scholarly journals HIV-1 Envelope Glycoprotein Cell Surface Localization Is Associated with Antibody-Induced Internalization

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1953
Author(s):  
Sai Priya Anand ◽  
Jérémie Prévost ◽  
Jade Descôteaux-Dinelle ◽  
Jonathan Richard ◽  
Dung N. Nguyen ◽  
...  
Keyword(s):  
Cell Surface ◽  
Neutralizing Antibodies ◽  
Surface Expression ◽  
Broadly Neutralizing Antibodies ◽  
Open Conformation ◽  
Surface Localization ◽  
Infected Cells ◽  
Cell Surface Localization ◽  
Underlying Mechanisms ◽  
Hiv 1

To minimize immune responses against infected cells, HIV-1 has evolved different mechanisms to limit the surface expression of its envelope glycoproteins (Env). Recent observations suggest that the binding of certain broadly neutralizing antibodies (bNAbs) targeting the ‘closed’ conformation of Env induces its internalization. On the other hand, non-neutralizing antibodies (nNAbs) that preferentially target Env in its ‘open’ conformation, remain bound to Env on the cell surface for longer periods of time. In this study, we attempt to better understand the underlying mechanisms behind the differential rates of antibody-mediated Env internalization. We demonstrate that ‘forcing’ open Env using CD4 mimetics allows for nNAb binding and results in similar rates of Env internalization as those observed upon the bNAb binding. Moreover, we can identify distinct populations of Env that are differentially targeted by Abs that mediate faster rates of internalization, suggesting that the mechanism of antibody-induced Env internalization partially depends on the localization of Env on the cell surface.

scholarly journals Antibody-Induced Internalization of HIV-1 Env Proteins Limits Surface Expression of the Closed Conformation of Env

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Sai Priya Anand ◽  
Jonathan R. Grover ◽  
William D. Tolbert ◽  
Jérémie Prévost ◽  
Jonathan Richard ◽  
...  
Keyword(s):  
Immune Responses ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Surface Expression ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity ◽  
Broadly Neutralizing Antibodies ◽  
Closed Conformation ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT To minimize immune responses against infected cells, HIV-1 limits the surface expression of its envelope glycoprotein (Env). Here, we demonstrate that this mechanism is specific for the Env conformation and affects the efficiency of antibody-dependent cellular cytotoxicity (ADCC). Using flow cytometry and confocal microscopy, we show that broadly neutralizing antibodies (bNAbs) targeting the “closed” conformation of Env induce its internalization from the surface. In contrast, non-neutralizing antibodies (nNAbs) are displayed on the cell surface for prolonged period of times. The bNAb-induced Env internalization can be decreased by blocking dynamin function, which translates into higher susceptibilities of infected cells to ADCC. Our results suggest that antibody-mediated Env internalization is a mechanism used by HIV-1 to evade immune responses against the “closed” conformation of Env expressed on HIV-1-infected cells. IMPORTANCE HIV-1 has evolved to acquire several strategies to limit the exposure of its envelope glycoproteins (Env) on the surface of infected cells. In this study, we show that antibody-induced Env internalization is conformation specific and reduces the susceptibility of infected cells to antibody-dependent cellular cytotoxicity (ADCC). Thus, a better understanding of this mechanism might help develop antibodies with improved capacities to mediate ADCC.

scholarly journals Enhanced clearance of HIV-1-infected cells by broadly neutralizing antibodies against HIV-1 in vivo

Science ◽  
2016 ◽  
Vol 352 (6288) ◽  
pp. 1001-1004 ◽  
Author(s):  
C.-L. Lu ◽  
D. K. Murakowski ◽  
S. Bournazos ◽  
T. Schoofs ◽  
D. Sarkar ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Broadly Neutralizing Antibodies ◽  
Infected Cells ◽  
Hiv 1

scholarly journals HIV-1 Vpr up-regulates expression of ligands for the activating NKG2D receptor and promotes NK cell–mediated killing

Blood ◽  
2010 ◽  
Vol 115 (7) ◽  
pp. 1354-1363 ◽  
Author(s):  
Jonathan Richard ◽  
Sardar Sindhu ◽  
Tram N. Q. Pham ◽  
Jean-Philippe Belzile ◽  
Éric A. Cohen
Keyword(s):  
Dna Damage ◽  
Cell Surface ◽  
Nk Cell ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Target Cells ◽  
Nkg2d Ligands ◽  
Infected Cells ◽  
Nkg2d Receptor ◽  
Hiv 1

AbstractHIV up-regulates cell-surface expression of specific ligands for the activating NKG2D receptor, including ULBP-1, -2, and -3, but not MICA or MICB, in infected cells both in vitro and in vivo. However, the viral factor(s) involved in NKG2D ligand expression still remains undefined. HIV-1 Vpr activates the DNA damage/stress-sensing ATR kinase and promotes G2 cell-cycle arrest, conditions known to up-regulate NKG2D ligands. We report here that HIV-1 selectively induces cell-surface expression of ULBP-2 in primary CD4+ T lymphocytes by a process that is Vpr dependent. Importantly, Vpr enhanced the susceptibility of HIV-1–infected cells to NK cell–mediated killing. Strikingly, Vpr alone was sufficient to up-regulate expression of all NKG2D ligands and thus promoted efficient NKG2D-dependent NK cell–mediated killing. Delivery of virion-associated Vpr via defective HIV-1 particles induced analogous biologic effects in noninfected target cells, suggesting that Vpr may act similarly beyond infected cells. All these activities relied on Vpr ability to activate the ATR-mediated DNA damage/stress checkpoint. Overall, these results indicate that Vpr is a key determinant responsible for HIV-1–induced up-regulation of NKG2D ligands and further suggest an immunomodulatory role for Vpr that may not only contribute to HIV-1–induced CD4+ T-lymphocyte depletion but may also take part in HIV-1–induced NK-cell dysfunction.

scholarly journals Incomplete Downregulation of CD4 Expression Affects HIV-1 Env Conformation and Antibody-Dependent Cellular Cytotoxicity Responses

2018 ◽  
Vol 92 (13) ◽  
pp. e00484-18 ◽  
Author(s):  
Jérémie Prévost ◽  
Jonathan Richard ◽  
Halima Medjahed ◽  
Audrey Alexander ◽  
Jennifer Jones ◽  
...  
Keyword(s):  
Cell Surface ◽  
Reporter Gene ◽  
Large Scale ◽  
Surface Expression ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity ◽  
Content Type ◽  
Infected Cells ◽  
Infectious Molecular Clones ◽  
Hiv 1

ABSTRACTHIV-1-infected cells expressing envelope glycoproteins (Env) in the CD4-bound conformation on their surfaces are targeted by antibody-dependent cellular cytotoxicity (ADCC) mediated by CD4-induced (CD4i) antibodies and sera from HIV-1-infected individuals (HIV+sera). By downregulating the surface expression of CD4, Nef prevents Env-CD4 interaction, thus protecting HIV-1-infected cells from ADCC. HIV-1 infectious molecular clones (IMCs) are widely used to measure ADCC. In order to facilitate the identification of infected cells and high-throughput ADCC analysis, reporter genes (e.g., theRenillaluciferase [LucR] gene) are often introduced into IMC constructs. We evaluated the susceptibility of HIV-1-infected CD4+T lymphocytes to ADCC using a panel of parental IMCs and derivatives that expressed the LucR reporter gene, utilizing different molecular strategies, including one specifically designed to retain Nef expression. We found that in some of these constructs, Nef expression in CD4+T cells was suboptimal, and consequently, CD4 downregulation was incomplete. CD4 molecules remaining on the cell surface resulted in the exposure of ADCC-mediating CD4i epitopes on Env and a dramatic increase in the susceptibility of the infected cells to ADCC. Strikingly, protection from ADCC was observed when cells were infected with the parental IMC, which exhibited strong CD4 downregulation. This discrepancy between the parental and Nef-impaired viruses was independent of the strains of Env expressed, but rather, it was correlated with the levels of CD4 surface expression. Overall, our results indicate that caution should be taken when selecting IMCs for ADCC measurements and that CD4 downregulation needs to be carefully monitored when drawing conclusions about the nature and magnitude of ADCC.IMPORTANCEIn-depth understanding of the susceptibility of HIV-1-infected cells to ADCC might help establish correlates of vaccine protection and guide the development of HIV-1 vaccine strategies. Different ADCC assays have been developed, including those using infectious molecular clones (IMCs) carrying a LucR reporter gene that greatly facilitates large-scale quantitative analysis. We previously reported different molecular strategies for introducing LucR while maintaining Nef expression and function and, consequently, CD4 surface downregulation. Here, we demonstrate that utilizing IMCs that exhibit impaired Nef expression can have undesirable consequences due to incomplete CD4 downregulation. CD4 molecules remaining on the cell surface resulted in the exposure of ADCC-mediating CD4i epitopes on Env and a dramatic increase in the susceptibility of the infected cells to ADCC. Overall, our results indicate that CD4 downregulation needs to be carefully monitored when drawing conclusions about the nature and magnitude of ADCC.

scholarly journals BST-2 Expression Modulates Small CD4-Mimetic Sensitization of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity

2017 ◽  
Vol 91 (11) ◽  
Author(s):  
Jonathan Richard ◽  
Jérémie Prévost ◽  
Benjamin von Bredow ◽  
Shilei Ding ◽  
Nathalie Brassard ◽  
...  
Keyword(s):  
Cell Surface ◽  
Immune Evasion ◽  
Surface Expression ◽  
Hiv Positive ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT Antibodies recognizing conserved CD4-induced (CD4i) epitopes on human immunodeficiency virus type 1 (HIV-1) Env and able to mediate antibody-dependent cellular cytotoxicity (ADCC) have been shown to be present in sera from most HIV-1-infected individuals. These antibodies preferentially recognize Env in its CD4-bound conformation. CD4 downregulation by Nef and Vpu dramatically reduces exposure of CD4i HIV-1 Env epitopes and therefore reduce the susceptibility of HIV-1-infected cells to ADCC mediated by HIV-positive (HIV+) sera. Importantly, this mechanism of immune evasion can be circumvented with small-molecule CD4 mimetics (CD4mc) that are able to transition Env into the CD4-bound conformation and sensitize HIV-1-infected cells to ADCC mediated by HIV+ sera. However, HIV-1 developed additional mechanisms to avoid ADCC, including Vpu-mediated BST-2 antagonism, which decreases the overall amount of Env present at the cell surface. Accordingly, BST-2 upregulation in response to alpha interferon (IFN-α) was shown to increase the susceptibility of HIV-1-infected cells to ADCC despite the activity of Vpu. Here we show that BST-2 upregulation by IFN-β and interleukin-27 (IL-27) also increases the surface expression of Env and thus boosts the ability of CD4mc to sensitize HIV-1-infected cells to ADCC by sera from HIV-1-infected individuals. IMPORTANCE HIV-1 evolved sophisticated strategies to conceal Env epitopes from ADCC-mediating antibodies present in HIV+ sera. Vpu-mediated BST-2 downregulation was shown to decrease ADCC responses by limiting the amount of Env present at the cell surface. This effect of Vpu was shown to be attenuated by IFN-α treatment. Here we show that in addition to IFN-α, IFN-β and IL-27 also affect Vpu-mediated BST-2 downregulation and greatly enhance ADCC responses against HIV-1-infected cells in the presence of CD4mc. These findings may inform strategies aimed at HIV prevention and eradication.

scholarly journals Dual pathways of human immunodeficiency virus (HIV-1) envelope glycoprotein trafficking modulate the selective exclusion of uncleaved oligomers from virions

2020 ◽  
Author(s):  
Shijian Zhang ◽  
Hanh T. Nguyen ◽  
Haitao Ding ◽  
Jia Wang ◽  
Shitao Zou ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Infected Cell ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Virus Infectivity ◽  
Virus Particles ◽  
Immunodeficiency Virus ◽  
Infected Cells ◽  
Hiv 1

The human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer is transported through the secretory pathway to the infected cell surface and onto virion particles. In the Golgi, the gp160 Env precursor is modified by complex sugars and proteolytically cleaved to produce the mature functional Env trimer, which resists antibody neutralization. We observed mostly uncleaved gp160 and smaller amounts of cleaved gp120 and gp41 Envs on the surface of HIV-1-infected or Env-expressing cells; however, cleaved Envs were relatively enriched in virions and virus-like particles (VLPs). This relative enrichment of cleaved Env in VLPs was observed for wild-type Envs, for Envs lacking the cytoplasmic tail and for CD4-independent, conformationally flexible Envs. On the cell surface, we identified three distinct populations of Envs: 1) the cleaved Env was transported through the Golgi, was modified by complex glycans, formed trimers that crosslinked efficiently, and was recognized by broadly neutralizing antibodies; 2) a small fraction of Env modified by complex carbohydrates escaped cleavage in the Golgi; and 3) the larger population of uncleaved Env lacked complex carbohydrates, crosslinked into diverse oligomeric forms, and was recognized by poorly neutralizing antibodies. This last group of more "open" Env oligomers reached the cell surface in the presence of Brefeldin A, apparently bypassing the Golgi apparatus. Relative to Envs transported through the Golgi, these uncleaved Envs were counterselected for virion incorporation. By employing two pathways for Env transport to the surface of infected cells, HIV-1 can misdirect host antibody responses towards conformationally flexible, uncleaved Env without compromising virus infectivity. IMPORTANCE The envelope glycoprotein (Env) trimers on the surface of human immunodeficiency virus (HIV-1) mediate the entry of the virus into host cells and serve as targets for neutralizing antibodies. The cleaved, functional Env is incorporated into virus particles from the surface of the infected cell. We found that an uncleaved form of Env is transported to the cell surface by an unconventional route, but this non-functional Env is mostly excluded from the virus. Thus, only one of the pathways by which Env is transported to the surface of infected cells results in efficient incorporation into virus particles, potentially allowing the uncleaved Env to act as a decoy to the host immune system without compromising virus infectivity.

scholarly journals Pre-existing resistant proviruses can compromise maintenance of remission by VRC01 in chronic HIV-1 infection

2020 ◽  
Author(s):  
Ananya Saha ◽  
Narendra M. Dixit
Keyword(s):  
Neutralizing Antibodies ◽  
Latent Reservoir ◽  
Broadly Neutralizing Antibodies ◽  
Art Initiation ◽  
Latently Infected ◽  
Infected Cells ◽  
Resistant Strains ◽  
Maintenance Of Remission ◽  
Hiv 1

AbstractBroadly neutralizing antibodies (bNAbs) of HIV-1 hold promise of eliciting long-term HIV-1 remission. Surprisingly, the bNAb VRC01, when administered concomitantly with the cessation of successful antiretroviral therapy (ART), failed rapidly in chronic HIV-1 patients. We hypothesized that the failure was due to VRC01-resistant strains that were formed before ART initiation, survived ART in latently infected cells, and were reactivated during VRC01 therapy. Current assay limitations preclude testing this hypothesis experimentally. We developed a mathematical model based on the hypothesis and challenged it with available clinical data. The model integrated within-host HIV-1 evolution, stochastic latency reactivation and viral dynamics with multiple dose VRC01 pharmacokinetics. With a virtual patient population, model predictions quantitatively captured data from two independent clinical trials. Accordingly, we attributed VRC01 failure to single-mutant VRC01-resistant proviruses in the latent reservoir triggering viral recrudescence, particularly during trough VRC01 levels. Accounting for pre-existing resistance may help bNAb therapies maximize HIV-1 remission.

scholarly journals Can Broadly Neutralizing HIV-1 Antibodies Help Achieve an ART-Free Remission?

2021 ◽  
Vol 12 ◽  
Author(s):  
Denise C. Hsu ◽  
John W. Mellors ◽  
Sandhya Vasan
Keyword(s):  
Neutralizing Antibodies ◽  
Immune Functions ◽  
Design Strategies ◽  
Broadly Neutralizing Antibodies ◽  
Therapeutic Vaccines ◽  
Infected Cells ◽  
Key Topics ◽  
Antibody Design ◽  
Cellular Immune ◽  
Hiv 1

Many broadly neutralizing antibodies (bnAbs) targeting the HIV-1 envelope glycoprotein are being assessed in clinical trials as strategies for HIV-1 prevention, treatment, and antiretroviral-free remission. BnAbs can neutralize HIV-1 and target infected cells for elimination. Concerns about HIV-1 resistance to single bnAbs have led to studies of bnAb combinations with non-overlapping resistance profiles. This review focuses on the potential for bnAbs to induce HIV-1 remission, either alone or in combination with latency reversing agents, therapeutic vaccines or other novel therapeutics. Key topics include preliminary activity of bnAbs in preclinical models and in human studies of HIV-1 remission, clinical trial designs, and antibody design strategies to optimize pharmacokinetics, coverage of rebound-competent virus, and enhancement of cellular immune functions.

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