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Tolbert WD, Gohain N, Alsahafi N, Van V, Orlandi C, Ding S, Martin L, Finzi A, Lewis GK, Ray K, Pazgier M. Targeting the Late Stage of HIV-1 Entry for Antibody-Dependent Cellular Cytotoxicity: Structural Basis for Env Epitopes in the C11 Region. Structure 2017; 25:1719-1731.e4. [PMID: 29056481 PMCID: PMC5677539 DOI: 10.1016/j.str.2017.09.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/28/2017] [Accepted: 09/18/2017] [Indexed: 01/14/2023]
Abstract
Antibodies can have an impact on HIV-1 infection in multiple ways, including antibody-dependent cellular cytotoxicity (ADCC), a correlate of protection observed in the RV144 vaccine trial. One of the most potent ADCC-inducing epitopes on HIV-1 Env is recognized by the C11 antibody. Here, we present the crystal structure, at 2.9 Å resolution, of the C11-like antibody N12-i3, in a quaternary complex with the HIV-1 gp120, a CD4-mimicking peptide M48U1, and an A32-like antibody, N5-i5. Antibody N12-i3 recognizes an epitope centered on the N-terminal "eighth strand" of a critical β sandwich, which our analysis indicates to be emblematic of a late-entry state, after the gp120 detachment. In prior entry states, this sandwich comprises only seven strands, with the eighth strand instead pairing with a portion of the gp120 C terminus. The conformational gymnastics of HIV-1 gp120 thus includes altered β-strand pairing, possibly to reduce immunogenicity, although nevertheless still recognized by the human immune system.
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Affiliation(s)
- William D. Tolbert
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Biochemistry and Molecular, Biology of University of Maryland School of Medicine, Baltimore, USA
| | - Neelakshi Gohain
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Biochemistry and Molecular, Biology of University of Maryland School of Medicine, Baltimore, USA
| | - Nirmin Alsahafi
- Centre de Recherche du CHUM, Université de Montréal, Montreal, Quebec, Canada,CEA, Joliot, Service d’Ingénierie Moléculaire des Protéines, F-91191 Gif-sur-Yvette, France
| | - Verna Van
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Biochemistry and Molecular, Biology of University of Maryland School of Medicine, Baltimore, USA
| | - Chiara Orlandi
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Microbiology and Immunology of University of Maryland School of Medicine, Baltimore, USA
| | - Shilei Ding
- Centre de Recherche du CHUM, Université de Montréal, Montreal, Quebec, Canada,Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
| | - Loïc Martin
- CEA, Joliot, Service d’Ingénierie Moléculaire des Protéines, F-91191 Gif-sur-Yvette, France
| | - Andrés Finzi
- Centre de Recherche du CHUM, Université de Montréal, Montreal, Quebec, Canada,Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada,Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
| | - George K. Lewis
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Microbiology and Immunology of University of Maryland School of Medicine, Baltimore, USA
| | - Krishanu Ray
- Department of Biochemistry and Molecular, Biology of University of Maryland School of Medicine, Baltimore, USA
| | - Marzena Pazgier
- Division of Vaccine Research, Institute of Human Virology, Biology of University of Maryland School of Medicine, Baltimore, USA,Department of Biochemistry and Molecular, Biology of University of Maryland School of Medicine, Baltimore, USA,To whom correspondence should be addressed: , 725 West Lombard Street, Baltimore, MD 21201, USA, Tel: (410) 706-4780, Fax: (410) 706-7583
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52
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Richard J, Ding S, Finzi A. Unlocking HIV-1 Env: implications for antibody attack. AIDS Res Ther 2017; 14:42. [PMID: 28893275 PMCID: PMC5594528 DOI: 10.1186/s12981-017-0168-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 08/11/2017] [Indexed: 01/29/2023] Open
Abstract
Collective evidence supporting a role of Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) in controlling HIV-1 transmission and disease progression emerged in the last few years. Non-neutralizing antibodies (nnAbs) recognizing conserved CD4-induced epitopes on Env and able to mediate potent ADCC against HIV-1-infected cells exposing Env in its CD4-bound conformation have been shown to be present in some RV144 vaccinees and most HIV-1-infected individuals. HIV-1 evolved sophisticated strategies to decrease exposure of this Env conformation by downregulating CD4 and by limiting the overall amount of cell-surface Env. In this review, we will summarize our contribution to this rapidly evolving field, discuss how structural properties of HIV-1 Env might have contributed to the modest efficacy of the RV144 trial and how we recently used this knowledge to develop new strategies aimed at sensitizing HIV-1-infected cells to ADCC mediated by easy to elicit nnAbs.
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53
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Bernard NF, Kiani Z, Tremblay-McLean A, Kant SA, Leeks CE, Dupuy FP. Natural Killer (NK) Cell Education Differentially Influences HIV Antibody-Dependent NK Cell Activation and Antibody-Dependent Cellular Cytotoxicity. Front Immunol 2017; 8:1033. [PMID: 28883824 PMCID: PMC5574056 DOI: 10.3389/fimmu.2017.01033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/10/2017] [Indexed: 11/13/2022] Open
Abstract
Immunotherapy using broadly neutralizing antibodies (bNAbs) endowed with Fc-mediated effector functions has been shown to be critical for protecting or controlling viral replication in animal models. In human, the RV144 Thai trial was the first trial to demonstrate a significant protection against HIV infection following vaccination. Analysis of the correlates of immune protection in this trial identified an association between the presence of antibody-dependent cellular cytotoxicity (ADCC) mediated by immunoglobulin G (IgG) antibodies (Abs) to HIV envelope (Env) V1/V2 loop structures and protection from infection, provided IgA Abs with competing specificity were not present. Systems serology analyses implicated a broader range of Ab-dependent functions in protection from HIV infection, including but not limited to ADCC and Ab-dependent NK cell activation (ADNKA) for secretion of IFN-γ and CCL4 and expression of the degranulation marker CD107a. The existence of such correlations in the absence of bNAbs in the RV144 trial suggest that NK cells could be instrumental in protecting against HIV infection by limiting viral spread through Fc-mediated functions such as ADCC and the production of antiviral cytokines/chemokines. Beside the engagement of FcγRIIIa or CD16 by the Fc portion of anti-Env IgG1 and IgG3 Abs, natural killer (NK) cells are also able to directly kill infected cells and produce cytokines/chemokines in an Ab-independent manner. Responsiveness of NK cells depends on the integration of activating and inhibitory signals through NK receptors, which is determined by a process during their development known as education. NK cell education requires the engagement of inhibitory NK receptors by their human leukocyte antigen ligands to establish tolerance to self while allowing NK cells to respond to self cells altered by virus infection, transformation, stress, and to allogeneic cells. Here, we review recent findings regarding the impact of inter-individual differences in NK cell education on Ab-dependent functions such as ADCC and ADNKA, including what is known about the HIV Env epitope specificity of ADCC competent Abs and the conformation of HIV Env on target cells used for ADCC assays.
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Affiliation(s)
- Nicole F Bernard
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada.,Chronic Viral Illness Service, McGill University Health Centre, Montreal, QC, Canada.,Division of Clinical Immunology, McGill University Health Centre, Montreal, QC, Canada
| | - Zahra Kiani
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Alexandra Tremblay-McLean
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Sanket A Kant
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Christopher E Leeks
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Franck P Dupuy
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
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54
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Plasticity and Epitope Exposure of the HIV-1 Envelope Trimer. J Virol 2017; 91:JVI.00410-17. [PMID: 28615206 DOI: 10.1128/jvi.00410-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/30/2017] [Indexed: 01/21/2023] Open
Abstract
We recently showed that mutations in the HIV-1 envelope (Env) destabilize the V3 loop, rendering neutralization-resistant viruses sensitive to V3-directed monoclonal antibodies (MAbs). Here, we investigated the propagation of this effect on other Env epitopes, with special emphasis on V2 loop exposure. Wild-type JR-FL and 19 mutant JR-FL pseudoviruses were tested for neutralization sensitivity to 21 MAbs specific for epitopes in V2, the CD4 binding site (CD4bs), and the CD4-induced (CD4i) region. Certain glycan mutants, mutations in the gp120 hydrophobic core, and mutations in residues involved in intraprotomer interactions exposed epitopes in the V2i region (which overlies the α4β7 integrin binding site) and the V3 crown, suggesting general destabilization of the distal region of the trimer apex. In contrast, other glycan mutants, mutations affecting interprotomer interactions, and mutations affecting the CD4bs exposed V3 but not V2i epitopes. These data indicate for the first time that V3 can move independently of V2, with V3 pivoting out from its "tucked" position in the trimer while apparently leaving the V2 apex intact. Notably, none of the mutations exposed V2 epitopes without also exposing V3, suggesting that movement of V2 releases V3. Most mutations increased sensitivity to CD4bs-directed MAbs without exposure of the CD4i epitope, implying these mutations facilitate the trimers' maintenance of an intermediate energy state between open and closed conformations. Taken together, these data indicate that several transient Env epitopes can be rendered more accessible to antibodies (Abs) via specific mutations, and this may facilitate the design of V1V2-targeting immunogens.IMPORTANCE Many epitopes of the HIV envelope (Env) spike are relatively inaccessible to antibodies (Abs) compared to their exposure in the open Env conformation induced by receptor binding. However, the reduced infection rate that resulted from the vaccine used in the RV144 HIV-1 vaccine trial was correlated with the elicitation of V2- and V3-directed antibodies. Previously, we identified various mechanisms responsible for destabilizing the V3 loop; here, we determined, via mutation of numerous Env residues, which of these elements maintain the V1V2 loop in an inaccessible state and which expose V1V2 and/or V3 epitopes. Notably, our data indicate that V3 can move independently of V2, but none of the mutations studied expose V2 epitopes without also exposing V3. Additionally, V1V2 can be rendered more accessible to Abs via specific mutations, facilitating the development of engineered V2 immunogens.
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Lewis GK, Pazgier M, Evans DT, Ferrari G, Bournazos S, Parsons MS, Bernard NF, Finzi A. Beyond Viral Neutralization. AIDS Res Hum Retroviruses 2017; 33:760-764. [PMID: 28084796 PMCID: PMC5695748 DOI: 10.1089/aid.2016.0299] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It has been known for more than 30 years that HIV-1 infection drives a very potent B cell response resulting in the production of anti-HIV-1 antibodies targeting several viral proteins, particularly its envelope glycoproteins (Env). Env epitopes are exposed on the surfaces of viral particles and infected cells where they are targets of potentially protective antibodies. These antibodies can interdict infection by neutralization and there is strong evidence suggesting that Fc-mediated effector function can also contribute to protection. Current evidence suggests that Fc-mediated effector function plays a role in protection against infection by broadly neutralizing antibodies and it might be important for protection by non-neutralizing antibodies. Fc-mediated effector function includes diverse mechanisms such as antibody-dependent cellular cytotoxicity (ADCC), antibody-mediated complement activation, antibody-dependent cellular phagocytosis, antibody-dependent cell-mediated virus inhibition, antibody-mediated trancytosis inhibition, and antibody-mediated virus opsonization. All these functions could be beneficial in fighting viral infections, including HIV-1. In this perspective, we discuss the latest developments in ADCC research discussed at the HIVR4P satellite session on non-neutralizing antibodies, with emphasis on the mechanisms of ADCC resistance used by HIV-1, the structural basis of epitopes recognized by antibodies that mediate ADCC, natural killer-cell education and ADCC, and murine models to study ADCC against HIV-1.
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Affiliation(s)
- George K. Lewis
- Division of Vaccine Research of Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Marzena Pazgier
- Division of Vaccine Research of Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - David T. Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin
| | - Guido Ferrari
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - Stylianos Bournazos
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, New York
| | - Matthew S. Parsons
- Department of Microbiology and Immunology, University of Melbourne, Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Nicole F. Bernard
- Research Institute of the McGill University Health Centre, Division of Experimental Medicine, McGill University, Quebec, Canada
| | - Andrés Finzi
- Centre de Recherche du CHUM, Université de Montréal, Quebec, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Quebec, Canada
- Department of Microbiology and Immunology, McGill University, Quebec, Canada
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56
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Anti-HIV-1 ADCC Antibodies following Latency Reversal and Treatment Interruption. J Virol 2017; 91:JVI.00603-17. [PMID: 28539449 DOI: 10.1128/jvi.00603-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 05/15/2017] [Indexed: 12/11/2022] Open
Abstract
There is growing interest in utilizing antibody-dependent cellular cytotoxicity (ADCC) to eliminate infected cells following reactivation from HIV-1 latency. A potential barrier is that HIV-1-specific ADCC antibodies decline in patients on long-term antiretroviral therapy (ART) and may not be sufficient to eliminate reactivated latently infected cells. It is not known whether reactivation from latency with latency-reversing agents (LRAs) could provide sufficient antigenic stimulus to boost HIV-1-specific ADCC. We found that treatment with the LRA panobinostat or a short analytical treatment interruption (ATI), 21 to 59 days, was not sufficient to stimulate an increase in ADCC-competent antibodies, despite viral rebound in all subjects who underwent the short ATI. In contrast, a longer ATI, 2 to 12 months, among subjects enrolled in the Strategies for Management of Antiretroviral Therapy (SMART) trial robustly boosted HIV-1 gp120-specific Fc receptor-binding antibodies and ADCC against HIV-1-infected cells in vitro These results show that there is a lag between viral recrudescence and the boosting of ADCC antibodies, which has implications for strategies toward eliminating latently infected cells.IMPORTANCE The "shock and kill" HIV-1 cure strategy aims to reactivate HIV-1 expression in latently infected cells and subsequently eliminate the reactivated cells through immune-mediated killing. Several latency reversing agents (LRAs) have been examined in vivo, but LRAs alone have not been able to achieve HIV-1 remission and prevent viral rebound following analytical treatment interruption (ATI). In this study, we examined whether LRA treatment or ATI can provide sufficient antigenic stimulus to boost HIV-1-specific functional antibodies that can eliminate HIV-1-infected cells. Our study has implications for the antigenic stimulus required for antilatency strategies and/or therapeutic vaccines to boost functional antibodies and assist in eliminating the latent reservoir.
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57
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BST-2 Expression Modulates Small CD4-Mimetic Sensitization of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity. J Virol 2017; 91:JVI.00219-17. [PMID: 28331088 DOI: 10.1128/jvi.00219-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/13/2017] [Indexed: 12/19/2022] Open
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.
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Lack of ADCC Breadth of Human Nonneutralizing Anti-HIV-1 Antibodies. J Virol 2017; 91:JVI.02440-16. [PMID: 28122982 DOI: 10.1128/jvi.02440-16] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 01/19/2017] [Indexed: 01/23/2023] Open
Abstract
Anti-human immunodeficiency virus type 1 (HIV-1) nonneutralizing antibodies (nnAbs) capable of antibody-dependent cellular cytotoxicity (ADCC) have been identified as a protective immune correlate in the RV144 vaccine efficacy trial. Broadly neutralizing antibodies (bNAbs) also mediate ADCC in cell culture and rely on their Fc region for optimal efficacy in animal models. Here, we selected 9 monoclonal nnAbs and 5 potent bNAbs targeting various epitopes and conformations of the gp120/41 complex and analyzed the potency of the two types of antibodies to bind and eliminate HIV-1-infected cells in culture. Regardless of their neutralizing activity, most of the selected antibodies recognized and killed cells infected with two laboratory-adapted HIV-1 strains. Some nnAbs also bound bystander cells that may have captured viral proteins. However, in contrast to the bNAbs, the nnAbs bound poorly to reactivated infected cells from 8 HIV-positive individuals and did not mediate effective ADCC against these cells. The nnAbs also inefficiently recognize cells infected with 8 different transmitted-founder (T/F) isolates. The addition of a synthetic CD4 mimetic enhanced the binding and killing efficacy of some of the nnAbs in an epitope-dependent manner without reaching the levels achieved by the most potent bNAbs. Overall, our data reveal important qualitative and quantitative differences between nnAbs and bNAbs in their ADCC capacity and strongly suggest that the breadth of recognition of HIV-1 by nnAbs is narrow.IMPORTANCE Most of the anti-HIV antibodies generated by infected individuals do not display potent neutralizing activities. These nonneutralizing antibodies (nnAbs) with antibody-dependent cellular cytotoxicity (ADCC) have been identified as a protective immune correlate in the RV144 vaccine efficacy trial. However, in primate models, the nnAbs do not protect against simian-human immunodeficiency virus (SHIV) acquisition. Thus, the role of nnAbs with ADCC activity in protection from infection remains debatable. In contrast, broadly neutralizing antibodies (bNAbs) neutralize a large array of viral strains and mediate ADCC in cell culture. We analyzed the capacities of 9 nnAbs and 5 bNAbs to eliminate infected cells. We selected 18 HIV-1 strains, including virus reactivated from the reservoir of HIV-positive individuals and transmitted-founder isolates. We report that the nnAbs bind poorly to cells infected with primary HIV-1 strains and do not mediate potent ADCC. Overall, our data show that the breadth of recognition of HIV-1 by nnAbs is narrow.
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59
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Influence of the Envelope gp120 Phe 43 Cavity on HIV-1 Sensitivity to Antibody-Dependent Cell-Mediated Cytotoxicity Responses. J Virol 2017; 91:JVI.02452-16. [PMID: 28100618 DOI: 10.1128/jvi.02452-16] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/12/2017] [Indexed: 01/29/2023] Open
Abstract
HIV-1-infected cells presenting envelope glycoproteins (Env) in the CD4-bound conformation on their surface are preferentially targeted by antibody-dependent cellular-mediated cytotoxicity (ADCC). HIV-1 has evolved sophisticated mechanisms to avoid the exposure of Env ADCC epitopes by downregulating CD4 and by limiting the overall amount of Env on the cell surface. In HIV-1, substitution of large residues such as histidine or tryptophan for serine 375 (S375H/W) in the gp120 Phe 43 cavity, where Phe 43 of CD4 contacts gp120, results in the spontaneous sampling of an Env conformation closer to the CD4-bound state. While residue S375 is well conserved in the majority of group M HIV-1 isolates, CRF01_AE strains have a naturally occurring histidine at this position (H375). Interestingly, CRF01_AE is the predominant circulating strain in Thailand, where the RV144 trial took place. In this trial, which resulted in a modest degree of protection, ADCC responses were identified as being part of the correlate of protection. Here we investigate the influence of the Phe 43 cavity on ADCC responses. Filling this cavity with a histidine or tryptophan residue in Env with a natural serine residue at this position (S375H/W) increased the susceptibility of HIV-1-infected cells to ADCC. Conversely, the replacement of His 375 by a serine residue (H375S) within HIV-1 CRF01_AE decreased the efficiency of the ADCC response. Our results raise the intriguing possibility that the presence of His 375 in the circulating strain where the RV144 trial was held contributed to the observed vaccine efficacy.IMPORTANCE HIV-1-infected cells presenting Env in the CD4-bound conformation on their surface are preferentially targeted by ADCC mediated by HIV-positive (HIV+) sera. Here we show that the gp120 Phe 43 cavity modulates the propensity of Env to sample this conformation and therefore affects the susceptibility of infected cells to ADCC. CRF01_AE HIV-1 strains have an unusual Phe 43 cavity-filling His 375 residue, which increases the propensity of Env to sample the CD4-bound conformation, thereby increasing susceptibility to ADCC.
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Yang Y, Zhu Q, Sun W, Guo J, Ning X, Li Q, Guo Y, Li J, Kou Z, Zhou Y. A recombinant multi-epitope protein MEP1 elicits efficient long-term immune responses against HIV-1 infection. Hum Vaccin Immunother 2017; 13:1-9. [PMID: 28281860 DOI: 10.1080/21645515.2017.1281488] [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: 01/10/2023] Open
Abstract
The effective protective HIV vaccine should elicit either protective antibodies or effective T cell response, or both. To improve the efficacy of HIV-1 vaccines, HLA polymorphism and HIV-1 diversity are 2 key factors to be considered for vaccine development. In this study, we expressed a recombinant multi-epitope protein MEP1 which has the same amino acid sequence as a DNA vaccine for Chinese population in our previous report. We found that MEP1 alone could elicit moderate levels of humoral and cellular immune responses, but these responses could not provide protection from challenge with a recombinant virus rTTV-lucgag, which expresses Gag of HIV-1 CRF_07BC. Nevertheless, when MEP1 was immunized with aluminum adjuvant, both humoral and cellular immune responses were significantly increased, and they were protective against virus infection; meanwhile, MEP1 with aluminum not only elicited early (10 d post immunization) but also a long-term (at least 44 weeks post immunization) immune responses in BALB/c mice. These results suggested that MEP1 has the potential to be developed as an effective vaccine candidate, and that suitable adjuvant is necessary for this protein to generate protective immune responses.
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Affiliation(s)
- Yi Yang
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China.,b Department of Microbiology , Third Military Medical University , Chongqing , China
| | - Qing Zhu
- c School of Laboratory Medicine and Life Science, Wenzhou Medical University , Wenzhou , Zhejiang , China
| | - Weilai Sun
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Jingjing Guo
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Xiuzhe Ning
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Qiao Li
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Yan Guo
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Junfeng Li
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China
| | - Zhihua Kou
- a State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology , Beijing , China.,c School of Laboratory Medicine and Life Science, Wenzhou Medical University , Wenzhou , Zhejiang , China
| | - Yusen Zhou
- c School of Laboratory Medicine and Life Science, Wenzhou Medical University , Wenzhou , Zhejiang , China
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