151
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Cavacini LA, Duval M, Robinson J, Posner MR. Interactions of human antibodies, epitope exposure, antibody binding and neutralization of primary isolate HIV-1 virions. AIDS 2002; 16:2409-17. [PMID: 12461414 DOI: 10.1097/00002030-200212060-00005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Development of an effective HIV vaccine has been limited because of the inherent structural properties of the HIV envelope on native virions and the failure of the immune system to respond in an effective manner. Identification of the interactions of human antibodies with virions resulting in neutralization will facilitate vaccine design. DESIGN Combinations of human monoclonal antibodies (hMAb) were studied for binding to and neutralization of primary isolate virions. METHODS Virion binding and neutralization were measured using primary isolate virions. RESULTS Antibodies and combinations of antibodies to epitopes exposed upon CD4 binding (CD4i) and V3 loop antibodies resulted in additive binding and neutralization of R5X4 virus. Antibodies did not bind to or neutralize R5 virus as well. The combination of V3 loop antibody with 2G12 resulted in enhanced neutralization and binding to the R5X4 isolate but not the R5 isolate. Preincubation of the R5X4 isolate with F240, a non-neutralizing anti-gp41 antibody, significantly enhanced binding and neutralization by CD4i hMAb and 2F5. F240 also enhanced the binding of 2F5 to the R5 isolate and the neutralization of the R5 isolate mediated by 2G12. CONCLUSIONS Neutralizing epitopes are obscured on intact primary isolate virions and are dynamically exposed upon ligand (CD4) interactions. Interestingly, a non-neutralizing antibody to gp41 also increased binding and neutralizing activity of some hMAb that poorly neutralized R5 virus. These data suggest that non-neutralizing epitopes may be appropriate targets for vaccine design and epitope exposure should be considered in the development of immunotherapeutic strategies for HIV.
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Affiliation(s)
- Lisa A Cavacini
- Division of Hematology-Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, BURL 556, Boston, MA 02215, USA
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152
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Allen TM, Kelleher AD, Zaunders J, Walker BD. STI and beyond: the prospects of boosting anti-HIV immune responses. Trends Immunol 2002; 23:456-60. [PMID: 12200068 DOI: 10.1016/s1471-4906(02)02297-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Twenty years into the HIV epidemic, highly active antiretroviral therapy (HAART) represents the only effective intervention to control HIV-1 disease progression. However, the prospect of life-long treatment with HAART is challenging given cumulative drug toxicities, difficulties with adherence to complicated regimens and the looming emergence of drug-resistant viruses. The challenges are even greater in resource-poor settings where costs and logistical problems with delivery represent formidable obstacles. Alternative approaches to long-term control of viral replication and disease progression are clearly needed.
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Affiliation(s)
- Todd M Allen
- Partners AIDS Research Center, Massachusetts General Hospital and Division of AIDS, Harvard Medical School, Boston, MA, USA.
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153
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Sanders RW, Vesanen M, Schuelke N, Master A, Schiffner L, Kalyanaraman R, Paluch M, Berkhout B, Maddon PJ, Olson WC, Lu M, Moore JP. Stabilization of the soluble, cleaved, trimeric form of the envelope glycoprotein complex of human immunodeficiency virus type 1. J Virol 2002; 76:8875-89. [PMID: 12163607 PMCID: PMC136973 DOI: 10.1128/jvi.76.17.8875-8889.2002] [Citation(s) in RCA: 361] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The envelope glycoprotein (Env) complex of human immunodeficiency virus type 1 has evolved a structure that is minimally immunogenic while retaining its natural function of receptor-mediated virus-cell fusion. The Env complex is trimeric; its six individual subunits (three gp120 and three gp41 subunits) are associated by relatively weak, noncovalent interactions. The induction of neutralizing antibodies after vaccination with individual Env subunits has proven very difficult, probably because they are inadequate mimics of the native complex. Our hypothesis is that a stable form of the Env complex, perhaps with additional modifications to rationally alter its antigenic structure, may be a better immunogen than the individual subunits. A soluble form of Env, SOS gp140, can be made that has gp120 stably linked to the gp41 ectodomain by an intermolecular disulfide bond. This protein is fully cleaved at the proteolysis site between gp120 and gp41. However, the gp41-gp41 interactions in SOS gp140 are too weak to maintain the protein in a trimeric configuration. Consequently, purified SOS gp140 is a monomer (N. Schülke, M. S. Vesanen, R. W. Sanders, P. Zhu, D. J. Anselma, A. R. Villa, P. W. H. I. Parren, J. M. Binley, K. H. Roux, P. J. Maddon, J. P. Moore, and W. C. Olson, J. Virol. 76:7760-7776, 2002). Here we describe modifications of SOS gp140 that increase its trimer stability. A variant SOS gp140, designated SOSIP gp140, contains an isoleucine-to-proline substitution at position 559 in the N-terminal heptad repeat region of gp41. This protein is fully cleaved, has favorable antigenic properties, and is predominantly trimeric. SOSIP gp140 trimers are noncovalently associated and can be partially purified by gel filtration chromatography. These gp140 trimers are dissociated into monomers by anionic detergents or heat but are relatively resistant to nonionic detergents, high salt concentrations, or exposure to a mildly acidic pH. SOSIP gp140 should be a useful reagent for structural and immunogenicity studies.
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Affiliation(s)
- Rogier W Sanders
- Department of Microbiology and Immunology, Weill Medical College, Cornell University, New York, New York 10021, USA
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154
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D'Souza MP, Allen MA, Johnston MI. HIV Vaccines: Biological and Clinical Considerations. Curr Infect Dis Rep 2002; 4:359-368. [PMID: 12126613 DOI: 10.1007/s11908-002-0029-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The discovery of an HIV-1 vaccine is a high priority. Recent advances in HIV vaccine development include an improved understanding about virus biology and structure, and the development of quantitative techniques that enable a detailed analysis of vaccine-induced immune responses in humans. The preclinical vaccine pipeline looks healthy, and a common feature of the new vaccine strategies is their ability to attenuate clinical disease rather than prevent HIV infection in nonhuman primates. Human clinical trials to evaluate the safety and immunogenicity of these vaccine candidates and strategies are being actively pursued.
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155
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Schülke N, Vesanen MS, Sanders RW, Zhu P, Lu M, Anselma DJ, Villa AR, Parren PWHI, Binley JM, Roux KH, Maddon PJ, Moore JP, Olson WC. Oligomeric and conformational properties of a proteolytically mature, disulfide-stabilized human immunodeficiency virus type 1 gp140 envelope glycoprotein. J Virol 2002; 76:7760-76. [PMID: 12097589 PMCID: PMC136400 DOI: 10.1128/jvi.76.15.7760-7776.2002] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We describe the further properties of a protein, designated SOS gp140, wherein the association of the gp120 and gp41 subunits of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein is stabilized by an intersubunit disulfide bond. HIV-1(JR-FL) SOS gp140, proteolytically uncleaved gp140 (gp140(UNC)), and gp120 were expressed in stably transfected Chinese hamster ovary cells and analyzed for antigenic and structural properties before and after purification. Compared with gp140(UNC), SOS gp140 reacted more strongly in surface plasmon resonance and radioimmunoprecipitation assays with the neutralizing monoclonal antibodies (MAbs) 2G12 (anti-gp120), 2F5 (anti-gp41), and 17b (to a CD4-induced epitope that overlaps the CCR5-binding site). In contrast, gp140(UNC) displayed the greater reactivity with nonneutralizing anti-gp120 and anti-gp41 MAbs. Immunoelectron microscopy studies suggested a model for SOS gp140 wherein the gp41 ectodomain (gp41(ECTO)) occludes the "nonneutralizing" face of gp120, consistent with the antigenic properties of this protein. We also report the application of Blue Native polyacrylamide gel electrophoresis (BN-PAGE), a high-resolution molecular sizing method, to the study of viral envelope proteins. BN-PAGE and other biophysical studies demonstrated that SOS gp140 was monomeric, whereas gp140(UNC) comprised a mixture of noncovalently associated and disulfide-linked dimers, trimers, and tetramers. The oligomeric and conformational properties of SOS gp140 and gp140(UNC) were largely unaffected by purification. An uncleaved gp140 protein containing the SOS cysteine mutations (SOS gp140(UNC)) was also oligomeric. Surprisingly, variable-loop-deleted SOS gp140 proteins were expressed (although not yet purified) as cleaved, noncovalently associated oligomers that were significantly more stable than the full-length protein. Overall, our findings have relevance for rational vaccine design.
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Affiliation(s)
- Norbert Schülke
- Progenics Pharmaceuticals Inc., Tarrytown, New York 10591, USA
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156
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Giannecchini S, Isola P, Sichi O, Matteucci D, Pistello M, Zaccaro L, Del Mauro D, Bendinelli M. AIDS vaccination studies using an ex vivo feline immunodeficiency virus model: failure to protect and possible enhancement of challenge infection by four cell-based vaccines prepared with autologous lymphoblasts. J Virol 2002; 76:6882-92. [PMID: 12072489 PMCID: PMC136316 DOI: 10.1128/jvi.76.14.6882-6892.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Immunogenicity and protective activity of four cell-based feline immunodeficiency virus (FIV) vaccines prepared with autologous lymphoblasts were investigated. One vaccine was composed of FIV-infected cells that were paraformaldehyde fixed at the peak of viral expression. The other vaccines were attempts to maximize the expression of protective epitopes that might become exposed as a result of virion binding to cells and essentially consisted of cells mildly fixed after saturation of their surface with adsorbed, internally inactivated FIV particles. The levels of FIV-specific lymphoproliferation exhibited by the vaccinees were comparable to the ones previously observed in vaccine-protected cats, but antibodies were largely directed to cell-derived constituents rather than to truly viral epitopes and had very poor FIV-neutralizing activity. Moreover, under one condition of testing, some vaccine sera enhanced FIV replication in vitro. As a further limit, the vaccines proved inefficient at priming animals for anamnestic immune responses. Two months after completion of primary immunization, the animals were challenged with a low dose of homologous ex vivo FIV. Collectively, 8 of 20 vaccinees developed infection versus one of nine animals mock immunized with fixed uninfected autologous lymphoblasts. After a boosting and rechallenge with a higher virus dose, all remaining animals became infected, thus confirming their lack of protection.
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MESH Headings
- AIDS Vaccines/administration & dosage
- AIDS Vaccines/immunology
- Acquired Immunodeficiency Syndrome/prevention & control
- Animals
- Antibodies, Viral/blood
- Antigens, Viral/immunology
- Cats
- Disease Models, Animal
- Feline Acquired Immunodeficiency Syndrome/prevention & control
- Female
- Immunization, Secondary
- Immunodeficiency Virus, Feline/immunology
- Immunodeficiency Virus, Feline/physiology
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/transplantation
- Leukocytes, Mononuclear/virology
- Lymphocyte Activation
- RNA, Viral/blood
- Transplantation, Autologous
- Vaccination
- Viral Vaccines/administration & dosage
- Viral Vaccines/immunology
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Affiliation(s)
- Simone Giannecchini
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Patrizia Isola
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Olimpia Sichi
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Donatella Matteucci
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Mauro Pistello
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Lucia Zaccaro
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Daniela Del Mauro
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
| | - Mauro Bendinelli
- Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy
- Corresponding author. Mailing address: Dipartimento di Biomedicina, Università di Pisa, Via San Zeno 37, I-56127 Pisa, Italy. Phone: 39-050-553562. Fax: 39-050-559455. E-mail:
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157
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Affiliation(s)
- L Stamatatos
- Seattle Biomedical Research Institute, Seattle, Washington, USA
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158
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Affiliation(s)
- A M Schultz
- International AIDS Vaccine Initiative, New York, New York, USA.
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159
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Yang X, Lee J, Mahony EM, Kwong PD, Wyatt R, Sodroski J. Highly stable trimers formed by human immunodeficiency virus type 1 envelope glycoproteins fused with the trimeric motif of T4 bacteriophage fibritin. J Virol 2002; 76:4634-42. [PMID: 11932429 PMCID: PMC155086 DOI: 10.1128/jvi.76.9.4634-4642.2002] [Citation(s) in RCA: 236] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) function as a trimer composed of three gp120 exterior glycoproteins and three gp41 transmembrane proteins. Soluble gp140 glycoproteins composed of the uncleaved ectodomains of gp120 and gp41 form unstable, heterogeneous oligomers, but soluble gp140 trimers can be stabilized by fusion with a C-terminal, trimeric GCN4 motif (X. Yang et al., J. Virol. 74:5716-5725, 2000). To understand the influence of the C-terminal trimerization domain on the properties of soluble HIV-1 envelope glycoprotein trimers, uncleaved, soluble gp140 glycoproteins were stabilized by fusion with another trimeric motif derived from T4 bacteriophage fibritin. The fibritin construct was more stable to heat and reducing conditions than the GCN4 construct. Both GCN4- and fibritin-stabilized soluble gp140 glycoproteins exhibited patterns of neutralizing and nonneutralizing antibody binding expected for the functional envelope glycoprotein spike. Of note, two potently neutralizing antibodies, immunoglobulin G1b12 and 2G12, exhibited the greatest recognition of the stabilized, soluble trimers, relative to recognition of the gp120 monomer. The observed similarities between the GCN4 and fibritin constructs indicate that the HIV-1 envelope glycoprotein ectodomains dictate many of the antigenic and structural features of these fusion proteins. The melting temperatures and ligand recognition properties of the GCN4- and fibritin-stabilized soluble gp140 glycoproteins suggest that these molecules assume conformations distinct from that of the fusion-active, six-helix bundle.
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Affiliation(s)
- Xinzhen Yang
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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160
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Liu J, Wang S, Hoxie JA, LaBranche CC, Lu M. Mutations that destabilize the gp41 core are determinants for stabilizing the simian immunodeficiency virus-CPmac envelope glycoprotein complex. J Biol Chem 2002; 277:12891-900. [PMID: 11830586 DOI: 10.1074/jbc.m110315200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human and simian immunodeficiency viruses (HIV and SIV) envelope glycoprotein consists of a trimer of two noncovalently and weakly associated subunits, gp120 and gp41. Upon binding of gp120 to cellular receptors, this labile native envelope complex undergoes conformational changes, resulting in a stable trimer-of-hairpins structure in gp41. Formation of the hairpin structure is thought to mediate membrane fusion by placing the viral and cellular membranes in close proximity. An in vitro-derived variant of SIVmac251, denoted CPmac, has acquired an unusually stable virion-associated gp120-gp41 complex. This unique phenotype is conferred by five amino acid substitutions in the gp41 ectodomain. Here we characterize the structural and physicochemical properties of the N40(L6)C38 model of the CPmac gp41 core. The 1.7-A resolution crystal structure of N40(L6)C38 is very similar to the six-helix bundle structure present in the parent SIVmac251 gp41. In both structures, three N40 peptides form a central three-stranded coiled coil, and three C38 peptides pack in an antiparallel orientation into hydrophobic grooves on the coiled-coil surface. Thermal unfolding studies show that the CPmac mutations destabilize the SIVmac251 six-helix bundle by 15 kJ/mol. Our results suggest that the formation of the gp41 trimer-of-hairpins structure is thermodynamically coupled to the conformational stability of the native envelope glycoprotein and raise the intriguing possibility that introduction of mutations to destabilize the six-helix bundle may lead to the stabilization of the trimeric gp120-gp41 complex. This study suggests a potential strategy for the production of stably folded envelope protein immunogens for HIV vaccine development.
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Affiliation(s)
- Jie Liu
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
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161
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Grundner C, Mirzabekov T, Sodroski J, Wyatt R. Solid-phase proteoliposomes containing human immunodeficiency virus envelope glycoproteins. J Virol 2002; 76:3511-21. [PMID: 11884575 PMCID: PMC136030 DOI: 10.1128/jvi.76.7.3511-3521.2002] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) exterior envelope glycoprotein gp120 mediates receptor binding and is the major target for neutralizing antibodies. A broadly neutralizing antibody response is likely to be a critical component of the immune response against HIV-1. Although antibodies against monomeric gp120 are readily elicited in immunized individuals, these antibodies are inefficient in neutralizing primary HIV-1 isolates. As a chronic pathogen, HIV-1 has evolved to avoid an optimal host response by a number of immune escape mechanisms. Monomeric gp120 that has dissociated from the functional trimer presents irrelevant epitopes that are not accessible on functional trimeric envelope glycoproteins. The resulting low level of antigenic cross-reactivity between monomeric gp120 and the functional spike may contribute to the inability of monomeric gp120 to elicit broadly neutralizing antibodies. Attempts to generate native, trimeric envelope glycoproteins as immunogens have been frustrated by both the lability of the gp120-gp41 interaction and the weak association between gp120 subunits. Here, we present solid-phase HIV-1 gp160DeltaCT (cytoplasmic tail-deleted) proteoliposomes (PLs) containing native, trimeric envelope glycoproteins in a physiologic membrane setting. We present data that indicate that the gp160DeltaCT glycoproteins on PLs are trimers and are recognized by several relevant conformational ligands in a manner similar to that for gp160DeltaCT oligomers expressed on the cell surface. The PLs represent a significant advance over present envelope glycoprotein formulations as candidate immunogens for HIV vaccine design and development.
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Affiliation(s)
- Christoph Grundner
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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162
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Abstract
Viral envelope glycoproteins promote viral infection by mediating the fusion of the viral membrane with the host-cell membrane. Structural and biochemical studies of two viral glycoproteins, influenza hemagglutinin and HIV-1 envelope protein, have led to a common model for viral entry. The fusion mechanism involves a transient conformational species that can be targeted by therapeutic strategies. This mechanism of infectivity is likely utilized by a wide variety of enveloped viruses for which similar therapeutic interventions should be possible.
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Affiliation(s)
- D M Eckert
- Howard Hughes Medical Institute, Whitehead Institute for Biomedical Research, Department of Biology, M.I.T., Cambridge, Massachusetts 02142, USA.
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163
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Binley JM, Sanders RW, Master A, Cayanan CS, Wiley CL, Schiffner L, Travis B, Kuhmann S, Burton DR, Hu SL, Olson WC, Moore JP. Enhancing the proteolytic maturation of human immunodeficiency virus type 1 envelope glycoproteins. J Virol 2002; 76:2606-16. [PMID: 11861826 PMCID: PMC135977 DOI: 10.1128/jvi.76.6.2606-2616.2002] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2001] [Accepted: 12/06/2001] [Indexed: 12/31/2022] Open
Abstract
In virus-infected cells, the envelope glycoprotein (Env) precursor, gp160, of human immunodeficiency virus type 1 is cleaved by cellular proteases into a fusion-competent gp120-gp41 heterodimer in which the two subunits are noncovalently associated. However, cleavage can be inefficient when recombinant Env is expressed at high levels, either as a full-length gp160 or as a soluble gp140 truncated immediately N-terminal to the transmembrane domain. We have explored several methods for obtaining fully cleaved Env for use as a vaccine antigen. We tested whether purified Env could be enzymatically digested with purified protease in vitro. Plasmin efficiently cleaved the Env precursor but also cut at a second site in gp120, most probably the V3 loop. In contrast, a soluble form of furin was specific for the gp120-gp41 cleavage site but cleaved inefficiently. Coexpression of Env with the full-length or soluble form of furin enhanced Env cleavage but also reduced Env expression. When the Env cleavage site (REKR) was mutated in order to see if its use by cellular proteases could be enhanced, several mutants were found to be processed more efficiently than the wild-type protein. The optimal cleavage site sequences were RRRRRR, RRRRKR, and RRRKKR. These mutations did not significantly alter the capacity of the Env protein to mediate fusion, so they have not radically perturbed Env structure. Furthermore, unlike that of wild-type Env, expression of the cleavage site mutants was not significantly reduced by furin coexpression. Coexpression of Env cleavage site mutants and furin is therefore a useful method for obtaining high-level expression of processed Env.
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Affiliation(s)
- James M Binley
- Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York 10021, USA.
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164
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Srivastava IK, Stamatatos L, Legg H, Kan E, Fong A, Coates SR, Leung L, Wininger M, Donnelly JJ, Ulmer JB, Barnett SW. Purification and characterization of oligomeric envelope glycoprotein from a primary R5 subtype B human immunodeficiency virus. J Virol 2002; 76:2835-47. [PMID: 11861851 PMCID: PMC135955 DOI: 10.1128/jvi.76.6.2835-2847.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human immunodeficiency virus (HIV) continues to be a major public health problem throughout the world, with high levels of mortality and morbidity associated with AIDS. Considerable efforts to develop an effective vaccine for HIV have been directed towards the generation of cellular, humoral, and mucosal immune responses. A major emphasis of our work has been toward the evaluation of oligomeric (o-gp140) forms of the HIV type 1 (HIV-1) envelope protein for their ability to induce neutralizing antibody responses. We have derived stable CHO cell lines expressing o-gp140 envelope protein from the primary non-syncytium-inducing (R5) subtype B strain HIV-1(US4). We have developed an efficient purification strategy to purify oligomers to near homogeneity. Using a combination of three detectors measuring intrinsic viscosity, light scattering, and refractive index, we calculated the molecular mass of the oligomer to be 474 kDa, consistent with either a trimer or a tetramer. The hydrodynamic radius (R(h)) of o-gp140 was determined to be 8.40 nm, compared with 5.07 nm for the monomer. The relatively smaller R(h) of the oligomer suggests that there are indeed differences between the foldings of o-gp140 and gp120. To assess the structural integrity of the purified trimers, we performed a detailed characterization of the glycosylation profile of o-gp140, its ability to bind soluble CD4, and also its ability to bind to a panel of monoclonal antibodies with known epitope specificities for the CD4 binding site, the CD4 inducible site, the V3 loop, and gp41. Immunogenicity studies with rabbits indicated that the purified o-gp140 protein was highly immunogenic and induced high-titer, high-avidity antibodies directed predominantly against conformational epitopes. These observations confirm the structural integrity of purified o-gp140 and its potential as a vaccine antigen.
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Affiliation(s)
- Indresh K Srivastava
- Department of Immunology and Infectious Diseases, Chiron Corporation, Emeryville, California 94608, USA.
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165
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Jin X, Ramanathan M, Barsoum S, Deschenes GR, Ba L, Binley J, Schiller D, Bauer DE, Chen DC, Hurley A, Gebuhrer L, El Habib R, Caudrelier P, Klein M, Zhang L, Ho DD, Markowitz M. Safety and immunogenicity of ALVAC vCP1452 and recombinant gp160 in newly human immunodeficiency virus type 1-infected patients treated with prolonged highly active antiretroviral therapy. J Virol 2002; 76:2206-16. [PMID: 11836398 PMCID: PMC135946 DOI: 10.1128/jvi.76.5.2206-2216.2002] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to boost immune responses in persons in whom highly active antiretroviral therapy (HAART) was initiated within 120 days of the onset of symptoms of newly acquired human immunodeficiency virus type 1 (HIV-1) infection, we administered vaccines containing a canarypox virus vector, vCP1452, with HIV-1 genes encoding multiple HIV-1 proteins, and recombinant gp160. Fifteen HIV-1-infected subjects who achieved sustained suppression of plasma viremia for at least 2 years were enrolled. While continuing antiretroviral therapy, each subject received at least four intramuscular injections of the vaccines on days 0, 30, 90, and 180. Adverse events were mild, with the most common being transient tenderness at the vCP1452 injection site. Of the 14 patients who completed vaccination, 13 had significant increases in anti-gp120 or anti-p24 antibody titers, and 9 had transient augmentation of their T-cell proliferation responses to gp160 and/or p24. HIV-1-specific CD8(+) T cells were quantified using an intracellular gamma interferon staining assay. Among 11 patients who had increased CD8(+) T-cell responses, seven had responses to more than one HIV-1 antigen. In summary, vaccination with vCP1452 and recombinant gp160 appears safe and immunogenic in newly HIV-1-infected patients on HAART.
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Affiliation(s)
- Xia Jin
- Aaron Diamond AIDS Research Center, The Rockefeller University, 455 1st Avenue, 7th Floor, New York, NY 10016, USA
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166
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Abstract
Clinical investigation in humans and experimental lentivirus infection in nonhuman primates have advanced our understanding of immune responses that control HIV-1 disease. Recently, immunization approaches in macaques have shown that the immune response can control viremia and improve clinical outcome. When such vaccine strategies are formulated to be similarly immunogenic in humans, they could form the basis for the development of candidate AIDS vaccines that would prevent infection, suppress progression to disease or reduce HIV-1 transmission in humans.
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Affiliation(s)
- J R Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 40 Convent Drive, Bethesda, MD 20892, USA.
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167
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Barnett SW, Lu S, Srivastava I, Cherpelis S, Gettie A, Blanchard J, Wang S, Mboudjeka I, Leung L, Lian Y, Fong A, Buckner C, Ly A, Hilt S, Ulmer J, Wild CT, Mascola JR, Stamatatos L. The ability of an oligomeric human immunodeficiency virus type 1 (HIV-1) envelope antigen to elicit neutralizing antibodies against primary HIV-1 isolates is improved following partial deletion of the second hypervariable region. J Virol 2001; 75:5526-40. [PMID: 11356960 PMCID: PMC114265 DOI: 10.1128/jvi.75.12.5526-5540.2001] [Citation(s) in RCA: 188] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Partial deletion of the second hypervariable region from the envelope of the primary-like SF162 virus increases the exposure of certain neutralization epitopes and renders the virus, SF162DeltaV2, highly susceptible to neutralization by clade B and non-clade B human immunodeficiency virus (HIV-positive) sera (L. Stamatatos and C. Cheng-Mayer, J. Virol. 78:7840-7845, 1998). This observation led us to propose that the modified, SF162DeltaV2-derived envelope may elicit higher titers of cross-reactive neutralizing antibodies than the unmodified SF162-derived envelope. To test this hypothesis, we immunized rabbits and rhesus macaques with the gp140 form of these two envelopes. In rabbits, both immunogens elicited similar titers of binding antibodies but the modified immunogen was more effective in eliciting neutralizing antibodies, not only against the SF162DeltaV2 and SF162 viruses but also against several heterologous primary HIV type 1 (HIV-1) isolates. In rhesus macaques both immunogens elicited potent binding antibodies, but again the modified immunogen was more effective in eliciting the generation of neutralizing antibodies against the SF162DeltaV2 and SF162 viruses. Antibodies capable of neutralizing several, but not all, heterologous primary HIV-1 isolates tested were elicited only in macaques immunized with the modified immunogen. The efficiency of neutralization of these heterologous isolates was lower than that recorded against the SF162 isolate. Our results strongly suggest that although soluble oligomeric envelope subunit vaccines may elicit neutralizing antibody responses against heterologous primary HIV-1 isolates, these responses will not be broad and potent unless specific modifications are introduced to increase the exposure of conserved neutralization epitopes.
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Affiliation(s)
- S W Barnett
- Chiron Corporation, Emeryville, California 94608-2916, USA
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