1
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Grunst MW, Ladd RA, Clark NM, Gil HM, Klenchin VA, Mason R, Franchini G, Roederer M, Evans DT. Antibody-dependent cellular cytotoxicity, infected cell binding and neutralization by antibodies to the SIV envelope glycoprotein. PLoS Pathog 2023; 19:e1011407. [PMID: 37253062 PMCID: PMC10256149 DOI: 10.1371/journal.ppat.1011407] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 06/09/2023] [Accepted: 05/08/2023] [Indexed: 06/01/2023] Open
Abstract
Antibodies specific for diverse epitopes of the simian immunodeficiency virus envelope glycoprotein (SIV Env) have been isolated from rhesus macaques to provide physiologically relevant reagents for investigating antibody-mediated protection in this species as a nonhuman primate model for HIV/AIDS. With increasing interest in the contribution of Fc-mediated effector functions to protective immunity, we selected thirty antibodies representing different classes of SIV Env epitopes for a comparison of antibody-dependent cellular cytotoxicity (ADCC), binding to Env on the surface of infected cells and neutralization of viral infectivity. These activities were measured against cells infected with neutralization-sensitive (SIVmac316 and SIVsmE660-FL14) and neutralization-resistant (SIVmac239 and SIVsmE543-3) viruses representing genetically distinct isolates. Antibodies to the CD4-binding site and CD4-inducible epitopes were identified with especially potent ADCC against all four viruses. ADCC correlated well with antibody binding to virus-infected cells. ADCC also correlated with neutralization. However, several instances of ADCC without detectable neutralization or neutralization without detectable ADCC were observed. The incomplete correspondence between ADCC and neutralization shows that some antibody-Env interactions can uncouple these antiviral activities. Nevertheless, the overall correlation between neutralization and ADCC implies that most antibodies that are capable of binding to Env on the surface of virions to block infectivity are also capable of binding to Env on the surface of virus-infected cells to direct their elimination by ADCC.
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Affiliation(s)
- Michael W. Grunst
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Ruby A. Ladd
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Natasha M. Clark
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Hwi Min Gil
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Vadim A. Klenchin
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Rosemarie Mason
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland, United States of America
| | - Genoveffa Franchini
- Animal Models and Retroviral Vaccines Section, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Mario Roederer
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, Maryland, United States of America
| | - David T. Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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2
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Fray EJ, Wu F, Simonetti FR, Zitzmann C, Sambaturu N, Molina-Paris C, Bender AM, Liu PT, Ventura JD, Wiseman RW, O'Connor DH, Geleziunas R, Leitner T, Ribeiro RM, Perelson AS, Barouch DH, Siliciano JD, Siliciano RF. Antiretroviral therapy reveals triphasic decay of intact SIV genomes and persistence of ancestral variants. Cell Host Microbe 2023; 31:356-372.e5. [PMID: 36809762 PMCID: PMC10583177 DOI: 10.1016/j.chom.2023.01.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 12/02/2022] [Accepted: 01/24/2023] [Indexed: 02/22/2023]
Abstract
The decay kinetics of HIV-1-infected cells are critical to understand virus persistence. We evaluated the frequency of simian immunodeficiency virus (SIV)-infected cells for 4 years of antiretroviral therapy (ART). The intact proviral DNA assay (IPDA) and an assay for hypermutated proviruses revealed short- and long-term infected cell dynamics in macaques starting ART ∼1 year after infection. Intact SIV genomes in circulating CD4+T cells showed triphasic decay with an initial phase slower than the decay of the plasma virus, a second phase faster than the second phase decay of intact HIV-1, and a stable third phase reached after 1.6-2.9 years. Hypermutated proviruses showed bi- or mono-phasic decay, reflecting different selective pressures. Viruses replicating at ART initiation had mutations conferring antibody escape. With time on ART, viruses with fewer mutations became more prominent, reflecting decay of variants replicating at ART initiation. Collectively, these findings confirm ART efficacy and indicate that cells enter the reservoir throughout untreated infection.
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Affiliation(s)
- Emily J Fray
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Fengting Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Francesco R Simonetti
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | | | | | - Alexandra M Bender
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Po-Ting Liu
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - John D Ventura
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Roger W Wiseman
- Wisconsin National Primate Research Center, Madison, WI 53715, USA
| | - David H O'Connor
- Wisconsin National Primate Research Center, Madison, WI 53715, USA
| | | | - Thomas Leitner
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Ruy M Ribeiro
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | | | - Dan H Barouch
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Janet D Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Robert F Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA.
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3
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Abstract
Measuring SARS-CoV-2 neutralizing antibodies after vaccination or natural infection remains a priority in the ongoing COVID-19 pandemic to determine immunity, especially against newly emerging variants. The gold standard for assessing antibody-mediated immunity against SARS-CoV-2 are cell-based live virus neutralization assays. These assays usually take several days, thereby limiting test capacities and the availability of rapid results. In this study, therefore, we developed a faster live virus assay, which detects neutralizing antibodies through the early measurement of antibody-mediated intracellular virus reduction by SARS-CoV-2 qRT-PCR. In our assay, Vero E6 cells are infected with virus isolates preincubated with patient sera and controls. After 24 h, the intracellular viral load is determined by qRT-PCR using a standard curve to calculate percent neutralization. Utilizing COVID-19 convalescent-phase sera, we show that our novel assay generates results with high sensitivity and specificity as we detected antiviral activity for all tested convalescent-phase sera, but no antiviral activity in prepandemic sera. The assay showed a strong correlation with a conventional virus neutralization assay (rS = 0.8910), a receptor-binding domain ELISA (rS = 0.8485), and a surrogate neutralization assay (rS = 0.8373), proving that quantifying intracellular viral RNA can be used to measure seroneutralization. Our assay can be adapted easily to new variants, as demonstrated by our cross-neutralization experiments. This characteristic is key for rapidly determining immunity against newly emerging variants. Taken together, the novel assay presented here reduces turnaround time significantly while making use of a highly standardized and sensitive SARS-CoV-2 qRT-PCR method as a readout.
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4
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Welles HC, King HAD, Nettey L, Cavett N, Gorman J, Zhou T, Tsybovsky Y, Du R, Song K, Nguyen R, Ambrozak D, Ransier A, Schramm CA, Doria-Rose NA, Swanstrom AE, Hoxie JA, LaBranche C, Montefiori DC, Douek DC, Kwong PD, Mascola JR, Roederer M, Mason RD. Broad coverage of neutralization-resistant SIV strains by second-generation SIV-specific antibodies targeting the region involved in binding CD4. PLoS Pathog 2022; 18:e1010574. [PMID: 35709309 PMCID: PMC9242510 DOI: 10.1371/journal.ppat.1010574] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 06/29/2022] [Accepted: 05/06/2022] [Indexed: 11/19/2022] Open
Abstract
Both SIV and SHIV are powerful tools for evaluating antibody-mediated prevention and treatment of HIV-1. However, owing to a lack of rhesus-derived SIV broadly neutralizing antibodies (bnAbs), testing of bnAbs for HIV-1 prevention or treatment has thus far been performed exclusively in the SHIV NHP model using bnAbs from HIV-1-infected individuals. Here we describe the isolation and characterization of multiple rhesus-derived SIV bnAbs capable of neutralizing most isolates of SIV. Eight antibodies belonging to two clonal families, ITS102 and ITS103, which target unique epitopes in the CD4 binding site (CD4bs) region, were found to be broadly neutralizing and together neutralized all SIV strains tested. A rare feature of these bnAbs and two additional antibody families, ITS92 and ITS101, which mediate strain-specific neutralizing activity against SIV from sooty mangabeys (SIVsm), was their ability to achieve near complete (i.e. 100%) neutralization of moderately and highly neutralization-resistant SIV. Overall, these newly identified SIV bnAbs highlight the potential for evaluating HIV-1 prophylactic and therapeutic interventions using fully simian, rhesus-derived bnAbs in the SIV NHP model, thereby circumventing issues related to rapid antibody clearance of human-derived antibodies, Fc mismatch and limited genetic diversity of SHIV compared to SIV.
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Affiliation(s)
- Hugh C. Welles
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hannah A. D. King
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
- U.S. Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, United States of America
| | - Leonard Nettey
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicole Cavett
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jason Gorman
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tongqing Zhou
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yaroslav Tsybovsky
- Vaccine Research Center Electron Microscopy Unit, Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Renguang Du
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kaimei Song
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Richard Nguyen
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David Ambrozak
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Amy Ransier
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Chaim A. Schramm
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicole A. Doria-Rose
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Adrienne E. Swanstrom
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - James A. Hoxie
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Celia LaBranche
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - David C. Montefiori
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Daniel C. Douek
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter D. Kwong
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John R. Mascola
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mario Roederer
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rosemarie D. Mason
- Vaccine Research Center, National Institutes of Health, Bethesda, Maryland, United States of America
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5
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APOBEC3F Constitutes a Barrier to Successful Cross-Species Transmission of Simian Immunodeficiency Virus SIVsmm to Humans. J Virol 2021; 95:e0080821. [PMID: 34132575 DOI: 10.1128/jvi.00808-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Simian immunodeficiency virus infecting sooty mangabeys (SIVsmm) has been transmitted to humans on at least nine occasions, giving rise to human immunodeficiency virus type 2 (HIV-2) groups A to I. SIVsmm isolates replicate in human T cells and seem capable of overcoming major human restriction factors without adaptation. However, only groups A and B are responsible for the HIV-2 epidemic in sub-Saharan Africa, and it is largely unclear whether adaptive changes were associated with spread in humans. To address this, we examined the sensitivity of infectious molecular clones (IMCs) of five HIV-2 strains and representatives of five different SIVsmm lineages to various APOBEC3 proteins. We confirmed that SIVsmm strains replicate in human T cells, albeit with more variable replication fitness and frequently lower efficiency than HIV-2 IMCs. Efficient viral propagation was generally dependent on intact vif genes, highlighting the need for counteraction of APOBEC3 proteins. On average, SIVsmm was more susceptible to inhibition by human APOBEC3D, -F, -G, and -H than HIV-2. For example, human APOBEC3F reduced infectious virus yield of SIVsmm by ∼80% but achieved only ∼40% reduction in the case of HIV-2. Functional and mutational analyses of human- and monkey-derived alleles revealed that an R128T polymorphism in APOBEC3F contributes to species-specific counteraction by HIV-2 and SIVsmm Vifs. In addition, a T84S substitution in SIVsmm Vif increased its ability to counteract human APOBEC3F. Altogether, our results confirm that SIVsmm Vif proteins show intrinsic activity against human APOBEC3 proteins but also demonstrate that epidemic HIV-2 strains evolved an increased ability to counteract this class of restriction factors during human adaptation. IMPORTANCE Viral zoonoses pose a significant threat to human health, and it is important to understand determining factors. SIVs infecting great apes gave rise to HIV-1. In contrast, SIVs infecting African monkey species have not been detected in humans, with one notable exception. SIVsmm from sooty mangabeys has crossed the species barrier to humans on at least nine independent occasions and seems capable of overcoming many innate defense mechanisms without adaptation. Here, we confirmed that SIVsmm Vif proteins show significant activity against human APOBEC3 proteins. Our analyses also revealed, however, that different lineages of SIVsmm are significantly more susceptible to inhibition by various human APOBEC3 proteins than HIV-2 strains. Mutational analyses suggest that an R128T substitution in APOBEC3F and a T84S change in Vif contribute to species-specific counteraction by HIV-2 and SIVsmm. Altogether, our results support that epidemic HIV-2 strains acquired increased activity against human APOBEC3 proteins to clear this restrictive barrier.
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6
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Dispinseri S, Secchi M, Pirillo MF, Tolazzi M, Borghi M, Brigatti C, De Angelis ML, Baratella M, Bazzigaluppi E, Venturi G, Sironi F, Canitano A, Marzinotto I, Tresoldi C, Ciceri F, Piemonti L, Negri D, Cara A, Lampasona V, Scarlatti G. Neutralizing antibody responses to SARS-CoV-2 in symptomatic COVID-19 is persistent and critical for survival. Nat Commun 2021; 12:2670. [PMID: 33976165 PMCID: PMC8113594 DOI: 10.1038/s41467-021-22958-8] [Citation(s) in RCA: 254] [Impact Index Per Article: 84.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 04/11/2021] [Indexed: 12/11/2022] Open
Abstract
Understanding how antibody responses to SARS-CoV-2 evolve during infection may provide important insight into therapeutic approaches and vaccination for COVID-19. Here we profile the antibody responses of 162 COVID-19 symptomatic patients in the COVID-BioB cohort followed longitudinally for up to eight months from symptom onset to find SARS-CoV-2 neutralization, as well as antibodies either recognizing SARS-CoV-2 spike antigens and nucleoprotein, or specific for S2 antigen of seasonal beta-coronaviruses and hemagglutinin of the H1N1 flu virus. The presence of neutralizing antibodies within the first weeks from symptoms onset correlates with time to a negative swab result (p = 0.002), while the lack of neutralizing capacity correlates with an increased risk of a fatal outcome (p = 0.008). Neutralizing antibody titers progressively drop after 5-8 weeks but are still detectable up to 8 months in the majority of recovered patients regardless of age or co-morbidities, with IgG to spike antigens providing the best correlate of neutralization. Antibody responses to seasonal coronaviruses are temporarily boosted, and parallel those to SARS-CoV-2 without dampening the specific response or worsening disease progression. Our results thus suggest compromised immune responses to the SARS-CoV-2 spike to be a major trait of COVID-19 patients with critical conditions, and thereby inform on the planning of COVID-19 patient care and therapy prioritization.
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Affiliation(s)
- Stefania Dispinseri
- Viral Evolution and Transmission Unit, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Massimiliano Secchi
- Diabetes Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy
- DNA Enzymology & Molecular Virology Unit, Institute of Molecular Genetics, National Research Council, Pavia, Italy
| | | | - Monica Tolazzi
- Viral Evolution and Transmission Unit, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Martina Borghi
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Cristina Brigatti
- Diabetes Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Maria Laura De Angelis
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Marco Baratella
- Viral Evolution and Transmission Unit, IRCCS Ospedale San Raffaele, Milan, Italy
| | | | - Giulietta Venturi
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Francesca Sironi
- Viral Evolution and Transmission Unit, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Andrea Canitano
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Ilaria Marzinotto
- Diabetes Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Cristina Tresoldi
- Molecular Hematology Unit, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Fabio Ciceri
- Hematology and Bone Marrow Transplantation Unit, IRCCS Ospedale San Raffaele, Milan, Italy
- School of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Lorenzo Piemonti
- Diabetes Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy
- School of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Donatella Negri
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Andrea Cara
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Vito Lampasona
- Diabetes Research Institute, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Gabriella Scarlatti
- Viral Evolution and Transmission Unit, IRCCS Ospedale San Raffaele, Milan, Italy.
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7
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Khoury DS, Wheatley AK, Ramuta MD, Reynaldi A, Cromer D, Subbarao K, O'Connor DH, Kent SJ, Davenport MP. Measuring immunity to SARS-CoV-2 infection: comparing assays and animal models. Nat Rev Immunol 2020; 20:727-738. [PMID: 33139888 PMCID: PMC7605490 DOI: 10.1038/s41577-020-00471-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2020] [Indexed: 01/08/2023]
Abstract
The rapid scale-up of research on coronavirus disease 2019 (COVID-19) has spawned a large number of potential vaccines and immunotherapies, accompanied by a commensurately large number of in vitro assays and in vivo models to measure their effectiveness. These assays broadly have the same end-goal - to predict the clinical efficacy of prophylactic and therapeutic interventions in humans. However, the apparent potency of different interventions can vary considerably between assays and animal models, leading to very different predictions of clinical efficacy. Complete harmonization of experimental methods may be intractable at the current pace of research. However, here we analyse a selection of existing assays for measuring antibody-mediated virus neutralization and animal models of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and provide a framework for comparing results between studies and reconciling observed differences in the effects of interventions. Finally, we propose how we might optimize these assays for better comparison of results from in vitro and animal studies to accelerate progress.
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Affiliation(s)
- David S Khoury
- Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
| | - Adam K Wheatley
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Mitchell D Ramuta
- Department of Pathology and Laboratory Medicine, Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Arnold Reynaldi
- Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
| | - Deborah Cromer
- Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
| | - Kanta Subbarao
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- WHO Collaborating Centre for Reference and Research on Influenza, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - David H O'Connor
- Department of Pathology and Laboratory Medicine, Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Stephen J Kent
- Department of Microbiology and Immunology, University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Melbourne Sexual Health Centre and Department of Infectious Diseases, Alfred Hospital and Central Clinical School, Monash University, Melbourne, Victoria, Australia
- ARC Centre for Excellence in Convergent Bio-Nano Science and Technology, The University of Melbourne, Parkville, Victoria, Australia
| | - Miles P Davenport
- Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia.
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8
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Martins MA, Gonzalez-Nieto L, Ricciardi MJ, Bailey VK, Dang CM, Bischof GF, Pedreño-Lopez N, Pauthner MG, Burton DR, Parks CL, Earl P, Moss B, Rakasz EG, Lifson JD, Desrosiers RC, Watkins DI. Rectal Acquisition of Simian Immunodeficiency Virus (SIV) SIVmac239 Infection despite Vaccine-Induced Immune Responses against the Entire SIV Proteome. J Virol 2020; 94:e00979-20. [PMID: 33028714 PMCID: PMC7925177 DOI: 10.1128/jvi.00979-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/25/2020] [Indexed: 11/20/2022] Open
Abstract
Given the complex biology of human immunodeficiency virus (HIV) and its remarkable capacity to evade host immune responses, HIV vaccine efficacy may benefit from the induction of both humoral and cellular immune responses of maximal breadth, potency, and longevity. Guided by this rationale, we set out to develop an immunization protocol aimed at maximizing the induction of anti-Envelope (anti-Env) antibodies and CD8+ T cells targeting non-Env epitopes in rhesus macaques (RMs). Our approach was to deliver the entire simian immunodeficiency virus (SIV) proteome by serial vaccinations. To that end, 12 RMs were vaccinated over 81 weeks with DNA, modified vaccinia Ankara (MVA), vesicular stomatitis virus (VSV), adenovirus type 5 (Ad5), rhesus monkey rhadinovirus (RRV), and DNA again. Both the RRV and the final DNA boosters delivered a near-full-length SIVmac239 genome capable of assembling noninfectious SIV particles and inducing T-cell responses against all nine SIV proteins. Compared to previous SIV vaccine trials, the present DNA-MVA-VSV-Ad5-RRV-DNA regimen resulted in comparable levels of Env-binding antibodies and SIV-specific CD8+ T-cells. Interestingly, one vaccinee developed low titers of neutralizing antibodies (NAbs) against SIVmac239, a tier 3 virus. Following repeated intrarectal marginal-dose challenges with SIVmac239, vaccinees were not protected from SIV acquisition but manifested partial control of viremia. Strikingly, the animal with the low-titer vaccine-induced anti-SIVmac239 NAb response acquired infection after the first SIVmac239 exposure. Collectively, these results highlight the difficulties in eliciting protective immunity against immunodeficiency virus infection.IMPORTANCE Our results are relevant to HIV vaccine development efforts because they suggest that increasing the number of booster immunizations or delivering additional viral antigens may not necessarily improve vaccine efficacy against immunodeficiency virus infection.
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Affiliation(s)
| | | | | | - Varian K Bailey
- Department of Pathology, University of Miami, Miami, Florida, USA
| | - Christine M Dang
- Department of Pathology, University of Miami, Miami, Florida, USA
| | - Georg F Bischof
- Department of Pathology, University of Miami, Miami, Florida, USA
| | | | - Matthias G Pauthner
- Department of Immunology and Microbiology, IAVI Neutralizing Antibody Center, Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, USA
| | - Dennis R Burton
- Department of Immunology and Microbiology, IAVI Neutralizing Antibody Center, Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, California, USA
| | - Christopher L Parks
- International AIDS Vaccine Initiative, AIDS Vaccine Design and Development Laboratory, Brooklyn, New York, USA
| | - Patricia Earl
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Bernard Moss
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Eva G Rakasz
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | | | - David I Watkins
- Department of Pathology, University of Miami, Miami, Florida, USA
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9
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Gardner MR, Fellinger CH, Kattenhorn LM, Davis-Gardner ME, Weber JA, Alfant B, Zhou AS, Prasad NR, Kondur HR, Newton WA, Weisgrau KL, Rakasz EG, Lifson JD, Gao G, Schultz-Darken N, Farzan M. AAV-delivered eCD4-Ig protects rhesus macaques from high-dose SIVmac239 challenges. Sci Transl Med 2019; 11:eaau5409. [PMID: 31341061 PMCID: PMC6716512 DOI: 10.1126/scitranslmed.aau5409] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 02/09/2019] [Accepted: 05/31/2019] [Indexed: 12/17/2022]
Abstract
A number of simian and simian human immunodeficiency viruses (SIV and SHIV, respectively) have been used to assess the efficacy of HIV-1 vaccine strategies. Among these, SIVmac239 is considered among the most stringent because, unlike SHIV models, its full genome has coevolved in its macaque host and its tier 3 envelope glycoprotein (Env) is exceptionally hard to neutralize. Here, we investigated the ability of eCD4-Ig, an antibody-like entry inhibitor that emulates the HIV-1 and SIV receptor and coreceptor, to prevent SIVmac239 infection. We show that rh-eCD4-IgI39N expressed by recombinant adeno-associated virus (AAV) vectors afforded four rhesus macaques complete protection from high-dose SIVmac239 challenges that infected all eight control macaques. However, rh-eCD4-IgI39N-expressing macaques eventually succumbed to serial escalating challenge doses that were 2, 8, 16, and 32 times the challenge doses that infected the control animals. Despite receiving greater challenge doses, these macaques had significantly lower peak and postpeak viral loads than the control group. Virus isolated from three of four macaques showed evidence of strong immune pressure from rh-eCD4-IgI39N, with mutations located in the CD4-binding site, which, in one case, exploited a point-mutation difference between rh-eCD4-IgI39N and rhesus CD4. Other escape pathways associated with clear fitness costs to the virus. Our data report effective protection of rhesus macaques from SIVmac239.
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Affiliation(s)
- Matthew R Gardner
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA.
| | - Christoph H Fellinger
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Lisa M Kattenhorn
- Department of Microbiology and Immunobiology, Harvard Medical School, New England Primate Research Center, Southborough, MA 01772, USA
| | - Meredith E Davis-Gardner
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Jesse A Weber
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Barnett Alfant
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Amber S Zhou
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Neha R Prasad
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Hema R Kondur
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Wendy A Newton
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715 USA
| | - Kimberly L Weisgrau
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715 USA
| | - Eva G Rakasz
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715 USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Guangping Gao
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Nancy Schultz-Darken
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715 USA
| | - Michael Farzan
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA.
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10
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Induction of neutralizing antibodies against tier 2 human immunodeficiency virus 1 in rhesus macaques infected with tier 1B simian/human immunodeficiency virus. Arch Virol 2019; 164:1297-1308. [PMID: 30820667 PMCID: PMC6469619 DOI: 10.1007/s00705-019-04173-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 01/17/2019] [Indexed: 11/21/2022]
Abstract
We previously developed CCR5-tropic neutralization-resistant simian/human immunodeficiency virus (SHIV) strains and a rhesus macaque model of infection with these SHIVs. We induced the production of neutralizing antibodies (nAbs) against HIV-1 by infecting rhesus macaques with different neutralization-resistant SHIV strains. First, SHIV-MK1 (MK1) (neutralization susceptible, tier 1B) with CCR5 tropism was generated from SHIV-KS661 using CXCR4 as the main co-receptor. nAbs against parental-lineage and heterologous tier 2 viruses were induced by tier 1B virus (MK1) infection of the rhesus macaque MM482. We analyzed viral resistance to neutralization over time in MM482 and observed that the infecting virus mutated from tier 1B to tier 2 at 36 weeks postinfection (wpi). In addition, an analysis of mutations showed that N169D, K187E, S190N, S239, T459N (T459D at 91 wpi), and V842A mutations were present after 36 wpi. This led to the appearance of neutralization-resistant viral clones. In addition, MK1 was passaged in three rhesus macaques to generate neutralization-resistant SHIV-MK38 (MK38) (tier 2). We evaluated nAb production by rhesus macaques infected with SHIV-MK38 #818 (#818) (tier 2), a molecular clone of MK38. Neutralization of the parental lineage was induced earlier than in macaques infected with tier 1B virus, and neutralization activity against heterologous tier 2 virus was beginning to develop. Therefore, CCR5-tropic neutralization-resistant SHIV-infected rhesus macaques may be useful models of anti-HIV-1 nAb production and will facilitate the development of a vaccine that elicits nAbs against HIV-1.
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11
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Martins MA, Bischof GF, Shin YC, Lauer WA, Gonzalez-Nieto L, Watkins DI, Rakasz EG, Lifson JD, Desrosiers RC. Vaccine protection against SIVmac239 acquisition. Proc Natl Acad Sci U S A 2019; 116:1739-1744. [PMID: 30642966 PMCID: PMC6358712 DOI: 10.1073/pnas.1814584116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The biological characteristics of HIV pose serious difficulties for the success of a preventive vaccine. Molecularly cloned SIVmac239 is difficult for antibodies to neutralize, and a variety of vaccine approaches have had great difficulty achieving protective immunity against it in rhesus monkey models. Here we report significant protection against i.v. acquisition of SIVmac239 using a long-lasting approach to vaccination. The vaccine regimen includes a replication-competent herpesvirus engineered to contain a near-full-length SIV genome that expresses all nine SIV gene products, assembles noninfectious SIV virion particles, and is capable of eliciting long-lasting effector-memory cellular immune responses to all nine SIV gene products. Vaccinated monkeys were significantly protected against acquisition of SIVmac239 following repeated marginal dose i.v. challenges over a 4-month period. Further work is needed to define the critical components necessary for eliciting this protective immunity, evaluate the breadth of the protection against a variety of strains, and explore how this approach may be extended to human use.
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Affiliation(s)
- Mauricio A Martins
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Georg F Bischof
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Young C Shin
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - William A Lauer
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Lucas Gonzalez-Nieto
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - David I Watkins
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Eva G Rakasz
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI 53715
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701
| | - Ronald C Desrosiers
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136;
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12
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High-Resolution Sequencing of Viral Populations during Early Simian Immunodeficiency Virus Infection Reveals Evolutionary Strategies for Rapid Escape from Emerging Env-Specific Antibody Responses. J Virol 2018; 92:JVI.01574-17. [PMID: 29343575 DOI: 10.1128/jvi.01574-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 01/08/2018] [Indexed: 01/01/2023] Open
Abstract
Primate lentiviruses, including the human and simian immunodeficiency viruses (HIV and SIV), produce infections marked by persistent, ongoing viral replication. This occurs despite the presence of virus-specific adaptive immune responses, including antibodies targeting the viral envelope glycoprotein (Env), and evolution of antibody-escape variants is a well-documented feature of lentiviral infection. Here, we examined the evolutionary dynamics of the SIV env gene during early infection (≤29 weeks postinfection) in a cohort of four SIVmac251-infected rhesus macaques. We tracked env evolution during acute and early infection using frequent sampling and ultradeep sequencing of viral populations, capturing a transmission bottleneck and the subsequent reestablishment of Env diversity. A majority of changes in the gp120 subunit mapped to two short clusters, one in the first variable region (V1) and one in V4, while most changes in the gp41 subunit appeared in the cytoplasmic domain. Variation in V1 was dominated by short duplications and deletions of repetitive sequence, while variation in V4 was marked by short in-frame deletions and closely overlapping substitutions. The most common substitutions in both patches did not alter viral replicative fitness when tested using a highly sensitive, deep-sequencing-based competition assay. Our results, together with the observation that very similar or identical patterns of sequence evolution also occur in different macaque species infected with related but divergent strains of SIV, suggest that resistance to early, strain-specific anti-Env antibodies is the result of temporally and mutationally predictable pathways of escape that occur during the early stages of infection.IMPORTANCE The envelope glycoprotein (Env) of primate lentiviruses mediates entry by binding to host cell receptors followed by fusion of the viral membrane with the cell membrane. The exposure of Env complexes on the surface of the virion results in targeting by antibodies, leading to selection for virus escape mutations. We used the SIV/rhesus macaque model to track in vivo evolution of variation in Env during acute/early infection in animals with and without antibody responses to Env, uncovering remarkable variation in animals with antibody responses within weeks of infection. Using a deep-sequencing-based fitness assay, we found substitutions associated with antibody escape had little to no effect on inherent replicative capacity. The ability to readily propagate advantageous changes that incur little to no replicative fitness costs may be a mechanism to maintain continuous replication under constant immune selection, allowing the virus to persist for months to years in the infected host.
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13
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White E, Wu F, Chertova E, Bess J, Roser JD, Lifson JD, Hirsch VM. Truncating the gp41 Cytoplasmic Tail of Simian Immunodeficiency Virus Decreases Sensitivity to Neutralizing Antibodies without Increasing the Envelope Content of Virions. J Virol 2018; 92:e01688-17. [PMID: 29142124 PMCID: PMC5774881 DOI: 10.1128/jvi.01688-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/07/2017] [Indexed: 12/30/2022] Open
Abstract
An incomplete understanding of native human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) envelope glycoproteins (Envs) impedes the development of structural models of Env and vaccine design. This shortcoming is due in part to the low number of Env trimers on virus particles. For SIV, this low expression level can be counteracted by truncating the cytoplasmic tail (CT) of Env. CT truncation has been shown to increase Env incorporation into the virion and is commonly used in vaccine and imaging studies, but its effects on viral antigenicity have not been fully elucidated. To study the effects of a CT truncation of Env in viruses in similar genetic contexts, we introduced stop codons into the CT of a SIVsmE660 molecular clone and two neutralizing antibody (NAb) escape variants. These viruses shared 98% sequence identity in Env but were characterized as either tier 1 (sensitive to neutralization), tier 2 (moderately resistant to neutralization), or tier 3 (resistant to neutralization). However, the introduction of premature stop codons in Env at position Q741/Q742 converted all three transfection-derived viruses to a tier 3-like phenotype, and these viruses were uniformly resistant to neutralization by sera from infected macaques and monoclonal antibodies (MAbs). These changes in neutralization sensitivity were not accompanied by an increase in either the virion Env content of infection-derived viruses or the infectivity of transfection-derived viruses in human cells, suggesting that CT mutations may result in global changes to the Env conformation. Our results demonstrate that some CT truncations can affect viral antigenicity and, as such, may not be suitable surrogate models of native HIV/SIV Env.IMPORTANCE Modifications to the SIV envelope protein (Env) are commonly used in structural and vaccine studies to stabilize and increase the expression of Env, often without consideration of effects on antigenicity. One such widespread modification is the truncation of the Env C-terminal tail. Here, we studied the effects of a particular cytoplasmic tail truncation in three SIVsm strains that have highly similar Env sequences but exhibit different sensitivities to neutralizing antibodies. After truncation of the Env CT, these viruses were all very resistant to neutralization by sera from infected macaques and monoclonal antibodies. The viruses with a truncated Env CT also did not exhibit the desired and typical increase in Env expression. These results underscore the importance of carefully evaluating the use of truncated Env as a model in HIV/SIV vaccine and imaging studies and of the continued need to find better models of native Env that contain fewer modifications.
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Affiliation(s)
- Ellen White
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Fan Wu
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
| | - Elena Chertova
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Julian Bess
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - James D Roser
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Vanessa M Hirsch
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, Maryland, USA
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14
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Dense Array of Spikes on HIV-1 Virion Particles. J Virol 2017; 91:JVI.00415-17. [PMID: 28446665 DOI: 10.1128/jvi.00415-17] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 04/17/2017] [Indexed: 11/20/2022] Open
Abstract
HIV-1 is rare among viruses for having a low number of envelope glycoprotein (Env) spikes per virion, i.e., ∼7 to 14. This exceptional feature has been associated with avoidance of humoral immunity, i.e., B cell activation and antibody neutralization. Virus-like particles (VLPs) with increased density of Env are being pursued for vaccine development; however, these typically require protein engineering that alters Env structure. Here, we used instead a strategy that targets the producer cell. We employed fluorescence-activated cell sorting (FACS) to sort for cells that are recognized by trimer cross-reactive broadly neutralizing antibody (bnAb) and not by nonneutralizing antibodies. Following multiple iterations of FACS, cells and progeny virions were shown to display higher levels of antigenically correct Env in a manner that correlated between cells and cognate virions (P = 0.027). High-Env VLPs, or hVLPs, were shown to be monodisperse and to display more than a 10-fold increase in spikes per particle by electron microscopy (average, 127 spikes; range, 90 to 214 spikes). Sequencing revealed a partial truncation in the C-terminal tail of Env that had emerged in the sort; however, iterative rounds of "cell factory" selection were required for the high-Env phenotype. hVLPs showed greater infectivity than standard pseudovirions but largely similar neutralization sensitivity. Importantly, hVLPs also showed superior activation of Env-specific B cells. Hence, high-Env HIV-1 virions, obtained through selection of producer cells, represent an adaptable platform for vaccine design and should aid in the study of native Env.IMPORTANCE The paucity of spikes on HIV is a unique feature that has been associated with evasion of the immune system, while increasing spike density has been a goal of vaccine design. Increasing the density of Env by modifying it in various ways has met with limited success. Here, we focused instead on the producer cell. Cells that stably express HIV spikes were screened on the basis of high binding by bnAbs and low binding by nonneutralizing antibodies. Levels of spikes on cells correlated well with those on progeny virions. Importantly, high-Env virus-like particles (hVLPs) were produced with a manifest array of well-defined spikes, and these were shown to be superior in activating desirable B cells. Our study describes HIV particles that are densely coated with functional spikes, which should facilitate the study of HIV spikes and their development as immunogens.
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15
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Alam M, Kuwata T, Shimura K, Yokoyama M, Ramirez Valdez KP, Tanaka K, Maruta Y, Oishi S, Fujii N, Sato H, Matsuoka M, Matsushita S. Enhanced antibody-mediated neutralization of HIV-1 variants that are resistant to fusion inhibitors. Retrovirology 2016; 13:70. [PMID: 27670680 PMCID: PMC5037607 DOI: 10.1186/s12977-016-0304-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 09/15/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND HIV-1 typically develops resistance to any single antiretroviral agent. Combined anti-retroviral therapy to reduce drug-resistance development is necessary to control HIV-1 infection. Here, to assess the utility of a combination of antibody and fusion inhibitor treatments, we investigated the potency of monoclonal antibodies at neutralizing HIV-1 variants that are resistant to fusion inhibitors. RESULTS Mutations that confer resistance to four fusion inhibitors, enfuvirtide, C34, SC34, and SC34EK, were introduced into the envelope of HIV-1JR-FL, a CCR5-tropic tier 2 strain. Pseudoviruses with these mutations were prepared and used for the assessment of neutralization sensitivity to an array of antibodies. The resulting neutralization data indicate that the potencies of some antibodies, especially of those against the CD4 binding site, V3 loop, and membrane-proximal external region epitopes, were increased by the mutations in gp41 that conferred resistance to the fusion inhibitors. C34-, SC34-, and SC34EK-resistant mutants showed more sensitivity to monoclonal antibodies than enfuvirtide-resistant mutants. An analysis of C34-resistant mutations revealed that the I37K mutation in gp41 HR1 is a key mutation for C34 resistance, low infectivity, neutralization sensitivity, epitope exposure, and slow fusion kinetics. The N126K mutation in the gp41 HR2 domain contributed to C34 resistance and neutralization sensitivity to anti-CD4 binding site antibodies. In the absence of L204I, the effect of N126K was antagonistic to that of I37K. The results of a molecular dynamic simulation of the envelope trimer confirmation suggest that an I37K mutation induces the augmentation of structural fluctuations prominently in the interface between gp41 and gp120. Our observations indicate that the "conformational unmasking" of envelope glycoprotein by an I37K mutation is one of the mechanisms of neutralization sensitivity enhancement. Furthermore, the enhanced neutralization of C34-resistant mutants in vivo was shown by its high rate of neutralization by IgG from HIV patient samples. CONCLUSIONS Mutations in gp41 that confer fusion inhibitor resistance exert enhanced sensitivity to broad neutralizing antibodies (e.g., VRC01 and 10E8) and other conventional antibodies developed in HIV-1 infected patients. Therefore, next-generation fusion inhibitors and monoclonal antibodies could be a potential combination for future regimens of combined antiretroviral therapy.
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Affiliation(s)
- Muntasir Alam
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
| | - Takeo Kuwata
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
| | - Kazuya Shimura
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Masaru Yokoyama
- Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kristel Paola Ramirez Valdez
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
| | - Kazuki Tanaka
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
| | - Yasuhiro Maruta
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
| | - Shinya Oishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Nobutaka Fujii
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hironori Sato
- Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masao Matsuoka
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Shuzo Matsushita
- Matsushita Project Laboratory, Center for AIDS Research, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811 Japan
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16
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Panico M, Bouché L, Binet D, O’Connor MJ, Rahman D, Pang PC, Canis K, North SJ, Desrosiers RC, Chertova E, Keele BF, Bess JW, Lifson JD, Haslam SM, Dell A, Morris HR. Mapping the complete glycoproteome of virion-derived HIV-1 gp120 provides insights into broadly neutralizing antibody binding. Sci Rep 2016; 6:32956. [PMID: 27604319 PMCID: PMC5015092 DOI: 10.1038/srep32956] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/17/2016] [Indexed: 12/31/2022] Open
Abstract
The surface envelope glycoprotein (SU) of Human immunodeficiency virus type 1 (HIV-1), gp120(SU) plays an essential role in virus binding to target CD4+ T-cells and is a major vaccine target. Gp120 has remarkably high levels of N-linked glycosylation and there is considerable evidence that this "glycan shield" can help protect the virus from antibody-mediated neutralization. In recent years, however, it has become clear that gp120 glycosylation can also be included in the targets of recognition by some of the most potent broadly neutralizing antibodies. Knowing the site-specific glycosylation of gp120 can facilitate the rational design of glycopeptide antigens for HIV vaccine development. While most prior studies have focused on glycan analysis of recombinant forms of gp120, here we report the first systematic glycosylation site analysis of gp120 derived from virions produced by infected T lymphoid cells and show that a single site is exclusively substituted with complex glycans. These results should help guide the design of vaccine immunogens.
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Affiliation(s)
- Maria Panico
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Laura Bouché
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Daniel Binet
- BioPharmaSpec, Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, UK
| | - Michael-John O’Connor
- BioPharmaSpec, Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, UK
| | - Dinah Rahman
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Poh-Choo Pang
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Kevin Canis
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Simon J. North
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | | | - Elena Chertova
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
| | - Brandon F. Keele
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
| | - Julian W. Bess
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, USA
| | - Stuart M. Haslam
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Anne Dell
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Howard R. Morris
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
- BioPharmaSpec, Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, UK
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17
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Matsuda K, Chen CY, Whitted S, Chertova E, Roser DJ, Wu F, Plishka RJ, Ourmanov I, Buckler-White A, Lifson JD, Strebel K, Hirsch VM. Enhanced antagonism of BST-2 by a neurovirulent SIV envelope. J Clin Invest 2016; 126:2295-307. [PMID: 27159392 PMCID: PMC4887162 DOI: 10.1172/jci83725] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 03/22/2016] [Indexed: 11/17/2022] Open
Abstract
Current antiretroviral therapy (ART) is not sufficient to completely suppress disease progression in the CNS, as indicated by the rising incidence of HIV-1-associated neurocognitive disorders (HAND) among infected individuals on ART. It is not clear why some HIV-1-infected patients develop HAND, despite effective repression of viral replication in the circulation. SIV-infected nonhuman primate models are widely used to dissect the mechanisms of viral pathogenesis in the CNS. Here, we identified 4 amino acid substitutions in the cytoplasmic tail of viral envelope glycoprotein gp41 of the neurovirulent virus SIVsm804E that enhance replication in macrophages and associate with enhanced antagonism of the host restriction factor BM stromal cell antigen 2 (BST-2). Rhesus macaques were inoculated with a variant of the parental virus SIVsmE543-3 that had been engineered to contain the 4 amino acid substitutions present in gp41 of SIVsm804E. Compared with WT virus-infected controls, animals infected with mutant virus exhibited higher viral load in cerebrospinal fluid. Together, these results are consistent with a potential role for BST-2 in the CNS microenvironment and suggest that BST-2 antagonists may serve as a possible target for countermeasures against HAND.
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Affiliation(s)
- Kenta Matsuda
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Chia-Yen Chen
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Sonya Whitted
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Elena Chertova
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - David J. Roser
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Fan Wu
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Ronald J. Plishka
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Ilnour Ourmanov
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Alicia Buckler-White
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Klaus Strebel
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
| | - Vanessa M. Hirsch
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA
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DeSantis MC, Kim JH, Song H, Klasse PJ, Cheng W. Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry. J Biol Chem 2016; 291:13088-97. [PMID: 27129237 DOI: 10.1074/jbc.m116.729210] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Indexed: 12/21/2022] Open
Abstract
The envelope glycoprotein (Env) gp120/gp41 is required for HIV-1 infection of host cells. Although in general it has been perceived that more Env gives rise to higher infectivity, the precise quantitative dependence of HIV-1 virion infectivity on Env density has remained unknown. Here we have developed a method to examine this dependence. This method involves 1) production of a set of single-cycle HIV-1 virions with varied density of Env on their surface, 2) site-specific labeling of Env-specific antibody Fab with a fluorophore at high efficiency, and 3) optical trapping virometry to measure the number of gp120 molecules on individual HIV-1 virions. The resulting gp120 density per virion is then correlated with the infectivity of the virions measured in cell culture. In the presence of DEAE-dextran, the polycation known to enhance HIV-1 infectivity in cell culture, virion infectivity follows gp120 density as a sigmoidal dependence and reaches an apparent plateau. This quantitative dependence can be described by a Hill equation, with a Hill coefficient of 2.4 ± 0.6. In contrast, in the absence of DEAE-dextran, virion infectivity increases monotonically with gp120 density and no saturation is observed under the experimental conditions. These results provide the first quantitative evidence that Env trimers cooperate on the virion surface to mediate productive infection by HIV-1. Moreover, as a result of the low number of Env trimers on individual virions, the number of additional Env trimers per virion that is required for the optimal infectivity will depend on the inclusion of facilitating agents during infection.
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Affiliation(s)
- Michael C DeSantis
- From the Department of Pharmaceutical Sciences, College of Pharmacy, and
| | - Jin H Kim
- From the Department of Pharmaceutical Sciences, College of Pharmacy, and
| | - Hanna Song
- From the Department of Pharmaceutical Sciences, College of Pharmacy, and
| | - Per Johan Klasse
- the Department of Microbiology and Immunology, Weill Cornell Medicine, Cornell University, New York, New York 10065
| | - Wei Cheng
- From the Department of Pharmaceutical Sciences, College of Pharmacy, and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109 and
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19
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Postler TS, Bixby JG, Desrosiers RC, Yuste E. Systematic analysis of intracellular trafficking motifs located within the cytoplasmic domain of simian immunodeficiency virus glycoprotein gp41. PLoS One 2014; 9:e114753. [PMID: 25479017 PMCID: PMC4257708 DOI: 10.1371/journal.pone.0114753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 11/13/2014] [Indexed: 12/19/2022] Open
Abstract
Previous studies have shown that truncation of the cytoplasmic-domain sequences of the simian immunodeficiency virus (SIV) envelope glycoprotein (Env) just prior to a potential intracellular-trafficking signal of the sequence YIHF can strongly increase Env protein expression on the cell surface, Env incorporation into virions and, at least in some contexts, virion infectivity. Here, all 12 potential intracellular-trafficking motifs (YXXΦ or LL/LI/IL) in the gp41 cytoplasmic domain (gp41CD) of SIVmac239 were analyzed by systematic mutagenesis. One single and 7 sequential combination mutants in this cytoplasmic domain were characterized. Cell-surface levels of Env were not significantly affected by any of the mutations. Most combination mutations resulted in moderate 3- to 8-fold increases in Env incorporation into virions. However, mutation of all 12 potential sites actually decreased Env incorporation into virions. Variant forms with 11 or 12 mutated sites exhibited 3-fold lower levels of inherent infectivity, while none of the other single or combination mutations that were studied significantly affected the inherent infectivity of SIVmac239. These minor effects of mutations in trafficking motifs form a stark contrast to the strong increases in cell-surface expression and Env incorporation which have previously been reported for large truncations of gp41CD. Surprisingly, mutation of potential trafficking motifs in gp41CD of SIVmac316, which differs by only one residue from gp41CD of SIVmac239, effectively recapitulated the increases in Env incorporation into virions observed with gp41CD truncations. Our results indicate that increases in Env surface expression and virion incorporation associated with truncation of SIVmac239 gp41CD are not fully explained by loss of consensus trafficking motifs.
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Affiliation(s)
- Thomas S. Postler
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, United States of America
| | - Jacqueline G. Bixby
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, United States of America
| | - Ronald C. Desrosiers
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, United States of America
| | - Eloísa Yuste
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, United States of America
- * E-mail:
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20
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Schwarzer R, Levental I, Gramatica A, Scolari S, Buschmann V, Veit M, Herrmann A. The cholesterol-binding motif of the HIV-1 glycoprotein gp41 regulates lateral sorting and oligomerization. Cell Microbiol 2014; 16:1565-81. [PMID: 24844300 DOI: 10.1111/cmi.12314] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/24/2014] [Accepted: 05/13/2014] [Indexed: 12/12/2022]
Abstract
Enveloped viruses often use membrane lipid rafts to assemble and bud, augment infection and spread efficiently. However, the molecular bases and functional consequences of the partitioning of viral glycoproteins into microdomains remain intriguing questions in virus biology. Here, we measured Foerster resonance energy transfer by fluorescence lifetime imaging microscopy (FLIM-FRET) to study the role of distinct membrane proximal regions of the human immunodeficiency virus glycoprotein gp41 for lipid raft partitioning in living Chinese hamster ovary cells (CHO-K1). Gp41 was labelled with a fluorescent protein at the exoplasmic face of the membrane, preventing any interference of the fluorophore with the proposed role of the transmembrane and cytoplasmic domains in lateral organization of gp41. Raft localization was deduced from interaction with an established raft marker, a fluorescently tagged glycophosphatidylinositol anchor and the cholesterol recognition amino acid consensus (CRAC) was identified as the crucial lateral sorting determinant in CHO-K1 cells. Interestingly, the raft association of gp41 indicates a substantial cell-to-cell heterogeneity of the plasma membrane microdomains. In complementary fluorescence polarization microscopy, a distinct CRAC requirement was found for the oligomerization of the gp41 variants. Our data provide further insight into the molecular basis and biological implications of the cholesterol dependent lateral sorting of viral glycoproteins for virus assembly at cellular membranes.
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Affiliation(s)
- Roland Schwarzer
- Department of Biology, Molecular Biophysics, Humboldt University, 10115, Berlin, Germany
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21
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Yasmeen A, Ringe R, Derking R, Cupo A, Julien JP, Burton DR, Ward AB, Wilson IA, Sanders RW, Moore JP, Klasse PJ. Differential binding of neutralizing and non-neutralizing antibodies to native-like soluble HIV-1 Env trimers, uncleaved Env proteins, and monomeric subunits. Retrovirology 2014; 11:41. [PMID: 24884783 PMCID: PMC4067080 DOI: 10.1186/1742-4690-11-41] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 05/14/2014] [Indexed: 12/13/2022] Open
Abstract
Background The trimeric envelope glycoproteins (Env) on the surface of HIV-1 virions are the targets for neutralizing antibodies (NAbs). No candidate HIV-1 immunogen has yet induced potent, broadly active NAbs (bNAbs). Part of the explanation may be that previously tested Env proteins inadequately mimic the functional, native Env complex. Trimerization and the proteolytic processing of Env precursors into gp120 and gp41 profoundly alter antigenicity, but soluble cleaved trimers are too unstable to serve as immunogens. By introducing stabilizing mutations (SOSIP), we constructed soluble, cleaved Env trimers derived from the HIV-1 subtype A isolate BG505 that resemble native Env spikes on virions both structurally and antigenically. Results We used surface plasmon resonance (SPR) to quantify antibody binding to different forms of BG505 Env: the proteolytically cleaved SOSIP.664 trimers, cleaved gp120-gp41ECTO protomers, and gp120 monomers. Non-NAbs to the CD4-binding site bound only marginally to the trimers but equally well to gp120-gp41ECTO protomers and gp120 monomers, whereas the bNAb VRC01, directed to the CD4bs, bound to all three forms. In contrast, bNAbs to V1V2 glycan-dependent epitopes bound preferentially (PG9 and PG16) or exclusively (PGT145) to trimers. We also explored the antigenic consequences of three different features of SOSIP.664 gp140 trimers: the engineered inter-subunit disulfide bond, the trimer-stabilizing I559P change in gp41ECTO, and proteolytic cleavage at the gp120-gp41ECTO junction. Each of these three features incrementally promoted native-like trimer antigenicity. We compared Fab and IgG versions of bNAbs and validated a bivalent model of IgG binding. The NAbs showed widely divergent binding kinetics and degrees of binding to native-like BG505 SOSIP.664. High off-rate constants and low stoichiometric estimates of NAb binding were associated with large amounts of residual infectivity after NAb neutralization of the corresponding BG505.T332N pseudovirus. Conclusions The antigenicity and structural integrity of cleaved BG505 SOSIP.664 trimers render these proteins good mimics of functional Env spikes on virions. In contrast, uncleaved gp140s antigenically resemble individual gp120-gp41ECTO protomers and gp120 monomers, but not native trimers. Although NAb binding to functional trimers may thus be both necessary and sufficient for neutralization, the kinetics and stoichiometry of the interaction influence the neutralizing efficacy of individual NAbs.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Per Johan Klasse
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, USA.
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Kulkarni V, Rosati M, Bear J, Pilkington GR, Jalah R, Bergamaschi C, Singh AK, Alicea C, Chowdhury B, Zhang GM, Kim EY, Wolinsky SM, Huang W, Guan Y, LaBranche C, Montefiori DC, Broderick KE, Sardesai NY, Valentin A, Felber BK, Pavlakis GN. Comparison of intradermal and intramuscular delivery followed by in vivo electroporation of SIV Env DNA in macaques. Hum Vaccin Immunother 2013; 9:2081-94. [PMID: 23811579 DOI: 10.4161/hv.25473] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A panel of SIVmac251 transmitted Env sequences were tested for expression, function and immunogenicity in mice and macaques. The immunogenicity of a DNA vaccine cocktail expressing SIVmac239 and three transmitted SIVmac251 Env sequences was evaluated upon intradermal or intramuscular injection followed by in vivo electroporation in macaques using sequential vaccination of gp160, gp120 and gp140 expressing DNAs. Both intradermal and intramuscular vaccination regimens using the gp160 expression plasmids induced robust humoral immune responses, which further improved using the gp120 expressing DNAs. The responses showed durability of binding and neutralizing antibody titers and high avidity for>1 y. The intradermal DNA delivery regimen induced higher cross-reactive responses able to neutralize the heterologous tier 1B-like SIVsmE660_CG7V. Analysis of cellular immune responses showed induction of Env-specific memory responses and cytotoxic granzyme B(+) T cells in both vaccine groups, although the magnitude of the responses were ~10x higher in the intramuscular/electroporation group. The cellular responses induced by both regimens were long lasting and could be detected ~1 y after the last vaccination. These data show that both DNA delivery methods are able to induce robust and durable immune responses in macaques.
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Affiliation(s)
- Viraj Kulkarni
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Margherita Rosati
- Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Jenifer Bear
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Guy R Pilkington
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Rashmi Jalah
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Cristina Bergamaschi
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Ashish K Singh
- Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Candido Alicea
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Bhabadeb Chowdhury
- Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Gen-Mu Zhang
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA; Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Eun-Young Kim
- Division of Infectious Diseases; The Feinberg School of Medicine; Northwestern University; Chicago, IL USA
| | - Steven M Wolinsky
- Division of Infectious Diseases; The Feinberg School of Medicine; Northwestern University; Chicago, IL USA
| | - Wensheng Huang
- Institute of Human Virology; Department of Microbiology and Immunology; University of Maryland School of Medicine; Baltimore, MD USA
| | - Yongjun Guan
- Institute of Human Virology; Department of Microbiology and Immunology; University of Maryland School of Medicine; Baltimore, MD USA
| | - Celia LaBranche
- Department of Surgery; Laboratory for AIDS Vaccine Research and Development; Duke University Medical Center; Durham, NC USA
| | - David C Montefiori
- Department of Surgery; Laboratory for AIDS Vaccine Research and Development; Duke University Medical Center; Durham, NC USA
| | | | | | - Antonio Valentin
- Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - Barbara K Felber
- Human Retrovirus Pathogenesis Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
| | - George N Pavlakis
- Human Retrovirus Section; Vaccine Branch; Center for Cancer Research; National Cancer Institute; Frederick, MD USA
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23
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Kuwata T, Kaori T, Enomoto I, Yoshimura K, Matsushita S. Increased infectivity in human cells and resistance to antibody-mediated neutralization by truncation of the SIV gp41 cytoplasmic tail. Front Microbiol 2013; 4:117. [PMID: 23717307 PMCID: PMC3653066 DOI: 10.3389/fmicb.2013.00117] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/25/2013] [Indexed: 11/23/2022] Open
Abstract
The role of antibodies in protecting the host from human immunodeficiency virus type 1 (HIV-1) infection is of considerable interest, particularly because the RV144 trial results suggest that antibodies contribute to protection. Although infection of non-human primates with simian immunodeficiency virus (SIV) is commonly used as an animal model of HIV-1 infection, the viral epitopes that elicit potent and broad neutralizing antibodies to SIV have not been identified. We isolated a monoclonal antibody (MAb) B404 that potently and broadly neutralizes various SIV strains. B404 targets a conformational epitope comprising the V3 and V4 loops of Env that intensely exposed when Env binds CD4. B404-resistant variants were obtained by passaging viruses in the presence of increasing concentration of B404 in PM1/CCR5 cells. Genetic analysis revealed that the Q733stop mutation, which truncates the cytoplasmic tail of gp41, was the first major substitution in Env during passage. The maximal inhibition by B404 and other MAbs were significantly decreased against a recombinant virus with a gp41 truncation compared with the parental SIVmac316. This indicates that the gp41 truncation was associated with resistance to antibody-mediated neutralization. The infectivities of the recombinant virus with the gp41 truncation were 7,900-, 1,000-, and 140-fold higher than those of SIVmac316 in PM1, PM1/CCR5, and TZM-bl cells, respectively. Immunoblotting analysis revealed that the gp41 truncation enhanced the incorporation of Env into virions. The effect of the gp41 truncation on infectivity was not obvious in the HSC-F macaque cell line, although the resistance of viruses harboring the gp41 truncation to neutralization was maintained. These results suggest that viruses with a truncated gp41 cytoplasmic tail were selected by increased infectivity in human cells and by acquiring resistance to neutralizing antibody.
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Affiliation(s)
- Takeo Kuwata
- Center for AIDS Research, Kumamoto University Kumamoto, Japan
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24
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Abstract
Envelope glycoproteins (Env) of lentiviruses typically possess unusually long cytoplasmic domains, often 150 amino acids or longer. It is becoming increasingly clear that these sequences contribute a diverse array of functional activities to the life cycle of their viruses. The cytoplasmic domain of gp41 (gp41CD) is required for replication of human immunodeficiency virus type 1 (HIV-1) in most but not all cell types, whereas it is largely dispensable for replication of simian immunodeficiency virus (SIV). Functionally, gp41CD has been shown to regulate rapid clathrin-mediated endocytosis of Env. The resultant low levels of Env expression at the cell surface likely serve as an immune avoidance mechanism to limit accessibility to the humoral immune response. Intracellular trafficking of Env is also regulated by gp41CD through interactions with a variety of cellular proteins. Furthermore, gp41CD has been implicated in the incorporation of Env into virions through an interaction with the virally encoded matrix protein. Most recently, the gp41CDs of HIV-1 and SIV were shown to activate the key cellular-transcription factor NF-κB via the serine/threonine kinase TAK1. Less well understood are the cytotoxicity- and apoptosis-inducing activities of gp41CD as well as potential roles in modulating the actin cytoskeleton and overcoming host cell restrictions. In this review, we summarize what is currently known about the cytoplasmic domains of HIV-1 and SIV and attempt to integrate the wealth of information in terms of defined functional activities.
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Affiliation(s)
- Thomas S. Postler
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, USA
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Ronald C. Desrosiers
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, USA
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25
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Bixby JG, Laur O, Johnson WE, Desrosiers RC. Diversity of envelope genes from an uncloned stock of SIVmac251. AIDS Res Hum Retroviruses 2010; 26:1115-31. [PMID: 20836705 DOI: 10.1089/aid.2010.0029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIDS vaccine and pathogenesis research will benefit from a more diverse array of cloned SIV challenge stocks from which to choose. Toward this end, 20 envelope genes were cloned from an extensively used, primary stock of uncloned SIVmac251. Each of the 20 clones had a unique sequence. Their translated sequences differed by as many as 26 amino acids from one another and by as many as 45 amino acids from the commonly used clone SIVmac239. Envelope sequences up to and including the membrane-spanning domain were exchanged into the infectious pathogenic SIVmac239 clone and virus stocks were produced by HEK293T cell transfection. Seventeen of the 20 recombinants were replication competent. The infectivities per ng p27 of the 17 new replication-competent recombinants in C8166-SEAP cells and in TZM-bl cells ranged from minus 32-fold to plus 7.6-fold relative to SIVmac239. A range of sensitivities to neutralization by sCD4 and by sera from SIV-infected macaques was observed but none was as sensitive to these neutralizing agents as SIVmac316, the highly macrophage-competent derivative of SIVmac239. Four strains that were most sensitive to sCD4 inhibition were also among the most sensitive to antibody-mediated neutralization. None of the new recombinant viruses replicated as well as SIVmac316 in primary alveolar macrophage cultures from rhesus monkeys but three of the strains did exhibit significant levels of delayed replication in these primary macrophages, reaching peak levels of virus production of ≥50 ng/ml p27 compared to 600-800 ng/ml p27 with SIVmac316. These new SIV clones are being contributed to the NIH AIDS Reagent Repository and are available to the scientific community.
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Affiliation(s)
- Jacqueline G. Bixby
- New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts
| | - Olga Laur
- New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts
| | - Welkin E. Johnson
- New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts
| | - Ronald C. Desrosiers
- New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts
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26
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27
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Faith SA, Wu Y, Kuhrt D, Steckbeck JD, Craigo JK, Clements JE, Cole KS. Induction of antibody-mediated neutralization in SIVmac239 by a naturally acquired V3 mutation. Virology 2010; 400:86-92. [PMID: 20153009 DOI: 10.1016/j.virol.2010.01.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/04/2010] [Accepted: 01/08/2010] [Indexed: 01/14/2023]
Abstract
Achieving humoral immunity against human immunodeficiency virus (HIV) is a major obstacle in AIDS vaccine development. Despite eliciting robust humoral responses to HIV, exposed hosts rarely produce broadly neutralizing antibodies. The present study utilizes simian immunodeficiency virus (SIV) to identify viral epitopes that conferred antibody neutralization to clone SIV/17E-CL, an in vivo variant derived from neutralization resistant SIVmac239. Neutralization assays using rhesus macaque monoclonal antibodies were performed on viruses engineered to express single or multiple amino acid mutations. Results identified a single amino acid mutation, P334R, in the carboxy-terminal half of the V3 loop as a critical residue that induced neutralization while retaining normal glycoprotein expression on the surface of the virus. Furthermore, the R334 residue yielded neutralization sensitivity by antibodies recognizing diverse conformational and linear epitopes of gp120, suggesting that neutralization phenotype was a consequence of global structural changes of the envelope protein rather than a specific site epitope.
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Affiliation(s)
- Seth A Faith
- University of Pittsburgh Center for Vaccine Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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28
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Kulkarni SS, Lapedes A, Tang H, Gnanakaran S, Daniels MG, Zhang M, Bhattacharya T, Li M, Polonis VR, McCutchan FE, Morris L, Ellenberger D, Butera ST, Bollinger RC, Korber BT, Paranjape RS, Montefiori DC. Highly complex neutralization determinants on a monophyletic lineage of newly transmitted subtype C HIV-1 Env clones from India. Virology 2009; 385:505-20. [PMID: 19167740 PMCID: PMC2677301 DOI: 10.1016/j.virol.2008.12.032] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 12/01/2008] [Accepted: 12/16/2008] [Indexed: 10/21/2022]
Abstract
Little is known about the neutralization properties of HIV-1 in India to optimally design and test vaccines. For this reason, a functional Env clone was obtained from each of ten newly acquired, heterosexually transmitted HIV-1 infections in Pune, Maharashtra. These clones formed a phylogenetically distinct genetic lineage within subtype C. As Env-pseudotyped viruses the clones were mostly resistant to IgG1b12, 2G12 and 2F5 but all were sensitive to 4E10. When compared to a large multi-subtype panel of Env-pseudotyped viruses (subtypes B, C and CRF02_AG) in neutralization assays with a multi-subtype panel of HIV-1-positive plasma samples, the Indian Envs were remarkably complex. With the exception of the Indian Envs, results of a hierarchical clustering analysis showed a strong subtype association with the patterns of neutralization susceptibility. From these patterns we were able to identify 19 neutralization cluster-associated amino acid signatures in gp120 and 14 signatures in the ectodomain and cytoplasmic tail of gp41. We conclude that newly transmitted Indian Envs are antigenically complex in spite of close genetic similarity. Delineation of neutralization-associated amino acid signatures provides a deeper understanding of the antigenic structure of HIV-1 Env.
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Affiliation(s)
| | - Alan Lapedes
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Haili Tang
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710
| | - S. Gnanakaran
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Marcus G. Daniels
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Ming Zhang
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Tanmoy Bhattacharya
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Ming Li
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710
| | - Victoria R. Polonis
- Walter Reed Army Institute of Research and the Henry M. Jackson Foundation, Rockville, Maryland 20850
| | - Francine E. McCutchan
- Walter Reed Army Institute of Research and the Henry M. Jackson Foundation, Rockville, Maryland 20850
| | - Lynn Morris
- National Institute for Communicable Diseases, Johannesburg, South Africa
| | | | | | - Robert C. Bollinger
- Division of Infectious Diseases, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Bette T. Korber
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico
| | | | - David C. Montefiori
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710
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29
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Jia B, Ng SK, DeGottardi MQ, Piatak M, Yuste E, Carville A, Mansfield KG, Li W, Richardson BA, Lifson JD, Evans DT. Immunization with single-cycle SIV significantly reduces viral loads after an intravenous challenge with SIV(mac)239. PLoS Pathog 2009; 5:e1000272. [PMID: 19165322 PMCID: PMC2621341 DOI: 10.1371/journal.ppat.1000272] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 12/15/2008] [Indexed: 12/24/2022] Open
Abstract
Strains of simian immunodeficiency virus (SIV) that are limited to a single cycle of infection were evaluated for the ability to elicit protective immunity against wild-type SIVmac239 infection of rhesus macaques by two different vaccine regimens. Six animals were inoculated at 8-week intervals with 6 identical doses consisting of a mixture of three different envelope variants of single-cycle SIV (scSIV). Six additional animals were primed with a mixture of cytoplasmic domain-truncated envelope variants of scSIV and boosted with two doses of vesicular stomatitis virus glycoprotein (VSV G) trans-complemented scSIV. While both regimens elicited detectable virus-specific T cell responses, SIV-specific T cell frequencies were more than 10-fold higher after boosting with VSV G trans-complemented scSIV (VSV G scSIV). Broad T cell recognition of multiple viral antigens and Gag-specific CD4+ T cell responses were also observed after boosting with VSV G scSIV. With the exception of a single animal in the repeated immunization group, all of the animals became infected following an intravenous challenge with SIVmac239. However, significantly lower viral loads and higher memory CD4+ T cell counts were observed in both immunized groups relative to an unvaccinated control group. Indeed, both scSIV immunization regimens resulted in containment of SIVmac239 replication after challenge that was as good as, if not better than, what has been achieved by other non-persisting vaccine vectors that have been evaluated in this challenge model. Nevertheless, the extent of protection afforded by scSIV was not as good as typically conferred by persistent infection with live, attenuated SIV. These observations have potentially important implications to the design of an effective AIDS vaccine, since they suggest that ongoing stimulation of virus-specific immune responses may be essential to achieving the degree of protection afforded by live, attenuated SIV. AIDS vaccine candidates based on recombinant DNA and/or viral vectors stimulate potent cellular immune responses. However, the extent of protection achieved by these vaccines has so far been disappointing. While live, attenuated strains of SIV afford more reliable protection in animal models, there are justifiable safety concerns with the use of live, attenuated HIV-1 in humans. As an experimental vaccine approach designed to uncouple immune activation from ongoing virus replication, we developed a genetic system for producing strains of SIV that are limited to a single cycle of infection. We compared repeated versus prime-boost vaccine regimens with single-cycle SIV for the ability to elicit protective immunity in rhesus macaques against a strain of SIV that is notoriously difficult to control by vaccination. Both vaccine regimens afforded significant containment of virus replication after challenge. Nevertheless, the extent of protection achieved by immunization with single-cycle SIV was not as good as the protection typically provided by persistent infection of animals with live, attenuated SIV. These observations have important implications for the design of an effective AIDS vaccine, since they suggest that ongoing stimulation of virus-specific immune responses may ultimately be necessary for achieving the robust protection afforded by live, attenuated SIV.
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Affiliation(s)
- Bin Jia
- Department of Microbiology and Molecular Genetics, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - Sharon K. Ng
- Department of Microbiology and Molecular Genetics, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - M. Quinn DeGottardi
- Department of Microbiology and Molecular Genetics, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - Michael Piatak
- AIDS and Cancer Virus Program, SAIC Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Eloísa Yuste
- Department of Microbiology and Molecular Genetics, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - Angela Carville
- Department of Pathology, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - Keith G. Mansfield
- Department of Pathology, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
| | - Wenjun Li
- Biostatistics Research Group, Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Barbra A. Richardson
- Department of Biostatistics, University of Washington, Seattle, Washington, United States of America
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, SAIC Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - David T. Evans
- Department of Microbiology and Molecular Genetics, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, United States of America
- * E-mail:
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30
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Potent antibody-mediated neutralization and evolution of antigenic escape variants of simian immunodeficiency virus strain SIVmac239 in vivo. J Virol 2008; 82:9739-52. [PMID: 18667507 DOI: 10.1128/jvi.00871-08] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we describe the evolution of antigenic escape variants in a rhesus macaque that developed unusually high neutralizing antibody titers to SIVmac239. By 42 weeks postinfection, 50% neutralization of SIVmac239 was achieved with plasma dilutions of 1:1,000. Testing of purified immunoglobulin confirmed that the neutralizing activity was antibody mediated. Despite the potency of the neutralizing antibody response, the animal displayed a typical viral load profile and progressed to terminal AIDS with a normal time course. Viral envelope sequences from week 16 and week 42 plasma contained an excess of nonsynonymous substitutions, predominantly in V1 and V4, including individual sites with ratios of nonsynonymous to synonymous substitution rates (dN/dS) highly suggestive of strong positive selection. Recombinant viruses encoding envelope sequences isolated from these time points remained resistant to neutralization by all longitudinal plasma samples, revealing the failure of the animal to mount secondary responses to the escaped variants. Substitutions at two sites with significant dN/dS values, one in V1 and one in V4, were independently sufficient to confer nearly complete resistance to neutralization. Substitutions at three additional sites, one in V4 and two in gp41, conferred moderate to high levels of resistance when tested individually. All the amino acid changes leading to escape resulted from single nucleotide substitutions. The observation that antigenic escape resulted from individual, single amino acid replacements at sites well separated in current structural models of Env indicates that the virus can utilize multiple independent pathways to rapidly achieve similar levels of resistance.
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31
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Crooks ET, Jiang P, Franti M, Wong S, Zwick MB, Hoxie JA, Robinson JE, Moore PL, Binley JM. Relationship of HIV-1 and SIV envelope glycoprotein trimer occupation and neutralization. Virology 2008; 377:364-78. [PMID: 18539308 DOI: 10.1016/j.virol.2008.04.045] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 03/21/2008] [Accepted: 04/24/2008] [Indexed: 11/26/2022]
Abstract
Insights into the process of HIV-1 neutralization may assist rational vaccine design. Here, we compared antibody neutralization against the JR-FL primary isolate and trimer binding affinities judged by native PAGE. Monovalent Fab-trimer binding and neutralization showed a direct quantitative relationship, implying that neutralization begins as each trimer is occupied by one antibody. At saturation, three Fab or soluble CD4 molecules engaged each trimer. In contrast, a maximum of one soluble CD4 molecule bound to functional SIV trimers with a truncated a gp41 tail. Remarkably, soluble CD4 was found to trigger dramatic enhancement of this virus. Unlike Fabs, a quantitative correlation between JR-FL trimer binding and neutralization was unclear for some, but not all IgGs, as neutralization was markedly increased, but trimer affinity was largely unchanged. In addition, only one molecule of certain gp41-specific IgGs appeared to be able to bind each trimer. We discuss the implications of these findings in weighing the relative contributions of size, multivalent binding and other possible effects of IgGs to explain their increased potency.
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Affiliation(s)
- Emma T Crooks
- Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121, USA
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32
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Gray ES, Moore PL, Bibollet-Ruche F, Li H, Decker JM, Meyers T, Shaw GM, Morris L. 4E10-resistant variants in a human immunodeficiency virus type 1 subtype C-infected individual with an anti-membrane-proximal external region-neutralizing antibody response. J Virol 2008; 82:2367-75. [PMID: 18094155 PMCID: PMC2258954 DOI: 10.1128/jvi.02161-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 12/12/2007] [Indexed: 01/24/2023] Open
Abstract
The broadly neutralizing monoclonal antibody (MAb) 4E10 recognizes a linear epitope in the C terminus of the membrane-proximal external region (MPER) of gp41. This epitope is particularly attractive for vaccine design because it is highly conserved among human immunodeficiency virus type 1 (HIV-1) strains and neutralization escape in vivo has not been observed. Multiple env genes were cloned from an HIV-1 subtype C virus isolated from a 7-year-old perinatally infected child who had anti-MPER neutralizing antibodies. One clone (TM20.13) was resistant to 4E10 neutralization as a result of an F673L substitution in the MPER. Frequency analysis showed that F673L was present in 33% of the viral variants and in all cases was linked to the presence of an intact 2F5 epitope. Two other envelope clones were sensitive to 4E10 neutralization, but TM20.5 was 10-fold less sensitive than TM20.6. Substitutions at positions 674 and 677 within the MPER rendered TM20.5 more sensitive to 4E10 but had no effect on TM20.6. Using chimeric and mutant constructs of these two variants, we further demonstrated that the lentivirus lytic peptide-2 domain in the cytoplasmic tail affected the accessibility of the 4E10 epitope, as well as virus infectivity. Collectively, these genetic changes in the face of a neutralizing antibody response to the MPER strongly suggested immune escape from antibody responses targeting this region.
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Affiliation(s)
- Elin S Gray
- National Institute for Communicable Diseases, Johannesburg, Private Bag X4, Sandringham 2131, Johannesburg, South Africa
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33
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Jung C, Le Doux JM. Lentiviruses inefficiently incorporate human parainfluenza type 3 envelope proteins. Biotechnol Bioeng 2008; 99:1016-27. [PMID: 17705232 DOI: 10.1002/bit.21622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have previously shown that the envelope glycoproteins of human parainfluenza type 3 (HPIV3), F and HN, are able to pseudotype lentiviruses, but the titers of these viruses are too low for use in clinical gene transfer. In this study we investigated the cause of these low titers. We compared the mRNA and protein expression levels of HN and F in transfected cells and in cells infected with wild-type HPIV3. Transfected cells contained similar levels of HN and F cytosolic mRNA, but fewer cell-surface HN and F proteins (3.8- and 1.3-fold less, respectively), than cells infected with wild-type HPIV3. To increase expression of HN in transfected cells, we codon-optimized HN and used it to transfect lentivirus producer cells. Cell surface expression of HN, as well as the amount of HN incorporated into virus particles, increased two- to threefold. Virus titers increased 1.2- to 6.4-fold, and the transduction efficiency of polarized MDCK cells via their apical surfaces increased 1.4-fold. Interestingly, even though codon optimization improved the expression levels of HN and virus titers, we found that HPIV3 pseudotyped viruses contained about 14-fold fewer envelope proteins than lentiviruses pseudotyped with the amphotropic envelope protein. Taken together, our findings suggest that titers are low, not because virus producer cells express levels of HPIV3 envelope proteins that are too low, but because too few of these proteins are incorporated by the lentiviruses for them to be able to efficiently transduce cells.
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Affiliation(s)
- Cindy Jung
- The Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Atlanta, Georgia 30332-0535, USA
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34
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Enhancing exposure of HIV-1 neutralization epitopes through mutations in gp41. PLoS Med 2008; 5:e9. [PMID: 18177204 PMCID: PMC2174964 DOI: 10.1371/journal.pmed.0050009] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 11/20/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The generation of broadly neutralizing antibodies is a priority in the design of vaccines against HIV-1. Unfortunately, most antibodies to HIV-1 are narrow in their specificity, and a basic understanding of how to develop antibodies with broad neutralizing activity is needed. Designing methods to target antibodies to conserved HIV-1 epitopes may allow for the generation of broadly neutralizing antibodies and aid the global fight against AIDS by providing new approaches to block HIV-1 infection. Using a naturally occurring HIV-1 Envelope (Env) variant as a template, we sought to identify features of Env that would enhance exposure of conserved HIV-1 epitopes. METHODS AND FINDINGS Within a cohort study of high-risk women in Mombasa, Kenya, we previously identified a subtype A HIV-1 Env variant in one participant that was unusually sensitive to neutralization. Using site-directed mutagenesis, the unusual neutralization sensitivity of this variant was mapped to two amino acid mutations within conserved sites in the transmembrane subunit (gp41) of the HIV-1 Env protein. These two mutations, when introduced into a neutralization-resistant variant from the same participant, resulted in 3- to >360-fold enhanced neutralization by monoclonal antibodies specific for conserved regions of both gp41 and the Env surface subunit, gp120, >780-fold enhanced neutralization by soluble CD4, and >35-fold enhanced neutralization by the antibodies found within a pool of plasmas from unrelated individuals. Enhanced neutralization sensitivity was not explained by differences in Env infectivity, Env concentration, Env shedding, or apparent differences in fusion kinetics. Furthermore, introduction of these mutations into unrelated viral Env sequences, including those from both another subtype A variant and a subtype B variant, resulted in enhanced neutralization susceptibility to gp41- and gp120-specific antibodies, and to plasma antibodies. This enhanced neutralization sensitivity exceeded 1,000-fold in several cases. CONCLUSIONS Two amino acid mutations within gp41 were identified that expose multiple discontinuous neutralization epitopes on diverse HIV-1 Env proteins. These exposed epitopes were shielded on the unmodified viral Env proteins, and several of the exposed epitopes encompass desired target regions for protective antibodies. Env proteins containing these modifications could act as a scaffold for presentation of such conserved domains, and may aid in developing methods to target antibodies to such regions.
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35
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Comparison of plasma viremia and antibody responses in macaques inoculated with envelope variants of single-cycle simian immunodeficiency virus differing in infectivity and cellular tropism. J Virol 2007; 82:321-34. [PMID: 17942538 DOI: 10.1128/jvi.01094-07] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular differences in the envelope glycoproteins of human immunodeficiency virus type 1 and simian immunodeficiency virus (SIV) determine virus infectivity and cellular tropism. To examine how these properties contribute to productive infection in vivo, rhesus macaques were inoculated with strains of single-cycle SIV (scSIV) engineered to express three different envelope glycoproteins with full-length (TM(open)) or truncated (TM(stop)) cytoplasmic tails. The 239 envelope uses CCR5 for infection of memory CD4(+) T cells, the 316 envelope also uses CCR5 but has enhanced infectivity for primary macrophages, and the 155T3 envelope uses CXCR4 for infection of both naive and memory CD4(+) T cells. Separate groups of six rhesus macaques were inoculated intravenously with mixtures of TM(open) and TM(stop) scSIV(mac)239, scSIV(mac)316, and scSIV(mac)155T3. A multiplex real-time PCR assay specific for unique sequence tags engineered into each virus was then used to measure viral loads for each strain independently. Viral loads in plasma peaked on day 4 for each strain and were resolved below the threshold of detection within 4 to 10 weeks. Truncation of the envelope cytoplasmic tail significantly increased the peak of viremia for all three envelope variants and the titer of SIV-specific antibody responses. Although peak viremias were similar for both R5- and X4-tropic viruses, clearance of scSIV(mac)155T3 TM(stop) was significantly delayed relative to the other strains, possibly reflecting the infection of a CXCR4(+) cell population that is less susceptible to the cytopathic effects of virus infection. These studies reveal differences in the peaks and durations of a single round of productive infection that reflect envelope-specific differences in infectivity, chemokine receptor specificity, and cellular tropism.
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36
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Polacino P, Cleveland B, Zhu Y, Kimata JT, Overbaugh J, Anderson D, Hu SL. Immunogenicity and protective efficacy of Gag/Pol/Env vaccines derived from temporal isolates of SIVmne against cognate virus challenge. J Med Primatol 2007; 36:254-65. [PMID: 17669214 DOI: 10.1111/j.1600-0684.2007.00243.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND We used the SIVmne model to examine the relative immunogenicity and protective efficacy of vaccines derived from temporal isolates of lentivirus infection. SIVmne170 is a molecular clone isolated from a pig-tailed macaque 170 weeks after inoculation with SIVmneCL8. METHODS We immunized pig-tailed macaques with Gag/Pol/Env vaccines derived from CL8 or 170 and examined their protective efficacy against CL8, 170, or chimeras 8/170 and 170/8, containing the 5' or 3' half of the respective parental genomes. RESULTS As expected, CL8 vaccines protected animals against the CL8, but not the 170 virus. Surprisingly, 170 vaccines not only failed to protect against the 170 virus, but also the less pathogenic CL8. Chimeric virus challenges revealed that the envelope antigen of CL8 represents an important target for protective immunity. CONCLUSIONS These results underscore the potential importance of targeting transmitted viruses through judicious choice of immunogens from early isolates for vaccine development.
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Affiliation(s)
- Patricia Polacino
- Washington National Primate Research Center, University of Washington, Seattle, WA, USA
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37
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Klasse PJ. Modeling how many envelope glycoprotein trimers per virion participate in human immunodeficiency virus infectivity and its neutralization by antibody. Virology 2007; 369:245-62. [PMID: 17825343 PMCID: PMC2317823 DOI: 10.1016/j.virol.2007.06.044] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/26/2007] [Accepted: 06/06/2007] [Indexed: 12/22/2022]
Abstract
Trimers of the HIV-1 envelope glycoprotein (Env) effectuate viral entry into susceptible cells. Therefore Env trimers are the targets for neutralizing antibodies. This study models the number of trimers required for virion infectivity. It also delineates the minimum number of antibody molecules that would neutralize a virion. First, Env function was assumed to be incremental (all envelope glycoprotein units contribute equally) or liminal (characterized by thresholds). Then, such models were combined and shown to fit published data on phenotypically mixed pseudotype viruses. Virions with 9 trimers would require around a median of 5 of them for strong infectivity; the proportion varies among strains and mutants. In addition, the models account for both liminal and incremental protomeric effects at the trimer level: different inert Env mutants may affect trimer function in different degrees. Because of compensatory effects at the virion and trimer levels, however, current data cannot differentiate between all plausible models. But the biophysically and mathematically rationalized blurring of thresholds yields candidate models that fit different data excellently.
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Affiliation(s)
- Per Johan Klasse
- Department of Microbiology and Immunology, Cornell University, Weill Medical College, 1300 York Avenue, Box 62, New York, NY 10021, USA.
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38
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Laird ME, Desrosiers RC. Infectivity and neutralization of simian immunodeficiency virus with FLAG epitope insertion in gp120 variable loops. J Virol 2007; 81:10838-48. [PMID: 17686865 PMCID: PMC2045528 DOI: 10.1128/jvi.00831-07] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A FLAG epitope tag was substituted within variable loop 1 (V1), 2 (V2), or 4 (V4) of the gp120 envelope glycoprotein of simian immunodeficiency virus strain 239 (SIV239) to evaluate the extent to which each variable loop may serve as a target for antibody-mediated neutralization. Two sites within each variable loop of SIV239 were chosen for individual epitope tag insertions. FLAG epitope substitutions were also made in the V1, V2, and V4 loops of a neutralization-sensitive derivative of SIV239, SIV316. Of the 10 FLAG-tagged recombinant viruses analyzed, three (SIV239FV1b, SIV239FV2b, and SIV239FV4a) replicated with kinetics similar to those of the parental strain, SIV239, in both CEMx174 cells and the immortalized rhesus monkey T-cell line 221. The SIV316FV1b and SIV316FV4a FLAG variants replicated with a substantial lag, and the five remaining recombinants did not replicate detectably. Both gp160 and gp120 from replication-competent FLAG variants could be immunoprecipitated from transfected 293T cells by the anti-gp120 rhesus monoclonal antibody (RhMAb) 3.11H, the anti-FLAG MAb M2, and CD4-immunoglobulin, whereas only unprocessed gp160 was detected in 293T cells transfected with replication-defective variants. Furthermore, gp120 was detectably incorporated only into virions that were infectious. SIV239FV1b was sensitive to neutralization by MAb M2, with a 50% inhibitory concentration of 1 mug/ml. Neither SIV239FV2b nor SIV239FV4a was sensitive to M2 neutralization. The ability of the M2 antibody to neutralize SIV239FV1b infectivity was associated with an increased ability of the M2 antibody to detect native, oligomeric SIV239FV1b envelope protein on the surfaces of cells relative to that for the other SIV FLAG variants. Furthermore, SIV239FV1b was globally more sensitive to antibody-mediated neutralization than was parental SIV239 when these strains were screened with a panel of anti-SIV MAbs of various specificities. These results indicate that the V1 loop can serve as an effective target for neutralization on SIV239FV1b. However, antibody-mediated neutralization of this variant, similar to that of other SIV239 variants that have been studied previously, was associated with a global increase in neutralization sensitivity. These results suggest that the variable loops on the neutralization-resistant SIV239 strain are difficult for antibodies to access effectively and that mutations that allow neutralization have global effects on the trimeric envelope glycoprotein structure and accessibility.
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Affiliation(s)
- Melissa E Laird
- New England Primate Research Center, One Pine Hill Drive, Box 9102, Southborough, MA 01772-9102, USA
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39
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Newman JT, Sturgeon TJ, Gupta P, Montelaro RC. Differential functional phenotypes of two primary HIV-1 strains resulting from homologous point mutations in the LLP domains of the envelope gp41 intracytoplasmic domain. Virology 2007; 367:102-16. [PMID: 17582453 PMCID: PMC2034414 DOI: 10.1016/j.virol.2007.05.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 04/09/2007] [Accepted: 05/21/2007] [Indexed: 01/10/2023]
Abstract
We previously reported that selected mutations of highly conserved arginine residues within the LLP regions of HIV-1(ME46) gp41 had diverse effects on Env function. In the current study, we sought to test if the observed LLP mutant phenotypes would be similar in HIV-1(89.6). The results of the current studies revealed that the LLP-1 mutations conferred reduced Env incorporation, infectivity, and replication phenotypes in both viruses, while homologous LLP-2 mutations had differential phenotypical effects between the two strains. In particular, several of the 89.6 LLP-2 mutant viruses were replication defective in CEMX174 cells despite having increased levels of Env incorporation, and with both strains, there were differential effects on infectivity. This comparison of homologous point mutations in two different strains of HIV supports the role of LLPs as determinants of Env function, but reveals for the first time the influence of virus strain on LLP mutant phenotypes.
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Affiliation(s)
- Jason T Newman
- Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, PA 15261, USA
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40
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Jones-Engel L, Steinkraus KA, Murray SM, Engel GA, Grant R, Aggimarangsee N, Lee BPYH, May C, Schillaci MA, Somgird C, Sutthipat T, Vojtech L, Zhao J, Linial ML. Sensitive assays for simian foamy viruses reveal a high prevalence of infection in commensal, free-ranging Asian monkeys. J Virol 2007; 81:7330-7. [PMID: 17475645 PMCID: PMC1933339 DOI: 10.1128/jvi.00343-07] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Foamy viruses (FV) are retroviruses that naturally infect many hosts, including most nonhuman primates (NHPs). Zoonotic infection by primate FV has been documented in people in Asia who reported contact with free-ranging macaques. FV transmission in Asia is a concern, given abundant human-NHP contact, particularly at monkey temples and in urban settings. We have developed three assays capable of detecting the presence of FV in Asian NHP species that are commensal with humans: enzyme-linked immunosorbent assay (ELISA), Western blot assays using recombinant viral Gag protein, and an indicator cell line that can detect macaque FV. The recombinant ELISA correlates very well with the presence of FV sequences detected by PCR. We have used these assays to demonstrate both that FV is highly prevalent among free-ranging NHPs and that seroconversion occurs at a young age in these animals. These assays should also prove useful for large-scale analysis of the prevalence of FV infections in human populations in Asia that are commensal with free-ranging NHPs.
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Affiliation(s)
- Lisa Jones-Engel
- Washington National Primate Research Center, University of Washington, Seattle, Washington, USA
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41
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Byland R, Vance PJ, Hoxie JA, Marsh M. A conserved dileucine motif mediates clathrin and AP-2-dependent endocytosis of the HIV-1 envelope protein. Mol Biol Cell 2006; 18:414-25. [PMID: 17108326 PMCID: PMC1783771 DOI: 10.1091/mbc.e06-06-0535] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During the assembly of enveloped viruses viral and cellular components essential for infectious particles must colocalize at specific membrane locations. For the human and simian immunodeficiency viruses (HIV and SIV), sorting of the viral envelope proteins (Env) to assembly sites is directed by trafficking signals located in the cytoplasmic domain of the transmembrane protein gp41 (TM). A membrane proximal conserved GYxxØ motif mediates endocytosis through interaction with the clathrin adaptor AP-2. However, experiments with SIV(mac239) Env indicate the presence of additional signals. Here we show that a conserved C-terminal dileucine in HIV(HxB2) also mediates endocytosis. Biochemical and morphological assays demonstrate that the C-terminal dileucine motif mediates internalization as efficiently as the GYxxØ motif and that both must be removed to prevent Env internalization. RNAi experiments show that depletion of the clathrin adaptor AP-2 leads to increased plasma membrane expression of HIV Env and that this adaptor is required for efficient internalization mediated by both signals. The redundancy of conserved endocytosis signals and the role of the SIV(mac239) Env GYxxØ motif in SIV pathogenesis, suggest that these motifs have functions in addition to endocytosis, possibly related to Env delivery to the site of viral assembly and/or incorporation into budding virions.
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Affiliation(s)
- Rahel Byland
- *Cell Biology Unit, MRC-Laboratory for Molecular Cell Biology and Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom; and
| | - Patricia J. Vance
- Hematology-Oncology Division, Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - James A. Hoxie
- Hematology-Oncology Division, Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Mark Marsh
- *Cell Biology Unit, MRC-Laboratory for Molecular Cell Biology and Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, United Kingdom; and
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Abstract
The search continues for an AIDS vaccine approach with a suitable safety and efficacy profile for use in individuals at risk of HIV-1 infection. A number of vaccine regimens based on recombinant DNA and/or viral vectors are now in clinical trials. However, these approaches may not provide adequate protection against the natural transmission of genetically diverse HIV-1 field isolates. Live attenuated strains of simian immunodeficiency virus (SIV) still afford the most reliable protection in animals. Unfortunately, justifiable safety concerns will likely preclude the use of live attenuated HIV-1 in humans for the foreseeable future. Genetically engineered strains of SIV, which are limited to a single cycle of infection have been recently developed and may provide a more promising safety and efficacy profile. These strains preserve many of the advantageous properties of live attenuated viruses but cannot regain a pathogenic phenotype through continuous cycles of virus replication.
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Affiliation(s)
- Bin Jia
- Harvard Medical School, Department of Microbiology & Molecular Genetics, New England Primate Research Center, One Pine Hill Drive, Southborough, MA 01772-9102, USA
| | - M Quinn DeGottardi
- Harvard Medical School, Department of Microbiology & Molecular Genetics, New England Primate Research Center, One Pine Hill Drive, Southborough, MA 01772-9102, USA
| | - David T Evans
- Harvard Medical School, Department of Microbiology & Molecular Genetics, New England Primate Research Center, One Pine Hill Drive, Southborough, MA 01772-9102, USA
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43
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Marzi A, Wegele A, Pöhlmann S. Modulation of virion incorporation of Ebolavirus glycoprotein: effects on attachment, cellular entry and neutralization. Virology 2006; 352:345-56. [PMID: 16777170 DOI: 10.1016/j.virol.2006.04.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 02/23/2006] [Accepted: 04/27/2006] [Indexed: 01/09/2023]
Abstract
The filoviruses Ebolavirus (EBOV) and Marburgvirus (MARV) cause severe hemorrhagic fever in humans and are potential agents of biological warfare. The envelope glycoprotein (GP) of filoviruses mediates viral entry into cells and is an attractive target for therapeutic intervention and vaccine design. Here, we asked if the efficiency of virion incorporation of EBOV-GP impacts attachment and entry into target cells and modulates susceptibility to neutralizing antibodies. In order to control the level of EBOV-GP expression, we generated cell lines expressing the GPs of the four known EBOV subspecies in an inducible fashion. Regulated expression of GP on the cell surface allowed production of reporter viruses harboring different amounts of GP. A pronounced reduction of virion incorporation of EBOV-GP had relatively little effect on virion infectivity, suggesting that only a few copies of GP might be sufficient for efficient engagement of cellular receptors. In contrast, optimal interactions with cellular attachment factors like the DC-SIGN protein required incorporation of high amounts of GP. Antibody-mediated neutralization of virions bearing high amounts of GP was slightly more efficient than neutralization of virions harboring low amounts of GP, suggesting that the efficiency of GP incorporation into virions might modulate susceptibility to neutralizing antibodies. Finally, regulated expression of GP in permissive 293 cells did not reduce EBOV-GP-driven infection but diminished vesicular stomatitis virus GP (VSV-G) and amphotropic murine leukemia virus (A-MLV) GP mediated entry in a dose-dependent manner. Therefore, intracellular GP does not seem to downmodulate expression of its receptor(s) but might alter expression and/or function of molecules involved in VSV-G and A-MLV-GP-dependent entry. Our results suggest that the efficiency of virion incorporation of GP could impact EBOV attachment to target cells and might modulate control of viral spread by the humoral immune response.
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Affiliation(s)
- Andrea Marzi
- Institute for Clinical and Molecular Virology, University Erlangen-Nürnberg, 91054 Erlangen, Germany
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44
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Zhu P, Liu J, Bess J, Chertova E, Lifson JD, Grisé H, Ofek GA, Taylor KA, Roux KH. Distribution and three-dimensional structure of AIDS virus envelope spikes. Nature 2006; 441:847-52. [PMID: 16728975 DOI: 10.1038/nature04817] [Citation(s) in RCA: 568] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 04/24/2006] [Indexed: 11/09/2022]
Abstract
Envelope glycoprotein (Env) spikes on AIDS retroviruses initiate infection of host cells and are therefore targets for vaccine development. Though crystal structures for partial Env subunits are known, the structure and distribution of native Env spikes on virions is obscure. We applied cryoelectron microscopy tomography to define ultrastructural details of spikes. Virions of wild-type human immunodeficiency virus 1 (HIV-1) and a mutant simian immunodeficiency virus (SIV) had approximately 14 and approximately 73 spikes per particle, respectively, with some clustering of HIV-1 spikes. Three-dimensional averaging showed that the surface glycoprotein (gp120) 'head' of each subunit of the trimeric SIV spike contains a primary mass, with two secondary lobes. The transmembrane glycoprotein 'stalk' of each trimer is composed of three independent legs that project obliquely from the trimer head, tripod-like. Reconciling available atomic structures with the three-dimensional whole spike density map yields insights into the orientation of Env spike structural elements and possible structural bases of their functions.
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Affiliation(s)
- Ping Zhu
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
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