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David T Evans - One of the best experts on this subject based on the ideXlab platform.

  • comparison of antibody dependent cell mediated Cytotoxicity and virus neutralization by hiv 1 env specific monoclonal antibodies
    Journal of Virology, 2016
    Co-Authors: Benjamin Von Bredow, Juan F Arias, Lisa N Heyer, Brian Moldt, Susan Zollapazner, Khoa Le, Dennis R. Burton, James E Robinson, David T Evans
    Abstract:

    UNLABELLED: Although antibodies to the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein have been studied extensively for their ability to block viral infectivity, little data are currently available on nonneutralizing functions of these antibodies, such as their ability to eliminate virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC). HIV-1 Env-specific antibodies of diverse specificities, including potent broadly neutralizing and nonneutralizing antibodies, were therefore tested for ADCC against cells infected with a lab-adapted HIV-1 isolate (HIV-1NL4-3), a primary HIV-1 isolate (HIV-1JR-FL), and a simian-human immunodeficiency virus (SHIV) adapted for pathogenic infection of rhesus macaques (SHIVAD8-EO). In accordance with the sensitivity of these viruses to neutralization, HIV-1NL4-3-infected cells were considerably more sensitive to ADCC, both in terms of the number of antibodies and magnitude of responses, than cells infected with HIV-1JR-FL or SHIVAD8-EO ADCC activity generally correlated with antibody binding to Env on the surfaces of virus-infected cells and with viral neutralization; however, neutralization was not always predictive of ADCC, as instances of ADCC in the absence of detectable neutralization, and vice versa, were observed. These results reveal incomplete overlap in the specificities of antibodies that mediate these antiviral activities and provide insights into the relationship between ADCC and neutralization important for the development of antibody-based vaccines and therapies for combating HIV-1 infection. IMPORTANCE: This study provides fundamental insights into the relationship between Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) and virus neutralization that may help to guide the development of antibody-based vaccines and immunotherapies for the prevention and treatment of HIV-1 infection.

  • envelope glycoprotein internalization protects human and simian immunodeficiency virus infected cells from antibody dependent cell mediated Cytotoxicity
    Journal of Virology, 2015
    Co-Authors: Benjamin Von Bredow, Juan F Arias, Lisa N Heyer, Eva G Rakasz, Matthew R Gardner, Michael Farzan, David T Evans
    Abstract:

    UNLABELLED The cytoplasmic tails of human and simian immunodeficiency virus (HIV and SIV, respectively) envelope glycoproteins contain a highly conserved, membrane-proximal endocytosis motif that prevents the accumulation of Env on the surface of infected cells prior to virus assembly. Using an assay designed to measure the killing of virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), we show that substitutions in this motif increase the susceptibility of HIV-1- and SIV-infected cells to ADCC in a manner that directly correlates with elevated Env levels on the surface of virus-infected cells. In the case of HIV-1, this effect is additive with a deletion in vpu recently shown to enhance the susceptibility of HIV-1-infected cells to ADCC as a result of tetherin-mediated retention of budding virions on the cell surface. These results reveal a previously unappreciated role for the membrane-proximal endocytosis motif of gp41 in protecting HIV-1- and SIV-infected cells from antibody responses by regulating the amount of Env present on the cell surface. IMPORTANCE This study reveals an unappreciated role for the membrane-proximal endocytosis motif of gp41 in protecting HIV-1- and SIV-infected cells from elimination by Env-specific antibodies. Thus, strategies designed to interfere with this mechanism of Env internalization may improve the efficacy of antibody-based vaccines and antiretroviral therapies designed to enhance the immunological control of HIV-1 replication in chronically infected individuals.

  • tetherin antagonism by vpu protects hiv infected cells from antibody dependent cell mediated Cytotoxicity
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Juan F Arias, Lisa N Heyer, Brian Moldt, Dennis R. Burton, Benjamin Von Bredow, Kim L Weisgrau, Eva G Rakasz, David T Evans
    Abstract:

    Tetherin is an IFN-inducible transmembrane protein that inhibits the detachment of enveloped viruses from infected cells. HIV-1 overcomes this restriction factor by expressing HIV-1 viral protein U (Vpu), which down-regulates and degrades tetherin. We report that mutations in Vpu that impair tetherin antagonism increase the susceptibility of HIV-infected cells to Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), and conversely that RNAi knockdown of tetherin, but not other cellular proteins down-modulated by Vpu, decreases the susceptibility of HIV-infected cells to ADCC. These results reveal that Vpu protects HIV-infected cells from ADCC as a function of its ability to counteract tetherin. By serving as link between innate and adaptive immunity, the antiviral activity of tetherin may be augmented by virus-specific antibodies, and hence much greater than previously appreciated.

  • a novel assay for antibody dependent cell mediated Cytotoxicity against hiv 1 or siv infected cells reveals incomplete overlap with antibodies measured by neutralization and binding assays
    Journal of Virology, 2012
    Co-Authors: Michael D Alpert, Lisa N Heyer, David E J Williams, Jackson D Harvey, Thomas C Greenough, Maria Allhorn, David T Evans
    Abstract:

    The resistance of human immunodeficiency virus type 1 (HIV-1) to antibody-mediated immunity often prevents the detection of antibodies that neutralize primary isolates of HIV-1. However, conventional assays for antibody functions other than neutralization are suboptimal. Current methods for measuring the killing of virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) are limited by the number of natural killer (NK) cells obtainable from individual donors, donor-to-donor variation, and the use of nonphysiological targets. We therefore developed an ADCC assay based on NK cell lines that express human or macaque CD16 and a CD4(+) T-cell line that expresses luciferase from a Tat-inducible promoter upon HIV-1 or simian immunodeficiency virus (SIV) infection. NK cells and virus-infected targets are mixed in the presence of serial plasma dilutions, and ADCC is measured as the dose-dependent loss of luciferase activity. Using this approach, ADCC titers were measured in plasma samples from HIV-infected human donors and SIV-infected macaques. For the same plasma samples paired with the same test viruses, this assay was approximately 2 orders of magnitude more sensitive than optimized assays for neutralizing antibodies-frequently allowing the measurement of ADCC in the absence of detectable neutralization. Although ADCC correlated with other measures of Env-specific antibodies, neutralizing and gp120 binding titers did not consistently predict ADCC activity. Hence, this assay affords a sensitive method for measuring antibodies capable of directing ADCC against HIV- or SIV-infected cells expressing native conformations of the viral envelope glycoprotein and reveals incomplete overlap of the antibodies that direct ADCC and those measured in neutralization and binding assays.

Lisa N Heyer - One of the best experts on this subject based on the ideXlab platform.

  • comparison of antibody dependent cell mediated Cytotoxicity and virus neutralization by hiv 1 env specific monoclonal antibodies
    Journal of Virology, 2016
    Co-Authors: Benjamin Von Bredow, Juan F Arias, Lisa N Heyer, Brian Moldt, Susan Zollapazner, Khoa Le, Dennis R. Burton, James E Robinson, David T Evans
    Abstract:

    UNLABELLED: Although antibodies to the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein have been studied extensively for their ability to block viral infectivity, little data are currently available on nonneutralizing functions of these antibodies, such as their ability to eliminate virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC). HIV-1 Env-specific antibodies of diverse specificities, including potent broadly neutralizing and nonneutralizing antibodies, were therefore tested for ADCC against cells infected with a lab-adapted HIV-1 isolate (HIV-1NL4-3), a primary HIV-1 isolate (HIV-1JR-FL), and a simian-human immunodeficiency virus (SHIV) adapted for pathogenic infection of rhesus macaques (SHIVAD8-EO). In accordance with the sensitivity of these viruses to neutralization, HIV-1NL4-3-infected cells were considerably more sensitive to ADCC, both in terms of the number of antibodies and magnitude of responses, than cells infected with HIV-1JR-FL or SHIVAD8-EO ADCC activity generally correlated with antibody binding to Env on the surfaces of virus-infected cells and with viral neutralization; however, neutralization was not always predictive of ADCC, as instances of ADCC in the absence of detectable neutralization, and vice versa, were observed. These results reveal incomplete overlap in the specificities of antibodies that mediate these antiviral activities and provide insights into the relationship between ADCC and neutralization important for the development of antibody-based vaccines and therapies for combating HIV-1 infection. IMPORTANCE: This study provides fundamental insights into the relationship between Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) and virus neutralization that may help to guide the development of antibody-based vaccines and immunotherapies for the prevention and treatment of HIV-1 infection.

  • envelope glycoprotein internalization protects human and simian immunodeficiency virus infected cells from antibody dependent cell mediated Cytotoxicity
    Journal of Virology, 2015
    Co-Authors: Benjamin Von Bredow, Juan F Arias, Lisa N Heyer, Eva G Rakasz, Matthew R Gardner, Michael Farzan, David T Evans
    Abstract:

    UNLABELLED The cytoplasmic tails of human and simian immunodeficiency virus (HIV and SIV, respectively) envelope glycoproteins contain a highly conserved, membrane-proximal endocytosis motif that prevents the accumulation of Env on the surface of infected cells prior to virus assembly. Using an assay designed to measure the killing of virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), we show that substitutions in this motif increase the susceptibility of HIV-1- and SIV-infected cells to ADCC in a manner that directly correlates with elevated Env levels on the surface of virus-infected cells. In the case of HIV-1, this effect is additive with a deletion in vpu recently shown to enhance the susceptibility of HIV-1-infected cells to ADCC as a result of tetherin-mediated retention of budding virions on the cell surface. These results reveal a previously unappreciated role for the membrane-proximal endocytosis motif of gp41 in protecting HIV-1- and SIV-infected cells from antibody responses by regulating the amount of Env present on the cell surface. IMPORTANCE This study reveals an unappreciated role for the membrane-proximal endocytosis motif of gp41 in protecting HIV-1- and SIV-infected cells from elimination by Env-specific antibodies. Thus, strategies designed to interfere with this mechanism of Env internalization may improve the efficacy of antibody-based vaccines and antiretroviral therapies designed to enhance the immunological control of HIV-1 replication in chronically infected individuals.

  • tetherin antagonism by vpu protects hiv infected cells from antibody dependent cell mediated Cytotoxicity
    Proceedings of the National Academy of Sciences of the United States of America, 2014
    Co-Authors: Juan F Arias, Lisa N Heyer, Brian Moldt, Dennis R. Burton, Benjamin Von Bredow, Kim L Weisgrau, Eva G Rakasz, David T Evans
    Abstract:

    Tetherin is an IFN-inducible transmembrane protein that inhibits the detachment of enveloped viruses from infected cells. HIV-1 overcomes this restriction factor by expressing HIV-1 viral protein U (Vpu), which down-regulates and degrades tetherin. We report that mutations in Vpu that impair tetherin antagonism increase the susceptibility of HIV-infected cells to Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), and conversely that RNAi knockdown of tetherin, but not other cellular proteins down-modulated by Vpu, decreases the susceptibility of HIV-infected cells to ADCC. These results reveal that Vpu protects HIV-infected cells from ADCC as a function of its ability to counteract tetherin. By serving as link between innate and adaptive immunity, the antiviral activity of tetherin may be augmented by virus-specific antibodies, and hence much greater than previously appreciated.

  • a novel assay for antibody dependent cell mediated Cytotoxicity against hiv 1 or siv infected cells reveals incomplete overlap with antibodies measured by neutralization and binding assays
    Journal of Virology, 2012
    Co-Authors: Michael D Alpert, Lisa N Heyer, David E J Williams, Jackson D Harvey, Thomas C Greenough, Maria Allhorn, David T Evans
    Abstract:

    The resistance of human immunodeficiency virus type 1 (HIV-1) to antibody-mediated immunity often prevents the detection of antibodies that neutralize primary isolates of HIV-1. However, conventional assays for antibody functions other than neutralization are suboptimal. Current methods for measuring the killing of virus-infected cells by Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) are limited by the number of natural killer (NK) cells obtainable from individual donors, donor-to-donor variation, and the use of nonphysiological targets. We therefore developed an ADCC assay based on NK cell lines that express human or macaque CD16 and a CD4(+) T-cell line that expresses luciferase from a Tat-inducible promoter upon HIV-1 or simian immunodeficiency virus (SIV) infection. NK cells and virus-infected targets are mixed in the presence of serial plasma dilutions, and ADCC is measured as the dose-dependent loss of luciferase activity. Using this approach, ADCC titers were measured in plasma samples from HIV-infected human donors and SIV-infected macaques. For the same plasma samples paired with the same test viruses, this assay was approximately 2 orders of magnitude more sensitive than optimized assays for neutralizing antibodies-frequently allowing the measurement of ADCC in the absence of detectable neutralization. Although ADCC correlated with other measures of Env-specific antibodies, neutralizing and gp120 binding titers did not consistently predict ADCC activity. Hence, this assay affords a sensitive method for measuring antibodies capable of directing ADCC against HIV- or SIV-infected cells expressing native conformations of the viral envelope glycoprotein and reveals incomplete overlap of the antibodies that direct ADCC and those measured in neutralization and binding assays.

Meiyun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • antibody dependent cell mediated Cytotoxicity epitopes on the hemagglutinin head region of pandemic h1n1 influenza virus play detrimental roles in h1n1 infected mice
    Frontiers in Immunology, 2017
    Co-Authors: Shuofeng Yuan, Bojian Zheng, Meiyun Zhang, Kwokman Vincent Poon, Lei Wen, Dong Yang, Zehua Sun, Huiping Shuai, Jie Zhou, Hin Chu
    Abstract:

    Engaging the Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) for killing of virus-infected cells and secretion of antiviral cytokines and chemokines was incorporated as one of the important features in the design of universal influenza vaccines. However, investigation of the ADCC epitopes on the highly immunogenic influenza hemagglutinin (HA) head region has been rarely reported. In this study, we determined the ADCC and antiviral activities of two putative ADCC epitopes, designated E1 and E2, on the HA-head of a pandemic H1N1 influenza virus in vitro and in a lethal mouse model. Our data demonstrated that sera from the E1-vaccinated mice could induce high ADCC activities. Importantly, the induction of ADCC response modestly decreased viral load in the lungs of H1N1-infected mice. However, the elevated ADCC significantly increased mouse alveolar damage and mortality than that of the PBS-vaccinated group (p<0.0001). The phenotype was potentially due to an exaggerated inflammatory cell infiltration triggered by ADCC, as an up-regulated release of cytotoxic granules (perforin) was observed in the lung tissue of E1-vaccinated mice after H1N1 influenza virus challenge. Overall, our data suggested that ADCC elicited by certain domains of HA head-region might have a detrimental rather than protective effect during influenza virus infection. Thus, future design of universal influenza vaccine shall strike a balance between the induction of protective immunity and potential side effects of ADCC.

  • identification of dominant antibody dependent cell mediated Cytotoxicity epitopes on the hemagglutinin antigen of pandemic h1n1 influenza virus
    Journal of Virology, 2013
    Co-Authors: Vikram Srivastava, Zheng Yang, Ivan Hung, Bojian Zheng, Meiyun Zhang
    Abstract:

    Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) bridges innate and adaptive immunity, and it involves both humoral and cellular immune responses. ADCC has been found to be a main route of immune protection against viral infections in vivo. Hemagglutinin (HA) of influenza virus is highly immunogenic and considered the most important target for immune protection. Several potent cross-reactive HA-specific neutralizing monoclonal antibodies (MAbs) have been reported, and their conserved neutralizing epitopes have been revealed, but there has been no report so far about ADCC epitopes on HA. Here we identified two dominant ADCC epitopes, designated E1 (amino acids [aa] 92 to 117) and E2 (aa 124 to 159), on HA of pandemic H1N1 influenza virus by epitope mapping of convalescent-phase plasma IgG antibodies from six H1N1-infected human subjects in China that exhibited different levels of ADCC activity. The E1 and E2 ADCC epitopes overlapped with immunodominant epitopes of HA. Depletion of purified patient plasma IgG antibodies with EBY100 yeast cells expressing E1 or E2 decreased the ADCC activity of the IgG antibodies. E1 and E2 sequences were found to be highly conserved in H1N1 strains but less so in other subtypes of influenza A viruses. Our study may aid in designing immunogens that can elicit antibodies with high ADCC activity. Vaccine immunogens designed to include the structural determinants of potent broadly neutralizing antibodies and ADCC epitopes may confer comprehensive immune protection against influenza virus infection.

Hiroaki Niiro - One of the best experts on this subject based on the ideXlab platform.

  • the cytotoxic effects of certolizumab pegol and golimumab mediated by transmembrane tumor necrosis factor α
    Inflammatory Bowel Diseases, 2013
    Co-Authors: Naoyasu Ueda, Hiroshi Tsukamoto, Hiroki Mitoma, Masahiro Ayano, Atsushi Tanaka, Shun Ichiro Ohta, Yasushi Inoue, Yojiro Arinobu, Hiroaki Niiro
    Abstract:

    BACKGROUND: Anti-tumor necrosis factor α (anti-TNF-α) agents have been successfully applied for the treatment of rheumatoid arthritis, Crohn's disease, and other chronic inflammatory diseases. Not only the neutralization of soluble TNF-α but also the effect on transmembrane TNF-α is important mechanisms of action of anti-TNF-α agents. This study investigated the cytotoxic effects of new anti-TNF-α agents, certolizumab pegol and golimumab, which are mediated by transmembrane TNF-α. METHODS: Transmembrane TNF-α-expressing Jurkat T cells that did not express TNF receptors were used. The binding ability of each anti-TNF-α agent to transmembrane TNF-α, Antibody-Dependent Cell-Mediated Cytotoxicity, complement-dependent Cytotoxicity, and the apoptotic effect were examined. RESULTS: Certolizumab pegol and golimumab bound to transmembrane TNF-α. Golimumab induced Antibody-Dependent Cell-Mediated Cytotoxicity and complement-dependent Cytotoxicity, which was comparable to infliximab and adalimumab. However, certolizumab pegol did not induce Antibody-Dependent Cell-Mediated Cytotoxicity or complement-dependent Cytotoxicity. Certolizumab pegol directly induced nonapoptotic cell death in transmembrane TNF-α-expressing cells. Golimumab induced a weaker apoptotic effect than infliximab and adalimumab. CONCLUSIONS: The cytotoxic effects of anti-TNF-α agents on TNF-α-expressing cells are considered to be associated with the clinical effect of these agents on granulomatous diseases. The direct cytotoxic effect of certolizumab pegol on TNF-α-producing cells may contribute to its clinical efficacy in Crohn's disease. Golimumab may be less effective for granulomatous diseases.

  • the cytotoxic effects of certolizumab pegol and golimumab mediated by transmembrane tumor necrosis factor α
    Inflammatory Bowel Diseases, 2013
    Co-Authors: Naoyasu Ueda, Hiroshi Tsukamoto, Hiroki Mitoma, Masahiro Ayano, Atsushi Tanaka, Shun Ichiro Ohta, Yasushi Inoue, Yojiro Arinobu, Hiroaki Niiro
    Abstract:

    BACKGROUND Anti-tumor necrosis factor α (anti-TNF-α) agents have been successfully applied for the treatment of rheumatoid arthritis, Crohn's disease, and other chronic inflammatory diseases. Not only the neutralization of soluble TNF-α but also the effect on transmembrane TNF-α is important mechanisms of action of anti-TNF-α agents. This study investigated the cytotoxic effects of new anti-TNF-α agents, certolizumab pegol and golimumab, which are mediated by transmembrane TNF-α. METHODS Transmembrane TNF-α-expressing Jurkat T cells that did not express TNF receptors were used. The binding ability of each anti-TNF-α agent to transmembrane TNF-α, Antibody-Dependent Cell-Mediated Cytotoxicity, complement-dependent Cytotoxicity, and the apoptotic effect were examined. RESULTS Certolizumab pegol and golimumab bound to transmembrane TNF-α. Golimumab induced Antibody-Dependent Cell-Mediated Cytotoxicity and complement-dependent Cytotoxicity, which was comparable to infliximab and adalimumab. However, certolizumab pegol did not induce Antibody-Dependent Cell-Mediated Cytotoxicity or complement-dependent Cytotoxicity. Certolizumab pegol directly induced nonapoptotic cell death in transmembrane TNF-α-expressing cells. Golimumab induced a weaker apoptotic effect than infliximab and adalimumab. CONCLUSIONS The cytotoxic effects of anti-TNF-α agents on TNF-α-expressing cells are considered to be associated with the clinical effect of these agents on granulomatous diseases. The direct cytotoxic effect of certolizumab pegol on TNF-α-producing cells may contribute to its clinical efficacy in Crohn's disease. Golimumab may be less effective for granulomatous diseases.

Mohan Srinivasan - One of the best experts on this subject based on the ideXlab platform.

  • glycan optimization of a human monoclonal antibody in the aquatic plant lemna minor
    Nature Biotechnology, 2006
    Co-Authors: Kevin M Cox, Jason D Sterling, Jeffrey T Regan, John R Gasdaska, Karen K Frantz, Charles G Peele, Amelia Nancy Black, David Passmore, Cristina Moldovanloomis, Mohan Srinivasan
    Abstract:

    N-glycosylation is critical to the function of monoclonal antibodies (mAbs) and distinguishes various systems used for their production. We expressed human mAbs in the small aquatic plant Lemna minor, which offers several advantages for manufacturing therapeutic proteins free of zoonotic pathogens1. Glycosylation of a mAb against human CD30 was optimized by co-expressing the heavy and light chains of the mAb with an RNA interference construct targeting expression of the endogenous α-1,3-fucosyltransferase and β-1,2-xylosyltransferase genes. The resultant mAbs contained a single major N-glycan species without detectable plant-specific N-glycans and had better Antibody-Dependent Cell-Mediated Cytotoxicity and effector cell receptor binding activities than mAbs expressed in cultured Chinese hamster ovary (CHO) cells.

  • glycan optimization of a human monoclonal antibody in the aquatic plant lemna minor
    Nature Biotechnology, 2006
    Co-Authors: Kevin M Cox, Jason D Sterling, Jeffrey T Regan, John R Gasdaska, Karen K Frantz, Charles G Peele, David Passmore, Cristina Moldovanloomis, Amelia Black, Mohan Srinivasan
    Abstract:

    N-glycosylation is critical to the function of monoclonal antibodies (mAbs) and distinguishes various systems used for their production. We expressed human mAbs in the small aquatic plant Lemna minor, which offers several advantages for manufacturing therapeutic proteins free of zoonotic pathogens. Glycosylation of a mAb against human CD30 was optimized by co-expressing the heavy and light chains of the mAb with an RNA interference construct targeting expression of the endogenous alpha-1,3-fucosyltransferase and beta-1,2-xylosyltransferase genes. The resultant mAbs contained a single major N-glycan species without detectable plant-specific N-glycans and had better Antibody-Dependent Cell-Mediated Cytotoxicity and effector cell receptor binding activities than mAbs expressed in cultured Chinese hamster ovary (CHO) cells.