1
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Zhang Z, Anang S, Nguyen HT, Fritschi C, Smith AB, Sodroski JG. Membrane HIV-1 envelope glycoproteins stabilized more strongly in a pretriggered conformation than natural virus Envs. iScience 2024; 27:110141. [PMID: 38979012 PMCID: PMC11228805 DOI: 10.1016/j.isci.2024.110141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/08/2024] [Accepted: 05/27/2024] [Indexed: 07/10/2024] Open
Abstract
The pretriggered conformation of the human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer ((gp120/gp41)3) is targeted by virus entry inhibitors and broadly neutralizing antibodies (bNAbs). The lability of pretriggered Env has hindered its characterization. Here, we produce membrane Env variants progressively stabilized in pretriggered conformations, in some cases to a degree beyond that found in natural HIV-1 strains. Pretriggered Env stability correlated with stronger trimer subunit association, increased virus sensitivity to bNAb neutralization, and decreased capacity to mediate cell-cell fusion and virus entry. For some highly stabilized Env mutants, after virus-host cell engagement, the normally inaccessible gp120 V3 region on an Env intermediate became targetable by otherwise poorly neutralizing antibodies. Thus, evolutionary pressure on HIV-1 Env to maintain trimer integrity, responsiveness to the CD4 receptor, and resistance to antibodies modulates pretriggered Env stability. The strongly stabilized pretriggered membrane Envs reported here will facilitate further characterization of this functionally important conformation.
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Affiliation(s)
- Zhiqing Zhang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Saumya Anang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Hanh T Nguyen
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher Fritschi
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Amos B Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Joseph G Sodroski
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
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2
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Webb NE, Sevareid CM, Sanchez C, Tobin NH, Aldrovandi GM. Natural Variation in HIV-1 Entry Kinetics Map to Specific Residues and Reveal an Interdependence Between Attachment and Fusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.25.600587. [PMID: 38979136 PMCID: PMC11230229 DOI: 10.1101/2024.06.25.600587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
HIV-1 entry kinetics reflect the fluid motion of the HIV envelope glycoprotein through at least three major structural configurations that drive virus-cell membrane fusion. The lifetime of each state is an important component of potency for inhibitors that target them. We used the time-of-addition inhibitor assay and a novel analytical strategy to define the kinetics of pre-hairpin exposure (using T20) and co-receptor engagement (via. maraviroc), through a characteristic delay metric, across a variety of naturally occurring HIV Env isolates. Among 257 distinct HIV-1 envelope isolates we found a remarkable breadth of T20 and maraviroc delays ranging from as early as 30 seconds to as late as 60 minutes. The most extreme delays were observed among transmission-linked clade C isolates. We identified four single-residue determinants of late T20 and maraviroc delays that are associated with either receptor engagement or gp41 function. Comparison of these delays with T20 sensitivity suggest co-receptor engagement and fusogenic activity in gp41 act cooperatively but sequentially to drive entry. Our findings support current models of entry where co-receptor engagement drives gp41 eclipse and have strong implications for the design of entry inhibitors and antibodies that target transient entry states. Author Summary The first step of HIV-1 infection is entry, where virus-cell membrane fusion is driven by the HIV-1 envelope glycoprotein through a series of conformational changes. Some of the most broadly active entry inhibitors work by binding conformations that exist only transiently during entry. The lifetimes of these states and the kinetics of entry are important elements of inhibitor activity for which little is known. We demonstrate a remarkable range of kinetics among 257 diverse HIV-1 isolates and find that this phenotype is highly flexible, with multiple single-residue determinants. Examination of the kinetics of two conformational landmarks shed light on novel kinetic features that offer new details about the role of co-receptor engagement and provide a framework to explain entry inhibitor synergy.
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3
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Sever B, Otsuka M, Fujita M, Ciftci H. A Review of FDA-Approved Anti-HIV-1 Drugs, Anti-Gag Compounds, and Potential Strategies for HIV-1 Eradication. Int J Mol Sci 2024; 25:3659. [PMID: 38612471 PMCID: PMC11012182 DOI: 10.3390/ijms25073659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
Acquired immunodeficiency syndrome (AIDS) is an enormous global health threat stemming from human immunodeficiency virus (HIV-1) infection. Up to now, the tremendous advances in combination antiretroviral therapy (cART) have shifted HIV-1 infection from a fatal illness into a manageable chronic disorder. However, the presence of latent reservoirs, the multifaceted nature of HIV-1, drug resistance, severe off-target effects, poor adherence, and high cost restrict the efficacy of current cART targeting the distinct stages of the virus life cycle. Therefore, there is an unmet need for the discovery of new therapeutics that not only bypass the limitations of the current therapy but also protect the body's health at the same time. The main goal for complete HIV-1 eradication is purging latently infected cells from patients' bodies. A potential strategy called "lock-in and apoptosis" targets the budding phase of the life cycle of the virus and leads to susceptibility to apoptosis of HIV-1 infected cells for the elimination of HIV-1 reservoirs and, ultimately, for complete eradication. The current work intends to present the main advantages and disadvantages of United States Food and Drug Administration (FDA)-approved anti-HIV-1 drugs as well as plausible strategies for the design and development of more anti-HIV-1 compounds with better potency, favorable pharmacokinetic profiles, and improved safety issues.
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Affiliation(s)
- Belgin Sever
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Türkiye;
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
| | - Masami Otsuka
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
- Department of Drug Discovery, Science Farm Ltd., Kumamoto 862-0976, Japan
| | - Mikako Fujita
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
| | - Halilibrahim Ciftci
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
- Department of Drug Discovery, Science Farm Ltd., Kumamoto 862-0976, Japan
- Department of Bioengineering Sciences, Izmir Katip Celebi University, Izmir 35620, Türkiye
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4
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Glögl M, Friedrich N, Cerutti G, Lemmin T, Kwon YD, Gorman J, Maliqi L, Mittl PRE, Hesselman MC, Schmidt D, Weber J, Foulkes C, Dingens AS, Bylund T, Olia AS, Verardi R, Reinberg T, Baumann NS, Rusert P, Dreier B, Shapiro L, Kwong PD, Plückthun A, Trkola A. Trapping the HIV-1 V3 loop in a helical conformation enables broad neutralization. Nat Struct Mol Biol 2023; 30:1323-1336. [PMID: 37605043 PMCID: PMC10497408 DOI: 10.1038/s41594-023-01062-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 07/11/2023] [Indexed: 08/23/2023]
Abstract
The third variable (V3) loop on the human immunodeficiency virus 1 (HIV-1) envelope glycoprotein trimer is indispensable for virus cell entry. Conformational masking of V3 within the trimer allows efficient neutralization via V3 only by rare, broadly neutralizing glycan-dependent antibodies targeting the closed prefusion trimer but not by abundant antibodies that access the V3 crown on open trimers after CD4 attachment. Here, we report on a distinct category of V3-specific inhibitors based on designed ankyrin repeat protein (DARPin) technology that reinstitute the CD4-bound state as a key neutralization target with up to >90% breadth. Broadly neutralizing DARPins (bnDs) bound V3 solely on open envelope and recognized a four-turn amphipathic α-helix in the carboxy-terminal half of V3 (amino acids 314-324), which we termed 'αV3C'. The bnD contact surface on αV3C was as conserved as the CD4 binding site. Molecular dynamics and escape mutation analyses underscored the functional relevance of αV3C, highlighting the potential of αV3C-based inhibitors and, more generally, of postattachment inhibition of HIV-1.
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Affiliation(s)
- Matthias Glögl
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Nikolas Friedrich
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Gabriele Cerutti
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Thomas Lemmin
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Young D Kwon
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jason Gorman
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Liridona Maliqi
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Peer R E Mittl
- Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Maria C Hesselman
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Daniel Schmidt
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Jacqueline Weber
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Caio Foulkes
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Adam S Dingens
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Tatsiana Bylund
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Adam S Olia
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Raffaello Verardi
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Reinberg
- Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Nicolas S Baumann
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Peter Rusert
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland
| | - Birgit Dreier
- Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Lawrence Shapiro
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich (UZH), Zurich, Switzerland
| | - Alexandra Trkola
- Institute for Medical Virology, University of Zurich (UZH), Zurich, Switzerland.
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5
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Tong T, D’Addabbo A, Xu J, Chawla H, Nguyen A, Ochoa P, Crispin M, Binley JM. Impact of stabilizing mutations on the antigenic profile and glycosylation of membrane-expressed HIV-1 envelope glycoprotein. PLoS Pathog 2023; 19:e1011452. [PMID: 37549185 PMCID: PMC10434953 DOI: 10.1371/journal.ppat.1011452] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/17/2023] [Accepted: 07/16/2023] [Indexed: 08/09/2023] Open
Abstract
Recent HIV-1 vaccine development has centered on "near native" soluble envelope glycoprotein (Env) trimers that are artificially stabilized laterally (between protomers) and apically (between gp120 and gp41). These mutations have been leveraged for use in membrane-expressed Env mRNA vaccines, although their effects in this context are unclear. To address this question, we used virus-like particle (VLP) produced in 293T cells. Uncleaved (UNC) trimers were laterally unstable upon gentle lysis from membranes. However, gp120/gp41 processing improved lateral stability. Due to inefficient gp120/gp41 processing, UNC is incorporated into VLPs. A linker between gp120 and gp41 neither improved trimer stability nor its antigenic profile. An artificially introduced enterokinase cleavage site allowed post-expression gp120/gp41 processing, concomitantly increasing trimer stability. Gp41 N-helix mutations I559P and NT1-5 imparted lateral trimer stability, but also reduced gp120/gp41 processing and/or impacted V2 apex and interface NAb binding. I559P consistently reduced recognition by HIV+ human plasmas, further supporting antigenic differences. Mutations in the gp120 bridging sheet failed to stabilize membrane trimers in a pre-fusion conformation, and also reduced gp120/gp41 processing and exposed non-neutralizing epitopes. Reduced glycan maturation and increased sequon skipping were common side effects of these mutations. In some cases, this may be due to increased rigidity which limits access to glycan processing enzymes. In contrast, viral gp120 did not show glycan skipping. A second, minor species of high mannose gp160 was unaffected by any mutations and instead bypasses normal folding and glycan maturation. Including the full gp41 cytoplasmic tail led to markedly reduced gp120/gp41 processing and greatly increased the proportion of high mannose gp160. Remarkably, monoclonal antibodies were unable to bind to this high mannose gp160 in native protein gels. Overall, our findings suggest caution in leveraging stabilizing mutations in nucleic acid-based immunogens to ensure they impart valuable membrane trimer phenotypes for vaccine use.
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Affiliation(s)
- Tommy Tong
- San Diego Biomedical Research Institute, San Diego, California, United States of America
| | - Alessio D’Addabbo
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Jiamin Xu
- San Diego Biomedical Research Institute, San Diego, California, United States of America
| | - Himanshi Chawla
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Albert Nguyen
- San Diego Biomedical Research Institute, San Diego, California, United States of America
| | - Paola Ochoa
- San Diego Biomedical Research Institute, San Diego, California, United States of America
| | - Max Crispin
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - James M. Binley
- San Diego Biomedical Research Institute, San Diego, California, United States of America
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6
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Schriek AI, van Haaren MM, Poniman M, Dekkers G, Bentlage AEH, Grobben M, Vidarsson G, Sanders RW, Verrips T, Geijtenbeek TBH, Heukers R, Kootstra NA, de Taeye SW, van Gils MJ. Anti-HIV-1 Nanobody-IgG1 Constructs With Improved Neutralization Potency and the Ability to Mediate Fc Effector Functions. Front Immunol 2022; 13:893648. [PMID: 35651621 PMCID: PMC9150821 DOI: 10.3389/fimmu.2022.893648] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022] Open
Abstract
The most effective treatment for HIV-1, antiretroviral therapy, suppresses viral replication and averts the disease from progression. Nonetheless, there is a need for alternative treatments as it requires daily administration with the possibility of side effects and occurrence of drug resistance. Broadly neutralizing antibodies or nanobodies targeting the HIV-1 envelope glycoprotein are explored as alternative treatment, since they mediate viral suppression and contribute to the elimination of virus-infected cells. Besides neutralization potency and breadth, Fc-mediated effector functions of bNAbs also contribute to the in vivo efficacy. In this study multivalent J3, 2E7 and 1F10 anti-HIV-1 broadly neutralizing nanobodies were generated to improve neutralization potency and IgG1 Fc fusion was utilized to gain Fc-mediated effector functions. Bivalent and trivalent nanobodies, coupled using long glycine-serine linkers, showed increased binding to the HIV-1 Env and enhanced neutralization potency compared to the monovalent variant. Fusion of an IgG1 Fc domain to J3 improved neutralization potency compared to the J3-bihead and restored Fc-mediated effector functions such as antibody-dependent cellular phagocytosis and trogocytosis, and natural killer cell activation. Due to their neutralization breadth and potency and their ability to induce effector functions these nanobody-IgG1 constructs may prove to be valuable towards alternative HIV-1 therapies.
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Affiliation(s)
- Angela I Schriek
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | - Marlies M van Haaren
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | - Meliawati Poniman
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | | | - Arthur E H Bentlage
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Marloes Grobben
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | - Gestur Vidarsson
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Rogier W Sanders
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands.,Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, NY, United States
| | - Theo Verrips
- Department of Biology, Faculty of Sciences, Utrecht University, Utrecht, Netherlands.,VerLin BV, Utrecht, Netherlands
| | - Teunis B H Geijtenbeek
- Department of Experimental Immunology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | | | - Neeltje A Kootstra
- Department of Experimental Immunology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | - Steven W de Taeye
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
| | - Marit J van Gils
- Department of Medical Microbiology, Amsterdam UMC, Amsterdam Institute for Infection and Immunity, University of Amsterdam, Amsterdam, Netherlands
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7
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Malladi S, Patel UR, Rajmani RS, Singh R, Pandey S, Kumar S, Khaleeq S, van Vuren PJ, Riddell S, Goldie S, Gayathri S, Chakraborty D, Kalita P, Pramanick I, Agarwal N, Reddy P, Girish N, Upadhyaya A, Khan MS, Kanjo K, Bhat M, Mani S, Bhattacharyya S, Siddiqui S, Tyagi A, Jha S, Pandey R, Tripathi S, Dutta S, McAuley AJ, Singanallur N, Vasan SS, Ringe RP, Varadarajan R. Immunogenicity and Protective Efficacy of a Highly Thermotolerant, Trimeric SARS-CoV-2 Receptor Binding Domain Derivative. ACS Infect Dis 2021; 7:2546-2564. [PMID: 34260218 PMCID: PMC8996237 DOI: 10.1021/acsinfecdis.1c00276] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Indexed: 02/07/2023]
Abstract
The receptor binding domain (RBD) of SARS-CoV-2 is the primary target of neutralizing antibodies. We designed a trimeric, highly thermotolerant glycan engineered RBD by fusion to a heterologous, poorly immunogenic disulfide linked trimerization domain derived from cartilage matrix protein. The protein expressed at a yield of ∼80-100 mg/L in transiently transfected Expi293 cells, as well as CHO and HEK293 stable cell lines and formed homogeneous disulfide-linked trimers. When lyophilized, these possessed remarkable functional stability to transient thermal stress of up to 100 °C and were stable to long-term storage of over 4 weeks at 37 °C unlike an alternative RBD-trimer with a different trimerization domain. Two intramuscular immunizations with a human-compatible SWE adjuvanted formulation elicited antibodies with pseudoviral neutralizing titers in guinea pigs and mice that were 25-250 fold higher than corresponding values in human convalescent sera. Against the beta (B.1.351) variant of concern (VOC), pseudoviral neutralization titers for RBD trimer were ∼3-fold lower than against wildtype B.1 virus. RBD was also displayed on a designed ferritin-like Msdps2 nanoparticle. This showed decreased yield and immunogenicity relative to trimeric RBD. Replicative virus neutralization assays using mouse sera demonstrated that antibodies induced by the trimers neutralized all four VOC to date, namely B.1.1.7, B.1.351, P.1, and B.1.617.2 without significant differences. Trimeric RBD immunized hamsters were protected from viral challenge. The excellent immunogenicity, thermotolerance, and high yield of these immunogens suggest that they are a promising modality to combat COVID-19, including all SARS-CoV-2 VOC to date.
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Affiliation(s)
- Sameer
Kumar Malladi
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Unnatiben Rajeshbhai Patel
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Raju S. Rajmani
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Randhir Singh
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Suman Pandey
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Sahil Kumar
- Virology
Unit, Institute of Microbial Technology,
Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160036, India
| | - Sara Khaleeq
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Petrus Jansen van Vuren
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
| | - Shane Riddell
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
| | - Sarah Goldie
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
| | - Savitha Gayathri
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Debajyoti Chakraborty
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Parismita Kalita
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Ishika Pramanick
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Nupur Agarwal
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Poorvi Reddy
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Nidhi Girish
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Aditya Upadhyaya
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Mohammad Suhail Khan
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Kawkab Kanjo
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Madhuraj Bhat
- Mynvax
Private Limited, ES12, Entrepreneurship Centre, SID, Indian Institute of Science, Bengaluru 560012, India
| | - Shailendra Mani
- Translational
Health Science and Technology Institute, NCR Biotech Science Cluster, Third Milestone, Gurugram-Faridabad
Expressway, Faridabad 121001, India
| | - Sankar Bhattacharyya
- Translational
Health Science and Technology Institute, NCR Biotech Science Cluster, Third Milestone, Gurugram-Faridabad
Expressway, Faridabad 121001, India
| | - Samreen Siddiqui
- Max Super
Speciality Hospital (A Unit of Devki Devi Foundation), Max Healthcare, Delhi 1100017, India
| | - Akansha Tyagi
- Max Super
Speciality Hospital (A Unit of Devki Devi Foundation), Max Healthcare, Delhi 1100017, India
| | - Sujeet Jha
- Max Super
Speciality Hospital (A Unit of Devki Devi Foundation), Max Healthcare, Delhi 1100017, India
| | - Rajesh Pandey
- Integrative
Genomics of Host-Pathogen (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Mall Road, Delhi 110007, India
| | - Shashank Tripathi
- Department
of Microbiology & Cell Biology, Indian
Institute of Science, Bengaluru 560012, India
- Centre
for Infectious Disease Research, Indian
Institute of Science, Bengaluru 560012, India
| | - Somnath Dutta
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
| | - Alexander J. McAuley
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
| | - Nagendrakumar
Balasubramanian Singanallur
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
| | - Seshadri S. Vasan
- Australian
Centre for Disease Preparedness (ACDP), Commonwealth Scientific and Industrial Research Organisation (CSIRO), 5 Portarlington Road, Geelong 3220, Victoria, Australia
- Department
of Health Sciences, University of York, York YO10 5DD, United Kingdom
| | - Rajesh P. Ringe
- Virology
Unit, Institute of Microbial Technology,
Council of Scientific and Industrial Research (CSIR), Sector 39-A, Chandigarh 160036, India
| | - Raghavan Varadarajan
- Molecular
Biophysics Unit (MBU), Indian Institute
of Science, Bengaluru 560012, India
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8
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Ang CG, Carter E, Haftl A, Zhang S, Rashad AA, Kutzler M, Abrams CF, Chaiken IM. Peptide Triazole Thiol Irreversibly Inactivates Metastable HIV-1 Env by Accessing Conformational Triggers Intrinsic to Virus-Cell Entry. Microorganisms 2021; 9:1286. [PMID: 34204725 PMCID: PMC8231586 DOI: 10.3390/microorganisms9061286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/03/2021] [Accepted: 06/09/2021] [Indexed: 11/16/2022] Open
Abstract
KR13, a peptide triazole thiol previously established to inhibit HIV-1 infection and cause virus lysis, was evaluated by flow cytometry against JRFL Env-presenting cells to characterize induced Env and membrane transformations leading to irreversible inactivation. Transiently transfected HEK293T cells were preloaded with calcein dye, treated with KR13 or its thiol-blocked analogue KR13b, fixed, and stained for gp120 (35O22), MPER (10E8), 6-helix-bundle (NC-1), immunodominant loop (50-69), and fusion peptide (VRC34.01). KR13 induced dose-dependent transformations of Env and membrane characterized by transient poration, MPER exposure, and 6-helix-bundle formation (analogous to native fusion events), but also reduced immunodominant loop and fusion peptide exposure. Using a fusion peptide mutant (V504E), we found that KR13 transformation does not require functional fusion peptide for poration. In contrast, simultaneous treatment with fusion inhibitor T20 alongside KR13 prevented membrane poration and MPER exposure, showing that these events require 6-helix-bundle formation. Based on these results, we formulated a model for PTT-induced Env transformation portraying how, in the absence of CD4/co-receptor signaling, PTT may provide alternate means of perturbing the metastable Env-membrane complex, and inducing fusion-like transformation. In turn, the results show that such transformations are intrinsic to Env and can be diverted for irreversible inactivation of the protein complex.
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Affiliation(s)
- Charles Gotuaco Ang
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19102, USA
| | - Erik Carter
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- Departments of Medicine and Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA;
| | - Ann Haftl
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- Department of Chemistry, College of Arts and Sciences, Drexel University, Philadelphia, PA 19102, USA
| | - Shiyu Zhang
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19102, USA
| | - Adel A. Rashad
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
| | - Michele Kutzler
- Departments of Medicine and Microbiology and Immunology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA;
| | - Cameron F. Abrams
- Department of Chemical and Biological Engineering, College of Engineering, Drexel University, Philadelphia, PA 19102, USA;
| | - Irwin M. Chaiken
- Department of Biochemistry and Molecular Biology, College of Medicine, Drexel University, Philadelphia, PA 19102, USA; (E.C.); (A.H.); (S.Z.); (A.A.R.)
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9
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Gonelli CA, King HAD, Mackenzie C, Sonza S, Center RJ, Purcell DFJ. Immunogenicity of HIV-1-Based Virus-Like Particles with Increased Incorporation and Stability of Membrane-Bound Env. Vaccines (Basel) 2021; 9:239. [PMID: 33801906 PMCID: PMC8002006 DOI: 10.3390/vaccines9030239] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/04/2021] [Accepted: 03/05/2021] [Indexed: 01/04/2023] Open
Abstract
An optimal prophylactic vaccine to prevent human immunodeficiency virus (HIV-1) transmission should elicit protective antibody responses against the HIV-1 envelope glycoprotein (Env). Replication-incompetent HIV-1 virus-like particles (VLPs) offer the opportunity to present virion-associated Env with a native-like structure during vaccination that closely resembles that encountered on infectious virus. Here, we optimized the incorporation of Env into previously designed mature-form VLPs (mVLPs) and assessed their immunogenicity in mice. The incorporation of Env into mVLPs was increased by replacing the Env transmembrane and cytoplasmic tail domains with those of influenza haemagglutinin (HA-TMCT). Furthermore, Env was stabilized on the VLP surface by introducing an interchain disulfide and proline substitution (SOSIP) mutations typically employed to stabilize soluble Env trimers. The resulting mVLPs efficiently presented neutralizing antibody epitopes while minimizing exposure of non-neutralizing antibody sites. Vaccination of mice with mVLPs elicited a broader range of Env-specific antibody isotypes than Env presented on immature VLPs or extracellular vesicles. The mVLPs bearing HA-TMCT-modified Env consistently induced anti-Env antibody responses that mediated modest neutralization activity. These mVLPs are potentially useful immunogens for eliciting neutralizing antibody responses that target native Env epitopes on infectious HIV-1 virions.
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Affiliation(s)
- Christopher A. Gonelli
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
| | - Hannah A. D. King
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
- Viral Entry and Vaccines Laboratory, Disease Elimination, Burnet Institute, Melbourne, VIC 3004, Australia
| | - Charlene Mackenzie
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
| | - Secondo Sonza
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
| | - Rob J. Center
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
- Viral Entry and Vaccines Laboratory, Disease Elimination, Burnet Institute, Melbourne, VIC 3004, Australia
| | - Damian F. J. Purcell
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (C.A.G.); (H.A.D.K.); (C.M.); (S.S.); (R.J.C.)
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10
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Lu M. Single-Molecule FRET Imaging of Virus Spike-Host Interactions. Viruses 2021; 13:v13020332. [PMID: 33669922 PMCID: PMC7924862 DOI: 10.3390/v13020332] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023] Open
Abstract
As a major surface glycoprotein of enveloped viruses, the virus spike protein is a primary target for vaccines and anti-viral treatments. Current vaccines aiming at controlling the COVID-19 pandemic are mostly directed against the SARS-CoV-2 spike protein. To promote virus entry and facilitate immune evasion, spikes must be dynamic. Interactions with host receptors and coreceptors trigger a cascade of conformational changes/structural rearrangements in spikes, which bring virus and host membranes in proximity for membrane fusion required for virus entry. Spike-mediated viral membrane fusion is a dynamic, multi-step process, and understanding the structure–function-dynamics paradigm of virus spikes is essential to elucidate viral membrane fusion, with the ultimate goal of interventions. However, our understanding of this process primarily relies on individual structural snapshots of endpoints. How these endpoints are connected in a time-resolved manner, and the order and frequency of conformational events underlying virus entry, remain largely elusive. Single-molecule Förster resonance energy transfer (smFRET) has provided a powerful platform to connect structure–function in motion, revealing dynamic aspects of spikes for several viruses: SARS-CoV-2, HIV-1, influenza, and Ebola. This review focuses on how smFRET imaging has advanced our understanding of virus spikes’ dynamic nature, receptor-binding events, and mechanism of antibody neutralization, thereby informing therapeutic interventions.
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Affiliation(s)
- Maolin Lu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
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11
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Rawi R, Rutten L, Lai YT, Olia AS, Blokland S, Juraszek J, Shen CH, Tsybovsky Y, Verardi R, Yang Y, Zhang B, Zhou T, Chuang GY, Kwong PD, Langedijk JPM. Automated Design by Structure-Based Stabilization and Consensus Repair to Achieve Prefusion-Closed Envelope Trimers in a Wide Variety of HIV Strains. Cell Rep 2020; 33:108432. [PMID: 33238130 PMCID: PMC7714614 DOI: 10.1016/j.celrep.2020.108432] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/21/2020] [Accepted: 11/04/2020] [Indexed: 12/27/2022] Open
Abstract
Soluble envelope (Env) trimers, stabilized in a prefusion-closed conformation, can elicit neutralizing responses against HIV-1 strains closely related to the immunizing trimer. However, to date such stabilization has succeeded with only a limited number of HIV-1 strains. To address this issue, here we develop ADROITrimer, an automated procedure involving structure-based stabilization and consensus repair, and generate "RnS-DS-SOSIP"-stabilized Envs from 180 diverse Env sequences. The vast majority of these RnS-DS-SOSIP Envs fold into prefusion-closed conformations as judged by antigenic analysis and size exclusion chromatography. Additionally, representative strains from clades AE, B, and C are stabilized in prefusion-closed conformations as shown by negative-stain electron microscopy, and the crystal structure of a clade A strain MI369.A5 Env trimer provides 3.5 Å resolution detail into stabilization and repair mutations. The automated procedure reported herein that yields well-behaved, soluble, prefusion-closed Env trimers from a majority of HIV-1 strains could have substantial impact on the development of an HIV-1 vaccine.
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Affiliation(s)
- Reda Rawi
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lucy Rutten
- Janssen Vaccines & Prevention, Archimedesweg 4-6, 2333 CN Leiden, the Netherlands
| | - Yen-Ting Lai
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Adam S Olia
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sven Blokland
- Janssen Vaccines & Prevention, Archimedesweg 4-6, 2333 CN Leiden, the Netherlands
| | - Jarek Juraszek
- Janssen Vaccines & Prevention, Archimedesweg 4-6, 2333 CN Leiden, the Netherlands
| | - Chen-Hsiang Shen
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yaroslav Tsybovsky
- Electron Microscopy Laboratory, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, MD 21701, USA
| | - Raffaello Verardi
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yongping Yang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Baoshan Zhang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tongqing Zhou
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gwo-Yu Chuang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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12
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Probing the Structure of the HIV-1 Envelope Trimer Using Aspartate Scanning Mutagenesis. J Virol 2020; 94:JVI.01426-20. [PMID: 32817217 DOI: 10.1128/jvi.01426-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/11/2020] [Indexed: 12/20/2022] Open
Abstract
HIV-1 envelope (Env) glycoprotein gp160 exists as a trimer of heterodimers on the viral surface. In most structures of the soluble ectodomain of trimeric HIV-1 envelope glycoprotein, the regions from 512 to 517 of the fusion peptide and from 547 to 568 of the N-heptad repeat are disordered. We used aspartate scanning mutagenesis of subtype B strain JRFL Env as an alternate method to probe residue burial in the context of cleaved, cell surface-expressed Env, as buried residues should be intolerant to substitution with Asp. The data are inconsistent with a fully disordered 547 to 568 stretch, as residues 548, 549, 550, 555, 556, 559, 562, and 566 to 569 are all sensitive to Asp substitution. In the fusion peptide region, residues 513 and 515 were also sensitive to Asp substitution, suggesting that the fusion peptide may not be fully exposed in native Env. gp41 is metastable in the context of native trimer. Introduction of Asp at residues that are exposed in the prefusion state but buried in the postfusion state is expected to destabilize the postfusion state and any intermediate states where the residue is buried. We therefore performed soluble CD4 (sCD4)-induced gp120 shedding experiments to identify Asp mutants at residues 551, 554 to 559, 561 to 567, and 569 that could prevent gp120 shedding. We also observed similar mutational effects on shedding for equivalent mutants in the context of clade C Env from isolate 4-2J.41. These substitutions can potentially be used to stabilize native-like trimer derivatives that are used as HIV-1 vaccine immunogens.IMPORTANCE In most crystal structures of the soluble ectodomain of the HIV-1 Env trimer, some residues in the fusion and N-heptad repeat regions are disordered. Whether this is true in the context of native, functional Env on the virion surface is not known. This knowledge may be useful for stabilizing Env in its prefusion conformation and will also help to improve understanding of the viral entry process. Burial of the charged residue Asp in a protein structure is highly destabilizing. We therefore used Asp scanning mutagenesis to probe the burial of apparently disordered residues in native Env and to examine the effect of mutations in these regions on Env stability and conformation as probed by antibody binding to cell surface-expressed Env, CD4-induced shedding of HIV-1 gp120, and viral infectivity studies. Mutations that prevent shedding can potentially be used to stabilize native-like Env constructs for use as vaccine immunogens.
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13
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Featherstone A, Aiken C. SERINC5 Inhibits HIV-1 Infectivity by Altering the Conformation of gp120 on HIV-1 Particles. J Virol 2020; 94:e00594-20. [PMID: 32796070 PMCID: PMC7527050 DOI: 10.1128/jvi.00594-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/03/2020] [Indexed: 01/25/2023] Open
Abstract
SERINC5 is a 10-transmembrane-domain cellular protein that is incorporated into budding HIV-1 particles and reduces HIV-1 infectivity by inhibiting virus-cell fusion. HIV-1 susceptibility to SERINC5 is determined by sequences in the viral Env glycoprotein gp120, and the antiviral effect of SERINC5 is counteracted by the viral accessory protein Nef. While the precise mechanism by which SERINC5 inhibits HIV-1 infectivity is unclear, previous studies have suggested that SERINC5 affects Env conformation. To define the effects of SERINC5 on Env conformation, we quantified the binding of HIV-1 particles to immobilized Env-specific monoclonal antibodies. We observed that SERINC5 reduced the binding of HIV-1 particles bearing a SERINC5-susceptible Env to antibodies that recognize the V3 loop, a soluble CD4 (sCD4)-induced epitope, and an N-linked glycan. In contrast, SERINC5 did not alter the capture of HIV-1 particles bearing the SERINC5-resistant Env protein. Moreover, the effect of SERINC5 on antibody-dependent virus capture was abrogated by Nef expression. Our results indicate that SERINC5 inhibits HIV-1 infectivity by altering the conformation of gp120 on virions and/or physical masking of specific HIV-1 Env epitopes.IMPORTANCE SERINC5 is a host cell protein that inhibits the infectivity of HIV-1 by a novel and poorly understood mechanism. Here, we provide evidence that the SERINC5 protein alters the conformation of the HIV-1 Env proteins and that this action is correlated with SERINC5's ability to inhibit HIV-1 infectivity. Defining the specific effects of SERINC5 on the HIV-1 glycoprotein conformation may be useful for designing new antiviral strategies targeting Env.
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Affiliation(s)
- Austin Featherstone
- Vanderbilt University Medical Center, Department of Pathology, Microbiology and Immunology, Nashville, Tennessee, USA
| | - Christopher Aiken
- Vanderbilt University Medical Center, Department of Pathology, Microbiology and Immunology, Nashville, Tennessee, USA
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14
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Malladi SK, Schreiber D, Pramanick I, Sridevi MA, Goldenzweig A, Dutta S, Fleishman SJ, Varadarajan R. One-step sequence and structure-guided optimization of HIV-1 envelope gp140. Curr Res Struct Biol 2020; 2:45-55. [PMID: 33688632 PMCID: PMC7939140 DOI: 10.1016/j.crstbi.2020.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Stabilization of the metastable envelope glycoprotein (Env) of HIV-1 is hypothesized to improve induction of broadly neutralizing antibodies. We improved the expression yield and stability of the HIV-1 envelope glycoprotein BG505SOSIP.664 gp140 by means of a previously described automated sequence and structure-guided computational thermostabilization approach, PROSS. This combines sequence conservation information with computational assessment of mutant stabilization, thus taking advantage of the extensive natural sequence variation present in HIV-1 Env. PROSS is used to design three gp140 variants with 17–45 mutations relative to the parental construct. One of the designs is experimentally observed to have a fourfold improvement in yield and a 4 °C increment in thermostability. In addition, the designed immunogens have similar antigenicity profiles to the native flexible linker version of wild type, BG505SOSIP.664 gp140 (NFL Wt) to major epitopes targeted by broadly neutralizing antibodies. PROSS eliminates the laborious process of screening many variants for stability and functionality, providing a proof of principle of the method for stabilization and improvement of yield without compromising antigenicity for next generation complex, highly glycosylated vaccine candidates. One-step stabilization of HIV-1 Env gp140. One-step yield improvement of HIV-1 Env gp140. Native-like oligomeric conformation of designed vaccine candidates. Unaltered antigenicity of designed vaccine candidates.
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Affiliation(s)
| | - David Schreiber
- Department of BioMolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ishika Pramanick
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru, India
| | | | - Adi Goldenzweig
- Department of BioMolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Somnath Dutta
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru, India
| | | | - Raghavan Varadarajan
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru, India
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15
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Ang CG, Hossain MA, Rajpara M, Bach H, Acharya K, Dick A, Rashad AA, Kutzler M, Abrams CF, Chaiken I. Metastable HIV-1 Surface Protein Env Sensitizes Cell Membranes to Transformation and Poration by Dual-Acting Virucidal Entry Inhibitors. Biochemistry 2020; 59:818-828. [PMID: 31942789 PMCID: PMC7362902 DOI: 10.1021/acs.biochem.9b01008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Dual-acting virucidal entry inhibitors (DAVEIs) have previously been shown to cause irreversible inactivation of HIV-1 Env-presenting pseudovirus by lytic membrane transformation. This study examined whether this transformation could be generalized to include membranes of Env-presenting cells. Flow cytometry was used to analyze HEK293T cells transiently transfected with increasing amounts of DNA encoding JRFL Env, loaded with calcein dye, and treated with serial dilutions of microvirin (Q831K/M83R)-DAVEI. Comparing calcein retention against intact Env expression (via Ab 35O22) on individual cells revealed effects proportional to Env expression. "Low-Env" cells experienced transient poration and calcein leakage, while "high-Env" cells were killed. The cell-killing effect was confirmed with an independent mitochondrial activity-based cell viability assay, showing dose-dependent cytotoxicity in response to DAVEI treatment. Transfection with increasing quantities of Env DNA showed further shifts toward "High-Env" expression and cytotoxicity, further reinforcing the Env dependence of the observed effect. Controls with unlinked DAVEI components showed no effect on calcein leakage or cell viability, confirming a requirement for covalently linked DAVEI compounds to achieve Env transformation. These data demonstrate that the metastability of Env is an intrinsic property of the transmembrane protein complex and can be perturbed to cause membrane disruption in both virus and cell contexts.
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Affiliation(s)
- Charles G Ang
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
- School of Biomedical Engineering, Science, and Health Systems , Drexel University , Philadelphia , Pennsylvania 19104 , United States
| | - Md Alamgir Hossain
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Marg Rajpara
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Harry Bach
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
- School of Biomedical Engineering, Science, and Health Systems , Drexel University , Philadelphia , Pennsylvania 19104 , United States
| | - Kriti Acharya
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Alexej Dick
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Adel A Rashad
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Michele Kutzler
- Department of Microbiology and Immunology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
| | - Cameron F Abrams
- Department of Chemical and Biological Engineering, College of Engineering , Drexel University , Philadelphia , Pennsylvania 19104 , United States
| | - Irwin Chaiken
- Department of Biochemistry and Molecular Biology, College of Medicine , Drexel University , Philadelphia , Pennsylvania 19102 , United States
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16
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Da LT, Lin M. Opening dynamics of HIV-1 gp120 upon receptor binding is dictated by a key hydrophobic core. Phys Chem Chem Phys 2019; 21:26003-26016. [PMID: 31764922 DOI: 10.1039/c9cp04613e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
HIV-1 entry is mediated firstly by the molecular recognition between the viral glycoprotein gp120 and its receptor CD4 on host T-cells. As a key antigen that can be targeted by neutralizing antibodies, gp120 has been a focus for extensive studies with efforts to understand its structural properties and conformational dynamics upon receptor binding. An atomistic-level revelation of gp120 opening dynamics activated by CD4, however, is still unknown. Here, by constructing a Markov State Model (MSM) based on hundreds of Molecular Dynamics (MD) simulations with an aggregated simulation time of ∼20 microseconds (μs), we identify the key metastable states of gp120 during its opening dynamics upon CD4 binding. The MSM provides a clear dynamic model whereby the identified metastable states coexist and can reach an equilibrium. More importantly, a hydrophobic core flanked by variable loops (V1V2 and V3) and the β20/21 region plays an essential role in triggering the gp120 opening. Any destabilizing effects introduced into the hydrophobic core, therefore, can be expected to promote transition of gp120 to an open state. Moreover, the variable loops demonstrate high flexibilities in fully open gp120. In particular, the V3 region is capable of exploring both closed and open conformations, even with the V1/V2 loops largely adopting an open form. In addition, the bridging sheet formation in gp120 is likely induced by the incoming co-receptor/antibody recognitions, since the V1/V2 structure is highly heterogeneous so that the bridging-sheet formed conformation is not the most populated state. Our studies provide deep insights into the dynamic features of gp120 and its molecular recognitions to the broadly neutralizing antibodies, which guides future attempts to design more effective gp120 immunogens.
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Affiliation(s)
- Lin-Tai Da
- Key Laboratory of System Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
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17
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Aldon Y, McKay PF, Allen J, Ozorowski G, Felfödiné Lévai R, Tolazzi M, Rogers P, He L, de Val N, Fábián K, Scarlatti G, Zhu J, Ward AB, Crispin M, Shattock RJ. Rational Design of DNA-Expressed Stabilized Native-Like HIV-1 Envelope Trimers. Cell Rep 2019; 24:3324-3338.e5. [PMID: 30232012 PMCID: PMC6167709 DOI: 10.1016/j.celrep.2018.08.051] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 05/16/2018] [Accepted: 08/17/2018] [Indexed: 11/17/2022] Open
Abstract
The HIV-1-envelope glycoprotein (Env) is the main target of antigen design for antibody-based prophylactic vaccines. The generation of broadly neutralizing antibodies (bNAb) likely requires the appropriate presentation of stabilized trimers preventing exposure of non-neutralizing antibody (nNAb) epitopes. We designed a series of membrane-bound Envs with increased trimer stability through the introduction of key stabilization mutations. We derived a stabilized HIV-1 trimer, ConSOSL.UFO.750, which displays a dramatic reduction in nNAb binding while maintaining high quaternary and MPER-specific bNAb binding. Its soluble counterpart, ConSOSL.UFO.664, displays similar antigenicity, and its native-like Env structure is confirmed by negative stain-EM and glycosylation profiling of the soluble ConSOSL.UFO.664 trimer. A rabbit immunization study demonstrated that the ConSOSL.UFO.664 can induce autologous tier 2 neutralization. We have successfully designed a stabilized native-like Env trimer amenable to nucleic acid or viral vector-based vaccination strategies. DNA-expressed closed pre-fusion native-like Env with preserved MPER exposure Env antigenicity varies across cell types and assays Muscle cells present properly folded and glycosylated membrane-bound Envs Fully glycosylated ConSOSL.UFO.664 induces autologous tier 2 neutralization
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Affiliation(s)
- Yoann Aldon
- Imperial College London, Department of Medicine, Division of Infectious Diseases, Section of Virology, Norfolk Place, London W2 1PG, UK
| | - Paul F McKay
- Imperial College London, Department of Medicine, Division of Infectious Diseases, Section of Virology, Norfolk Place, London W2 1PG, UK
| | - Joel Allen
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Réka Felfödiné Lévai
- Department of Immunology, National Food Chain Safety Office, Directorate of Veterinary Medicinal Products, Budapest, Hungary
| | - Monica Tolazzi
- Viral Evolution and Transmission Unit, Division of Immunology, Transplantation, and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Paul Rogers
- Imperial College London, Department of Medicine, Division of Infectious Diseases, Section of Virology, Norfolk Place, London W2 1PG, UK
| | - Linling He
- Department of Integrative Structural and Computational Biology, Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Natalia de Val
- Department of Integrative Structural and Computational Biology, Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Katalin Fábián
- Department of Immunology, National Food Chain Safety Office, Directorate of Veterinary Medicinal Products, Budapest, Hungary
| | - Gabriella Scarlatti
- Viral Evolution and Transmission Unit, Division of Immunology, Transplantation, and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Jiang Zhu
- Department of Integrative Structural and Computational Biology, Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, Collaboration for AIDS Vaccine Discovery, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Max Crispin
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford, UK; Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Robin J Shattock
- Imperial College London, Department of Medicine, Division of Infectious Diseases, Section of Virology, Norfolk Place, London W2 1PG, UK.
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18
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Abstract
Single-molecule Förster resonance energy transfer (smFRET) imaging has emerged as a powerful tool to probe conformational dynamics of viral proteins, identify novel structural intermediates that are hiding in averaging population-based measurements, permit access to the energetics of transitions and as such to the precise molecular mechanisms of viral replication. One strength of smFRET is the capability of characterizing biological molecules in their fully hydrated/native state, which are not necessarily available to other structural methods. Elegant experimental design for physiologically relevant conditions, such as intact virions, has permitted the detection of previously unknown conformational states of viral glycoproteins, revealed asymmetric intermediates, and allowed access to the real-time imaging of conformational changes during viral fusion. As more laboratories are applying smFRET, our understanding of the molecular mechanisms and the dynamic nature of viral proteins throughout the virus life cycle are predicted to improve and assist the development of novel antiviral therapies and vaccine design.
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Affiliation(s)
- Maolin Lu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, United States.
| | - Xiaochu Ma
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, United States
| | - Walther Mothes
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, United States.
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19
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Effects of the SOS (A501C/T605C) and DS (I201C/A433C) Disulfide Bonds on HIV-1 Membrane Envelope Glycoprotein Conformation and Function. J Virol 2019; 93:JVI.00304-19. [PMID: 30944182 DOI: 10.1128/jvi.00304-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/29/2019] [Indexed: 02/06/2023] Open
Abstract
Most broadly neutralizing antibodies and many entry inhibitors target the pretriggered (state 1) conformation of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env). Here we examine two previously reported Env mutants designed to be stabilized in this conformation by the introduction of artificial disulfide bonds: A501C/T605C (called SOS) and I201C/A433C (called DS). SOS Env supported virus entry and cell-cell fusion only after exposure to a reducing agent, dithiothreitol (DTT). Deletion of the Env cytoplasmic tail improved the efficiency with which the SOS Env supported virus infection in a reducing environment. The antigenicity of the SOS Env was similar to that of the unmodified Env, except for greater sensitivity to some state 1-preferring ligands. In contrast, viruses with the DS Env were not infectious, even after DTT treatment. The proteolytic maturation of the DS Env on both cell surfaces and virions was severely compromised compared with that of the unmodified Env. The DS Env exhibited detectable cell-fusing activity when DTT was present. However, the profiles of cell-surface Env recognition and cell-cell fusion inhibition by antibodies differed for the DS Env and the unmodified Env. Thus, the DS Env appears to be stabilized in an off-pathway conformation that is nonfunctional on the virus. The SOS change exerted more subtle, context-dependent effects on Env conformation and function.IMPORTANCE The human immunodeficiency virus type 1 (HIV-1) envelope proteins (Envs) bind receptors on the host cell and change shape to allow the virus to enter the cell. Most virus-inhibiting antibodies and drugs recognize a particular shape of Env called state 1. Disulfide bonds formed by cysteine residues have been introduced into soluble forms of the flexible envelope proteins in an attempt to lock them into state 1 for use in vaccines and as research tools. We evaluated the effect of these cysteine substitutions on the ability of the membrane Env to support virus entry and on susceptibility to inhibition by antibodies and small molecules. We found that the conformation of the envelope proteins with the cysteine substitutions differed from that of the unmodified membrane envelope proteins. Awareness of these effects can assist efforts to create stable HIV-1 Env complexes that more closely resemble the state 1 conformation.
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20
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Ananthaswamy N, Fang Q, AlSalmi W, Jain S, Chen Z, Klose T, Sun Y, Liu Y, Mahalingam M, Chand S, Tovanabutra S, Robb ML, Rossmann MG, Rao VB. A sequestered fusion peptide in the structure of an HIV-1 transmitted founder envelope trimer. Nat Commun 2019; 10:873. [PMID: 30787293 PMCID: PMC6382815 DOI: 10.1038/s41467-019-08825-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 02/01/2019] [Indexed: 12/23/2022] Open
Abstract
The envelope protein of human immunodeficiency virus-1 (HIV-1) and its fusion peptide are essential for cell entry and vaccine design. Here, we describe the 3.9-Å resolution structure of an envelope protein trimer from a very early transmitted founder virus (CRF01_AE T/F100) complexed with Fab from the broadly neutralizing antibody (bNAb) 8ANC195. The overall T/F100 trimer structure is similar to other reported "closed" state prefusion trimer structures. In contrast, the fusion peptide, which is exposed to solvent in reported closed structures, is sequestered (buried) in the hydrophobic core of the T/F100 trimer. A buried conformation has previously been observed in "open" state structures formed after CD4 receptor binding. The T/F100 trimer binds poorly to bNAbs including the fusion peptide-specific bNAbs PGT151 and VRC34.01. The T/F100 structure might represent a prefusion state, intermediate between the closed and open states. These observations are relevant to mechanisms of HIV-1 transmission and vaccine design.
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Affiliation(s)
- Neeti Ananthaswamy
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
| | - Qianglin Fang
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Wadad AlSalmi
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
| | - Swati Jain
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
| | - Zhenguo Chen
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.,The Fifth People's Hospital of Shanghai & Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, People's Republic of China
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Yingyuan Sun
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Yue Liu
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Marthandan Mahalingam
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
| | - Subhash Chand
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA
| | - Sodsai Tovanabutra
- U.S. Military HIV Research Program, Henry M. Jackson Foundation for the Advancement of Military Medicine, Silver Spring, MD, 20910, USA
| | - Merlin L Robb
- U.S. Military HIV Research Program, Henry M. Jackson Foundation for the Advancement of Military Medicine, Silver Spring, MD, 20910, USA
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
| | - Venigalla B Rao
- Department of Biology, The Catholic University of America, Washington, DC, 20064, USA.
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21
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Conformational Differences between Functional Human Immunodeficiency Virus Envelope Glycoprotein Trimers and Stabilized Soluble Trimers. J Virol 2019; 93:JVI.01709-18. [PMID: 30429345 DOI: 10.1128/jvi.01709-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 11/07/2018] [Indexed: 01/11/2023] Open
Abstract
Binding to the receptor CD4 triggers entry-related conformational changes in the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer, (gp120/gp41)3 Soluble versions of HIV-1 Env trimers (sgp140 SOSIP.664) stabilized by a gp120-gp41 disulfide bond and a change (I559P) in gp41 have been structurally characterized. Here, we use cross-linking/mass spectrometry to evaluate the conformations of functional membrane Env and sgp140 SOSIP.664. Differences were detected in the gp120 trimer association domain and C terminus and in the gp41 heptad repeat 1 (HR1) region. Whereas the membrane Env trimer exposes the gp41 HR1 coiled coil only after CD4 binding, the sgp140 SOSIP.664 HR1 coiled coil was accessible to the gp41 HR2 peptide even in the absence of CD4. Our results delineate differences in both gp120 and gp41 subunits between functional membrane Env and the sgp140 SOSIP.664 trimer and provide distance constraints that can assist validation of candidate structural models of the native HIV-1 Env trimer.IMPORTANCE HIV-1 envelope glycoprotein spikes mediate the entry of the virus into host cells and are a major target for vaccine-induced antibodies. Soluble forms of the envelope glycoproteins that are stable and easily produced have been characterized extensively and are being considered as vaccines. Here, we present evidence that these stabilized soluble envelope glycoproteins differ in multiple respects from the natural HIV-1 envelope glycoproteins. By pinpointing these differences, our results can guide the improvement of envelope glycoprotein preparations to achieve greater similarity to the viral envelope glycoprotein spike, potentially increasing their effectiveness as a vaccine.
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22
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SOSIP Changes Affect Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Conformation and CD4 Engagement. J Virol 2018; 92:JVI.01080-18. [PMID: 30021898 DOI: 10.1128/jvi.01080-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 07/13/2018] [Indexed: 01/31/2023] Open
Abstract
The entry of human immunodeficiency virus into host cells is mediated by the envelope glycoprotein (Env) trimeric spike, which consists of three exterior gp120 subunits and three transmembrane gp41 subunits. The trimeric Env undergoes extensive conformational rearrangement upon interaction with the CD4 receptor, transitioning from the unliganded, "closed" State 1 to more-open downstream State 2 and State 3 conformations. Changes in "restraining" amino acid residues, such as leucine 193 and isoleucine 423, destabilize State 1 Env, which then assumes entry-competent, downstream conformations. The introduction of an artificial disulfide bond linking the gp120 and gp41 subunits (SOS) in combination with the I559P (IP) change has allowed structural characterization of soluble gp140 (sgp140) trimers. The conformation of these SOSIP-stabilized sgp140 trimers has been suggested to represent the closed native State 1 conformation. Here we compare the impact on the membrane Env conformation of the SOSIP changes with that of the well-characterized changes (L193R and I423A) that shift Env to downstream States 2 and 3. The results presented here suggest that the SOSIP changes stabilize Env in a conformation that differs from State 1 but also from the downstream Env conformations stabilized by L193R or I423A.IMPORTANCE The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer is triggered by receptor binding to mediate the entry of the virus into cells. Most structural studies of Env trimers have utilized truncated soluble gp140 Envs stabilized with the I559P and SOS changes. Here we present evidence indicating that these stabilizing changes have a profound impact on the conformation of Env, moving Env away from the native pretriggered Env conformation. Our studies underscore the need to acquire structural information on the pretriggered Env conformation, which is recognized by most broadly reactive neutralizing antibodies.
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23
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Yang L, Sharma SK, Cottrell C, Guenaga J, Tran K, Wilson R, Behrens AJ, Crispin M, de Val N, Wyatt RT. Structure-Guided Redesign Improves NFL HIV Env Trimer Integrity and Identifies an Inter-Protomer Disulfide Permitting Post-Expression Cleavage. Front Immunol 2018; 9:1631. [PMID: 30065725 PMCID: PMC6056610 DOI: 10.3389/fimmu.2018.01631] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/02/2018] [Indexed: 11/13/2022] Open
Abstract
Soluble HIV-1 envelope glycoprotein (Env) trimers are under active investigation as vaccine candidates in relevant pre-clinical models. Like SOSIPs, the cleavage-independent native flexibly linked (NFL) trimers are faithful mimics of the Env spike. Here, we analyzed multiple new designs to explore alternative modifications, informing tertiary interactions, while maintaining NFL trimer homogeneity and integrity. Accordingly, we performed a proline (P) substitution screen in the gp41 heptad repeat 1 region, identifying other trimer-enhancing Ps, including L555P. This P improved trimer integrity compared to I559P in selected properties. Next, we screened 15 structure-guided potential cysteine pairs in gp140 and found that A501C-L663C ("CC2") forms an inter-protomer disulfide bond that demonstrably increased NFL trimer thermostability. We combined these two approaches with trimer-derived substitutions, coupled with glycine substitutions at helix-to-coil transitions, developed by our group. To increase the exposure of the fusion peptide (FP) N-terminus, we engineered an enterokinase (EK) cleavage site upstream of the FP for controlled post-expression cleavage. In combination, the redesigns resulted in highly stable and homogeneous NFL mimics derived from different clades. Following recombinant EK cleavage, the NFL trimers retained covalent linkage, maintaining a native-like structure while displaying enhanced stability and favorable antigenic features. These trimers also displayed increased exposure of neutralizing epitopes in the FP and gp120/gp41 interface, while retaining other neutralizing epitopes and occluding non-neutralizing elements. This array of Env-structure-guided designs reveals additional interactive regions in the prefusion state of the HIV Env spike, affording the development of novel antigens and immunogens.
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Affiliation(s)
- Lifei Yang
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States
| | - Shailendra Kumar Sharma
- International AIDS Vaccine Initiative, Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA, United States
| | - Christopher Cottrell
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States
| | - Javier Guenaga
- International AIDS Vaccine Initiative, Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA, United States
| | - Karen Tran
- International AIDS Vaccine Initiative, Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA, United States
| | - Richard Wilson
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States
| | - Anna-Janina Behrens
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, United Kingdom
| | - Max Crispin
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, United Kingdom
- Centre for Biological Sciences, Institute of Life Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom
| | - Natalia de Val
- Center for Molecular Microscopy (CMM), Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, United States
| | - Richard T. Wyatt
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States
- International AIDS Vaccine Initiative, Neutralizing Antibody Center, The Scripps Research Institute, La Jolla, CA, United States
- Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA, United States
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24
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Comparison of Uncleaved and Mature Human Immunodeficiency Virus Membrane Envelope Glycoprotein Trimers. J Virol 2018; 92:JVI.00277-18. [PMID: 29618643 DOI: 10.1128/jvi.00277-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/26/2018] [Indexed: 12/21/2022] Open
Abstract
The mature envelope glycoprotein (Env) spike on the surfaces of human immunodeficiency virus type 1 (HIV-1)-infected cells and virions is derived from proteolytic cleavage of a trimeric gp160 glycoprotein precursor. In these studies, we compared the conformations of cleaved and uncleaved membrane Envs with truncated cytoplasmic tails to those of stabilized soluble gp140 SOSIP.664 Env trimers. Deletion of the gp41 cytoplasmic tail did not significantly affect the sensitivity of viruses with the HIV-1AD8 Env to inhibition by antibodies or a CD4-mimetic compound. After glutaraldehyde fixation and purification from membranes, a cleaved Env exhibited a hydrodynamic radius of ∼10 nm and an antibody-binding profile largely consistent with that expected based on virus neutralization sensitivity. The purified cleaved Env trimers exhibited a hollow architecture with a central void near the trimer axis. Uncleaved Env, cross-linked and purified in parallel, exhibited a hydrodynamic radius similar to that of the cleaved Env. However, the uncleaved Env was recognized by poorly neutralizing antibodies and appeared by negative-stain electron microscopy to sample multiple conformations. Compared with membrane Envs, stabilized soluble gp140 SOSIP.664 Env trimers appear to be more compact, as reflected in their smaller hydrodynamic radii and negative-stain electron microscopy structures. The antigenic features of the soluble gp140 SOSIP.664 Env trimers differed from those of the cleaved membrane Env, particularly in gp120 V3 and some CD4-binding-site epitopes. Thus, proteolytic maturation allows the membrane-anchored Env to achieve a conformation that retains functional metastability but masks epitopes for poorly neutralizing antibodies.IMPORTANCE The entry of human immunodeficiency virus type 1 (HIV-1) into host cells is mediated by the envelope glycoprotein (Env) spike on the surface of the virus. Host antibodies elicited during natural HIV-1 infection or by vaccination can potentially recognize the Env spike and block HIV-1 infection. However, the changing shape of the HIV-1 Env spike protects the virus from antibody binding. Understanding the shapes of natural and man-made preparations of HIV-1 Envs will assist the development of effective vaccines against the virus. Here, we evaluate the effects of several Env modifications commonly used to produce Env preparations for vaccine studies and the determination of structure. We found that the cleavage of the HIV-1 Env precursor helps Env to assume its natural shape, which resists the binding of many commonly elicited antibodies. Stabilized soluble Envs exhibit more compact shapes but expose some Env elements differently than the natural Env.
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25
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Rutten L, Lai YT, Blokland S, Truan D, Bisschop IJM, Strokappe NM, Koornneef A, van Manen D, Chuang GY, Farney SK, Schuitemaker H, Kwong PD, Langedijk JPM. A Universal Approach to Optimize the Folding and Stability of Prefusion-Closed HIV-1 Envelope Trimers. Cell Rep 2018; 23:584-595. [PMID: 29642014 PMCID: PMC6010203 DOI: 10.1016/j.celrep.2018.03.061] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 03/05/2018] [Accepted: 03/13/2018] [Indexed: 12/28/2022] Open
Abstract
The heavily glycosylated native-like envelope (Env) trimer of HIV-1 is expected to have low immunogenicity, whereas misfolded forms are often highly immunogenic. High-quality correctly folded Envs may therefore be critical for developing a vaccine that induces broadly neutralizing antibodies. Moreover, the high variability of Env may require immunizations with multiple Envs. Here, we report a universal strategy that provides for correctly folded Env trimers of high quality and yield through a repair-and-stabilize approach. In the repair stage, we utilized a consensus strategy that substituted rare strain-specific residues with more prevalent ones. The stabilization stage involved structure-based design and experimental assessment confirmed by crystallographic feedback. Regions important for the refolding of Env were targeted for stabilization. Notably, the α9-helix and an intersubunit β sheet proved to be critical for trimer stability. Our approach provides a means to produce prefusion-closed Env trimers from diverse HIV-1 strains, a substantial advance for vaccine development.
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Affiliation(s)
- Lucy Rutten
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Yen-Ting Lai
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - Sven Blokland
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Daphne Truan
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Ilona J M Bisschop
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Nika M Strokappe
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Annemart Koornneef
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Danielle van Manen
- Janssen Vaccines & Prevention, Archimedesweg 4-6, Leiden 2333, the Netherlands
| | - Gwo-Yu Chuang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - S Katie Farney
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | | | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA.
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26
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Espy N, Pacheco B, Sodroski J. Adaptation of HIV-1 to cells with low expression of the CCR5 coreceptor. Virology 2017; 508:90-107. [PMID: 28521215 DOI: 10.1016/j.virol.2017.04.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 11/19/2022]
Abstract
The binding of the human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer ((gp120/gp41)3) to the receptors CD4 and CCR5 triggers virus entry into host cells. To identify Env regions that respond to CCR5 binding, HIV-1 was serially passaged on a CD4-positive canine cell line expressing progressively lower levels of CCR5. HIV-1 replication was observed in cells expressing ~1300 CCR5 molecules/cell. Env changes that conferred this low-CCR5 replication phenotype were located outside of the known CCR5-binding region of the gp120 Env subunit and did not apparently increase CCR5 binding affinity. The adaptation-associated changes, located in the gp120 α1 helix and in the gp41 HR1 heptad repeat and membrane-proximal external region (MPER), enhanced HIV-1 replication in cells at all levels of CCR5 expression. The adapted Envs exhibited a greater propensity to undergo conformational changes, as evidenced by increased exposure of conserved regions near the CD4- and CCR5-binding sites.
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Affiliation(s)
- Nicole Espy
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Beatriz Pacheco
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA
| | - Joseph Sodroski
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA; Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA.
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27
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Rathore U, Saha P, Kesavardhana S, Kumar AA, Datta R, Devanarayanan S, Das R, Mascola JR, Varadarajan R. Glycosylation of the core of the HIV-1 envelope subunit protein gp120 is not required for native trimer formation or viral infectivity. J Biol Chem 2017; 292:10197-10219. [PMID: 28446609 DOI: 10.1074/jbc.m117.788919] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/26/2017] [Indexed: 01/05/2023] Open
Abstract
The gp120 subunit of the HIV-1 envelope (Env) protein is heavily glycosylated at ∼25 glycosylation sites, of which ∼7-8 are located in the V1/V2 and V3 variable loops and the others in the remaining core gp120 region. Glycans partially shield Env from recognition by the host immune system and also are believed to be indispensable for proper folding of gp120 and for viral infectivity. Previous attempts to alter glycosylation sites in Env typically involved mutating the glycosylated asparagine residues to structurally similar glutamines or alanines. Here, we confirmed that such mutations at multiple glycosylation sites greatly diminish viral infectivity and result in significantly reduced binding to both neutralizing and non-neutralizing antibodies. Therefore, using an alternative approach, we combined evolutionary information with structure-guided design and yeast surface display to produce properly cleaved HIV-1 Env variants that lack all 15 core gp120 glycans, yet retain conformational integrity and multiple-cycle viral infectivity and bind to several broadly neutralizing antibodies (bNAbs), including trimer-specific antibodies and a germline-reverted version of the bNAb VRC01. Our observations demonstrate that core gp120 glycans are not essential for folding, and hence their likely primary role is enabling immune evasion. We also show that our glycan removal approach is not strain restricted. Glycan-deficient Env derivatives can be used as priming immunogens because they should engage and activate a more divergent set of germlines than fully glycosylated Env. In conclusion, these results clarify the role of core gp120 glycosylation and illustrate a general method for designing glycan-free folded protein derivatives.
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Affiliation(s)
- Ujjwal Rathore
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Piyali Saha
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Sannula Kesavardhana
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Aditya Arun Kumar
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - Rohini Datta
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | | | - Raksha Das
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India
| | - John R Mascola
- the Vaccine Research Center, NIAID, National Institutes of Health, Bethesda, Maryland 20814, and
| | - Raghavan Varadarajan
- From the Molecular Biophysics Unit, Indian Institute of Science, 560012 Bangalore, India, .,the Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, 560064 Bangalore, India
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28
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Residues in the gp41 Ectodomain Regulate HIV-1 Envelope Glycoprotein Conformational Transitions Induced by gp120-Directed Inhibitors. J Virol 2017; 91:JVI.02219-16. [PMID: 28003492 DOI: 10.1128/jvi.02219-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 12/15/2016] [Indexed: 01/08/2023] Open
Abstract
Interactions between the gp120 and gp41 subunits of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer maintain the metastable unliganded form of the viral spike. Binding of gp120 to the receptor, CD4, changes the Env conformation to promote gp120 interaction with the second receptor, CCR5 or CXCR4. CD4 binding also induces the transformation of Env into the prehairpin intermediate, in which the gp41 heptad repeat 1 (HR1) coiled coil is assembled at the trimer axis. In nature, HIV-1 Envs must balance the requirements to maintain the noncovalent association of gp120 with gp41 and to evade the host antibody response with the need to respond to CD4 binding. Here we show that the gp41 HR1 region contributes to gp120 association with the unliganded Env trimer. Changes in particular amino acid residues in the gp41 HR1 region decreased the efficiency with which Env moved from the unliganded state. Thus, these gp41 changes decreased the sensitivity of HIV-1 to cold inactivation and ligands that require Env conformational changes to bind efficiently. Conversely, these gp41 changes increased HIV-1 sensitivity to small-molecule entry inhibitors that block Env conformational changes induced by CD4. Changes in particular gp41 HR1 amino acid residues can apparently affect the relative stability of the unliganded state and CD4-induced conformations. Thus, the gp41 HR1 region contributes to the association with gp120 and regulates Env transitions from the unliganded state to downstream conformations.IMPORTANCE The development of an efficient vaccine able to prevent HIV infection is a worldwide priority. Knowledge of the envelope glycoprotein structure and the conformational changes that occur after receptor engagement will help researchers to develop an immunogen able to elicit antibodies that block HIV-1 transmission. Here we identify residues in the HIV-1 transmembrane envelope glycoprotein that stabilize the unliganded state by modulating the transitions from the unliganded state to the CD4-bound state.
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Kesavardhana S, Das R, Citron M, Datta R, Ecto L, Srilatha NS, DiStefano D, Swoyer R, Joyce JG, Dutta S, LaBranche CC, Montefiori DC, Flynn JA, Varadarajan R. Structure-based Design of Cyclically Permuted HIV-1 gp120 Trimers That Elicit Neutralizing Antibodies. J Biol Chem 2016; 292:278-291. [PMID: 27879316 DOI: 10.1074/jbc.m116.725614] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 11/18/2016] [Indexed: 11/06/2022] Open
Abstract
A major goal for HIV-1 vaccine development is an ability to elicit strong and durable broadly neutralizing antibody (bNAb) responses. The trimeric envelope glycoprotein (Env) spikes on HIV-1 are known to contain multiple epitopes that are susceptible to bNAbs isolated from infected individuals. Nonetheless, all trimeric and monomeric Env immunogens designed to date have failed to elicit such antibodies. We report the structure-guided design of HIV-1 cyclically permuted gp120 that forms homogeneous, stable trimers, and displays enhanced binding to multiple bNAbs, including VRC01, VRC03, VRC-PG04, PGT128, and the quaternary epitope-specific bNAbs PGT145 and PGDM1400. Constructs that were cyclically permuted in the V1 loop region and contained an N-terminal trimerization domain to stabilize V1V2-mediated quaternary interactions, showed the highest homogeneity and the best antigenic characteristics. In guinea pigs, a DNA prime-protein boost regimen with these new gp120 trimer immunogens elicited potent neutralizing antibody responses against highly sensitive Tier 1A isolates and weaker neutralizing antibody responses with an average titer of about 115 against a panel of heterologous Tier 2 isolates. A modest fraction of the Tier 2 virus neutralizing activity appeared to target the CD4 binding site on gp120. These results suggest that cyclically permuted HIV-1 gp120 trimers represent a viable platform in which further modifications may be made to eventually achieve protective bNAb responses.
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Affiliation(s)
- Sannula Kesavardhana
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Raksha Das
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Michael Citron
- Merck & Company, Inc., West Point, Pennsylvania 19486, and
| | - Rohini Datta
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Linda Ecto
- Merck & Company, Inc., West Point, Pennsylvania 19486, and
| | | | | | - Ryan Swoyer
- Merck & Company, Inc., West Point, Pennsylvania 19486, and
| | - Joseph G Joyce
- Merck & Company, Inc., West Point, Pennsylvania 19486, and
| | - Somnath Dutta
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Celia C LaBranche
- the Department of Surgery, Duke University, Durham, North Carolina 27705
| | - David C Montefiori
- the Department of Surgery, Duke University, Durham, North Carolina 27705
| | | | - Raghavan Varadarajan
- From the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India,
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Gao K, Zhang Y, Lou J. Exploring the membrane fusion mechanism through force-induced disassembly of HIV-1 six-helix bundle. Biochem Biophys Res Commun 2016; 473:1185-1190. [PMID: 27079239 DOI: 10.1016/j.bbrc.2016.04.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/08/2016] [Indexed: 10/22/2022]
Abstract
Enveloped virus, such as HIV-1, employs membrane fusion mechanism to invade into host cell. HIV-1 gp41 ectodomain uses six-helix bundle configuration to accomplish this process. Using molecular dynamic simulations, we confirmed the stability of this six-helix bundle by showing high occupancy of hydrogen bonds and hydrophobic interactions. Key residues and interactions important for the bundle integration were characterized by force-induced unfolding simulations of six-helix bundle, exhibiting the collapse order of these groups of interactions. Moreover, our results in some way concerted with a previous theory that the formation of coiled-coil choose a route which involved cooperative interactions between the N-terminal and C-terminal helix.
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Affiliation(s)
- Kai Gao
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong Zhang
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jizhong Lou
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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31
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Banerjee S, Shi H, Habte HH, Qin Y, Cho MW. Modulating immunogenic properties of HIV-1 gp41 membrane-proximal external region by destabilizing six-helix bundle structure. Virology 2016; 490:17-26. [PMID: 26803471 DOI: 10.1016/j.virol.2016.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/05/2016] [Accepted: 01/09/2016] [Indexed: 01/31/2023]
Abstract
The C-terminal alpha-helix of gp41 membrane-proximal external region (MPER; (671)NWFDITNWLWYIK(683)) encompassing 4E10/10E8 epitopes is an attractive target for HIV-1 vaccine development. We previously reported that gp41-HR1-54Q, a trimeric protein comprised of the MPER in the context of a stable six-helix bundle (6HB), induced strong immune responses against the helix, but antibodies were directed primarily against the non-neutralizing face of the helix. To better target 4E10/10E8 epitopes, we generated four putative fusion intermediates by introducing double point mutations or deletions in the heptad repeat region 1 (HR1) that destabilize 6HB in varying degrees. One variant, HR1-∆10-54K, elicited antibodies in rabbits that targeted W672, I675 and L679, which are critical for 4E10/10E8 recognition. Overall, the results demonstrated that altering structural parameters of 6HB can influence immunogenic properties of the MPER and antibody targeting. Further exploration of this strategy could allow development of immunogens that could lead to induction of 4E10/10E8-like antibodies.
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Affiliation(s)
- Saikat Banerjee
- Department of Biomedical Sciences, College of Veterinary Medicine; and Center for Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Ames, IA 50011, United States
| | - Heliang Shi
- Department of Biomedical Sciences, College of Veterinary Medicine; and Center for Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Ames, IA 50011, United States
| | - Habtom H Habte
- Department of Biomedical Sciences, College of Veterinary Medicine; and Center for Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Ames, IA 50011, United States
| | - Yali Qin
- Department of Biomedical Sciences, College of Veterinary Medicine; and Center for Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Ames, IA 50011, United States
| | - Michael W Cho
- Department of Biomedical Sciences, College of Veterinary Medicine; and Center for Advanced Host Defenses, Immunobiotics and Translational Comparative Medicine, Iowa State University, Ames, IA 50011, United States.
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32
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Effects of the I559P gp41 change on the conformation and function of the human immunodeficiency virus (HIV-1) membrane envelope glycoprotein trimer. PLoS One 2015; 10:e0122111. [PMID: 25849367 PMCID: PMC4388519 DOI: 10.1371/journal.pone.0122111] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 02/20/2015] [Indexed: 12/21/2022] Open
Abstract
The mature human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) trimer is produced by proteolytic cleavage of a precursor and consists of three gp120 exterior and three gp41 transmembrane subunits. The metastable Env complex is induced to undergo conformational changes required for virus entry by the binding of gp120 to the receptors, CD4 and CCR5/CXCR4. An isoleucine-to-proline change (I559P) in the gp41 ectodomain has been used to stabilize soluble forms of HIV-1 Env trimers for structural characterization and for use as immunogens. In the native membrane-anchored HIV-1BG505 Env, the I559P change modestly decreased proteolytic maturation, increased the non-covalent association of gp120 with the Env trimer, and resulted in an Env conformation distinctly different from that of the wild-type HIV-1BG505 Env. Compared with the wild-type Env, the I559P Env was recognized inefficiently by polyclonal sera from HIV-1-infected individuals, by several gp41-directed antibodies, by some antibodies against the CD4-binding site of gp120, and by antibodies that preferentially recognize the CD4-bound Env. Some of the gp120-associated antigenic differences between the wild-type HIV-1BG505 Env and the I559P mutant were compensated by the SOS disulfide bond between gp120 and gp41, which has been used to stabilize cleaved soluble Env trimers. Nonetheless, regardless of the presence of the SOS changes, Envs with proline 559 were recognized less efficiently than Envs with isoleucine 559 by the VRC01 neutralizing antibody, which binds the CD4-binding site of gp120, and the PGT151 neutralizing antibody, which binds a hybrid gp120-gp41 epitope. The I559P change completely eliminated the ability of the HIV-1BG505 Env to mediate cell-cell fusion and virus entry, and abolished the capacity of the SOS Env to support virus infection in the presence of a reducing agent. These results suggest that differences exist between the quaternary structures of functional Env spikes and I559P Envs.
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