scholarly journals Relative contribution of free-virus and synaptic transmission to the spread of HIV-1 through target cell populations

2013 ◽  
Vol 9 (1) ◽  
pp. 20121049 ◽  
Author(s):  
Natalia L. Komarova ◽  
Daniela Anghelina ◽  
Igor Voznesensky ◽  
Benjamin Trinité ◽  
David N. Levy ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Target Cells ◽  
Free Virus ◽  
Virus Growth ◽  
Relative Contribution ◽  
Immunodeficiency Virus ◽  
Virological Synapses ◽  
Transmission Pathways ◽  
Hiv 1

Human immunodeficiency virus can spread through target cells by transmission of cell-free virus or directly from cell-to-cell via formation of virological synapses. Although cell-to-cell transmission has been described as much more efficient than cell-free infection, the relative contribution of the two transmission pathways to virus growth during multiple rounds of replication remains poorly defined. Here, we fit a mathematical model to previously published and newly generated in vitro data, and determine that free-virus and synaptic transmission contribute approximately equally to the growth of the virus population.

scholarly journals Predominant Mode of Human Immunodeficiency Virus Transfer between T Cells Is Mediated by Sustained Env-Dependent Neutralization-Resistant Virological Synapses

2007 ◽  
Vol 81 (22) ◽  
pp. 12582-12595 ◽  
Author(s):  
Ping Chen ◽  
Wolfgang Hübner ◽  
Matthew A. Spinelli ◽  
Benjamin K. Chen
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Productive Infection ◽  
Target Cells ◽  
Free Virus ◽  
Virus Transfer ◽  
Immunodeficiency Virus ◽  
Virological Synapses ◽  
Viral Transfer ◽  
Hiv 1

ABSTRACT Cell-free human immunodeficiency virus type 1 (HIV-1) can initiate infections, but contact between infected and uninfected T cells can enhance viral spread through intercellular structures called virological synapses (VS). The relative contribution of VS to cell-free viral transfer has not been carefully measured. Using an ultrasensitive, fluorescent virus transfer assay, we estimate that when VS between HIV-expressing Jurkat T cells and primary CD4+ T cells are formed, cell-associated transfer of virus is 18,000-fold more efficient than uptake of cell-free virus. Furthermore, in contrast to cell-free virus uptake, the VS deposits virus rapidly into focal, trypsin-resistant compartments in target T cells. This massive virus internalization requires Env-CD4 receptor interactions but is resistant to inhibition by patient-derived neutralizing antisera that inhibit homologous cell-free virus. Deleting the Env cytoplasmic tail does not abrogate VS-mediated transfer, but it renders the VS sensitive to neutralizing antibodies, suggesting that the tail limits exposure of VS-neutralizing epitopes on the surface of infected cells. Dynamic live imaging of the VS reveals that HIV-expressing cells are polarized and make sustained, Env-dependent contacts with target cells through uropod-like structures. The polarized T-cell morphology, Env-CD4 coordinated adhesion, and viral transfer from HIV-infected to uninfected cells suggest that VS allows HIV-1 to evade antibody neutralization and to disseminate efficiently. Future studies will discern to what extent this massive viral transfer contributes to productive infection or viral dissemination through the migration of virus-carrying T cells.

scholarly journals Inhibitory Effect of Individual or Combinations of Broadly Neutralizing Antibodies and Antiviral Reagents against Cell-Free and Cell-to-Cell HIV-1 Transmission

2015 ◽  
Vol 89 (15) ◽  
pp. 7813-7828 ◽  
Author(s):  
Randi B. Gombos ◽  
Dror Kolodkin-Gal ◽  
Leila Eslamizar ◽  
Joshua O. Owuor ◽  
Emanuele Mazzola ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Neutralizing Antibodies ◽  
Virus Transmission ◽  
Target Cells ◽  
Broadly Neutralizing Antibodies ◽  
Free Virus ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACTTo date, most therapeutic and vaccine candidates for human immunodeficiency virus type 1 (HIV-1) are evaluated preclinically for efficacy against cell-free viral challenges. However, cell-associated HIV-1 is suggested to be a major contributor to sexual transmission by mucosal routes. To determine if neutralizing antibodies or inhibitors block cell-free and cell-associated virus transmission of diverse HIV-1 strains with different efficiencies, we tested 12 different antibodies and five inhibitors against four green fluorescent protein (GFP)-labeled HIV-1 envelope (Env) variants from transmitted/founder (T/F) or chronic infection isolates. We evaluated antibody/inhibitor-mediated virus neutralization using either TZM-bl target cells, in which infectivity was determined by virus-driven luciferase expression, or A3R5 lymphoblastoid target cells, in which infectivity was evaluated by GFP expression. In both the TZM-bl and A3R5 assays, cell-free virus or infected CD4+lymphocytes were used as targets for neutralization. We further hypothesized that the combined use of specific neutralizing antibodies targeting HIV-1 Env would more effectively prevent cell-associated virus transmission than the use of individual antibodies. The tested antibody combinations included two gp120-directed antibodies, VRC01 and PG9, or VRC01 with the gp41-directed antibody 10E8. Our results demonstrated that cell-associated virus was less sensitive to neutralizing antibodies and inhibitors, particularly using the A3R5 neutralization assay, and the potencies of these neutralizing agents differed among Env variants. A combination of different neutralizing antibodies that target specific sites on gp120 led to a significant reduction in cell-associated virus transmission. These assays will help identify ideal combinations of broadly neutralizing antibodies to use for passive preventive antibody administration and further characterize targets for the most effective neutralizing antibodies/inhibitors.IMPORTANCEPrevention of the transmission of human immunodeficiency virus type 1 (HIV-1) remains a prominent goal of HIV research. The relative contribution of HIV-1 within an infected cell versus cell-free HIV-1 to virus transmission remains debated. It has been suggested that cell-associated virus is more efficient at transmitting HIV-1 and more difficult to neutralize than cell-free virus. Several broadly neutralizing antibodies and retroviral inhibitors are currently being studied as potential therapies against HIV-1 transmission. The present study demonstrates a decrease in neutralizing antibody and inhibitor efficiencies against cell-associated compared to cell-free HIV-1 transmission among different strains of HIV-1. We also observed a significant reduction in virus transmission using a combination of two different neutralizing antibodies that target specific sites on the outermost region of HIV-1, the virus envelope. Therefore, our findings support the use of antibody combinations against both cell-free and cell-associated virus in future candidate therapy regimens.

scholarly journals How Many Human Immunodeficiency Virus Type 1-Infected Target Cells Can a Cytotoxic T-Lymphocyte Kill?

2005 ◽  
Vol 79 (21) ◽  
pp. 13579-13586 ◽  
Author(s):  
W. David Wick ◽  
Otto O. Yang ◽  
Lawrence Corey ◽  
Steven G. Self
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT The antiviral role of CD8+ cytotoxic T lymphocytes (CTLs) in human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. Specifically, the degree to which CTLs reduce viral replication by killing HIV-1-infected cells in vivo is not known. Here we employ mathematical models of the infection process and CTL action to estimate the rate that CTLs can kill HIV-1-infected cells from in vitro and in vivo data. Our estimates, which are surprisingly consistent considering the disparities between the two experimental systems, demonstrate that on average CTLs can kill from 0.7 to 3 infected target cells per day, with the variability in this figure due to epitope specificity or other factors. These results are compatible with the observed decline in viremia after primary infection being primarily a consequence of CTL activity and have interesting implications for vaccine design.

scholarly journals Formation of Syncytia Is Repressed by Tetraspanins in Human Immunodeficiency Virus Type 1-Producing Cells

2009 ◽  
Vol 83 (15) ◽  
pp. 7467-7474 ◽  
Author(s):  
Jia Weng ◽  
Dimitry N. Krementsov ◽  
Sandhya Khurana ◽  
Nathan H. Roy ◽  
Markus Thali
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Target Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT In vitro propagation studies have established that human immunodeficiency virus type 1 (HIV-1) is most efficiently transmitted at the virological synapse that forms between producer and target cells. Despite the presence of the viral envelope glycoprotein (Env) and CD4 and chemokine receptors at the respective surfaces, producer and target cells usually do not fuse with each other but disengage after the viral particles have been delivered, consistent with the idea that syncytia, at least in vitro, are not required for HIV-1 spread. Here, we tested whether tetraspanins, which are well known regulators of cellular membrane fusion processes that are enriched at HIV-1 exit sites, regulate syncytium formation. We found that overexpression of tetraspanins in producer cells leads to reduced syncytium formation, while downregulation has the opposite effect. Further, we document that repression of Env-induced cell-cell fusion by tetraspanins depends on the presence of viral Gag, and we demonstrate that fusion repression requires the recruitment of Env by Gag to tetraspanin-enriched microdomains (TEMs). However, sensitivity to fusion repression by tetraspanins varied for different viral strains, despite comparable recruitment of their Envs to TEMs. Overall, these data establish tetraspanins as negative regulators of HIV-1-induced cell-cell fusion, and they start delineating the requirements for this regulation.

scholarly journals Syndecan-Fc Hybrid Molecule as a Potent In Vitro Microbicidal Anti-HIV-1 Agent

2010 ◽  
Vol 54 (7) ◽  
pp. 2753-2766 ◽  
Author(s):  
Michael D. Bobardt ◽  
Udayan Chatterji ◽  
Lana Schaffer ◽  
Lot de Witte ◽  
Philippe A. Gallay
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Sexual Transmission ◽  
Antiviral Agent ◽  
Target Cells ◽  
Hybrid Molecule ◽  
Immunodeficiency Virus ◽  
Anti Hiv ◽  
Hiv 1

ABSTRACT In the absence of a vaccine, there is an urgent need for the development of safe and effective topical microbicides to prevent the sexual transmission of human immunodeficiency virus type 1 (HIV-1). In this study, we proposed to develop a novel class of microbicides using syndecan as the antiviral agent. Specifically, we generated a soluble syndecan-Fc hybrid molecule by fusing the ectodomain of syndecan-1 to the Fc domain of a human IgG. We then tested the syndecan-Fc hybrid molecule for various in vitro microbicidal anti-HIV-1 properties. Remarkably, the syndecan-Fc hybrid molecule possesses multiple attractive microbicidal properties: (i) it blocks HIV-1 infection of primary targets including T cells, macrophages, and dendritic cells (DC); (ii) it exhibits a broad range of antiviral activity against primary HIV-1 isolates, multidrug resistant HIV-1 isolates, HIV-2, and simian immunodeficiency virus (SIV); (iii) it prevents transmigration of HIV-1 through human primary genital epithelial cells; (iv) it prevents HIV-1 transfer from dendritic cells to CD4+ T cells; (v) it is potent when added 2 h prior to addition of HIV-1 to target cells; (vi) it is potent at a low pH; (vii) it blocks HIV-1 infectivity when diluted in genital fluids; and (viii) it prevents herpes simplex virus infection. The heparan sulfate chains of the syndecan-Fc hybrid molecule are absolutely required for HIV-1 neutralization. Several lines of evidence suggest that the highly conserved Arg298 in the V3 region of gp120 serves as the locus for the syndecan-Fc hybrid molecule neutralization. In conclusion, this study suggests that the syndecan-Fc hybrid molecule represents the prototype of a new generation of microbicidal agents that may have promise for HIV-1 prevention.

scholarly journals Functional Evaluation of DC-SIGN Monoclonal Antibodies Reveals DC-SIGN Interactions with ICAM-3 Do Not Promote Human Immunodeficiency Virus Type 1 Transmission

2002 ◽  
Vol 76 (12) ◽  
pp. 5905-5914 ◽  
Author(s):  
Li Wu ◽  
Thomas D. Martin ◽  
Rosemay Vazeux ◽  
Derya Unutmaz ◽  
Vineet N. KewalRamani
Keyword(s):  
T Cells ◽  
Monoclonal Antibodies ◽  
Virus Transmission ◽  
Interleukin 4 ◽  
Intercellular Adhesion Molecule ◽  
Target Cells ◽  
Functional Evaluation ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT DC-SIGN, a type II membrane-spanning C-type lectin that is expressed on the surface of dendritic cells (DC), captures and promotes human and simian immunodeficiency virus (HIV and SIV) infection of CD4+ T cells in trans. To better understand the mechanism of DC-SIGN-mediated virus transmission, we generated and functionally evaluated a panel of seven monoclonal antibodies (MAbs) against DC-SIGN family molecules. Six of the MAbs reacted with myeloid-lineage DC, whereas one MAb preferentially bound DC-SIGNR/L-SIGN, a homolog of DC-SIGN. Characterization of hematopoietic cells also revealed that stimulation of monocytes with interleukin-4 (IL-4) or IL-13 was sufficient to induce expression of DC-SIGN. All DC-SIGN-reactive MAbs competed with intercellular adhesion molecule 3 (ICAM-3) for adhesion to DC-SIGN and blocked HIV-1 transmission to T cells that was mediated by THP-1 cells expressing DC-SIGN. Similar but less efficient MAb blocking of DC-mediated HIV-1 transmission was observed, indicating that HIV-1 transmission to target cells via DC may not be dependent solely on DC-SIGN. Attempts to neutralize DC-SIGN capture and transmission of HIV-1 with soluble ICAM-3 prophylaxis were limited in success, with a maximal inhibition of 60%. In addition, disrupting DC-SIGN/ICAM-3 interactions between cells with MAbs did not impair DC-SIGN-mediated HIV-1 transmission. Finally, forced expression of ICAM-3 on target cells did not increase their susceptibility to HIV-1 transmission mediated by DC-SIGN. While these findings do not discount the role of intercellular contact in facilitating HIV-1 transmission, our in vitro data indicate that DC-SIGN interactions with ICAM-3 do not promote DC-SIGN-mediated virus transmission.

scholarly journals Envelope-Dependent, Cyclophilin-Independent Effects of Glycosaminoglycans on Human Immunodeficiency Virus Type 1 Attachment and Infection

2002 ◽  
Vol 76 (12) ◽  
pp. 6332-6343 ◽  
Author(s):  
Yi-jun Zhang ◽  
Theodora Hatziioannou ◽  
Trinity Zang ◽  
Douglas Braaten ◽  
Jeremy Luban ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Target Cells ◽  
Independent Manner ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Cell surface glycosaminoglycans (GAGs), in particular heparan sulfate (HS), have been proposed to mediate the attachment of human immunodeficiency virus type 1 (HIV-1) to target cells prior to virus entry, and both the viral gp120 envelope protein and virion-associated cyclophilin A (CypA) have been shown to directly interact with HS and its analogues. To determine the role of GAGs in HIV attachment and infection, we generated HIV-susceptible derivatives of CHO cell lines that either express high levels of GAGs (CHO-K1) or lack GAGs (pgsA745). Using a panel of HIV-1 envelopes, we found that cell surface GAG-mediated effects on virion attachment and infection vary in an envelope strain-dependent but coreceptor-independent manner. In fact, cell surface GAG-mediated enhancement of infection is confined to isolates that contain a highly positively charged V3-loop sequence, while infection by most strains is apparently inhibited by the presence of GAGs. Moreover, the enhancing and inhibitory effects of polycations and polyanions on HIV-1 infection are largely dependent on the presence of cell surface GAGs. These observations are consistent with a model in which GAGs influence in vitro HIV-1 infection primarily by modifying the charge characteristics of the target cell surface. Finally, the effects of GAGs on HIV-1 infection are observed to an equivalent extent whether CypA is present in or absent from virions. Overall, these data exclude a major role for GAGs in mediating the attachment of many HIV-1 strains to target cells via interactions with virion-associated gp120 or CypA.

scholarly journals Capsid lattice destabilization leads to premature loss of the viral genome and integrase enzyme during HIV-1 infection

2020 ◽  
Author(s):  
Jenna E. Eschbach ◽  
Jennifer L. Elliott ◽  
Wen Li ◽  
Kaneil K. Zadrozny ◽  
Keanu Davis ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Reverse Transcription ◽  
Viral Genome ◽  
Target Cells ◽  
Viral Core ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACTThe human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein forms a conical lattice around the viral ribonucleoprotein complex (vRNP) consisting of a dimeric viral genome and associated proteins, together constituting the viral core. Upon entry into target cells, the viral core undergoes a process termed uncoating, during which CA molecules are shed from the lattice. Although the timing and degree of uncoating are important for reverse transcription and integration, the molecular basis of this phenomenon remains unclear. Using complementary approaches, we assessed the impact of core destabilization on the intrinsic stability of the CA lattice in vitro and fates of viral core components in infected cells. We found that substitutions in CA can impact the intrinsic stability of the CA lattice in vitro in the absence of vRNPs, which mirrored findings from assessment of CA stability in virions. Altering CA stability tended to increase the propensity to form morphologically aberrant particles, in which the vRNPs were mislocalized between the CA lattice and the viral lipid envelope. Importantly, destabilization of the CA lattice led to premature dissociation of CA from vRNPs in target cells, which was accompanied by proteasomal-independent losses of the viral genome and integrase enzyme. Overall, our studies show that the CA lattice protects the vRNP from untimely degradation in target cells and provide the mechanistic basis of how CA stability influences reverse transcription.AUTHOR SUMMARYThe human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein forms a conical lattice around the viral RNA genome and the associated viral enzymes and proteins, together constituting the viral core. Upon infection of a new cell, viral cores are released into the cytoplasm where they undergo a process termed “uncoating”, i.e. shedding of CA molecules from the conical lattice. Although proper and timely uncoating has been shown to be important for reverse transcription, the molecular mechanisms that link these two events remain poorly understood. In this study, we show that destabilization of the CA lattice leads to premature dissociation of CA from viral cores, which exposes the viral genome and the integrase enzyme for degradation in target cells. Thus, our studies demonstrate that the CA lattice protects the viral ribonucleoprotein complexes from untimely degradation in target cells and provide the first causal link between how CA stability affects reverse transcription.

scholarly journals Human Immunodeficiency Virus Type 1 Spinoculation Enhances Infection through Virus Binding

2000 ◽  
Vol 74 (21) ◽  
pp. 10074-10080 ◽  
Author(s):  
Una O'Doherty ◽  
William J. Swiggard ◽  
Michael H. Malim
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Target Cells ◽  
Virus Binding ◽  
Viral Particles ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The study of early events in the human immunodeficiency virus type 1 (HIV-1) life cycle can be limited by the relatively low numbers of cells that can be infected synchronously in vitro. Although the efficiency of HIV-1 infection can be substantially improved by centrifugal inoculation (spinoculation or shell vial methods), the underlying mechanism of enhancement has not been defined. To understand spinoculation in greater detail, we have used real-time PCR to quantitate viral particles in suspension, virions that associate with cells, and the ability of those virions to give rise to reverse transcripts. We report that centrifugation of HIV-1IIIBvirions at 1,200 × g for 2 h at 25°C increases the number of particles that bind to CEM-SS T-cell targets by ∼40-fold relative to inoculation by simple virus-cell mixing. Following subsequent incubation at 37°C for 5 h to allow membrane fusion and uncoating to occur, the number of reverse transcripts per target cell was similarly enhanced. Indeed, by culturing spinoculated samples for 24 h, ∼100% of the target cells were reproducibly shown to be productively infected, as judged by the expression of p24 gag . Because the modestg forces employed in this procedure were found to be capable of sedimenting viral particles and because CD4-specific antibodies were effective at blocking virus binding, we propose that spinoculation works by depositing virions on the surfaces of target cells and that diffusion is the major rate-limiting step for viral adsorption under routine in vitro pulsing conditions. Thus, techniques that accelerate the binding of viruses to target cells not only promise to facilitate the experimental investigation of postentry steps of HIV-1 infection but should also help to enhance the efficacy of virus-based genetic therapies.

scholarly journals Interactions between Natural Killer Cells and Antibody Fc Result in Enhanced Antibody Neutralization of Human Immunodeficiency Virus Type 1

2005 ◽  
Vol 79 (4) ◽  
pp. 2042-2049 ◽  
Author(s):  
Donald N. Forthal ◽  
Gary Landucci ◽  
Tran B. Phan ◽  
Juan Becerra
Keyword(s):  
Human Immunodeficiency Virus ◽  
Nk Cells ◽  
Natural Killer ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Target Cells ◽  
Virus Growth ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Antibodies can prevent lentivirus infections in animals and may play a role in controlling viral burden in established infection. In preventing and particularly in controlling infection, antibodies likely function in the presence of large quantities of virus. In this study, we explored the mechanisms by which antibodies neutralize large inocula of human immunodeficiency virus type 1 (HIV-1) on different target cells. Immunoglobulin G (IgG) from HIV-infected patients was tested for neutralizing activity against primary R5 strains of HIV-1 at inocula ranging from 100 to 20,000 50% tissue culture infective doses. At all virus inocula, inhibition by antibody was enhanced when target cells for virus growth were monocyte-depleted, peripheral blood mononuclear cells (PBMCs) rather than CD4+ lymphocytes. However, enhanced inhibition on PBMCs was greatest with larger amounts of virus. Depleting PBMCs of natural killer (NK) cells, which express Fc receptors for IgG (FcγRs), abrogated the enhanced antibody inhibition, whereas adding NK cells to CD4+ lymphocytes restored inhibition. There was no enhanced inhibition on PBMCs when F(ab′)2 was used. Further experiments demonstrated that the release of β-chemokines, most likely through FcγR triggering of NK cells, contributed modestly to the antiviral activity of antibody on PBMCs and that antibody-coated virus adsorbed to uninfected cells provided a target for NK cell-mediated inhibition of HIV-1. These results indicate that Fc-FcγR interactions enhance the ability of antibody to neutralize HIV-1. Since FcγR-bearing cells are always present in vivo, FcγR-mediated antibody function may play a role in the ability of antibody to control lentivirus infection.

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