scholarly journals Disassembly of HIV envelope glycoprotein trimer immunogens is driven by antibodies elicited via immunization

2021 ◽  
Author(s):  
Hannah L. Turner ◽  
Raiees Andrabi ◽  
Christopher A. Cottrell ◽  
Sara T. Richey ◽  
Ge Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Epitope Mapping ◽  
Antibody Responses ◽  
Viral Fusion ◽  
Protein Subunit ◽  
Subunit Vaccines ◽  
Hiv Envelope ◽  
Viral Surface

AbstractRationally designed protein subunit vaccines are being developed for a variety of viruses including influenza, RSV, SARS-CoV-2 and HIV. These vaccines are based on stabilized versions of the primary targets of neutralizing antibodies on the viral surface, namely viral fusion glycoproteins. While these immunogens display the epitopes of potent neutralizing antibodies, they also present epitopes recognized by non or weakly neutralizing (“off-target”) antibodies. Using our recently developed electron microscopy epitope mapping approach, we have uncovered a phenomenon wherein off-target antibodies elicited by HIV trimer subunit vaccines cause the otherwise highly stabilized trimeric proteins to degrade into cognate protomers. Further, we show that these protomers expose an expanded suite of off-target epitopes, normally occluded inside the prefusion conformation of trimer, that subsequently elicit further off-target antibody responses. Our study provides critical insights for further improvement of HIV subunit trimer vaccines for future rounds of the iterative vaccine design process.

scholarly journals Disassembly of HIV envelope glycoprotein trimer immunogens is driven by antibodies elicited via immunization

2021 ◽  
Vol 7 (31) ◽  
pp. eabh2791
Author(s):  
Hannah L. Turner ◽  
Raiees Andrabi ◽  
Christopher A. Cottrell ◽  
Sara T. Richey ◽  
Ge Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Epitope Mapping ◽  
Antibody Responses ◽  
Viral Fusion ◽  
Protein Subunit ◽  
Subunit Vaccines ◽  
Hiv Envelope ◽  
Viral Surface

Rationally designed protein subunit vaccines are being developed for a variety of viruses including influenza, RSV, SARS-CoV-2, and HIV. These vaccines are based on stabilized versions of the primary targets of neutralizing antibodies on the viral surface, namely, viral fusion glycoproteins. While these immunogens display the epitopes of potent neutralizing antibodies, they also present epitopes recognized by non-neutralizing or weakly neutralizing (“off-target”) antibodies. Using our recently developed electron microscopy polyclonal epitope mapping approach, we have uncovered a phenomenon wherein off-target antibodies elicited by HIV trimer subunit vaccines cause the otherwise highly stabilized trimeric proteins to degrade into cognate protomers. Further, we show that these protomers expose an expanded suite of off-target epitopes, normally occluded inside the prefusion conformation of trimer, that subsequently elicit further off-target antibody responses. Our study provides critical insights for further improvement of HIV subunit trimer vaccines for future rounds of the iterative vaccine design process.

scholarly journals Mapping polyclonal antibody responses in non-human primates vaccinated with HIV Env trimer subunit vaccines

2019 ◽  
Author(s):  
Bartek Nogal ◽  
Matteo Bianchi ◽  
Christopher A. Cottrell ◽  
Robert N. Kirchdoerfer ◽  
Leigh M. Sewall ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Humoral Response ◽  
Antibody Responses ◽  
Subunit Vaccines ◽  
Immunogen Design ◽  
Antibody Specificities ◽  
Hiv Envelope ◽  
High Degree ◽  
Protected Animal ◽  
Molecular Description

SUMMARYRational immunogen design aims to focus antibody responses to vulnerable sites on the primary antigens. Given the size of these antigens there is however potential for eliciting unwanted, off-target responses. Here, we used our electron microscopy polyclonal epitope mapping approach to describe the antibody specificities elicited by immunization of non-human primates with soluble HIV envelope trimers and subsequent repeated viral challenge. An increased diversity of epitopes recognized, and the approach angle by which these antibodies bound, constituted a hallmark of the humoral response in most protected animals. We also show that fusion peptide-specific antibodies are responsible for some neutralization breadth. Moreover, cryoEM analysis of a fully-protected animal revealed a high degree of clonality within a subset of putatively neutralizing antibodies, enabling a detailed molecular description of the antibody paratope. Our results provide important insights into the immune response against a vaccine candidate that entered into clinical trials earlier this year.

scholarly journals Dimerization of Dengue Virus E Subunits Impacts Antibody Function and Domain Focus

2020 ◽  
Vol 94 (18) ◽  
Author(s):  
Ashlie Thomas ◽  
Devina J. Thiono ◽  
Stephan T. Kudlacek ◽  
John Forsberg ◽  
Lakshmanane Premkumar ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Virus Vaccine ◽  
Neutralizing Antibodies ◽  
Quaternary Structure ◽  
Protein Structures ◽  
Protein Subunit ◽  
Subunit Vaccines ◽  
E Protein ◽  
Vaccine Antigens ◽  
Viral Surface

ABSTRACT Dengue virus (DENV) is responsible for the most prevalent and significant arthropod-borne viral infection of humans. The leading DENV vaccines are based on tetravalent live-attenuated virus platforms. In practice, it has been challenging to induce balanced and effective responses to each of the four DENV serotypes because of differences in the replication efficiency and immunogenicity of individual vaccine components. Unlike live vaccines, tetravalent DENV envelope (E) protein subunit vaccines are likely to stimulate balanced immune responses, because immunogenicity is replication independent. However, E protein subunit vaccines have historically performed poorly, in part because the antigens utilized were mainly monomers that did not display quaternary-structure epitopes found on E dimers and higher-order structures that form the viral envelope. In this study, we compared the immunogenicity of DENV2 E homodimers and DENV2 E monomers. The stabilized DENV2 homodimers, but not monomers, were efficiently recognized by virus-specific and flavivirus cross-reactive potently neutralizing antibodies that have been mapped to quaternary-structure epitopes displayed on the viral surface. In mice, the dimers stimulated 3-fold-higher levels of virus-specific neutralizing IgG that recognized epitopes different from those recognized by lower-level neutralizing antibodies induced by monomers. The dimer induced a stronger E domain I (EDI)- and EDII-targeted response, while the monomer antigens stimulated an EDIII epitope response and induced fusion loop epitope antibodies that are known to facilitate antibody-dependent enhancement (ADE). This study shows that DENV E subunit antigens that have been designed to mimic the structural organization of the viral surface are better vaccine antigens than E protein monomers. IMPORTANCE Dengue virus vaccine development is particularly challenging because vaccines have to provide protection against four different dengue virus stereotypes. The leading dengue virus vaccine candidates in clinical testing are all based on live-virus vaccine platforms and struggle to induce balanced immunity. Envelope subunit antigens have the potential to overcome these limitations but have historically performed poorly as vaccine antigens, because the versions tested previously were presented as monomers and not in their natural dimer configuration. This study shows that the authentic presentation of DENV2 E-based subunits has a strong impact on antibody responses, underscoring the importance of mimicking the complex protein structures that are found on DENV particle surfaces when designing subunit vaccines.

scholarly journals Biomaterials and oxygen join forces to shape the immune response and boost SARS-CoV-2 vaccines

2020 ◽  
Author(s):  
Thibault Colombani ◽  
Loek Eggermont ◽  
Zachary Rogers ◽  
Lindsay McKay ◽  
Laura Avena ◽  
...  
Keyword(s):  
Immune Response ◽  
Neutralizing Antibodies ◽  
High Titer ◽  
Full Potential ◽  
Protein Subunit ◽  
Subunit Vaccines ◽  
Health Crisis ◽  
Th2 Immune Response ◽  
Protective Antibodies ◽  
Advanced Biomaterials

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an unprecedented global health crisis, resulting in a critical need for effective vaccines that generate protective antibodies. Protein subunit vaccines represent a promising approach but often lack the immunogenicity required for strong immune stimulation. To overcome this challenge, we first demonstrate that advanced biomaterials boost effectiveness of SARS-CoV-2 protein subunit vaccines. Additionally, we report that oxygen is a powerful immunological co-adjuvant, a game-changer in the field for unlocking the full potential of vaccines. Mice immunized with oxygen-generating cryogel vaccines exhibited a robust and balanced Th1 and Th2 immune response, leading to sustained and high titer production of neutralizing antibodies against SARS-CoV-2. Our data indicate that this platform is a revolutionary technology with the potential to reinforce any vaccine.

scholarly journals HIV envelope tail truncation confers resistance to SERINC5 restriction

2021 ◽  
Vol 118 (21) ◽  
pp. e2101450118
Author(s):  
Tafhima Haider ◽  
Xenia Snetkov ◽  
Clare Jolly
Keyword(s):  
T Cells ◽  
Envelope Glycoprotein ◽  
Cytoplasmic Tail ◽  
Restriction Factor ◽  
Viral Fusion ◽  
Restriction Factors ◽  
Complete Resistance ◽  
Hiv Envelope ◽  
Hiv 1

SERINC5 is a potent lentiviral restriction factor that gets incorporated into nascent virions and inhibits viral fusion and infectivity. The envelope glycoprotein (Env) is a key determinant for SERINC restriction, but many aspects of this relationship remain incompletely understood, and the mechanism of SERINC5 restriction remains unresolved. Here, we have used mutants of HIV-1 and HIV-2 to show that truncation of the Env cytoplasmic tail (ΔCT) confers complete resistance of both viruses to SERINC5 and SERINC3 restriction. Critically, fusion of HIV-1 ΔCT virus was not inhibited by SERINC5 incorporation into virions, providing a mechanism to explain how EnvCT truncation allows escape from restriction. Neutralization and inhibitor assays showed ΔCT viruses have an altered Env conformation and fusion kinetics, suggesting that EnvCT truncation dysregulates the processivity of entry, in turn allowing Env to escape targeting by SERINC5. Furthermore, HIV-1 and HIV-2 ΔCT viruses were also resistant to IFITMs, another entry-targeting family of restriction factors. Notably, while the EnvCT is essential for Env incorporation into HIV-1 virions and spreading infection in T cells, HIV-2 does not require the EnvCT. Here, we reveal a mechanism by which human lentiviruses can evade two potent Env-targeting restriction factors but show key differences in the capacity of HIV-1 and HIV-2 to exploit this. Taken together, this study provides insights into the interplay between HIV and entry-targeting restriction factors, revealing viral plasticity toward mechanisms of escape and a key role for the long lentiviral EnvCT in regulating these processes.

scholarly journals Nanoparticle Vaccines for Inducing HIV-1 Neutralizing Antibodies

Vaccines ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 76 ◽  
Author(s):  
Mitch Brinkkemper ◽  
Kwinten Sliepen
Keyword(s):  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Critical Role ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Broadly Neutralizing Antibodies ◽  
Viral Membrane ◽  
Immunodeficiency Virus ◽  
Hiv 1

The enormous sequence diversity between human immunodeficiency virus type 1 (HIV-1) strains poses a major roadblock for generating a broadly protective vaccine. Many experimental HIV-1 vaccine efforts are therefore aimed at eliciting broadly neutralizing antibodies (bNAbs) that are capable of neutralizing the majority of circulating HIV-1 strains. The envelope glycoprotein (Env) trimer on the viral membrane is the sole target of bNAbs and the key component of vaccination approaches aimed at eliciting bNAbs. Multimeric presentation of Env on nanoparticles often plays a critical role in these strategies. Here, we will discuss the different aspects of nanoparticles in Env vaccination, including recent insights in immunological processes underlying their perceived advantages, the different nanoparticle platforms and the various immunogenicity studies that employed nanoparticles to improve (neutralizing) antibody responses against Env.

scholarly journals A Conformational Switch in Human Immunodeficiency Virus gp41 Revealed by the Structures of Overlapping Epitopes Recognized by Neutralizing Antibodies

2009 ◽  
Vol 83 (17) ◽  
pp. 8451-8462 ◽  
Author(s):  
Robert Pejchal ◽  
Johannes S. Gach ◽  
Florence M. Brunel ◽  
Rosa M. Cardoso ◽  
Robyn L. Stanfield ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Neutralizing Antibodies ◽  
Helical Structure ◽  
Viral Fusion ◽  
Fab Fragment ◽  
Conformational Switch ◽  
Immunodeficiency Virus ◽  
Hiv Envelope ◽  
Hiv 1

ABSTRACT The membrane-proximal external region (MPER) of the human immunodeficiency virus (HIV) envelope glycoprotein (gp41) is critical for viral fusion and infectivity and is the target of three of the five known broadly neutralizing HIV type 1 (HIV-1) antibodies, 2F5, Z13, and 4E10. Here, we report the crystal structure of the Fab fragment of Z13e1, an affinity-enhanced variant of monoclonal antibody Z13, in complex with a 12-residue peptide corresponding to the core epitope (W670NWFDITN677) at 1.8-Å resolution. The bound peptide adopts an S-shaped conformation composed of two tandem, perpendicular helical turns. This conformation differs strikingly from the α-helical structure adopted by an overlapping MPER peptide bound to 4E10. Z13e1 binds to an elbow in the MPER at the membrane interface, making relatively few interactions with conserved aromatics (Trp672 and Phe673) that are critical for 4E10 recognition. The comparison of the Z13e1 and 4E10 epitope structures reveals a conformational switch such that neutralization can occur by the recognition of the different conformations and faces of the largely amphipathic MPER. The Z13e1 structure provides significant new insights into the dynamic nature of the MPER, which likely is critical for membrane fusion, and it has significant implications for mechanisms of HIV-1 neutralization by MPER antibodies and for the design of HIV-1 immunogens.

scholarly journals Improved Elicitation of Neutralizing Antibodies against Primary Human Immunodeficiency Viruses by Soluble Stabilized Envelope Glycoprotein Trimers

2001 ◽  
Vol 75 (3) ◽  
pp. 1165-1171 ◽  
Author(s):  
Xinzhen Yang ◽  
Richard Wyatt ◽  
Joseph Sodroski
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Immunodeficiency Virus ◽  
Human Immunodeficiency Viruses ◽  
Functional Envelope ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus (HIV-1) envelope glycoprotein subunits, such as the gp120 exterior glycoprotein, typically elicit antibodies that neutralize T-cell-line-adapted (TCLA), but not primary, clinical isolates of HIV-1. Here we compare the immunogenicity of gp120 and soluble stabilized trimers, which were designed to resemble the functional envelope glycoprotein oligomers of primary and TCLA HIV-1 strains. For both primary and TCLA virus proteins, soluble stabilized trimers generated neutralizing antibody responses more efficiently than gp120 did. Trimers derived from a primary isolate elicited antibodies that neutralized primary and TCLA HIV-1 strains. By contrast, trimers derived from a TCLA isolate generated antibodies that neutralized only the homologous TCLA virus. Thus, soluble stabilized envelope glycoprotein trimers derived from primary HIV-1 isolates represent defined immunogens capable of eliciting neutralizing antibodies that are active against clinically relevant HIV-1 strains.

scholarly journals Structures of SARS-CoV-2 B.1.351 neutralizing antibodies provide insights into cocktail design against concerning variants

2021 ◽  
Author(s):  
Shuo Du ◽  
Pulan Liu ◽  
Zhiying Zhang ◽  
Tianhe Xiao ◽  
Ayijiang Yasimayi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibodies ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Antibody Responses ◽  
Spike Protein ◽  
Receptor Binding Domain ◽  
Humoral Antibody ◽  
Cryo Electron Microscopy ◽  
Antibody Cocktail

The spread of the SARS-CoV-2 variants could seriously dampen the global effort to tackle the COVID-19 pandemic. Recently, we investigated the humoral antibody responses of SARS-CoV-2 convalescent patients and vaccinees towards circulating variants, and identified a panel of monoclonal antibodies (mAbs) that could efficiently neutralize the B.1.351 (Beta) variant. Here we investigate how these mAbs target the B.1.351 spike protein using cryo-electron microscopy. In particular, we show that two superpotent mAbs, BD-812 and BD-836, have non-overlapping epitopes on the receptor-binding domain (RBD) of spike. Both block the interaction between RBD and the ACE2 receptor; and importantly, both remain fully efficacious towards the B.1.617.1 (Kappa) and B.1.617.2 (Delta) variants. The BD-812/BD-836 pair could thus serve as an ideal antibody cocktail against the SARS-CoV-2 VOCs.

scholarly journals Elicitation of potent serum neutralizing antibody responses in rabbits by immunization with an HIV-1 clade C trimeric Env derived from an Indian elite neutralizer

2020 ◽  
Author(s):  
Rajesh Kumar ◽  
Suprit Deshpande ◽  
Leigh M. Sewall ◽  
Gabriel Ozorowski ◽  
Christopher A. Cottrell ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Clade C ◽  
Immunogen Design ◽  
Env Protein ◽  
Immunogenic Properties ◽  
Hiv 1

AbstractEvaluating the structure-function relationship of viral envelope (Env) evolution and the development of broadly cross-neutralizing antibodies (bnAbs) in natural infection can inform rational immunogen design. In the present study, we examined the magnitude and specificity of autologous neutralizing antibodies induced in rabbits by a novel HIV-1 clade C Env protein (1PGE-THIVC) vis-à-vis those developed in an elite neutralizer from whom the env sequence was obtained that was used to prepare the soluble Env protein. The thermostable 1PGE-THIVC Env displayed a native like pre-fusion closed conformation in solution as determined by small angle X-ray scattering (SAXS) and negative stain electron microscopy (EM). This closed spike conformation of 1PGE-THIVC Env trimers was correlated with weak or undetectable binding of non-neutralizing monoclonal antibodies (mAbs) compared to neutralizing mAbs. Furthermore, 1PGE-THIVC SOSIP induced potent neutralizing antibodies in rabbits to autologous virus variants. The autologous neutralizing antibody specificity induced in rabbits by 1PGE-THIVC was mapped to the C3/V4 region (T362/P401) of viral Env. This observation agreed with electron microscopy polyclonal epitope mapping (EMPEM) of the Env trimer complexed with IgG Fab prepared from the immunized rabbit sera. While the specificity of antibodies elicited in rabbits associated with neutralizing autologous viruses were distinct to those developed in the elite neutralizer, EMPEM analysis demonstrated significant changes to Env conformations when incubated with polyclonal antibody sera from the elite neutralizer, suggesting these antibodies lead to the destabilization of Env trimers. Our study not only shows distinct mechanisms associated with potent neutralization of sequence matched and unmatched autologous viruses by antibodies induced in rabbits and in the elite neutralizer, but also highlights how neutralizing antibodies developed during the course of natural infection can impact viral Env conformations.Author SummaryThe interplay between circulating virus variants and broadly cross neutralizing polyclonal antibodies developed in a subset of elite neutralizers is widely believed to provide strategies for rational immunogen design. In the present study, we studied the structural, antigenic and immunogenic properties of a thermostable soluble trimeric protein with near native pre-fusion conformation prepared using the primary sequence of an HIV-1 clade C env isolated from the broadly cross neutralizing plasma of an elite neutralizer. This novel SOSIP Env trimer demonstrated comparable antigenic, structural and immunogenic properties that favoured several ongoing subunit vaccine design efforts. The novel clade C SOSIP induced polyclonal neutralizing antibody response developed in rabbits not only differed in its epitope specificity compared to that elicited in natural infection in presence of pool of viral quasispecies but also showed how they differ in their ability to influence Env structure and conformation. A better understanding of how vaccine-induced polyclonal neutralizing antibody responses compares to responses that developed in natural infection will improve our knowledge in designing better vaccine design strategies.

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