scholarly journals Conformational States of a Soluble, Uncleaved HIV-1 Envelope Trimer

2017 ◽  
Vol 91 (10) ◽  
Author(s):  
Yuhang Liu ◽  
Junhua Pan ◽  
Yongfei Cai ◽  
Nikolaus Grigorieff ◽  
Stephen C. Harrison ◽  
...  
Keyword(s):  
Viral Entry ◽  
Clinical Studies ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Recombinant Form ◽  
Soluble Form ◽  
Compact Structure ◽  
Antigenic Properties ◽  
Hiv 1 ◽  
Gp140 Trimer

ABSTRACT The HIV-1 envelope spike [Env; trimeric (gp160)3 cleaved to (gp120/gp41)3] induces membrane fusion, leading to viral entry. It is also the viral component targeted by neutralizing antibodies. Vaccine development requires production, in quantities suitable for clinical studies, of a recombinant form that resembles functional Env. HIV-1 gp140 trimers—the uncleaved ectodomains of (gp160)3—from a few selected viral isolates adopt a compact conformation with many antigenic properties of native Env spikes. One is currently being evaluated in a clinical trial. We report here low-resolution (20 Å) electron cryomicroscopy (cryoEM) structures of this gp140 trimer, which adopts two principal conformations, one closed and the other slightly open. The former is indistinguishable at this resolution from those adopted by a stabilized, cleaved trimer (SOSIP) or by a membrane-bound Env trimer with a truncated cytoplasmic tail (EnvΔCT). The latter conformation is closer to a partially open Env trimer than to the fully open conformation induced by CD4. These results show that a stable, uncleaved HIV-1 gp140 trimer has a compact structure close to that of native Env. IMPORTANCE Development of any HIV vaccine with a protein component (for either priming or boosting) requires production of a recombinant form to mimic the trimeric, functional HIV-1 envelope spike in quantities suitable for clinical studies. Our understanding of the envelope structure has depended in part on a cleaved, soluble trimer, known as SOSIP.664, stabilized by several modifications, including an engineered disulfide. This construct, which is difficult to produce in large quantities, has yet to induce better antibody responses than those to other envelope-based immunogens, even in animal models. The uncleaved ectodomain of the envelope protein, called gp140, has also been made as a soluble form to mimic the native Env present on the virion surface. Most HIV-1 gp140 preparations are not stable, however, and have an inhomogeneous conformation. The results presented here show that gp140 preparations from suitable isolates can adopt a compact, native-like structure, supporting its use as a vaccine candidate.

scholarly journals Identification of HIV-1 Envelope Mutations that Enhance Entry Using Macaque CD4 and CCR5

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 241
Author(s):  
Jeremy I. Roop ◽  
Noah A. Cassidy ◽  
Adam S. Dingens ◽  
Jesse D. Bloom ◽  
Julie Overbaugh
Keyword(s):  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Bound States ◽  
Vaccine Development ◽  
Rhesus Macaques ◽  
Heptad Repeat ◽  
Design Strategies ◽  
Model Studies ◽  
Macaque Model ◽  
Hiv 1

Although Rhesus macaques are an important animal model for HIV-1 vaccine development research, most transmitted HIV-1 strains replicate poorly in macaque cells. A major genetic determinant of this species-specific restriction is a non-synonymous mutation in macaque CD4 that results in reduced HIV-1 Envelope (Env)-mediated viral entry compared to human CD4. Recent research efforts employing either laboratory evolution or structure-guided design strategies have uncovered several mutations in Env’s gp120 subunit that enhance binding of macaque CD4 by transmitted/founder HIV-1 viruses. In order to identify additional Env mutations that promote infection of macaque cells, we utilized deep mutational scanning to screen thousands of Env point mutants for those that enhance HIV-1 entry via macaque receptors. We identified many uncharacterized amino acid mutations in the N-terminal heptad repeat (NHR) and C-terminal heptad repeat (CHR) regions of gp41 that increased entry into cells bearing macaque receptors up to 9-fold. Many of these mutations also modestly increased infection of cells bearing human CD4 and CCR5 (up to 1.5-fold). NHR/CHR mutations identified by deep mutational scanning that enhanced entry also increased sensitivity to neutralizing antibodies targeting the MPER epitope, and to inactivation by cold-incubation, suggesting that they promote sampling of an intermediate trimer conformation between closed and receptor bound states. Identification of this set of mutations can inform future macaque model studies, and also further our understanding of the relationship between Env structure and function.

scholarly journals Comparable Antigenicity and Immunogenicity of Oligomeric Forms of a Novel, Acute HIV-1 Subtype C gp145 Envelope for Use in Preclinical and Clinical Vaccine Research

2015 ◽  
Vol 89 (15) ◽  
pp. 7478-7493 ◽  
Author(s):  
Lindsay Wieczorek ◽  
Shelly J. Krebs ◽  
Vaniambadi Kalyanaraman ◽  
Stephen Whitney ◽  
Sodsai Tovanabutra ◽  
...  
Keyword(s):  
Clinical Research ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Good Manufacturing Practice ◽  
Subtype C ◽  
Peripheral Blood Mononuclear ◽  
Antigenic Properties ◽  
Cell Assays ◽  
Env Protein ◽  
Hiv 1

ABSTRACTEliciting broadly reactive functional antibodies remains a challenge in human immunodeficiency virus type 1 (HIV-1) vaccine development that is complicated by variations in envelope (Env) subtype and structure. The majority of new global HIV-1 infections are subtype C, and novel antigenic properties have been described for subtype C Env proteins. Thus, an HIV-1 subtype C Env protein (CO6980v0c22) from an infected person in the acute phase (Fiebig stage I/II) was developed as a research reagent and candidate immunogen. The gp145 envelope is a novel immunogen with a fully intact membrane-proximal external region (MPER), extended by a polylysine tail. Soluble gp145 was enriched for trimers that yielded the expected “fan blade” motifs when visualized by cryoelectron microscopy. CO6980v0c22 gp145 reacts with the 4E10, PG9, PG16, and VRC01 HIV-1 neutralizing monoclonal antibodies (MAbs), as well as the V1/V2-specific PGT121, 697, 2158, and 2297 MAbs. Different gp145 oligomers were tested for immunogenicity in rabbits, and purified dimers, trimers, and larger multimers elicited similar levels of cross-subtype binding and neutralizing antibodies to tier 1 and some tier 2 viruses. Immunized rabbit sera did not neutralize the highly resistant CO6980v0c22 pseudovirus but did inhibit the homologous infectious molecular clone in a peripheral blood mononuclear cell (PBMC) assay. This Env is currently in good manufacturing practice (GMP) production to be made available for use as a clinical research tool and further evaluation as a candidate vaccine.IMPORTANCEAt present, the product pipeline for HIV vaccines is insufficient and is limited by inadequate capacity to produce large quantities of vaccine to standards required for human clinical trials. Such products are required to evaluate critical questions of vaccine formulation, route, dosing, and schedule, as well as to establish vaccine efficacy. The gp145 Env protein presented in this study forms physical trimers, binds to many of the well-characterized broad neutralizing MAbs that target conserved Env epitopes, and induce cross-subtype neutralizing antibodies as measured in both cell line and primary cell assays. This subtype C Env gp145 protein is currently undergoing good manufacturing practice production for use as a reagent for preclinical studies and for human clinical research. This product will serve as a reagent for comparative studies and may represent a next-generation candidate HIV immunogen.

scholarly journals Antigenicity-defined conformations of an extremely neutralization-resistant HIV-1 envelope spike

2017 ◽  
Vol 114 (17) ◽  
pp. 4477-4482 ◽  
Author(s):  
Yongfei Cai ◽  
Selen Karaca-Griffin ◽  
Jia Chen ◽  
Sai Tian ◽  
Nicholas Fredette ◽  
...  
Keyword(s):  
Sequence Variation ◽  
Vaccine Development ◽  
Antibody Responses ◽  
Antigenic Properties ◽  
Monomeric Gp120 ◽  
Small Set ◽  
Membrane Bound ◽  
Hiv 1 ◽  
Neutralizing Epitopes ◽  
Gp140 Trimer

The extraordinary genetic diversity of the HIV-1 envelope spike [Env; trimeric (gp160)3, cleaved to (gp120/gp41)3] poses challenges for vaccine development. Envs of different clinical isolates exhibit different sensitivities to antibody-mediated neutralization. Envs of difficult-to-neutralize viruses are thought to be more stable and conformationally homogeneous trimers than those of easy-to-neutralize viruses, thereby providing more effective concealment of conserved, functionally critical sites. In this study we have characterized the antigenic properties of an Env derived from one of the most neutralization-resistant HIV-1 isolates, CH120.6. Sequence variation at neutralizing epitopes does not fully account for its exceptional resistance to antibodies. The full-length, membrane-bound CH120.6 Env is indeed stable and conformationally homogeneous. Its antigenicity correlates closely with its neutralization sensitivity, and major changes in antigenicity upon CD4 engagement appear to be restricted to the coreceptor site. The CH120.6 gp140 trimer, the soluble and uncleaved ectodomain of (gp160)3, retains many antigenic properties of the intact Env, consistent with a conformation close to that of Env spikes on a virion, whereas its monomeric gp120 exposes many nonneutralizing or strain-specific epitopes. Thus, trimer organization and stability are important determinants not only for occluding many epitopes but also for conferring resistance to neutralization by all but a small set of antibodies. Env preparations derived from neutralization-resistant viruses may induce irrelevant antibody responses less frequently than do other Envs and may be excellent templates for developing soluble immunogens.

SARS-CoV-2 Biology Insights, Part IV.Antibody-Dependent Enhancement (ADE) and the tricky “Herd Immunity”: narrative review (Preprint)

2020 ◽  
Author(s):  
Laura Lafon-Hughes
Keyword(s):  
Viral Infection ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Whooping Cough ◽  
Common Knowledge ◽  
Herd Immunity ◽  
Life Quality ◽  
Host Cells ◽  
System P

BACKGROUND It is common knowledge that vaccination has improved our life quality and expectancy since it succeeded in achieving almost eradication of several diseases including chickenpox (varicella), diphtheria, hepatitis A and B, measles, meningococcal, mumps, pneumococcal, polio, rotavirus, rubella, tetanus and whooping cough (pertussis) Vaccination success is based on vaccine induction of neutralizing antibodies that help fight the infection (e.g. by a virus), preventing the disease. Conversely, Antibody-dependent enhancement (ADE) of a viral infection occurs when anti-viral antibodies facilitate viral entry into host cells and enhance viral infection in these cells. ADE has been previously studied in Dengue and HIV viruses and explains why a second infection with Dengue can be lethal. As already reviewed in Part I and Part II, SARS-Cov-2 shares with HIV not only 4 sequences in the Spike protein but also the capacity to attack the immune system. OBJECTIVE As HIV presents ADE, we wondered whether this was also the case regarding SARS-CoV-2. METHODS A literature review was done through Google. RESULTS SARS-CoV-2 presents ADE. As SARS, which does not have the 4 HIV-like inserts, has the same property, ADE would not be driven by the HIV-like spike sequences. CONCLUSIONS ADE can explain the failure of herd immunity-based strategies and will also probably hamper anti-SARS-CoV-2 vaccine development. As reviewed in Part I, there fortunately are promising therapeutic strategies for COVID-19, which should be further developed. In the meantime, complementary countermeasures to protect mainly the youth from this infection are presented to be discussed in Part V Viewpoint.

scholarly journals Broadly neutralizing antibodies and vaccine design against HIV-1 infection

2019 ◽  
Vol 14 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Qian Wang ◽  
Linqi Zhang
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Vaccine Design ◽  
Therapeutic Interventions ◽  
Type I ◽  
Broadly Neutralizing Antibodies ◽  
Dynamic Studies ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Remarkable Progress

AbstractRemarkable progress has been achieved for prophylactic and therapeutic interventions against human immunodeficiency virus type I (HIV-1) through antiretroviral therapy. However, vaccine development has remained challenging. Recent discoveries in broadly neutralizing monoclonal antibodies (bNAbs) has led to the development of multiple novel vaccine approaches for inducing bNAbs-like antibody response. Structural and dynamic studies revealed several vulnerable sites and states of the HIV-1 envelop glycoprotein (Env) during infection. Our review aims to highlight these discoveries and rejuvenate our endeavor in HIV-1 vaccine design and development.

scholarly journals Broad Neutralization of Viral Pathogens

2014 ◽  
Vol 70 (a1) ◽  
pp. C245-C245
Author(s):  
Ian Wilson
Keyword(s):  
Hepatitis C ◽  
Binding Site ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Functional Characterization ◽  
Antigenic Site ◽  
Soluble Form ◽  
Receptor Binding Site ◽  
Fusion Domain ◽  
Hiv 1

Influenza, Hepatitis C, and HIV-1 continue to constitute significant threats to global health. We have structurally and functionally characterized several potent, broadly neutralizing antibodies (bnAbs) against HIV-1, influenza and hepatitis C viruses. The surface antigens of these viruses are the main target of neutralizing antibodies. However, most antibodies are strain-specific and protect only against highly related strains within the same subtype. Recently, a number of antibodies have been identified that are much broader and neutralize across multiple subtypes and types of these viruses through binding to functionally conserved sites, such as the receptor binding site or the fusion domain. For example, co-crystal structures of bnAbs with influenza hemagglutinin (HA) identified highly conserved sites in the fusion domain (stem) and in the receptor binding site (head) as target for broad neutralization[1]. HCV is also genetically diverse, but some antibodies have potent neutralizing activity across most genotypes of the virus. One family of these antibodies targets a conserved antigenic site on the HCV E2 envelope glycoprotein that overlaps with the CD81 receptor-binding site[2]. For HIV-1, structural and functional characterization of different families of bnAbs have led to identification of novel epitopes on HIV-1 Env, many of which involve glycans. These glycan-dependent Abs have unique features that enable them to penetrate the glycan shield and bind complex epitopes that consist of sugars and underlying protein segments on gp120 on HIV-1 Env. Recent x-ray[3] and EM structures of a soluble form of HIV-1 Env have revealed that the epitopes are more extensive and complex than previously appreciated. This structural information is now being used to aid in structure-assisted vaccine design for HIV-1, HCV and for a more universal flu vaccine. IAW is supported by NIH grants AI100663, AI082362, AI84817, AI099275 and GM094586 and the Crucell Vaccine Institute.

scholarly journals Reverse Immunology Approach to Define a New HIV-gp41-Neutralizing Epitope

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Karim Dorgham ◽  
Nicolas Pietrancosta ◽  
Amel Affoune ◽  
Olivier Lucar ◽  
Tahar Bouceba ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Molecular Design ◽  
Docking Studies ◽  
Viral Envelope ◽  
Broadly Neutralizing Antibodies ◽  
Immunodeficiency Virus ◽  
Surface Envelope ◽  
Hiv 1

The design of immunogens susceptible to elicit potent and broadly neutralizing antibodies against the human immunodeficiency virus type 1 (HIV-1) remains a veritable challenge in the course of vaccine development. Viral envelope proteins adopt different conformational states during the entry process, allowing the presentation of transient neutralizing epitopes. We focused on the highly conserved 3S motif of gp41, which is exposed to the surface envelope in its trimeric prefusion state. Vaccination with a W614A-modified 3S peptide induces in animals neutralizing anti-HIV-1 antibodies among which we selected clone F8. We used F8 as bait to select for W614A-3S phage-peptide mimics. Binding and molecular docking studies revealed that F8 interacts similarly with W614A-3S and a Mim_F8-1 mimotope, despite their lack of sequence homology, suggesting structural mimicry. Finally, vaccination of mice with the purified Mim_F8-1 phage elicited HIV-1-neutralizing antibodies that bound to the cognate W614A-3S motif. Collectively, our findings provide new insights into the molecular design of immunogens to elicit antibodies with neutralizing properties.

scholarly journals Reducing V3 Antigenicity and Immunogenicity on Soluble, Native-Like HIV-1 Env SOSIP Trimers

2017 ◽  
Vol 91 (15) ◽  
Author(s):  
Rajesh P. Ringe ◽  
Gabriel Ozorowski ◽  
Kimmo Rantalainen ◽  
Weston B. Struwe ◽  
Katie Matthews ◽  
...  
Keyword(s):  
Animal Models ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Tier 2 ◽  
Present Generation ◽  
Coreceptor Binding ◽  
Tier 1 ◽  
Immunogen Design ◽  
V3 Region ◽  
Hiv 1

ABSTRACT Native-like trimers of the SOSIP design are being developed as immunogens in human immunodeficiency virus type 1 (HIV-1) vaccine development programs. These trimers display the epitopes for multiple broadly neutralizing antibodies (bNAbs) but can also expose binding sites for some types of nonneutralizing antibodies (non-NAbs). Among the latter are epitopes in the gp120 V3 region that are highly immunogenic when SOSIP trimers are evaluated in animal models. It is presently uncertain whether antibodies against V3 can interfere with the induction of NAbs, but there are good arguments in favor of suppressing such “off-target” immune responses. Accordingly, we have assessed how to minimize the exposure of V3 non-NAb epitopes and thereby reduce their immunogenicity by introducing N-glycans within the V3 region of BG505 SOSIP trimers. We found that inserting glycans at positions 306 and 314 (termed M1 and M7) markedly reduced V3 antigenicity while improving the presentation of trimer apex bNAb epitopes. Both added glycans were shown to be predominantly of the Man6GlcNAc2 form. The additional introduction of the E64K ground-state stabilizing substitution markedly reduced or ablated soluble CD4 (sCD4) induction of non-NAb epitopes in V3 and/or associated with the coreceptor binding site. When a V3 glycan- and E64K-modified trimer variant, BG505 SOSIP.664-E64K.M1M7, was tested in rabbits, V3 immunogenicity was eliminated while the autologous NAb response was unchanged. IMPORTANCE Trimeric proteins are being developed for future HIV-1 vaccine trials in humans, with the goal of eliciting broadly active neutralizing antibodies (NAbs) that are active against a wide variety of circulating strains. In animal models, the present generation of native-like trimer immunogens, exemplified by the BG505 SOSIP.664 construct, induces narrow-specificity antibodies against the neutralization-resistant (tier-2), sequence-matched virus and more broadly active antibodies against sequence-divergent atypically neutralization-sensitive (tier-1) viruses. A concern in the trimer immunogen design field has been whether the latter off-target antibodies might interfere with the induction of the more desired responses to tier-2 epitopes. Here, we have inserted two glycans into the dominant site for tier-1 NAbs, the gp120 V3 region, to block the induction of off-target antibodies. We characterized the new trimers, tested them as immunogens in rabbits, and found that the blocking glycans eliminated the induction of tier-1 NAbs to V3-epitopes.

scholarly journals Breadth of Neutralizing Antibodies Elicited by Stable, Homogeneous Clade A and Clade C HIV-1 gp140 Envelope Trimers in Guinea Pigs

2010 ◽  
Vol 84 (7) ◽  
pp. 3270-3279 ◽  
Author(s):  
Joseph P. Nkolola ◽  
Hanqin Peng ◽  
Ethan C. Settembre ◽  
Michael Freeman ◽  
Lauren E. Grandpre ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Neutralizing Antibodies ◽  
Recombinant Adenovirus ◽  
Neutralizing Antibody ◽  
Tier 2 ◽  
Antigenic Properties ◽  
Tier 1 ◽  
Clade C ◽  
Gp140 Envelope ◽  
Hiv 1

ABSTRACT The native envelope (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) is trimeric, and thus trimeric Env vaccine immunogens are currently being explored in preclinical immunogenicity studies. Key challenges have included the production and purification of biochemically homogeneous and stable trimers and the evaluation of these immunogens utilizing standardized virus panels for neutralization assays. Here we report the binding and neutralizing antibody (NAb) responses elicited by clade A (92UG037.8) and clade C (CZA97.012) Env gp140 trimer immunogens in guinea pigs. These trimers have been selected and engineered for optimal biochemical stability and have defined antigenic properties. Purified gp140 trimers with Ribi adjuvant elicited potent, cross-clade NAb responses against tier 1 viruses as well as detectable but low-titer NAb responses against select tier 2 viruses from clades A, B, and C. In particular, the clade C trimer elicited NAbs that neutralized 27%, 20%, and 47% of tier 2 viruses from clades A, B, and C, respectively. Heterologous DNA prime, protein boost as well as DNA prime, recombinant adenovirus boost regimens expressing these antigens, however, did not result in an increased magnitude or breadth of NAb responses in this system. These data demonstrate the immunogenicity of stable, homogeneous clade A and clade C gp140 trimers and exemplify the utility of standardized tier 1 and tier 2 virus panels for assessing the NAb responses of candidate HIV-1 Env immunogens.

scholarly journals Expression and Solubilization of Insect Cell-Based Rabies Virus Glycoprotein and Assessment of Its Immunogenicity and Protective Efficacy in Mice

2011 ◽  
Vol 18 (10) ◽  
pp. 1673-1679 ◽  
Author(s):  
R. Ramya ◽  
B. Mohana Subramanian ◽  
V. Sivakumar ◽  
R. L. Senthilkumar ◽  
K. R. S. Sambasiva Rao ◽  
...  
Keyword(s):  
Rabies Virus ◽  
Insect Cell ◽  
Neutralizing Antibodies ◽  
Subunit Vaccine ◽  
Vaccine Development ◽  
Protective Efficacy ◽  
Vector System ◽  
Soluble Form ◽  
Rabies Virus Glycoprotein ◽  
Virus Glycoprotein

ABSTRACTRabies is a fatal zoonotic disease of serious public health and economic significance worldwide. The rabies virus glycoprotein (RVG) has been the major target for subunit vaccine development, since it harbors domains responsible for induction of virus-neutralizing antibodies, infectivity, and neurovirulence. The glycoprotein (G) was cloned using the baculovirus expression vector system (BEVS) and expressed inSpodoptera frugiperda(Sf-9) cells. In order to obtain a soluble form of G suitable for experimentation in mice, 18 different combinations of buffers and detergents were evaluated for their ability to solubilize the insect cell membrane-associated G. The combination that involved 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) detergent in lysis buffer 1, formulated with Tris, NaCl, 10% dimethyl sulfoxide (DMSO), and EDTA, gave the highest yield of soluble G, as evidenced by the experimental data. Subsequently, several other parameters, such as the concentration of CHAPS and the duration and temperature of the treatment for the effective solubilization of G, were optimized. The CHAPS detergent, buffered at a concentration of 0.4% to 0.7% (wt/vol) at room temperature (23 to 25°C) for 30 min to 1 h using buffer 1, containing 10% DMSO, resulted in consistently high yields. The G solubilized using CHAPS detergent was found to be immunogenic when tested in mice, as evidenced by high virus-neutralizing antibody titers in sera and 100% protection upon virulent intracerebral challenge with the challenge virus standard (CVS) strain of rabies virus. The results of the mice study indicated that G solubilized with CHAPS detergent retained the immunologically relevant domains in the native conformation, thereby paving the way for producing a cell-free and efficacious subunit vaccine.

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