synapse. It is now thought that many retroviruses and other viruses spread via a virological synapse, which may be defined as a virus-induced, specialized area of cell-to-cell contact that promotes the directed transmission of the virus between cells. We summarize here the mechanisms leading to the formation of the HTLV-1 virological synapse and the role played by HTLV-1 Tax protein. We propose a model of HTLV-1 transmission between T-cells based on the three-dimensional ultrastructure of the virological synapse. Finally, in the light of recent advances, we discuss the possible routes of HTLV-1 spread across the virological synapse.
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Sattentau QJ. Cell-to-Cell Spread of Retroviruses. Viruses 2010; 2:1306-1321. [PMID: 21994681 PMCID: PMC3185708 DOI: 10.3390/v2061306] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 06/02/2010] [Accepted: 06/03/2010] [Indexed: 12/19/2022] Open
Abstract
Viruses from several families use direct cell-to-cell infection to disseminate between cells. Retroviruses are a relatively recent addition to this list, and appear to spread cell-to-cell by induction of multimolecular complexes termed virological synapses that assemble at the interface between infected and receptor-expressing target cells. Over the past five years, detailed insight into the cellular and molecular basis of virological synapse-mediated retroviral cell-to-cell spread has been obtained, but important questions and controversies have been raised that remain to be resolved. This review will focus on recent advances in the field with emphasis on areas in which work still needs to be done.
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Affiliation(s)
- Quentin J. Sattentau
- The Sir William Dunn School of Pathology, The University of Oxford, South Parks Road, Oxford OX13RE, UK; E-Mail: ; Tel.: +44 1865 275511; Fax: +44 1865 275515
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Abstract
Viral infections spread based on the ability of viruses to overcome multiple barriers and move from cell to cell, tissue to tissue, and person to person and even across species. While there are fundamental differences between these types of transmissions, it has emerged that the ability of viruses to utilize and manipulate cell-cell contact contributes to the success of viral infections. Central to the excitement in the field of virus cell-to-cell transmission is the idea that cell-to-cell spread is more than the sum of the processes of virus release and entry. This implies that virus release and entry are efficiently coordinated to sites of cell-cell contact, resulting in a process that is distinct from its individual components. In this review, we will present support for this model, illustrate the ability of viruses to utilize and manipulate cell adhesion molecules, and discuss the mechanism and driving forces of directional spreading. An understanding of viral cell-to-cell spreading will enhance our ability to intervene in the efficient spreading of viral infections.
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Surface Transmission or Polarized Egress? Lessons Learned from HTLV Cell-to-Cell Transmission. Viruses 2010; 2:601-605. [PMID: 21994650 PMCID: PMC3185612 DOI: 10.3390/v2020601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 02/08/2010] [Indexed: 01/28/2023] Open
Abstract
Commentary on Pais-Correia, A.M.; Sachse, M.; Guadagnini, S.; Robbiati, V.; Lasserre, R.; Gessain, A.; Gout, O.; Alcover, A.; Thoulouze, M.I. Biofilm-like extracellular viral assemblies mediate HTLV-1 cell-to-cell transmission at virological synapses. Nat. Med.2010, 16, 83–89.
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