scholarly journals Highly Stable Trimers Formed by Human Immunodeficiency Virus Type 1 Envelope Glycoproteins Fused with the Trimeric Motif of T4 Bacteriophage Fibritin

2002 ◽  
Vol 76 (9) ◽  
pp. 4634-4642 ◽  
Author(s):  
Xinzhen Yang ◽  
Juliette Lee ◽  
Erin M. Mahony ◽  
Peter D. Kwong ◽  
Richard Wyatt ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Envelope Glycoproteins ◽  
Immunodeficiency Virus ◽  
T4 Bacteriophage ◽  
Hiv 1

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.

scholarly journals Stoichiometry of Antibody Neutralization of Human Immunodeficiency Virus Type 1

2005 ◽  
Vol 79 (6) ◽  
pp. 3500-3508 ◽  
Author(s):  
Xinzhen Yang ◽  
Svetla Kurteva ◽  
Sandra Lee ◽  
Joseph Sodroski
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Envelope Glycoproteins ◽  
Antibody Neutralization ◽  
Antibody Molecule ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus envelope glycoproteins function as trimers on the viral surface, where they are targeted by neutralizing antibodies. Different monoclonal antibodies neutralize human immunodeficiency virus type 1 (HIV-1) infectivity by binding to structurally and functionally distinct moieties on the envelope glycoprotein trimer. By measuring antibody neutralization of viruses with mixtures of neutralization-sensitive and neutralization-resistant envelope glycoproteins, we demonstrate that the HIV-1 envelope glycoprotein trimer is inactivated by the binding of a single antibody molecule. Virus neutralization requires essentially all of the functional trimers to be occupied by at least one antibody. This model applies to antibodies differing in neutralizing potency and to virus isolates with various neutralization sensitivities. Understanding these requirements for HIV-1 neutralization by antibodies will assist in establishing goals for an effective AIDS vaccine.

scholarly journals Characterization of Stable, Soluble Trimers Containing Complete Ectodomains of Human Immunodeficiency Virus Type 1 Envelope Glycoproteins

2000 ◽  
Vol 74 (12) ◽  
pp. 5716-5725 ◽  
Author(s):  
Xinzhen Yang ◽  
Michael Farzan ◽  
Richard Wyatt ◽  
Joseph Sodroski
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cleavage Site ◽  
Neutralizing Antibodies ◽  
Coiled Coil ◽  
Envelope Glycoproteins ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins function as a membrane-anchored trimer of three gp120 exterior glycoproteins and three gp41 transmembrane glycoproteins. Previously, we reported three approaches to stabilize soluble trimers containing parts of the gp41 ectodomains: addition of GCN4 trimeric helices, disruption of the cleavage site between gp120 and gp41, and introduction of cysteines in the gp41 coiled coil to form intersubunit disulfide bonds. Here, we applied similar approaches to stabilize soluble gp140 trimers including the complete gp120 and gp41 ectodomains. A combination of fusion with the GCN4 trimeric sequences and disruption of the gp120-gp41 cleavage site resulted in relatively homogeneous gp140 trimers with exceptional stability. The gp120 epitopes recognized by neutralizing antibodies are intact and exposed on these gp140 trimers. By contrast, the nonneutralizing antibody epitopes on the gp120 subunits of the soluble trimers are relatively occluded compared with those on monomeric gp120 preparations. This antigenic similarity to the functional HIV-1 envelope glycoproteins and the presence of the complete gp41 ectodomain should make the soluble gp140 trimers useful tools for structural and immunologic studies.

scholarly journals Enhancement of human immunodeficiency virus type 1 infection by antisera to peptides from the envelope glycoproteins gp120/gp41.

1991 ◽  
Vol 174 (6) ◽  
pp. 1557-1563 ◽  
Author(s):  
S B Jiang ◽  
K Lin ◽  
A R Neurath
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Neutralizing Antibodies ◽  
Rational Design ◽  
Envelope Glycoproteins ◽  
V3 Loop ◽  
Immunodeficiency Virus ◽  
Hiv 1

Human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins (gp120 and gp41) elicit virus-neutralizing antibodies (VNAB) and also antibodies enhancing HIV-1 infection (EAB). Several epitopes eliciting VNAB have been defined, the principal virus-neutralizing determinant being assigned to the V3 loop of gp120. To provide a background for a rational design of anti-HIV vaccines, it also appears important to define domains eliciting EAB. This was accomplished by screening antisera against synthetic peptides covering almost the entire sequence of gp120/gp41 for their enhancing effects on HIV-1 infection of MT-2 cells, a continuous T cell line. Many (16/30) of the antisera significantly enhanced HIV-1 in the presence of human complement. Antibodies to complement receptor type 2 (CR2) abrogated the antibody-mediated enhancement of HIV-1 infection. Antisera to V3 hypervariable loops of 21 distinct HIV-1 isolates were also tested for their enhancing effects on HIV-1IIIB infection. 11 of these sera contained VNAB and 10 enhanced HIV-1IIIB infection. All antisera with virus-enhancing activity contained antibodies crossreactive with the V3 loop of HIV-1IIIB, and the virus-enhancing activity increased with increasing serological crossreactivity. These results suggest that immunization with antigens encompassing V3 loops may elicit EAB rather than protective antibodies if epitopes on the immunogen and the predominant HIV-1 isolate infecting a population are insufficiently matched, i.e., crossreactive serologically but not at the level of virus neutralization.

scholarly journals Evaluating the Immunogenicity of a Disulfide-Stabilized, Cleaved, Trimeric Form of the Envelope Glycoprotein Complex of Human Immunodeficiency Virus Type 1

2005 ◽  
Vol 79 (14) ◽  
pp. 8812-8827 ◽  
Author(s):  
Simon Beddows ◽  
Norbert Schülke ◽  
Marc Kirschner ◽  
Kelly Barnes ◽  
Michael Franti ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Immunodeficiency Virus ◽  
Monomeric Gp120 ◽  
Membrane Bound ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) complex comprises three gp120 exterior glycoproteins each noncovalently linked to a gp41 transmembrane glycoprotein. Monomeric gp120 proteins can elicit antibodies capable of neutralizing atypically sensitive test viruses in vitro, but these antibodies are ineffective against representative primary isolates and the gp120 vaccines failed to provide protection against HIV-1 transmission in vivo. Alternative approaches to raising neutralizing antibodies are therefore being pursued. Here we report on the antibody responses generated in rabbits against a soluble, cleaved, trimeric form of HIV-1JR-FL Env. In this construct, the gp120 and gp41 moieties are covalently linked by an intermolecular disulfide bond (SOS gp140), and an I559P substitution has been added to stabilize gp41-gp41 interactions (SOSIP gp140). We investigated the value of DNA priming and compared the use of membrane-bound and soluble priming antigens and of repeat boosting with soluble and particulate protein antigen. Compared to monomeric gp120, SOSIP gp140 trimers elicited approximately threefold lower titers of anti-gp120 antibodies. Priming with DNA encoding a membrane-bound form of the SOS gp140 protein, followed by several immunizations with soluble SOSIP gp140 trimers, resulted in antibodies capable of neutralizing sensitive strains at high titers. A subset of these sera also neutralized, at lower titers, HIV-1JR-FL and some other primary isolates in pseudovirus and/or whole-virus assays. Neutralization of these viruses was immunoglobulin mediated and was predominantly caused by antibodies to gp120 epitopes, but not the V3 region.

scholarly journals Role of Matrix in an Early Postentry Step in the Human Immunodeficiency Virus Type 1 Life Cycle

1998 ◽  
Vol 72 (5) ◽  
pp. 4116-4126 ◽  
Author(s):  
Rosemary E. Kiernan ◽  
Akira Ono ◽  
George Englund ◽  
Eric O. Freed
Keyword(s):  
Human Immunodeficiency Virus ◽  
Life Cycle ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Viral Envelope ◽  
Envelope Glycoproteins ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The matrix protein of human immunodeficiency virus type 1 (HIV-1) has been reported to play a crucial role in the targeting of the Gag polyprotein precursor to the plasma membrane and in the incorporation of viral envelope glycoproteins into budding virions. In this report, we present evidence that mutation of a highly conserved Leu at matrix amino acid 20 blocks or markedly delays virus replication in a range of cell types, including T-cell lines, primary human peripheral blood mononuclear cells, and monocyte-derived macrophages. These mutations do not impair virus assembly and release, RNA encapsidation, or envelope glycoprotein incorporation into virions but rather cause significant defects in an early step in the virus life cycle, as measured by single-cycle infectivity assays and the analysis of viral DNA synthesis early postinfection. This infectivity defect is independent of the type of envelope glycoprotein carried on mutant virions; similar results are obtained in pseudotyping experiments using wild-type or truncated HIV-1 envelope glycoproteins, the amphotropic murine leukemia virus envelope, or the vesicular stomatitis G protein. Intriguingly, matrix residue 20 mutations also increase the apparent binding of Gag to membrane, accelerate the kinetics of Gag processing, and induce defects in endogenous reverse transcriptase activity without affecting virion density or morphology. These results help elucidate the function of matrix in HIV-1 replication.

scholarly journals Subunit Stoichiometry of Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Trimers during Virus Entry into Host Cells

2006 ◽  
Vol 80 (9) ◽  
pp. 4388-4395 ◽  
Author(s):  
Xinzhen Yang ◽  
Svetla Kurteva ◽  
Xinping Ren ◽  
Sandra Lee ◽  
Joseph Sodroski
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Virus Entry ◽  
Envelope Glycoproteins ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) function as a homotrimer of gp120/gp41 heterodimers to support virus entry. During the process of virus entry, an individual HIV-1 envelope glycoprotein trimer binds the cellular receptors CD4 and CCR5/CXCR4 and mediates the fusion of the viral and the target cellular membranes. By studying the function of heterotrimers between wild-type and nonfunctional mutant envelope glycoproteins, we found that two wild-type subunits within an envelope glycoprotein trimer are required to support virus entry. Complementation between HIV-1 envelope glycoprotein mutants defective in different functions to allow virus entry was not evident. These results assist our understanding of the mechanisms whereby the HIV-1 envelope glycoproteins mediate virus entry and membrane fusion and guide attempts to inhibit these processes.

scholarly journals Introduction of Exogenous Epitopes in the Variable Regions of the Human Immunodeficiency Virus Type 1 Envelope Glycoprotein: Effect on Viral Infectivity and the Neutralization Phenotype

2009 ◽  
Vol 83 (16) ◽  
pp. 7883-7893 ◽  
Author(s):  
Aaron Wallace ◽  
Leonidas Stamatatos
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Viral Envelope ◽  
Variable Regions ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT In this study we examined whether human immunodeficiency virus type 1 (HIV-1) is equally susceptible to neutralization by a given antibody when the epitope of this antibody is introduced at different positions within the viral envelope glycoprotein (Env). To this end, we introduced two exogenous “epitope tags” at different locations within three major Env regions in two distinct HIV-1 isolates. We examined how the introduction of the exogenous epitopes affects Env expression, Env incorporation into virions, Env fusogenic potential, and viral susceptibility to neutralization. Our data indicate that even within the same Env region, the exact positioning of the epitope impacts the susceptibility of the virus to neutralization by the antibody that binds to that epitope. Our data also indicate that even if the same epitope is introduced in the exact same position on two different Envs, its exposure and, as a result, the neutralization susceptibility of the virus, can be very different. In contrast to the findings of previous studies conducted with HIV-1 isolates other than those used here, but in agreement with results obtained with simian immunodeficiency virus, we observed that tagging of the fourth variable region of Env (V4) did not result in neutralization by the anti-tag antibodies. Our data indicate that epitopes in V4 are not properly exposed within the functional HIV-1 trimeric Env spike, suggesting that V4 may not be a good target for vaccine-elicited neutralizing antibodies.

scholarly journals Long-Acting BMS-378806 Analogues Stabilize the State-1 Conformation of the Human Immunodeficiency Virus Type 1 Envelope Glycoproteins

2020 ◽  
Vol 94 (10) ◽  
Author(s):  
Shitao Zou ◽  
Shijian Zhang ◽  
Althea Gaffney ◽  
Haitao Ding ◽  
Maolin Lu ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Immunodeficiency Virus ◽  
Long Acting ◽  
State 1 ◽  
Hiv 1

ABSTRACT During human immunodeficiency virus type 1 (HIV-1) entry into cells, the viral envelope glycoprotein (Env) trimer [(gp120/gp41)3] binds the receptors CD4 and CCR5 and fuses the viral and cell membranes. CD4 binding changes Env from a pretriggered (state-1) conformation to more open downstream conformations. BMS-378806 (here called BMS-806) blocks CD4-induced conformational changes in Env important for entry and is hypothesized to stabilize a state-1-like Env conformation, a key vaccine target. Here, we evaluated the effects of BMS-806 on the conformation of Env on the surface of cells and virus-like particles. BMS-806 strengthened the labile, noncovalent interaction of gp120 with the Env trimer, enhanced or maintained the binding of most broadly neutralizing antibodies, and decreased the binding of poorly neutralizing antibodies. Thus, in the presence of BMS-806, the cleaved Env on the surface of cells and virus-like particles exhibits an antigenic profile consistent with a state-1 conformation. We designed novel BMS-806 analogues that stabilized the Env conformation for several weeks after a single application. These long-acting BMS-806 analogues may facilitate enrichment of the metastable state-1 Env conformation for structural characterization and presentation to the immune system. IMPORTANCE The envelope glycoprotein (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) mediates the entry of the virus into host cells and is also the target for antibodies. During virus entry, Env needs to change shape. Env flexibility also contributes to the ability of HIV-1 to evade the host immune response; many shapes of Env raise antibodies that cannot recognize the functional Env and therefore do not block virus infection. We found that an HIV-1 entry inhibitor, BMS-806, stabilizes the functional shape of Env. We developed new variants of BMS-806 that stabilize Env in its natural state for long periods of time. The availability of such long-acting stabilizers of Env shape will allow the natural Env conformation to be characterized and tested for efficacy as a vaccine.

scholarly journals Transitions to and from the CD4-Bound Conformation Are Modulated by a Single-Residue Change in the Human Immunodeficiency Virus Type 1 gp120 Inner Domain

2009 ◽  
Vol 83 (17) ◽  
pp. 8364-8378 ◽  
Author(s):  
Aemro Kassa ◽  
Navid Madani ◽  
Arne Schön ◽  
Hillel Haim ◽  
Andrés Finzi ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Envelope Glycoprotein ◽  
Bound State ◽  
Single Amino Acid ◽  
Envelope Glycoproteins ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Binding to the primary receptor CD4 induces conformational changes in the human immunodeficiency virus type 1 (HIV-1) gp120 envelope glycoprotein that allow binding to the coreceptor (CCR5 or CXCR4) and ultimately trigger viral membrane-cell membrane fusion mediated by the gp41 transmembrane envelope glycoprotein. Here we report the derivation of an HIV-1 gp120 variant, H66N, that confers envelope glycoprotein resistance to temperature extremes. The H66N change decreases the spontaneous sampling of the CD4-bound conformation by the HIV-1 envelope glycoproteins, thus diminishing CD4-independent infection. The H66N change also stabilizes the HIV-1 envelope glycoprotein complex once the CD4-bound state is achieved, decreasing the probability of CD4-induced inactivation and revealing the enhancing effects of soluble CD4 binding on HIV-1 infection. In the CD4-bound conformation, the highly conserved histidine 66 is located between the receptor-binding and gp41-interactive surfaces of gp120. Thus, a single amino acid change in this strategically positioned gp120 inner domain residue influences the propensity of the HIV-1 envelope glycoproteins to negotiate conformational transitions to and from the CD4-bound state.

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