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      Elimination of HIV-1-infected cells by broadly neutralizing antibodies

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          Abstract

          The Fc region of HIV-1 Env-specific broadly neutralizing antibodies (bNAbs) is required for suppressing viraemia, through mechanisms which remain poorly understood. Here, we identify bNAbs that exert antibody-dependent cellular cytotoxicity (ADCC) in cell culture and kill HIV-1-infected lymphocytes through natural killer (NK) engagement. These antibodies target the CD4-binding site, the glycans/V3 and V1/V2 loops on gp120, or the gp41 moiety. The landscape of Env epitope exposure at the surface and the sensitivity of infected cells to ADCC vary considerably between viral strains. Efficient ADCC requires sustained cell surface binding of bNAbs to Env, and combining bNAbs allows a potent killing activity. Furthermore, reactivated infected cells from HIV-positive individuals expose heterogeneous Env epitope patterns, with levels that are often but not always sufficient to trigger killing by bNAbs. Our study delineates the parameters controlling ADCC activity of bNAbs, and supports the use of the most potent antibodies to clear the viral reservoir.

          Abstract

          Broadly neutralizing antibodies (bNAbs) are promising as potential therapies targeting HIV-1 but their overall antiviral activity remains to be fully elucidated. Here the authors evaluate the ability of a panel of bNAbs to trigger antibody-dependent cellular cytotoxicity and identify the most effective antibody combinations.

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          Most cited references 24

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          Stimulation of HIV-1-specific cytolytic T lymphocytes facilitates elimination of latent viral reservoir after virus reactivation.

          Highly active antiretroviral therapy (HAART) suppresses HIV-1 replication but cannot eliminate the virus because HIV-1 establishes latent infection. Interruption of HAART leads to a rapid rebound of viremia, so life-long treatment is required. Efforts to purge the latent reservoir have focused on reactivating latent proviruses without inducing global T cell activation. However, the killing of the infected cells after virus reactivation, which is essential for elimination of the reservoir, has not been assessed. Here we show that after reversal of latency in an in vitro model, infected resting CD4(+) T cells survived despite viral cytopathic effects, even in the presence of autologous cytolytic T lymphocytes (CTLs) from most patients on HAART. Antigen-specific stimulation of patient CTLs led to efficient killing of infected cells. These results demonstrate that stimulating HIV-1-specific CTLs prior to reactivating latent HIV-1 may be essential for successful eradication efforts and should be considered in future clinical trials. Copyright © 2012 Elsevier Inc. All rights reserved.
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            Antibodies in HIV-1 vaccine development and therapy.

            Despite 30 years of study, there is no HIV-1 vaccine and, until recently, there was little hope for a protective immunization. Renewed optimism in this area of research comes in part from the results of a recent vaccine trial and the use of single-cell antibody-cloning techniques that uncovered naturally arising, broad and potent HIV-1-neutralizing antibodies (bNAbs). These antibodies can protect against infection and suppress established HIV-1 infection in animal models. The finding that these antibodies develop in a fraction of infected individuals supports the idea that new approaches to vaccination might be developed by adapting the natural immune strategies or by structure-based immunogen design. Moreover, the success of passive immunotherapy in small-animal models suggests that bNAbs may become a valuable addition to the armamentarium of drugs that work against HIV-1.
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              Broadly neutralizing anti-HIV-1 antibodies require Fc effector functions for in vivo activity.

              Broadly neutralizing antibodies (bNAbs) against HIV-1 provide both effective pre-exposure prophylaxis and treatment of HIV-1 infection in murine and nonhuman primate models, suggesting their potential use in humans. Although much is known about the role of variable domains in the neutralization breadth and potency of these bNAbs, the contribution of Fc domains to their activities is, by contrast, poorly characterized. Assessment of the in vivo activity of several bNAbs revealed that FcγR-mediated effector function contributes substantially to their capacity to block viral entry, suppress viremia, and confer therapeutic activity. Enhanced in vivo potency of anti-HIV-1 bNAbs was associated with preferential engagement of activating, but not inhibitory FcγRs, and Fc domain-engineered bNAb variants with selective binding capacity for activating FcγRs displayed augmented protective activity. These findings reveal key roles for Fc effector function in the in vivo activity of anti-HIV-1 bNAbs and provide strategies for generating bNAbs with improved efficacy. Copyright © 2014 Elsevier Inc. All rights reserved.
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                Author and article information

                Journal
                Nat Commun
                Nat Commun
                Nature Communications
                Nature Publishing Group
                2041-1723
                03 March 2016
                2016
                : 7
                Affiliations
                [1 ]Virus and Immunity Unit, Department of Virology, Institut Pasteur , Paris 75015, France
                [2 ]CNRS-URA 3015 , Paris 75015, France
                [3 ]Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur , Paris 75015, France
                [4 ]CNRS-URA 1961 , Paris 75015, France
                [5 ]Université Paris Sud, UMR-1184 , Le Kremlin Bicêtre 94276, France
                [6 ]CEA, DSV/iMETI, Division of Immuno-Virology, IDMIT , Fontenay-aux-Roses 92260, France
                [7 ]Inserm, U1184, Center for Immunology of Viral Infections and Autoimmune Diseases , Le Kremlin Bicêtre 94276, France
                [8 ]APHP, Service de Médecine Interne–Immunologie Clinique, Hôpitaux Universitaires Paris Sud , Le Kremlin Bicêtre 94276, France
                [9 ]Vaccine Research Institute , Creteil 94000, France
                Author notes
                Article
                ncomms10844
                10.1038/ncomms10844
                4782064
                26936020
                Copyright © 2016, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.

                This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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