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Wu C, Raheem IT, Nahas DD, Citron M, Kim PS, Montefiori DC, Ottinger EA, Hepler RW, Hrin R, Patel SB, Soisson SM, Joyce JG. Stabilized trimeric peptide immunogens of the complete HIV-1 gp41 N-heptad repeat and their use as HIV-1 vaccine candidates. Proc Natl Acad Sci U S A 2024; 121:e2317230121. [PMID: 38768344 PMCID: PMC11145295 DOI: 10.1073/pnas.2317230121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 03/29/2024] [Indexed: 05/22/2024] Open
Abstract
Efforts to develop an HIV-1 vaccine include those focusing on conserved structural elements as the target of broadly neutralizing monoclonal antibodies. MAb D5 binds to a highly conserved hydrophobic pocket on the gp41 N-heptad repeat (NHR) coiled coil and neutralizes through prevention of viral fusion and entry. Assessment of 17-mer and 36-mer NHR peptides presenting the D5 epitope in rodent immunogenicity studies showed that the longer peptide elicited higher titers of neutralizing antibodies, suggesting that neutralizing epitopes outside of the D5 pocket may exist. Although the magnitude and breadth of neutralization elicited by NHR-targeting antigens are lower than that observed for antibodies directed to other epitopes on the envelope glycoprotein complex, it has been shown that NHR-directed antibodies are potentiated in TZM-bl cells containing the FcγRI receptor. Herein, we report the design and evaluation of covalently stabilized trimeric 51-mer peptides encompassing the complete gp41 NHR. We demonstrate that these peptide trimers function as effective antiviral entry inhibitors and retain the ability to present the D5 epitope. We further demonstrate in rodent and nonhuman primate immunization studies that our 51-mer constructs elicit a broader repertoire of neutralizing antibody and improved cross-clade neutralization of primary HIV-1 isolates relative to 17-mer and 36-mer NHR peptides in A3R5 and FcγR1-enhanced TZM-bl assays. These results demonstrate that sensitive neutralization assays can be used for structural enhancement of moderately potent neutralizing epitopes. Finally, we present expanded trimeric peptide designs which include unique low-molecular-weight scaffolds that provide versatility in our immunogen presentation strategy.
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Affiliation(s)
- Chengwei Wu
- Discovery Chemistry, Merck & Co., Inc., West Point, PA19486
| | | | | | - Michael Citron
- Discovery Biology, Merck & Co., Inc., West Point, PA19486
| | - Peter S. Kim
- Office of the President, Merck & Co., Inc., West Point, PA19486
| | | | | | | | - Renee Hrin
- Discovery Biology, Merck & Co., Inc., West Point, PA19486
| | | | | | - Joseph G. Joyce
- Process Research and Development, Merck & Co., Inc., West Point, PA19486
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2
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Bruun TUJ, Tang S, Erwin G, Deis L, Fernandez D, Kim PS. Structure-guided stabilization improves the ability of the HIV-1 gp41 hydrophobic pocket to elicit neutralizing antibodies. J Biol Chem 2023; 299:103062. [PMID: 36841484 PMCID: PMC10064241 DOI: 10.1016/j.jbc.2023.103062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 02/27/2023] Open
Abstract
The hydrophobic pocket found in the N-heptad repeat (NHR) region of HIV-1 gp41 is a highly conserved epitope that is the target of various HIV-1-neutralizing monoclonal antibodies. Although the high conservation of the pocket makes it an attractive vaccine candidate, it has been challenging to elicit potent anti-NHR antibodies via immunization. Here, we solved a high-resolution structure of the NHR mimetic IQN17, and, consistent with previous ligand-bound gp41 pocket structures, we observed remarkable conformational plasticity of the pocket. The high malleability of this pocket led us to test whether we could improve the immunogenicity of the gp41 pocket by stabilizing its conformation. We show that the addition of five amino acids at the C terminus of IQN17, to generate IQN22, introduces a stabilizing salt bridge at the base of the peptide that rigidifies the pocket. Mice immunized with IQN22 elicited higher avidity antibodies against the gp41 pocket and a more potent, albeit still weak, neutralizing response against HIV-1 compared with IQN17. Stabilized epitope-focused immunogens could serve as the basis for future HIV-1 fusion-inhibiting vaccines.
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Affiliation(s)
- Theodora U J Bruun
- Sarafan ChEM-H, Stanford University, Stanford, California, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Shaogeng Tang
- Sarafan ChEM-H, Stanford University, Stanford, California, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Graham Erwin
- Sarafan ChEM-H, Stanford University, Stanford, California, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Lindsay Deis
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Daniel Fernandez
- Sarafan ChEM-H, Stanford University, Stanford, California, USA; Chem-H Macromolecular Structure Knowledge Center (MSKC), Stanford University, Stanford, California, USA
| | - Peter S Kim
- Sarafan ChEM-H, Stanford University, Stanford, California, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA; Chan Zuckerberg Biohub, San Francisco, California, USA.
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Rubio AA, Filsinger Interrante MV, Bell BN, Brown CL, Bruun TUJ, LaBranche CC, Montefiori DC, Kim PS. A Derivative of the D5 Monoclonal Antibody That Targets the gp41 N-Heptad Repeat of HIV-1 with Broad Tier-2-Neutralizing Activity. J Virol 2021; 95:e0235020. [PMID: 33980592 PMCID: PMC8274607 DOI: 10.1128/jvi.02350-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/30/2021] [Indexed: 01/11/2023] Open
Abstract
HIV-1 infection is initiated by the viral glycoprotein Env, which, after interaction with cellular coreceptors, adopts a transient conformation known as the prehairpin intermediate (PHI). The N-heptad repeat (NHR) is a highly conserved region of gp41 exposed in the PHI; it is the target of the FDA-approved drug enfuvirtide and of neutralizing monoclonal antibodies (mAbs). However, to date, these mAbs have only been weakly effective against tier-1 HIV-1 strains, which are most sensitive to neutralizing antibodies. Here, we engineered and tested 11 IgG variants of D5, an anti-NHR mAb, by recombining previously described mutations in four of D5's six antibody complementarity-determining regions. One variant, D5_AR, demonstrated 6-fold enhancement in the 50% inhibitory dose (ID50) against lentivirus pseudotyped with HXB2 Env. D5_AR exhibited weak cross-clade neutralizing activity against a diverse set of tier-2 HIV-1 viruses, which are less sensitive to neutralizing antibodies than tier-1 viruses and are the target of current antibody-based vaccine efforts. In addition, the neutralization potency of D5_AR IgG was greatly enhanced in target cells expressing FcγRI, with ID50 values of <0.1 μg/ml; this immunoglobulin receptor is expressed on macrophages and dendritic cells, which are implicated in the early stages of HIV-1 infection of mucosal surfaces. D5 and D5_AR have equivalent neutralization potency in IgG, Fab, and single-chain variable-fragment (scFv) formats, indicating that neutralization is not impacted by steric hindrance. Taken together, these results provide support for vaccine strategies that target the PHI by eliciting antibodies against the gp41 NHR and support investigation of anti-NHR mAbs in nonhuman primate passive immunization studies. IMPORTANCE Despite advances in antiretroviral therapy, HIV remains a global epidemic and has claimed more than 32 million lives. Accordingly, developing an effective HIV vaccine remains an urgent public health need. The gp41 N-heptad repeat (NHR) of the HIV-1 prehairpin intermediate (PHI) is highly conserved (>90%) and is inhibited by the FDA-approved drug enfuvirtide, making it an attractive vaccine target. However, to date, anti-NHR antibodies have not been potent. Here, we engineered D5_AR, a more potent variant of the anti-NHR antibody D5, and established its ability to inhibit HIV-1 strains that are more difficult to neutralize and are more representative of circulating strains (tier-2 strains). The neutralizing activity of D5_AR was greatly potentiated in cells expressing FcγRI; FcγRI is expressed on cells that are implicated at the earliest stages of sexual HIV-1 transmission. Taken together, these results bolster efforts to target the gp41 NHR and the PHI for vaccine development.
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Affiliation(s)
- Adonis A. Rubio
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Department of Biology, Stanford University School of Humanities & Sciences, Stanford, California, USA
| | - Maria V. Filsinger Interrante
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Stanford Biophysics Program, Stanford University School of Medicine, Stanford, California, USA
- Stanford Medical Scientist Training Program, Stanford University School of Medicine, Stanford, California, USA
| | - Benjamin N. Bell
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA
| | - Clayton L. Brown
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Theodora U. J. Bruun
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
| | - Celia C. LaBranche
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - David C. Montefiori
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Peter S. Kim
- Stanford ChEM-H, Stanford University, Stanford, California, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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Membrane Env Liposomes Facilitate Immunization with Multivalent Full-Length HIV Spikes. J Virol 2021; 95:e0000521. [PMID: 33883221 DOI: 10.1128/jvi.00005-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
A major goal of HIV vaccine design is to elicit broadly neutralizing antibodies (bNAbs). Such bNAbs target HIV's trimeric, membrane-embedded envelope glycoprotein spikes (mEnv). Soluble Env (sEnv) trimers have been used as vaccines, but engineering sEnvs for stability, multivalency, and desired antigenicity is problematic and deletes key neutralizing epitopes on glycoprotein 41 (gp41) while creating neoepitopes that elicit unwanted antibodies. Meanwhile, multivalent mEnv vaccines are challenging to develop due to trimer instability and low mEnv copy number amid other extraneous proteins on virus-like particles. Here, we describe a multivalent mEnv vaccine platform that does not require protein engineering or extraneous proteins. mEnv trimers were fixed, purified, and combined with naked liposomes in mild detergent. On removal of detergent, mEnv spikes were observed embedded in liposome particles (mean diameter, 133 nm) in correct orientation. These particles were recognized by HIV bNAbs and not non-NAbs and are designated mEnv liposomes (MELs). Following a sequential immunization scheme in rabbits, MELs elicited antibodies that neutralized tier 2 HIV isolates. Analysis of serum antibody specificities, including those to epitopes involving a missing conserved N-glycosylation site at position 197 near the CD4 binding site on two of the immunogens, provides clues on how NAb responses can be improved with modified immunogens. In sum, MELs are a biochemically defined platform that enables rational immunization strategies to elicit HIV bNAbs using multimerized mEnv. IMPORTANCE A vaccine that induced broadly neutralizing antibodies against HIV would likely end the AIDS pandemic. Such antibodies target membrane-embedded envelope glycoprotein spikes (mEnv) that HIV uses to enter cells. Due to HIV Env's low expression and instability, soluble stabilized Env trimers have been used as vaccine candidates, but these have an altered base that disrupts targets of HIV broadly neutralizing antibodies that bind near the membrane and are not available for all HIV isolates. Here, we describe membrane Env liposomes (MELs) that display a multivalent array of stable mEnvs on liposome particles. MELs showed the expected antibody recognition properties, including targeting parts of mEnv missing on soluble Envs. Immunization with MELs elicited antibodies that neutralized diverse HIV isolates. The MEL platform facilitates vaccine development with potentially any HIV Env at high valency, and a similar approach may be useful for eliciting antibodies to membrane-embedded targets of therapeutic interest.
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The high-affinity immunoglobulin receptor FcγRI potentiates HIV-1 neutralization via antibodies against the gp41 N-heptad repeat. Proc Natl Acad Sci U S A 2021; 118:2018027118. [PMID: 33431684 PMCID: PMC7826338 DOI: 10.1073/pnas.2018027118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Despite decades of research, an effective HIV-1 vaccine remains elusive. One potential vaccine target is the N-heptad repeat (NHR) region of gp41, which is the target of the FDA-approved drug enfuvirtide. However, monoclonal antibodies and antisera targeting this region have only been modestly neutralizing to date. Here, we show that the neutralization potency of the well-characterized anti-NHR antibody D5 is increased >5,000-fold by expression of FcγRI (CD64) on cells. Since FcγRI is expressed on macrophages and dendritic cells, which are implicated in the early establishment of HIV-1 infection following sexual transmission, these results may be important to HIV-1 vaccine development. The HIV-1 gp41 N-heptad repeat (NHR) region of the prehairpin intermediate, which is transiently exposed during HIV-1 viral membrane fusion, is a validated clinical target in humans and is inhibited by the Food and Drug Administration (FDA)-approved drug enfuvirtide. However, vaccine candidates targeting the NHR have yielded only modest neutralization activities in animals; this inhibition has been largely restricted to tier-1 viruses, which are most sensitive to neutralization by sera from HIV-1–infected individuals. Here, we show that the neutralization activity of the well-characterized NHR-targeting antibody D5 is potentiated >5,000-fold in TZM-bl cells expressing FcγRI compared with those without, resulting in neutralization of many tier-2 viruses (which are less susceptible to neutralization by sera from HIV-1–infected individuals and are the target of current antibody-based vaccine efforts). Further, antisera from guinea pigs immunized with the NHR-based vaccine candidate (ccIZN36)3 neutralized tier-2 viruses from multiple clades in an FcγRI-dependent manner. As FcγRI is expressed on macrophages and dendritic cells, which are present at mucosal surfaces and are implicated in the early establishment of HIV-1 infection following sexual transmission, these results may be important in the development of a prophylactic HIV-1 vaccine.
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Ahmadi K, Farasat A, Rostamian M, Johari B, Madanchi H. Enfuvirtide, an HIV-1 fusion inhibitor peptide, can act as a potent SARS-CoV-2 fusion inhibitor: an in silico drug repurposing study. J Biomol Struct Dyn 2021; 40:5566-5576. [PMID: 33438525 PMCID: PMC7814568 DOI: 10.1080/07391102.2021.1871958] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Regarding the urgency of therapeutic measures for coronavirus disease 2019 (COVID-19) pandemic, the use of available drugs with FDA approval is preferred because of the less time and cost required for their development. In silico drug repurposing is an accurate way to speed up the screening of the existing FDA-approved drugs to find a therapeutic option for COVID-19. The similarity in SARS-CoV-2 and HIV-1 fusion mechanism to host cells can be a key point for Inhibit SARS-CoV-2 entry into host cells by HIV fusion inhibitors. Accordingly, in this study, an HIV-1 fusion inhibitor called Enfuvirtide (Enf) was selected. The affinity and essential residues involving in the Enf binding to the S2 protein of SARS-CoV-2, HIV-1 gp41 protein and angiotensin-converting enzyme 2 (ACE-2) as a negative control, was evaluated using molecular docking. Eventually, Enf-S2 and Enf-gp41 protein complexes were simulated by molecular dynamics (MD) in terms of binding affinity and stability. Based on the most important criteria such as docking score, cluster size, energy and dissociation constant, the strongest interaction was observed between Enf with the S2 protein. In addition, MD results confirmed that Enf-S2 protein interaction was remarkably stable and caused the S2 protein residues to undergo the fewest fluctuations. In conclusion, it can be stated that Enf can act as a strong SARS-CoV-2 fusion inhibitor and demonstrates the potential to enter the clinical trial phase of COVID-19. Communicated by Ramaswamy H. Sarma
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Affiliation(s)
- Khadijeh Ahmadi
- Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Alireza Farasat
- Cellular and Molecular Research Center, Research Institute for Prevention of Non Communicable Diseases, Qazvin University of Medical Sciences, Qazvin, Iran.,Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Mosayeb Rostamian
- Infectious Diseases Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Behrooz Johari
- Department of Medical Biotechnology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Hamid Madanchi
- Department of Biotechnology, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.,Drug Design and Bioinformatics Unit, Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
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Pu J, Wang Q, Xu W, Lu L, Jiang S. Development of Protein- and Peptide-Based HIV Entry Inhibitors Targeting gp120 or gp41. Viruses 2019; 11:v11080705. [PMID: 31374953 PMCID: PMC6722851 DOI: 10.3390/v11080705] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 07/26/2019] [Accepted: 07/26/2019] [Indexed: 01/08/2023] Open
Abstract
Application of highly active antiretroviral drugs (ARDs) effectively reduces morbidity and mortality in HIV-infected individuals. However, the emergence of multiple drug-resistant strains has led to the increased failure of ARDs, thus calling for the development of anti-HIV drugs with targets or mechanisms of action different from those of the current ARDs. The first peptide-based HIV entry inhibitor, enfuvirtide, was approved by the U.S. FDA in 2003 for treatment of HIV/AIDS patients who have failed to respond to the current ARDs, which has stimulated the development of several series of protein- and peptide-based HIV entry inhibitors in preclinical and clinical studies. In this review, we highlighted the properties and mechanisms of action for those promising protein- and peptide-based HIV entry inhibitors targeting the HIV-1 gp120 or gp41 and discussed their advantages and disadvantages, compared with the current ARDs.
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Affiliation(s)
- Jing Pu
- Shanghai Public Health Clinical Center and School of Basic Medical Sciences, Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Fudan University, Shanghai 200032, China
| | - Qian Wang
- Shanghai Public Health Clinical Center and School of Basic Medical Sciences, Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Fudan University, Shanghai 200032, China
| | - Wei Xu
- Shanghai Public Health Clinical Center and School of Basic Medical Sciences, Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Fudan University, Shanghai 200032, China
| | - Lu Lu
- Shanghai Public Health Clinical Center and School of Basic Medical Sciences, Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Fudan University, Shanghai 200032, China.
| | - Shibo Jiang
- Shanghai Public Health Clinical Center and School of Basic Medical Sciences, Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Fudan University, Shanghai 200032, China.
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, NY 10065, USA.
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8
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Mathew E, Zhu H, Connelly SM, Sullivan MA, Brewer MG, Piepenbrink MS, Kobie JJ, Dewhurst S, Dumont ME. Display of the HIV envelope protein at the yeast cell surface for immunogen development. PLoS One 2018; 13:e0205756. [PMID: 30335821 PMCID: PMC6193675 DOI: 10.1371/journal.pone.0205756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 10/01/2018] [Indexed: 11/22/2022] Open
Abstract
As a step toward the development of variant forms of Env with enhanced immunogenic properties, we have expressed the glycoprotein in the yeast surface display system in a form that can be subjected to random mutagenesis followed by screening for forms with enhanced binding to germline antibodies. To optimize the expression and immunogenicity of the yeast-displayed Env protein, we tested different approaches for cell wall anchoring, expression of gp120 and gp140 Env from different viral strains, the effects of introducing mutations designed to stabilize Env, and the effects of procedures for altering N-linked glycosylation of Env. We find that diverse forms of HIV envelope glycoprotein can be efficiently expressed at the yeast cell surface and that gp140 forms of Env are effectively cleaved by Kex2p, the yeast furin protease homolog. Multiple yeast-displayed gp120 and gp140 proteins are capable of binding to antibodies directed against the V3-variable loop, CD4 binding site, and gp41 membrane-proximal regions, including some antibodies whose binding is known to depend on Env conformation and N-linked glycan. Based on antibody recognition and sensitivity to glycosidases, yeast glycosylation patterns partially mimic high mannose-type N-glycosylation in mammalian cells. However, yeast-displayed Env is not recognized by some anti-Env antibodies sensitive to quaternary structure, suggesting either that the displayed protein exists in a monomeric state or that for these antibodies, yeast glycosylation in certain regions hinders recognition or access. Consistent with studies in other systems, reconstructed predicted unmutated precursors to anti-Env antibodies exhibit little affinity for the yeast-displayed envelope protein.
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Affiliation(s)
- Elizabeth Mathew
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Hong Zhu
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Sara M. Connelly
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Mark A. Sullivan
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Matthew G. Brewer
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Michael S. Piepenbrink
- Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, United States of America
| | - James J. Kobie
- Infectious Diseases Division, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Stephen Dewhurst
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Mark E. Dumont
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY, United States of America
- * E-mail:
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9
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Falkenhagen A, Joshi S. HIV Entry and Its Inhibition by Bifunctional Antiviral Proteins. MOLECULAR THERAPY-NUCLEIC ACIDS 2018; 13:347-364. [PMID: 30340139 PMCID: PMC6197789 DOI: 10.1016/j.omtn.2018.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 09/05/2018] [Accepted: 09/05/2018] [Indexed: 12/14/2022]
Abstract
HIV entry is a highly specific and time-sensitive process that can be divided into receptor binding, coreceptor binding, and membrane fusion. Bifunctional antiviral proteins (bAVPs) exploit the multi-step nature of the HIV entry process by binding to two different extracellular targets. They are generated by expressing a fusion protein containing two entry inhibitors with a flexible linker. The resulting fusion proteins exhibit exceptional neutralization potency and broad cross-clade inhibition. In this review, we summarize the HIV entry process and provide an overview of the design, antiviral potency, and methods of delivery of bAVPs. Additionally, we discuss the advantages and limitations of bAVPs for HIV prevention and treatment.
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Affiliation(s)
- Alexander Falkenhagen
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Sadhna Joshi
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E2, Canada.
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Bamunusinghe D, Liu Q, Plishka R, Dolan MA, Skorski M, Oler AJ, Yedavalli VRK, Buckler-White A, Hartley JW, Kozak CA. Recombinant Origins of Pathogenic and Nonpathogenic Mouse Gammaretroviruses with Polytropic Host Range. J Virol 2017; 91:e00855-17. [PMID: 28794032 PMCID: PMC5640873 DOI: 10.1128/jvi.00855-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/26/2017] [Indexed: 01/06/2023] Open
Abstract
Ecotropic, xenotropic, and polytropic mouse leukemia viruses (E-, X-, and P-MLVs) exist in mice as infectious viruses and endogenous retroviruses (ERVs) inserted into mouse chromosomes. All three MLV subgroups are linked to leukemogenesis, which involves generation of recombinants with polytropic host range. Although P-MLVs are deemed to be the proximal agents of disease induction, few biologically characterized infectious P-MLVs have been sequenced for comparative analysis. We analyzed the complete genomes of 16 naturally occurring infectious P-MLVs, 12 of which were typed for pathogenic potential. We sought to identify ERV progenitors, recombinational hot spots, and segments that are always replaced, never replaced, or linked to pathogenesis or host range. Each P-MLV has an E-MLV backbone with P- or X-ERV replacements that together cover 100% of the recombinant genomes, with different substitution patterns for X- and P-ERVs. Two segments are always replaced, both coding for envelope (Env) protein segments: the N terminus of the surface subunit and the cytoplasmic tail R peptide. Viral gag gene replacements are influenced by host restriction genes Fv1 and Apobec3 Pathogenic potential maps to the env transmembrane subunit segment encoding the N-heptad repeat (HR1). Molecular dynamics simulations identified three novel interdomain salt bridges in the lymphomagenic virus HR1 that could affect structural stability, entry or sensitivity to host immune responses. The long terminal repeats of lymphomagenic P-MLVs are differentially altered by recombinations, duplications, or mutations. This analysis of the naturally occurring, sometimes pathogenic P-MLV recombinants defines the limits and extent of intersubgroup recombination and identifies specific sequence changes linked to pathogenesis and host interactions.IMPORTANCE During virus-induced leukemogenesis, ecotropic mouse leukemia viruses (MLVs) recombine with nonecotropic endogenous retroviruses (ERVs) to produce polytropic MLVs (P-MLVs). Analysis of 16 P-MLV genomes identified two segments consistently replaced: one at the envelope N terminus that alters receptor choice and one in the R peptide at the envelope C terminus, which is removed during virus assembly. Genome-wide analysis shows that nonecotropic replacements in the progenitor ecotropic MLV genome are more extensive than previously appreciated, covering 100% of the genome; contributions from xenotropic and polytropic ERVs differentially alter the regions responsible for receptor determination or subject to APOBEC3 and Fv1 restriction. All pathogenic viruses had modifications in the regulatory elements in their long terminal repeats and differed in a helical segment of envelope involved in entry and targeted by the host immune system. Virus-induced leukemogenesis thus involves generation of complex recombinants, and specific replacements are linked to pathogenesis and host restrictions.
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Affiliation(s)
- Devinka Bamunusinghe
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Qingping Liu
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Ronald Plishka
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Michael A Dolan
- Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Matthew Skorski
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Andrew J Oler
- Bioinformatics and Computational Biosciences Branch, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Venkat R K Yedavalli
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Alicia Buckler-White
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Janet W Hartley
- Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Christine A Kozak
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
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11
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Weber J, Peng H, Rader C. From rabbit antibody repertoires to rabbit monoclonal antibodies. Exp Mol Med 2017; 49:e305. [PMID: 28336958 PMCID: PMC5382564 DOI: 10.1038/emm.2017.23] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 12/22/2016] [Indexed: 12/11/2022] Open
Abstract
In this review, we explain why and how rabbit monoclonal antibodies have become outstanding reagents for laboratory research and increasingly for diagnostic and therapeutic applications. Starting with the unique ontogeny of rabbit B cells that affords highly distinctive antibody repertoires rich in in vivo pruned binders of high diversity, affinity and specificity, we describe the generation of rabbit monoclonal antibodies by hybridoma technology, phage display and alternative methods, along with an account of successful humanization strategies.
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Affiliation(s)
- Justus Weber
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL, USA
| | - Haiyong Peng
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL, USA
| | - Christoph Rader
- Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL, USA
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12
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Sood C, Marin M, Chande A, Pizzato M, Melikyan GB. SERINC5 protein inhibits HIV-1 fusion pore formation by promoting functional inactivation of envelope glycoproteins. J Biol Chem 2017; 292:6014-6026. [PMID: 28179429 DOI: 10.1074/jbc.m117.777714] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/07/2017] [Indexed: 12/24/2022] Open
Abstract
The host proteins, SERINC3 and SERINC5, have been recently shown to incorporate into HIV-1 particles and compromise their ability to fuse with target cells, an effect that is antagonized by the viral Nef protein. Envelope (Env) glycoproteins from different HIV-1 isolates exhibit a broad range of sensitivity to SERINC-mediated restriction, and the mechanism by which SERINCs interfere with HIV-1 fusion remains unclear. Here, we show that incorporation of SERINC5 into virions in the absence of Nef inhibits the formation of small fusion pores between viruses and cells. Strikingly, we found that SERINC5 promotes spontaneous functional inactivation of sensitive but not resistant Env glycoproteins. Although SERINC5-Env interaction was not detected by co-immunoprecipitation, incorporation of this protein enhanced the exposure of the conserved gp41 domains and sensitized the virus to neutralizing antibodies and gp41-derived inhibitory peptides. These results imply that SERINC5 restricts HIV-1 fusion at a step prior to small pore formation by selectively inactivating sensitive Env glycoproteins, likely through altering their conformation. The increased HIV-1 sensitivity to anti-gp41 antibodies and peptides suggests that SER5 also delays refolding of the remaining fusion-competent Env trimers.
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Affiliation(s)
- Chetan Sood
- From the Department of Pediatrics, Emory University, Atlanta, Georgia 30322 and
| | - Mariana Marin
- From the Department of Pediatrics, Emory University, Atlanta, Georgia 30322 and
| | - Ajit Chande
- the Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Massimo Pizzato
- the Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Gregory B Melikyan
- From the Department of Pediatrics, Emory University, Atlanta, Georgia 30322 and
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13
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Identification of Human Anti-HIV gp160 Monoclonal Antibodies That Make Effective Immunotoxins. J Virol 2017; 91:JVI.01955-16. [PMID: 27852851 DOI: 10.1128/jvi.01955-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/07/2016] [Indexed: 11/20/2022] Open
Abstract
The envelope (Env) glycoprotein of HIV is the only intact viral protein expressed on the surface of both virions and infected cells. Env is the target of neutralizing antibodies (Abs) and has been the subject of intense study in efforts to produce HIV vaccines. Therapeutic anti-Env Abs can also exert antiviral effects via Fc-mediated effector mechanisms or as cytotoxic immunoconjugates, such as immunotoxins (ITs). In the course of screening monoclonal antibodies (MAbs) for their ability to deliver cytotoxic agents to infected or Env-transfected cells, we noted disparities in their functional activities. Different MAbs showed diverse functions that did not correlate with each other. For example, MAbs against the external loop region of gp41 made the most effective ITs against infected cells but did not neutralize virus and bound only moderately to the same cells that they killed so effectively when they were used in ITs. There were also differences in IT-mediated killing among transfected and infected cell lines that were unrelated to the binding of the MAb to the target cells. Our studies of a well-characterized antigen demonstrate that MAbs against different epitopes have different functional activities and that the binding of one MAb can influence the interaction of other MAbs that bind elsewhere on the antigen. These results have implications for the use of MAbs and ITs to kill HIV-infected cells and eradicate persistent reservoirs of HIV infection. IMPORTANCE There is increased interest in using antibodies to treat and cure HIV infection. Antibodies can neutralize free virus and kill cells already carrying the virus. The virus envelope (Env) is the only HIV protein expressed on the surfaces of virions and infected cells. In this study, we examined a panel of human anti-Env antibodies for their ability to deliver cell-killing toxins to HIV-infected cells and to perform other antiviral functions. The ability of an antibody to make an effective immunotoxin could not be predicted from its other functional characteristics, such as its neutralizing activity. Anti-HIV immunotoxins could be used to eliminate virus reservoirs that persist despite effective antiretroviral therapy.
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14
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Khasnis MD, Halkidis K, Bhardwaj A, Root MJ. Receptor Activation of HIV-1 Env Leads to Asymmetric Exposure of the gp41 Trimer. PLoS Pathog 2016; 12:e1006098. [PMID: 27992602 PMCID: PMC5222517 DOI: 10.1371/journal.ppat.1006098] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/09/2017] [Accepted: 11/29/2016] [Indexed: 11/18/2022] Open
Abstract
Structural rearrangements of HIV-1 glycoprotein Env promote viral entry through membrane fusion. Env is a symmetric homotrimer with each protomer composed of surface subunit gp120 and transmembrane subunit gp41. Cellular CD4- and chemokine receptor-binding to gp120 coordinate conformational changes in gp41, first to an extended prehairpin intermediate (PHI) and, ultimately, into a fusogenic trimer-of-hairpins (TOH). HIV-1 fusion inhibitors target gp41 in the PHI and block TOH formation. To characterize structural transformations into and through the PHI, we employed asymmetric Env trimers containing both high and low affinity binding sites for individual fusion inhibitors. Asymmetry was achieved using engineered Env heterotrimers composed of protomers deficient in either CD4- or chemokine receptor-binding. Linking receptor engagement to inhibitor affinity allowed us to assess conformational changes of individual Env protomers in the context of a functioning trimer. We found that the transition into the PHI could occur symmetrically or asymmetrically depending on the stoichiometry of CD4 binding. Sequential engagement of multiple CD4s promoted progressive exposure of individual fusion inhibitor binding sites in a CD4-dependent fashion. By contrast, engagement of only a single CD4 molecule led to a delayed, but symmetric, exposure of the gp41 trimer. This complex coupling between Env-CD4 interaction and gp41 exposure explained the multiphasic fusion-inhibitor titration observed for a mutant Env homotrimer with a naturally asymmetric gp41. Our results suggest that the spatial and temporal exposure of gp41 can proceed in a nonconcerted, asymmetric manner depending on the number of CD4s that engage the Env trimer. The findings have important implications for the mechanism of viral membrane fusion and the development of vaccine candidates designed to elicit neutralizing antibodies targeting gp41 in the PHI. For HIV, cellular invasion requires merging viral and cellular membranes, an event achieved through the activity of the viral fusion protein Env. Env consists of three gp120 and three gp41 subunits symmetrically arranged on the viral surface. The gp120 subunits bind cellular receptors, which, in turn, coordinate gp41 conformational changes that promote membrane fusion. Understanding these structural rearrangements illuminates the mechanism of viral membrane fusion, and also spurs development of targeted inhibitors of viral entry and vaccine candidates that elicit antiviral immune responses. In this study, we employed a novel strategy to investigate individual subunits in the context of functioning Env complexes. The strategy links distinct gp120-receptor interactions to conformational changes that expose specific gp41 subunits. We found that, despite the initial symmetric arrangement of its subunits, Env conformational changes most often proceed quite asymmetrically, leading to exposure of only one-third of the gp41 trimer for much of the fusion event. This finding might explain why attempts to elicit potent anti-HIV antibodies to a fully exposed gp41 trimer have been largely unsuccessful. The study gives us a glimpse of the early structural transitions leading to Env-mediated membrane fusion and provides a framework for interrogating the fusion proteins of other membrane-encapsulated viruses.
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Affiliation(s)
- Mukta D. Khasnis
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Konstantine Halkidis
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Anshul Bhardwaj
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States of America
| | - Michael J. Root
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, United States of America
- * E-mail:
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15
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Louis JM, Baber JL, Clore GM. The C34 Peptide Fusion Inhibitor Binds to the Six-Helix Bundle Core Domain of HIV-1 gp41 by Displacement of the C-Terminal Helical Repeat Region. Biochemistry 2015; 54:6796-805. [PMID: 26506247 DOI: 10.1021/acs.biochem.5b01021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational transition of the core domain of HIV-1 gp41 from a prehairpin intermediate to a six-helix bundle is responsible for virus-cell fusion. Several inhibitors which target the N-heptad repeat helical coiled-coil trimer that is fully accessible in the prehairpin intermediate have been designed. One such inhibitor is the peptide C34 derived from the C-heptad repeat of gp41 that forms the exterior of the six-helix bundle. Here, using a variety of biophysical techniques, including dye tagging, size-exclusion chromatography combined with multiangle light scattering, double electron-electron resonance EPR spectroscopy, and circular dichroism, we investigate the binding of C34 to two six-helix bundle mimetics comprising N- and C-heptad repeats either without (core(SP)) or with (core(S)) a short spacer connecting the two. In the case of core(SP), C34 directly exchanges with the C-heptad repeat. For core(S), up to two molecules of C34 bind the six-helix bundle via displacement of the C-heptad repeat. These results suggest that fusion inhibitors such as C34 can target a continuum of transitioning conformational states from the prehairpin intermediate to the six-helix bundle prior to the occurrence of irreversible fusion of viral and target cell membranes.
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Affiliation(s)
- John M Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
| | - James L Baber
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
| | - G Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
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16
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Sun Y, Sholler GS, Shukla GS, Pero SC, Carman CL, Zhao P, Krag DN. Autologous antibodies that bind neuroblastoma cells. J Immunol Methods 2015. [PMID: 26210205 DOI: 10.1016/j.jim.2015.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Antibody therapy of neuroblastoma is promising and our goal is to derive antibodies from patients with neuroblastoma for developing new therapeutic antibodies. The feasibility of using residual bone marrow obtained for clinical indications as a source of tumor cells and a source of antibodies was assessed. From marrow samples, neuroblastoma cells were recovered, grown in cell culture and also implanted into mice to create xenografts. Mononuclear cells from the marrow were used as a source to generate phage display antibody libraries and also hybridomas. Growth of neuroblastoma patient cells was possible both in vitro and as xenografts. Antibodies from the phage libraries and from the monoclonal hybridomas bound autologous neuroblastoma cells with some selectivity. It appears feasible to recover neuroblastoma cells from residual marrow specimens and to generate human antibodies that bind autologous neuroblastoma cells. Expansion of this approach is underway to collect more specimens, optimize methods to generate antibodies, and to evaluate the bioactivity of neuroblastoma-binding antibodies.
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Affiliation(s)
- Yujing Sun
- Department of Surgery, Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Giselle S Sholler
- Helen DeVos Children's Hospital, Grand Rapids, MI 49503, USA; Michigan State University, Grand Rapids, MI 49503, USA
| | - Girja S Shukla
- Department of Surgery, Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Stephanie C Pero
- Department of Surgery, Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Chelsea L Carman
- Department of Surgery, Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Ping Zhao
- Helen DeVos Children's Hospital, Grand Rapids, MI 49503, USA; Michigan State University, Grand Rapids, MI 49503, USA
| | - David N Krag
- Department of Surgery, Vermont Cancer Center, University of Vermont College of Medicine, Burlington, VT 05405, USA.
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17
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Novel neutralising antibodies targeting the N-terminal helical region of the transmembrane envelope protein p15E of the porcine endogenous retrovirus (PERV). Immunol Res 2014; 58:9-19. [PMID: 23729215 DOI: 10.1007/s12026-013-8430-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Previously, immunising different species with the transmembrane envelope protein p15E of the porcine endogenous retrovirus (PERV), neutralising antibodies were induced which recognised epitopes in the fusion peptide proximal region (FPPR) and in the membrane-proximal external region (MPER). Only the MPER-specific antibodies were shown to neutralise and these antibodies targeted epitopes in the MPER similarly localised as the epitopes recognised by antibodies broadly neutralising HIV-1 such as 2F5 and 4E10. To study whether neutralising antibodies could be induced immunising with subunits of p15E, recombinant proteins corresponding to the N-terminal, the C-terminal helical region (NHR, CHR) and a p15E with a mutation in the Cys-Cys loop were produced. Whereas none of these antigens induced MPER-specific neutralising antibodies, the animals immunised with the FPPR/NHR subunit and the mutated p15E produced neutralising antibodies binding to the NHR. Therefore, for the first time, antibodies specific for the NHR and neutralising PERV were described.
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18
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Louis JM, Aniana A, Lohith K, Sayer JM, Roche J, Bewley CA, Clore GM. Binding of HIV-1 gp41-directed neutralizing and non-neutralizing fragment antibody binding domain (Fab) and single chain variable fragment (ScFv) antibodies to the ectodomain of gp41 in the pre-hairpin and six-helix bundle conformations. PLoS One 2014; 9:e104683. [PMID: 25105806 PMCID: PMC4126735 DOI: 10.1371/journal.pone.0104683] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 07/16/2014] [Indexed: 11/25/2022] Open
Abstract
We previously reported a series of antibodies, in fragment antigen binding domain (Fab) formats, selected from a human non-immune phage library, directed against the internal trimeric coiled-coil of the N-heptad repeat (N-HR) of HIV-1 gp41. Broadly neutralizing antibodies from that series bind to both the fully exposed N-HR trimer, representing the pre-hairpin intermediate state of gp41, and to partially-exposed N-HR helices within the context of the gp41 six-helix bundle. While the affinities of the Fabs for pre-hairpin intermediate mimetics vary by only 2 to 20-fold between neutralizing and non-neutralizing antibodies, differences in inhibition of viral entry exceed three orders of magnitude. Here we compare the binding of neutralizing (8066) and non-neutralizing (8062) antibodies, differing in only four positions within the CDR-H2 binding loop, in Fab and single chain variable fragment (ScFv) formats, to several pre-hairpin intermediate and six-helix bundle constructs of gp41. Residues 56 and 58 of the mini-antibodies are shown to be crucial for neutralization activity. There is a large differential (≥150-fold) in binding affinity between neutralizing and non-neutralizing antibodies to the six-helix bundle of gp41 and binding to the six-helix bundle does not involve displacement of the outer C-terminal helices of the bundle. The binding stoichiometry is one six-helix bundle to one Fab or three ScFvs. We postulate that neutralization by the 8066 antibody is achieved by binding to a continuum of states along the fusion pathway from the pre-hairpin intermediate all the way to the formation of the six-helix bundle, but prior to irreversible fusion between viral and cellular membranes.
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Affiliation(s)
- John M. Louis
- Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (JML); (GMC)
| | - Annie Aniana
- Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Katheryn Lohith
- Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jane M. Sayer
- Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Julien Roche
- Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Carole A. Bewley
- Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - G. Marius Clore
- Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (JML); (GMC)
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19
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Kim AS, Leaman DP, Zwick MB. Antibody to gp41 MPER alters functional properties of HIV-1 Env without complete neutralization. PLoS Pathog 2014; 10:e1004271. [PMID: 25058619 PMCID: PMC4110039 DOI: 10.1371/journal.ppat.1004271] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 06/11/2014] [Indexed: 01/08/2023] Open
Abstract
Human antibody 10E8 targets the conserved membrane proximal external region (MPER) of envelope glycoprotein (Env) subunit gp41 and neutralizes HIV-1 with exceptional potency. Remarkably, HIV-1 containing mutations that reportedly knockout 10E8 binding to linear MPER peptides are partially neutralized by 10E8, producing a local plateau in the dose response curve. Here, we found that virus partially neutralized by 10E8 becomes significantly less neutralization sensitive to various MPER antibodies and to soluble CD4 while becoming significantly more sensitive to antibodies and fusion inhibitors against the heptad repeats of gp41. Thus, 10E8 modulates sensitivity of Env to ligands both pre- and post-receptor engagement without complete neutralization. Partial neutralization by 10E8 was influenced at least in part by perturbing Env glycosylation. With unliganded Env, 10E8 bound with lower apparent affinity and lower subunit occupancy to MPER mutant compared to wild type trimers. However, 10E8 decreased functional stability of wild type Env while it had an opposite, stabilizing effect on MPER mutant Envs. Clade C isolates with natural MPER polymorphisms also showed partial neutralization by 10E8 with altered sensitivity to various gp41-targeted ligands. Our findings suggest a novel mechanism of virus neutralization by demonstrating how antibody binding to the base of a trimeric spike cross talks with adjacent subunits to modulate Env structure and function. The ability of an antibody to stabilize, destabilize, partially neutralize as well as alter neutralization sensitivity of a virion spike pre- and post-receptor engagement may have implications for immunotherapy and vaccine design.
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Affiliation(s)
- Arthur S. Kim
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Daniel P. Leaman
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Michael B. Zwick
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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20
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The transmembrane proteins contribute to immunodeficiencies induced by HIV-1 and other retroviruses. AIDS 2014; 28:1081-90. [PMID: 24445366 DOI: 10.1097/qad.0000000000000195] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Many microorganisms including retroviruses suppress the immune system of the infected host in order to maintain infection. Unfortunately, it is still unclear how retroviruses induce immunosuppression. There is increasing evidence of a common mechanism based on their transmembrane envelope proteins. This review therefore summarizes evidence of the involvement of the transmembrane envelope proteins in the immunopathogenesis of different retroviruses including HIV-1. Mutations in the immunosuppressive (isu) domain of the transmembrane envelope protein of several retroviruses abrogate the immunosuppressive activities in vitro and in vivo. Most importantly, virus sequences with such abrogating mutations were never found in HIV-1-infected individuals despite the fact that the mutated viruses are replication-competent. However, there is also evidence for additional, perhaps even divergent, strategies for each retrovirus. For example, in contrast to many other retroviruses, the HIV directly interacts with immune cells and infects them. In addition, HIV uses several accessory proteins to evade the immune response. Furthermore, the possible contribution of the transmembrane envelope proteins of endogenous retroviruses to immunosuppression when expressed on tumor cells or in the placenta is analyzed.
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21
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Gustchina E, Li M, Ghirlando R, Schuck P, Louis JM, Pierson J, Rao P, Subramaniam S, Gustchina A, Clore GM, Wlodawer A. Complexes of neutralizing and non-neutralizing affinity matured Fabs with a mimetic of the internal trimeric coiled-coil of HIV-1 gp41. PLoS One 2013; 8:e78187. [PMID: 24244293 PMCID: PMC3820714 DOI: 10.1371/journal.pone.0078187] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/08/2013] [Indexed: 11/18/2022] Open
Abstract
A series of mini-antibodies (monovalent and bivalent Fabs) targeting the conserved internal trimeric coiled-coil of the N-heptad repeat (N-HR) of HIV-1 gp41 has been previously constructed and reported. Crystal structures of two closely related monovalent Fabs, one (Fab 8066) broadly neutralizing across a wide panel of HIV-1 subtype B and C viruses, and the other (Fab 8062) non-neutralizing, representing the extremes of this series, were previously solved as complexes with 5-Helix, a gp41 pre-hairpin intermediate mimetic. Binding of these Fabs to covalently stabilized chimeric trimers of N-peptides of HIV-1 gp41 (named (CCIZN36)3 or 3-H) has now been investigated using X-ray crystallography, cryo-electron microscopy, and a variety of biophysical methods. Crystal structures of the complexes between 3-H and Fab 8066 and Fab 8062 were determined at 2.8 and 3.0 Å resolution, respectively. Although the structures of the complexes with the neutralizing Fab 8066 and its non-neutralizing counterpart Fab 8062 were generally similar, small differences between them could be correlated with the biological properties of these antibodies. The conformations of the corresponding CDRs of each antibody in the complexes with 3-H and 5-Helix are very similar. The adaptation to a different target upon complex formation is predominantly achieved by changes in the structure of the trimer of N-HR helices, as well as by adjustment of the orientation of the Fab molecule relative to the N-HR in the complex, via rigid-body movement. The structural data presented here indicate that binding of three Fabs 8062 with high affinity requires more significant changes in the structure of the N-HR trimer compared to binding of Fab 8066. A comparative analysis of the structures of Fabs complexed to different gp41 intermediate mimetics allows further evaluation of biological relevance for generation of neutralizing antibodies, as well as provides novel structural insights into immunogen design.
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Affiliation(s)
- Elena Gustchina
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mi Li
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
- Basic Research Program, SAIC-Frederick, Frederick, Maryland, United States of America
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter Schuck
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John M. Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jason Pierson
- FEI Company, Hillsboro, Oregon, United States of America
| | - Prashant Rao
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Alla Gustchina
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - G. Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alexander Wlodawer
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
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22
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Demirkhanyan L, Marin M, Lu W, Melikyan GB. Sub-inhibitory concentrations of human α-defensin potentiate neutralizing antibodies against HIV-1 gp41 pre-hairpin intermediates in the presence of serum. PLoS Pathog 2013; 9:e1003431. [PMID: 23785290 PMCID: PMC3681749 DOI: 10.1371/journal.ppat.1003431] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 05/02/2013] [Indexed: 12/13/2022] Open
Abstract
Human defensins are at the forefront of the host responses to HIV and other pathogens in mucosal tissues. However, their ability to inactivate HIV in the bloodstream has been questioned due to the antagonistic effect of serum. In this study, we have examined the effect of sub-inhibitory concentrations of human α-defensin HNP-1 on the kinetics of early steps of fusion between HIV-1 and target cells in the presence of serum. Direct measurements of HIV-cell fusion using an enzymatic assay revealed that, in spite of the modest effect on the extent of fusion, HNP-1 prolonged the exposure of functionally important transitional epitopes of HIV-1 gp41 on the cell surface. The increased lifetime of gp41 intermediates in the presence of defensin was caused by a delay in the post-coreceptor binding steps of HIV-1 entry that correlated with the marked enhancement of the virus' sensitivity to neutralizing anti-gp41 antibodies. By contrast, the activity of antibodies to gp120 was not affected. HNP-1 appeared to specifically potentiate antibodies and peptides targeting the first heptad repeat domain of gp41, while its effect on inhibitors and antibodies to other gp41 domains was less prominent. Sub-inhibitory concentrations of HNP-1 also promoted inhibition of HIV-1 entry into peripheral blood mononuclear cells by antibodies and, more importantly, by HIV-1 immune serum. Our findings demonstrate that: (i) sub-inhibitory doses of HNP-1 potently enhance the activity of a number of anti-gp41 antibodies and peptide inhibitors, apparently by prolonging the lifetime of gp41 intermediates; and (ii) the efficiency of HIV-1 fusion inhibitors and neutralizing antibodies is kinetically restricted. This study thus reveals an important role of α-defensin in enhancing adaptive immune responses to HIV-1 infection and suggests future strategies to augment these responses. Human neutrophil peptide 1 (HNP-1) is a small cationic peptide that can directly block HIV-1 entry in the absence of serum. However, since serum attenuates the anti-HIV activity of this peptide, HNP-1 is unlikely to inhibit infection in the bloodstream. Here, we demonstrate that sub-inhibitory doses of HNP-1 in the presence of serum can strongly enhance the activity of neutralizing antibodies and inhibitors targeting transiently exposed intermediate conformations of HIV-1 gp41. HNP-1 appears to exert this effect by delaying post-coreceptor binding steps of fusion and thereby prolonging the exposure of gp41 intermediates. These results imply that the HIV-1 fusion kinetics is an important determinant of sensitivity to neutralizing antibodies and peptides against transiently exposed functional domains of gp41. The surprising synergy between sub-inhibitory concentrations of HNP-1 and anti-gp41 antibodies suggests new strategies to sensitize the virus to circulating antibodies by developing compounds that prolong the exposure of conserved gp41 epitopes on the cell surface.
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Affiliation(s)
- Lusine Demirkhanyan
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
| | - Mariana Marin
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Gregory B. Melikyan
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
- Children's Healthcare of Atlanta, Atlanta, Georgia, United States of America
- * E-mail:
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Wang G, Wang X, Xu Q, Cheng Z. Polyclonal Antibody Against Conserved Peptide in Transmembrane Protein of Avian Leukosis Virus Subgroup J. Monoclon Antib Immunodiagn Immunother 2013; 32:211-5. [DOI: 10.1089/mab.2012.0101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Guihua Wang
- Molecular Pathology Laboratory, Department of Fundamental Veterinary, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an, China
| | - Xiaowei Wang
- Molecular Pathology Laboratory, Department of Fundamental Veterinary, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Qingqing Xu
- Molecular Pathology Laboratory, Department of Fundamental Veterinary, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Ziqiang Cheng
- Molecular Pathology Laboratory, Department of Fundamental Veterinary, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an, China
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Abstract
Most neutralizing antibodies act at the earliest steps of viral infection and block interaction of the virus with cellular receptors to prevent entry into host cells. The inability to induce neutralizing antibodies to HIV has been a major obstacle to HIV vaccine research since the early days of the epidemic. However, in the past three years, the definition of a neutralizing antibody against HIV has been revolutionized by the isolation of extremely broad and potent neutralizing antibodies from HIV-infected individuals. Considerable hurdles remain for inducing neutralizing antibodies to a protective level after immunization. Meanwhile, novel technologies to bypass the induction of antibodies are being explored to provide prophylactic antibody-based interventions. This review addresses the challenge of inducing HIV neutralizing antibodies upon immunization and considers notable recent advances in the field. A greater understanding of the successes and failures for inducing a neutralizing response upon immunization is required to accelerate the development of an effective HIV vaccine.
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Affiliation(s)
- Laura E McCoy
- Wohl Virion Centre, Division of Infection and Immunity, University College London, London WC1E 6BT, England, UK
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25
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Generation of HIV-1 potent and broad neutralizing antibodies by immunization with postfusion HR1/HR2 complex. AIDS 2013; 27:717-30. [PMID: 23719346 DOI: 10.1097/qad.0b013e32835cfca5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND The envelope glycoproteins are major targets for HIV vaccines. The N-terminal and the C-terminal regions of the gp41 interact to form six helix bundles that are responsible for the fusion between the viral and the target cell membranes. Monoclonal antibodies (Abs) able to disrupt the formation of this complex or to interfere with it could inhibit HIV fusion. Most of the well described gp41-specific broadly neutralizing Abs target conformational epitopes within the membrane proximal region of gp41 (MPER) and recognize linear peptides. METHOD AND RESULTS In this study, a stable human transfected cell line, expressing a well folded heptad repeat regions 1 (HR1)/HR2 postfusion complex was developed. Transfected cells were highly immunogenic in mice and allowed the generation of 40 complex specific B-cell clones. Three of them were able to neutralize efficiently both HIV-1 laboratory adapted virus and primary isolates from different clades. Two neutralizing Abs (Nabs) FC-2 and FC-3 bound to a recombinant folded gp140 and blocked with a high potency HR1/HR2 fusion complex formation in vitro. The conformational epitopes of the three antibodies are different to 2F5, 4E10, D5 or NC-1 and mainly located in the MPER region. Abs were capable of inhibiting syncytium formation by blocking spatial interactions between HR1 and HR2 regions. CONCLUSION These findings suggest that immunogenicity of gp41 is achievable and that the use of a fusion complex expressing human cell line is a highly potent immunogen to generate neutralizing antibodies against gp41 envelope glycoprotein.
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26
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Leaman DP, Zwick MB. Increased functional stability and homogeneity of viral envelope spikes through directed evolution. PLoS Pathog 2013; 9:e1003184. [PMID: 23468626 PMCID: PMC3585149 DOI: 10.1371/journal.ppat.1003184] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 12/21/2012] [Indexed: 11/19/2022] Open
Abstract
The functional HIV-1 envelope glycoprotein (Env) trimer, the target of anti-HIV-1 neutralizing antibodies (Abs), is innately labile and coexists with non-native forms of Env. This lability and heterogeneity in Env has been associated with its tendency to elicit non-neutralizing Abs. Here, we use directed evolution to overcome instability and heterogeneity of a primary Env spike. HIV-1 virions were subjected to iterative cycles of destabilization followed by replication to select for Envs with enhanced stability. Two separate pools of stable Env variants with distinct sequence changes were selected using this method. Clones isolated from these viral pools could withstand heat, denaturants and other destabilizing conditions. Seven mutations in Env were associated with increased trimer stability, primarily in the heptad repeat regions of gp41, but also in V1 of gp120. Combining the seven mutations generated a variant Env with superior homogeneity and stability. This variant spike moreover showed resistance to proteolysis and to dissociation by detergent. Heterogeneity within the functional population of hyper-stable Envs was also reduced, as evidenced by a relative decrease in a proportion of virus that is resistant to the neutralizing Ab, PG9. The latter result may reflect a change in glycans on the stabilized Envs. The stabilizing mutations also increased the proportion of secreted gp140 existing in a trimeric conformation. Finally, several Env-stabilizing substitutions could stabilize Env spikes from HIV-1 clades A, B and C. Spike stabilizing mutations may be useful in the development of Env immunogens that stably retain native, trimeric structure. A vaccine is needed to prevent HIV/AIDS but eliciting potent neutralizing antibodies (Abs) against primary isolates has been a major stumbling block. The target of HIV-1 neutralizing antibodies is the native envelope glycoprotein (Env) trimer that is displayed on the surface of the virus. Virion associated Env typically elicits antibodies that cannot neutralize primary viruses. However, because native Env trimers can dissociate and coexist with non-fusogenic forms of Env interpreting these results are difficult. Here, we used directed evolution to select for virions that display native Env with increased stability and homogeneity. HIV-1 virions were subjected to increasingly harsh treatments that destabilize Env trimers, and the variants that survived each treatment were expanded. We could identify seven different mutations in Env that increased its stability of function in the face of multiple destabilizing treatments. When these mutations were combined, the resulting mutant Env trimers were far more stable than the original Env protein. Incorporating trimer-stabilizing mutations into Env-based immunogens should facilitate vaccine research by mitigating the confounding effects of non-native byproducts of Env decay. A similar approach may be used on other pathogens with potential vaccine targets that are difficult to isolate and maintain in a native form.
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Affiliation(s)
- Daniel P. Leaman
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
| | - Michael B. Zwick
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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27
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Gao G, Wieczorek L, Peachman KK, Polonis VR, Alving CR, Rao M, Rao VB. Designing a soluble near full-length HIV-1 gp41 trimer. J Biol Chem 2012. [PMID: 23184960 DOI: 10.1074/jbc.m112.424432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The HIV-1 envelope spike is a trimer of heterodimers composed of an external glycoprotein gp120 and a transmembrane glycoprotein gp41. gp120 initiates virus entry by binding to host receptors, whereas gp41 mediates fusion between viral and host membranes. Although the basic pathway of HIV-1 entry has been extensively studied, the detailed mechanism is still poorly understood. Design of gp41 recombinants that mimic key intermediates is essential to elucidate the mechanism as well as to develop potent therapeutics and vaccines. Here, using molecular genetics and biochemical approaches, a series of hypotheses was tested to overcome the extreme hydrophobicity of HIV-1 gp41 and design a soluble near full-length gp41 trimer. The two long heptad repeat helices HR1 and HR2 of gp41 ectodomain were mutated to disrupt intramolecular HR1-HR2 interactions but not intermolecular HR1-HR1 interactions. This resulted in reduced aggregation and improved solubility. Attachment of a 27-amino acid foldon at the C terminus and slow refolding channeled gp41 into trimers. The trimers appear to be stabilized in a prehairpin-like structure, as evident from binding of a HR2 peptide to exposed HR1 grooves, lack of binding to hexa-helical bundle-specific NC-1 mAb, and inhibition of virus neutralization by broadly neutralizing antibodies 2F5 and 4E10. Fusion to T4 small outer capsid protein, Soc, allowed display of gp41 trimers on the phage nanoparticle. These approaches for the first time led to the design of a soluble gp41 trimer containing both the fusion peptide and the cytoplasmic domain, providing insights into the mechanism of entry and development of gp41-based HIV-1 vaccines.
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Affiliation(s)
- Guofen Gao
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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28
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Role of human immunodeficiency virus type 1 envelope structure in the induction of broadly neutralizing antibodies. J Virol 2012; 86:13152-63. [PMID: 23015715 DOI: 10.1128/jvi.01110-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Very soon after the discovery of neutralizing antibodies (NAbs) toward human immunodeficiency virus type 1 (HIV-1) infection, it became apparent that characterization of these NAbs would be an important step in finding a cure for or a vaccine to eradicate HIV-1. Since the initial description of broadly cross-clade NAbs naturally produced in HIV-1 patients, numerous studies have described new viral targets for these antibodies. More recently, studies concerning new groups of patients able to control their viremia, such as long-term nonprogressors (LTNPs) or elite controllers, have described the generation of numerous envelope-targeted NAbs. Recent studies have marked a new stage in research on NAbs with the description of antibodies obtained from a worldwide screening of HIV-positive patients. These studies have permitted the discovery of NAb families with great potential for both neutralization and neutralization breadth, such as PG, PGT, CH, and highly active agonistic anti-CD4 binding site antibodies (HAADs), of which VRC01 and its variants are members. These antibodies are able to neutralize more than 80% of circulating strains without any autoreactivity and can be rapidly integrated into clinical trials in order to test their protective potential. In this review, we will focus on new insights into HIV-1 envelope structure and their implications for the generation of potent NAbs.
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Design and characterization of a peptide mimotope of the HIV-1 gp120 bridging sheet. Int J Mol Sci 2012; 13:5674-5699. [PMID: 22754323 PMCID: PMC3382813 DOI: 10.3390/ijms13055674] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 04/26/2012] [Accepted: 05/02/2012] [Indexed: 01/02/2023] Open
Abstract
The Bridging Sheet domain of HIV-1 gp120 is highly conserved among the HIV-1 strains and allows HIV-1 binding to host cells via the HIV-1 coreceptors. Further, the bridging sheet domain is a major target to neutralize HIV-1 infection. We rationally designed four linear peptide epitopes that mimic the three-dimensional structure of bridging sheet by using molecular modeling. Chemically synthesized peptides BS3 and BS4 showed a fair degree of antigenicity when tested in ELISA with IgG purified from HIV(+) broadly neutralizing sera while the production of synthetic peptides BS1 and BS2 failed due to their high degree of hydrophobicity. To overcome this limitation, we linked all four BS peptides to the COOH-terminus of GST protein to test both their antigenicity and immunogenicity. Only the BS1 peptide showed good antigenicity; however, no envelope specific antibodies were elicited upon mice immunization. Therefore we performed further analyses by linking BS1 peptide to the NH2-terminus of the E2 scaffold from the Geobacillus Stearothermophylus PDH complex. The E2-BS1 fusion peptide showed good antigenic results, however only one immunized rabbit elicited good antibody titers towards both the monomeric and oligomeric viral envelope glycoprotein (Env). In addition, moderate neutralizing antibodies response was elicited against two HIV-1 clade B and one clade C primary isolates. These preliminary data validate the peptide mimotope approach as a promising tool to obtain an effective HIV-1 vaccine.
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30
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Delhalle S, Schmit JC, Chevigné A. Phages and HIV-1: from display to interplay. Int J Mol Sci 2012; 13:4727-4794. [PMID: 22606007 PMCID: PMC3344243 DOI: 10.3390/ijms13044727] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 03/26/2012] [Accepted: 03/30/2012] [Indexed: 11/16/2022] Open
Abstract
The complex hide-and-seek game between HIV-1 and the host immune system has impaired the development of an efficient vaccine. In addition, the high variability of the virus impedes the long-term control of viral replication by small antiviral drugs. For more than 20 years, phage display technology has been intensively used in the field of HIV-1 to explore the epitope landscape recognized by monoclonal and polyclonal HIV-1-specific antibodies, thereby providing precious data about immunodominant and neutralizing epitopes. In parallel, biopanning experiments with various combinatorial or antibody fragment libraries were conducted on viral targets as well as host receptors to identify HIV-1 inhibitors. Besides these applications, phage display technology has been applied to characterize the enzymatic specificity of the HIV-1 protease. Phage particles also represent valuable alternative carriers displaying various HIV-1 antigens to the immune system and eliciting antiviral responses. This review presents and summarizes the different studies conducted with regard to the nature of phage libraries, target display mode and biopanning procedures.
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Affiliation(s)
- Sylvie Delhalle
- Laboratory of Retrovirology, CRP-Sante, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg; E-Mails: (J.-C.S.); (A.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +352-26970211; Fax: +352-26970221
| | - Jean-Claude Schmit
- Laboratory of Retrovirology, CRP-Sante, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg; E-Mails: (J.-C.S.); (A.C.)
- Service National des Maladies Infectieuses, Centre Hospitalier Luxembourg, 4, rue E. Barblé, L-1210 Luxembourg, Luxembourg
| | - Andy Chevigné
- Laboratory of Retrovirology, CRP-Sante, 84, Val Fleuri, L-1526 Luxembourg, Luxembourg; E-Mails: (J.-C.S.); (A.C.)
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Binding of anti-membrane-proximal gp41 monoclonal antibodies to CD4-liganded and -unliganded human immunodeficiency virus type 1 and simian immunodeficiency virus virions. J Virol 2011; 86:1820-31. [PMID: 22090143 DOI: 10.1128/jvi.05489-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The broadly neutralizing monoclonal antibodies (MAbs) 4E10, 2F5, and Z13e1 target membrane-proximal external region (MPER) epitopes of HIV-1 gp41 in a manner that remains controversial. The requirements for initial lipid bilayer binding and/or CD4 ligation have been proposed. To further investigate these issues, we probed for binding of these MAbs to human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) virions with protein A-conjugated gold (PAG) nanoparticles using negative-stain electron microscopy. We found moderate levels of PAG associated with unliganded HIV-1 and SIV virions incubated with the three MAbs. Significantly higher levels of PAG were associated with CD4-liganded HIV-1 (epitope-positive) but not SIV (epitope-negative) virions. A chimeric SIV virion displaying the HIV-1 4E10 epitope also showed significantly higher PAG association after CD4 ligation and incubation with 4E10. MAbs accumulated rapidly on CD4-liganded virions and slowly on unliganded virions, although both reached similar levels in time. Anti-MPER epitope-specific binding was stable to washout. Virions incubated with an irrelevant MAb or CD4-only (no MAb) showed negligible PAG association, as did a vesicle-rich fraction devoid of virions. Preincubation with Fab 4E10 inhibited both specific and nonspecific 4E10 IgG binding. Our data provide evidence for moderate association of anti-MPER MAbs to viral surfaces but not lipid vesicles, even in the absence of cognate epitopes. Significantly greater MAb interaction occurs in epitope-positive virions following long incubation or CD4 ligation. These findings are consistent with a two-stage binding model where these anti-MPER MAbs bind first to the viral lipid bilayer and then to the MPER epitopes following spontaneous or induced exposure.
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32
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Mikell I, Sather DN, Kalams SA, Altfeld M, Alter G, Stamatatos L. Characteristics of the earliest cross-neutralizing antibody response to HIV-1. PLoS Pathog 2011; 7:e1001251. [PMID: 21249232 PMCID: PMC3020924 DOI: 10.1371/journal.ppat.1001251] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 12/08/2010] [Indexed: 12/24/2022] Open
Abstract
Recent cross-sectional analyses of HIV-1+ plasmas have indicated that broadly cross-reactive neutralizing antibody responses are developed by 10%-30% of HIV-1+ subjects. The timing of the initial development of such anti-viral responses is unknown. It is also unknown whether the emergence of these responses coincides with the appearance of antibody specificities to a single or multiple regions of the viral envelope glycoprotein (Env). Here we analyzed the cross-neutralizing antibody responses in longitudinal plasmas collected soon after and up to seven years after HIV-1 infection. We find that anti-HIV-1 cross-neutralizing antibody responses first become evident on average at 2.5 years and, in rare cases, as early as 1 year following infection. If cross-neutralizing antibody responses do not develop during the first 2-3 years of infection, they most likely will not do so subsequently. Our results indicate a potential link between the development of cross-neutralizing antibody responses and specific activation markers on T cells, and with plasma viremia levels. The earliest cross-neutralizing antibody response targets a limited number of Env regions, primarily the CD4-binding site and epitopes that are not present on monomeric Env, but on the virion-associated trimeric Env form. In contrast, the neutralizing activities of plasmas from subjects that did not develop cross-neutralizing antibody responses target epitopes on monomeric gp120 other than the CD4-BS. Our study provides information that is not only relevant to better understanding the interaction of the human immune system with HIV but may guide the development of effective immunization protocols. Since antibodies to complex epitopes that are present on the virion-associated envelope spike appear to be key components of earliest cross-neutralizing activities of HIV-1+ plasmas, then emphasis should be made to elicit similar antibodies by vaccination.
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Affiliation(s)
- Iliyana Mikell
- Seattle BioMed, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - D. Noah Sather
- Seattle BioMed, Seattle, Washington, United States of America
| | - Spyros A. Kalams
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Marcus Altfeld
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Boston, Massachusetts, United States of America
| | - Galit Alter
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Boston, Massachusetts, United States of America
| | - Leonidas Stamatatos
- Seattle BioMed, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Sabin C, Corti D, Buzon V, Seaman MS, Lutje Hulsik D, Hinz A, Vanzetta F, Agatic G, Silacci C, Mainetti L, Scarlatti G, Sallusto F, Weiss R, Lanzavecchia A, Weissenhorn W. Crystal structure and size-dependent neutralization properties of HK20, a human monoclonal antibody binding to the highly conserved heptad repeat 1 of gp41. PLoS Pathog 2010; 6:e1001195. [PMID: 21124990 PMCID: PMC2987821 DOI: 10.1371/journal.ppat.1001195] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 10/14/2010] [Indexed: 11/19/2022] Open
Abstract
The human monoclonal antibody (mAb) HK20 neutralizes a broad spectrum of primary HIV-1 isolates by targeting the highly conserved heptad repeat 1 (HR1) of gp41, which is transiently exposed during HIV-1 entry. Here we present the crystal structure of the HK20 Fab in complex with a gp41 mimetic 5-Helix at 2.3 Å resolution. HK20 employs its heavy chain CDR H2 and H3 loops to bind into a conserved hydrophobic HR1 pocket that is occupied by HR2 residues in the gp41 post fusion conformation. Compared to the previously described HR1-specific mAb D5, HK20 approaches its epitope with a different angle which might favor epitope access and thus contribute to its higher neutralization breadth and potency. Comparison of the neutralization activities of HK20 IgG, Fab and scFv employing both single cycle and multiple cycle neutralization assays revealed much higher potencies for the smaller Fab and scFv over IgG, implying that the target site is difficult to access for complete antibodies. Nevertheless, two thirds of sera from HIV-1 infected individuals contain significant titers of HK20-inhibiting antibodies. The breadth of neutralization of primary isolates across all clades, the higher potencies for C-clade viruses and the targeting of a distinct site as compared to the fusion inhibitor T-20 demonstrate the potential of HK20 scFv as a therapeutic tool.
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Affiliation(s)
- Charles Sabin
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - Davide Corti
- Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Victor Buzon
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - Mike S. Seaman
- Division of Viral Pathogenesis, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - David Lutje Hulsik
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | - Andreas Hinz
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, Grenoble, France
| | | | | | - Chiara Silacci
- Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Lara Mainetti
- Viral Evolution and Transmission Unit, Division of Immunology, Transplant and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Gabriella Scarlatti
- Viral Evolution and Transmission Unit, Division of Immunology, Transplant and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | | | - Robin Weiss
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Bellinzona, Switzerland
- Institute of Microbiology, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Winfried Weissenhorn
- Unit of Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, Grenoble, France
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Gustchina E, Li M, Louis JM, Anderson DE, Lloyd J, Frisch C, Bewley CA, Gustchina A, Wlodawer A, Clore GM. Structural basis of HIV-1 neutralization by affinity matured Fabs directed against the internal trimeric coiled-coil of gp41. PLoS Pathog 2010; 6:e1001182. [PMID: 21085615 PMCID: PMC2978731 DOI: 10.1371/journal.ppat.1001182] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 10/06/2010] [Indexed: 01/22/2023] Open
Abstract
The conserved internal trimeric coiled-coil of the N-heptad repeat (N-HR) of HIV-1 gp41 is transiently exposed during the fusion process by forming a pre-hairpin intermediate, thus representing an attractive target for the design of fusion inhibitors and neutralizing antibodies. In previous studies we reported a series of broadly neutralizing mini-antibodies derived from a synthetic naïve human combinatorial antibody library by panning against a mimetic of the trimeric N-HR coiled coil, followed by affinity maturation using targeted diversification of the CDR-H2 loop. Here we report crystal structures of the N-HR mimetic 5-Helix with two Fabs that represent the extremes of this series: Fab 8066 is broadly neutralizing across a wide panel of B and C type HIV-1 viruses, whereas Fab 8062 is non-neutralizing. The crystal structures reveal important differences in the conformations of the CDR-H2 loops in the complexes that propagate into other regions of the antigen-antibody interface, and suggest that both neutralization properties and affinity for the target can be attributed, at least in part, to the differences in the interactions of the CDR-H2 loops with the antigen. Furthermore, modeling of the complex of an N-HR trimer with three Fabs suggests that the CDR-H2 loop may be involved in close intermolecular contacts between neighboring antibody molecules, and that such contacts may hinder the formation of complexes between the N-HR trimer and more than one antibody molecule depending on the conformation of the bound CDR-H2 loop which is defined by its interactions with antigen. Comparison with the crystal structure of the complex of 5-Helix with another neutralizing monoclonal antibody known as D5, derived using an entirely different antibody library and panning procedure, reveals remarkable convergence in the optimal sequence and conformation of the CDR-H2 loop.
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Affiliation(s)
- Elena Gustchina
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mi Li
- Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
- Basic Research Program, SAIC-Frederick, Frederick, Maryland, United States of America
| | - John M. Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - D. Eric Anderson
- Proteomics and Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John Lloyd
- Proteomics and Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | | | - Carole A. Bewley
- Laboratory of Biorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alla Gustchina
- Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - Alexander Wlodawer
- Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - G. Marius Clore
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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Vaccination with peptide mimetics of the gp41 prehairpin fusion intermediate yields neutralizing antisera against HIV-1 isolates. Proc Natl Acad Sci U S A 2010; 107:10655-60. [PMID: 20483992 DOI: 10.1073/pnas.1004261107] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Eliciting a broadly neutralizing polyclonal antibody response against HIV-1 remains a major challenge. One approach to vaccine development is prevention of HIV-1 entry into cells by blocking the fusion of viral and cell membranes. More specifically, our goal is to elicit neutralizing antibodies that target a transient viral entry intermediate (the prehairpin intermediate) formed by the HIV-1 gp41 protein. Because this intermediate is transient, a stable mimetic is required to elicit an immune response. Previously, a series of engineered peptides was used to select a mAb (denoted D5) that binds to the surface of the gp41 prehairpin intermediate, as demonstrated by x-ray crystallographic studies. D5 inhibits the replication of HIV-1 clinical isolates, providing proof-of-principle for this vaccine approach. Here, we describe a series of peptide mimetics of the gp41 prehairpin intermediate designed to permit a systematic analysis of the immune response generated in animals. To improve the chances of detecting weak neutralizing polyclonal responses, two strategies were employed in the initial screening: use of a neutralization-hypersensitive virus and concentration of the IgG fraction from immunized animal sera. This allowed incremental improvements through iterative cycles of design, which led to vaccine candidates capable of generating a polyclonal antibody response, detectable in unfractionated sera, that neutralize tier 1 HIV-1 and simian HIV primary isolates in vitro. Our findings serve as a starting point for the design of more potent immunogens to elicit a broadly neutralizing response against the gp41 prehairpin intermediate.
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Leaman DP, Kinkead H, Zwick MB. In-solution virus capture assay helps deconstruct heterogeneous antibody recognition of human immunodeficiency virus type 1. J Virol 2010; 84:3382-95. [PMID: 20089658 PMCID: PMC2838137 DOI: 10.1128/jvi.02363-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/06/2010] [Indexed: 01/27/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) on whole virions is heterogeneous, so molecular analysis of Env with monoclonal antibodies (MAbs) is challenging. Virus capture assays (VCAs) involving immobilized MAbs are typically used, but these assays suffer from immobilization artifacts and do not provide binding constants. Furthermore, we show here that certain HIV-1 neutralizing MAbs, including 2G12, 4E10, 2F5, Z13e1, and D5, will capture virion particles completely devoid of Env. We modified the VCA such that MAbs and virions are incubated in solution, and unbound MAbs are removed prior to the capture step. This modification nearly eliminated evidence of Env-independent binding by MAbs to virions and allowed determination of apparent affinity constants in solution. Three important qualitative observations were further revealed. First, neutralizing MAbs 2F5, 4E10, and Z13e1 against the membrane-proximal external region (MPER) of HIV-1 gp41 were found to capture virions efficiently only if a significant amount of uncleaved gp160 or synthetic MPER peptide was present. Second, we show how non-native forms of Env vary by Env genotype and that Env from HIV-1(JR-FL) is more homogeneously trimeric than that from HIV-1(JR-CSF). Third, we determined that Env containing all or parts of gp41, including uncleaved gp160, binds spontaneously to free virions. This exogenous Env is an indiscriminate molecular "bridge" between Env-specific Ab and virions and can affect VCA analyses, particularly using pseudotyped virions. Heterogeneity in Env from endogenous and exogenous sources might also subvert humoral immunity to HIV-1, so in-solution VCAs may help to dissect this heterogeneity for vaccine design purposes.
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Affiliation(s)
- Daniel P. Leaman
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
| | - Heather Kinkead
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
| | - Michael B. Zwick
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037
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37
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Montgomery DL, Wang YJ, Hrin R, Luftig M, Su B, Miller MD, Wang F, Haytko P, Huang L, Vitelli S, Condra J, Liu X, Hampton R, Carfi A, Pessi A, Bianchi E, Joyce J, Lloyd C, Geleziunas R, Bramhill D, King VM, Finnefrock AC, Strohl W, An Z. Affinity maturation and characterization of a human monoclonal antibody against HIV-1 gp41. MAbs 2009; 1:462-74. [PMID: 20065653 DOI: 10.4161/mabs.1.5.9214] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The human D5 monoclonal antibody binds to the highly conserved hydrophobic pocket on the N-terminal heptad repeat (NHR) trimer of HIV-1 gp41 and exhibits modest yet relatively broad neutralization activity. Both binding and neutralization depend on residues in the complementarity determining regions (CDRs) of the D5 IgG variable domains on heavy chain (VH) and light chain (VL). In an effort to increase neutralization activity to a wider range of HIV-1 strains, we have affinity matured the parental D5 scFv by randomizing selected residues in 5 of its 6 CDRs. The resulting scFv variants derived from four different CDR changes showed enhanced binding affinities to gp41 NHR mimetic (5-helix) which correlated to improved neutralization potencies by up to 8-fold. However, when converted to IgG1s, these D5 variants had up to a 12-fold reduction in neutralization potency over their corresponding scFvs despite their slightly enhanced in vitro binding affinities. Remarkably, D5 variant IgG1s bearing residue changes in CDRs that interact with epitope residues N-terminal to the hydrophobic pocket (such as VH CDR3 and VL CDR3) retained more neutralization potency than those containing residue changes in pocket-interacting CDRs (such as VH CDR2). These results provide compelling evidence for the existence of a steric block to an IgG that extends to the gp41 NHR hydrophobic pocket region, and can be a useful guide for developing therapeutic antibodies and vaccines circumventing this block.
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Affiliation(s)
- Donna L Montgomery
- Department of Biologics Research, Merck Research Laboratories, West Point, PA, USA.
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38
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Gustchina E, Louis JM, Frisch C, Ylera F, Lechner A, Bewley CA, Clore GM. Affinity maturation by targeted diversification of the CDR-H2 loop of a monoclonal Fab derived from a synthetic naïve human antibody library and directed against the internal trimeric coiled-coil of gp41 yields a set of Fabs with improved HIV-1 neutralization potency and breadth. Virology 2009; 393:112-9. [PMID: 19695655 DOI: 10.1016/j.virol.2009.07.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Revised: 06/28/2009] [Accepted: 07/19/2009] [Indexed: 10/20/2022]
Abstract
Previously we reported a broadly HIV-1 neutralizing mini-antibody (Fab 3674) of modest potency that was derived from a human non-immune phage library by panning against the chimeric gp41-derived construct N(CCG)-gp41. This construct presents the N-heptad repeat of the gp41 ectodomain as a stable, helical, disulfide-linked trimer that extends in helical phase from the six-helix bundle of gp41. In this paper, Fab 3674 was subjected to affinity maturation against the N(CCG)-gp41 antigen by targeted diversification of the CDR-H2 loop to generate a panel of Fabs with diverse neutralization activity. Three affinity-matured Fabs selected for further study, Fabs 8060, 8066 and 8068, showed significant increases in both potency and breadth of neutralization against HIV-1 pseudotyped with envelopes of primary isolates from the standard subtype B and C HIV-1 reference panels. The parental Fab 3674 is 10-20-fold less potent in monovalent than bivalent format over the entire B and C panels of HIV-1 pseudotypes. Of note is that the improved neutralization activity of the affinity-matured Fabs relative to the parental Fab 3674 was, on average, significantly greater for the Fabs in monovalent than bivalent format. This suggests that the increased avidity of the Fabs for the target antigen in bivalent format can be partially offset by kinetic and/or steric advantages afforded by the smaller monovalent Fabs. Indeed, the best affinity-matured Fab (8066) in monovalent format ( approximately 50 kDa) was comparable in HIV-1 neutralization potency to the parental Fab 3674 in bivalent format ( approximately 120 kDa) across the subtype B and C reference panels.
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Affiliation(s)
- Elena Gustchina
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
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39
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Kang YK, Andjelic S, Binley JM, Crooks ET, Franti M, Iyer SPN, Donovan GP, Dey AK, Zhu P, Roux KH, Durso RJ, Parsons TF, Maddon PJ, Moore JP, Olson WC. Structural and immunogenicity studies of a cleaved, stabilized envelope trimer derived from subtype A HIV-1. Vaccine 2009; 27:5120-32. [PMID: 19567243 DOI: 10.1016/j.vaccine.2009.06.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 05/30/2009] [Accepted: 06/09/2009] [Indexed: 11/30/2022]
Abstract
SOSIP gp140 trimers represent a soluble, stabilized, proteolytically cleaved form of the HIV-1 envelope (Env) glycoproteins. SOSIP gp140 derived from a subtype A HIV-1 isolate, KNH1144, forms exceptionally stable trimers that resemble virion-associated Env in antigenicity and topology. Here, we used electron microscopy to demonstrate that KNH1144 SOSIP gp140 trimers bound three soluble CD4 molecules in a symmetrical orientation similar to that seen for native Env. We compared the immunogenicities of KNH1144 SOSIP gp140 trimers and gp120 monomers in rabbits and found that the trimers were superior at eliciting neutralizing antibodies (NAbs) to homologous virus as well as neutralization-sensitive subtype B and C viruses. The NAb specificities for SOSIP antisera mapped in part to the CD4 binding site on gp120. We also observed adjuvant-dependent induction of antibodies to the residual levels of host cell proteins (HCPs) contained in the purified Env preparations. When present, HCP antibodies enhanced pseudovirus infection. Our findings are relevant for the further development of Env-based vaccines for HIV-1.
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Affiliation(s)
- Yun Kenneth Kang
- Progenics Pharmaceuticals, Inc., Tarrytown, NY 10591, United States.
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40
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Walker LM, Bowley DR, Burton DR. Efficient recovery of high-affinity antibodies from a single-chain Fab yeast display library. J Mol Biol 2009; 389:365-75. [PMID: 19376130 DOI: 10.1016/j.jmb.2009.04.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 04/03/2009] [Accepted: 04/09/2009] [Indexed: 11/15/2022]
Abstract
Yeast display is a powerful technology for the isolation of monoclonal antibodies (mAbs) against a target antigen. Antibody libraries have been displayed on the surface of yeast as both single-chain variable fragment (scFv) and antigen binding fragment (Fab). Here, we combine these two formats to display well-characterized mAbs as single-chain Fabs (scFabs) on the surface of yeast and construct the first scFab yeast display antibody library. When expressed on the surface of yeast, two out of three anti-human immunodeficiency virus (HIV)-1 mAbs bound with higher affinity as scFabs than scFvs. Also, the soluble scFab preparations exhibited binding and neutralization profiles comparable to that of the corresponding Fab fragments. Display of an immune HIV-1 scFab library on the surface of yeast, followed by rounds of sorting against HIV-1 gp120, allowed for the selection of 13 antigen-specific clones. When the same cDNA was used to construct the library in an scFv format, a similar number but a lower affinity set of clones were selected. Based on these results, yeast-displayed scFab libraries can be constructed and selected with high efficiency, characterized without the need for a reformatting step, and used to isolate higher-affinity antibodies than scFv libraries.
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Affiliation(s)
- Laura M Walker
- Department of Immunology and Microbial Science and IAVI Neutralizing Antibody Center, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Yuan W, Li X, Kasterka M, Gorny MK, Zolla-Pazner S, Sodroski J. Oligomer-specific conformations of the human immunodeficiency virus (HIV-1) gp41 envelope glycoprotein ectodomain recognized by human monoclonal antibodies. AIDS Res Hum Retroviruses 2009; 25:319-28. [PMID: 19292593 DOI: 10.1089/aid.2008.0213] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Trimerization of the human immunodeficiency virus (HIV-1) envelope glycoproteins is mediated by the ectodomain of the gp41 transmembrane glycoprotein. Here we investigate oligomer-specific conformations of gp41 by using monoclonal antibodies (MAbs) from HIV-1-infected humans. Human MAbs directed against the cluster I region of gp41 recognized trimeric, dimeric, and monomeric forms of soluble envelope glycoproteins; thus, the integrity of the cluster I epitopes is minimally affected by the oligomeric state. In contrast, human MAbs to the cluster II region were all oligomers specific. One cluster II MAb, 126-6, recognized exclusively the trimeric form of envelope glycoproteins, whereas the others recognized both trimeric and dimeric forms. Thus, a distinct trimer-specific conformation exists in the cluster II region of gp41. Analysis of soluble envelope glycoprotein mutants revealed that gp41 sequences immediately N-terminal to isoleucine 646 contribute to the formation of both the trimer and the trimer-specific conformational epitope.
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Affiliation(s)
- Wen Yuan
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia 22908
- Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, Virginia 22908
| | - Xing Li
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115
- Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts 02115
| | - Marta Kasterka
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia 22908
| | - Miroslaw K. Gorny
- Department of Pathology, New York University School of Medicine, New York, New York 10016
| | - Susan Zolla-Pazner
- Department of Pathology, New York University School of Medicine, New York, New York 10016
- Veterans Affairs Medical Center, New York, New York 10010
| | - Joseph Sodroski
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115
- Department of Pathology, Division of AIDS, Harvard Medical School, Boston, Massachusetts 02115
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
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42
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Sequestering of the prehairpin intermediate of gp41 by peptide N36Mut(e,g) potentiates the human immunodeficiency virus type 1 neutralizing activity of monoclonal antibodies directed against the N-terminal helical repeat of gp41. J Virol 2008; 82:10032-41. [PMID: 18667502 DOI: 10.1128/jvi.01050-08] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) neutralization can be effected by several classes of inhibitors that target distinct regions of gp41 that are accessible in the prehairpin intermediate (PHI) state and block the formation of the six-helix bundle (6-HB) conformation of gp41. The N-heptad repeat (N-HR) of gp41 is the site of action of two classes of inhibitors. One class binds to the trimeric N-HR coiled coil, while the other, exemplified by the peptide N36(Mut(e,g)), disrupts the trimer and sequesters the PHI through the formation of heterotrimers. We recently reported a neutralizing Fab (Fab 3674), selected from a nonimmune phage library, that binds to the trimeric N-HR coiled coil through an epitope that remains exposed in the 6-HB and is also present in heterotrimers of the N-HR and N36(Mut(e,g)) peptide. Here we show that N36(Mut(e,g)) prolongs the temporal window during which the virus is susceptible to neutralization by the bivalent Fab 3674 and that bivalent Fab 3674 and N36(Mut(e,g)) neutralize HXB2 and SF162 strains of HIV-1, as well as isolates of diverse primary B and C HIV-1 strains, synergistically in a Env-pseudotyped virus neutralization assay. N36(Mut(e,g)) also rescues neutralizing activity of Fab 3674 against resistant virus strains and renders a series of related nonneutralizing Fabs neutralizing. Moreover, N36(Mut(e,g)) exhibits the same effects on the broadly neutralizing 2F5 and 4E10 monoclonal antibodies directed against the membrane-proximal extended region of gp41. The mechanistic implications of these findings are discussed.
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