scholarly journals Structural basis of broad HIV neutralization by a vaccine-induced cow antibody

2020 ◽  
Vol 6 (22) ◽  
pp. eaba0468 ◽  
Author(s):  
Robyn L. Stanfield ◽  
Zachary T. Berndsen ◽  
Ruiqi Huang ◽  
Devin Sok ◽  
Gabrielle Warner ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Site Directed Mutagenesis ◽  
Structural Basis ◽  
Broadly Neutralizing Antibodies ◽  
Receptor Binding Site ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Small Footprint ◽  
Hiv Neutralization ◽  
Hiv Envelope

Potent broadly neutralizing antibodies (bnAbs) to HIV have been very challenging to elicit by vaccination in wild-type animals. Here, by x-ray crystallography, cryo–electron microscopy, and site-directed mutagenesis, we structurally and functionally elucidate the mode of binding of a potent bnAb (NC-Cow1) elicited in cows by immunization with the HIV envelope (Env) trimer BG505 SOSIP.664. The exceptionally long (60 residues) third complementarity-determining region of the heavy chain (CDR H3) of NC-Cow1 forms a mini domain (knob) on an extended stalk that navigates through the dense glycan shield on Env to target a small footprint on the gp120 CD4 receptor binding site with no contact of the other CDRs to the rest of the Env trimer. These findings illustrate, in molecular detail, how an unusual vaccine-induced cow bnAb to HIV Env can neutralize with high potency and breadth.

scholarly journals A glycoside analog of mammalian oligomannose formulated with a TLR4-stimulating adjuvant elicits HIV-1 cross-reactive antibodies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean-François Bruxelle ◽  
Tess Kirilenko ◽  
Nino Trattnig ◽  
Yiqiu Yang ◽  
Matteo Cattin ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Envelope Protein ◽  
Protein Sequence ◽  
Neutralizing Antibodies ◽  
Human Antibody ◽  
Broadly Neutralizing Antibodies ◽  
Specific Antibodies ◽  
Strong Binding ◽  
Hiv Envelope ◽  
Hiv 1

AbstractThe occurrence of oligomannose-specific broadly neutralizing antibodies (bnAbs) has spurred efforts to develop immunogens that can elicit similar antibodies. Here, we report on the antigenicity and immunogenicity of a CRM197-conjugate of a previously reported oligomannose mimetic. Oligomannose-specific bnAbs that are less dependent on interactions with the HIV envelope protein sequence showed strong binding to the glycoconjugates, with affinities approximating those reported for their cognate epitope. The glycoconjugate is also recognized by inferred germline precursors of oligomannose-specific bnAbs, albeit with the expected low avidity, supporting its potential as an immunogen. Immunization of human-antibody transgenic mice revealed that only a TLR4-stimulating adjuvant formulation resulted in antibodies able to bind a panel of recombinant HIV trimers. These antibodies bound at relatively modest levels, possibly explaining their inability to neutralize HIV infectivity. Nevertheless, these findings contribute further to understanding conditions for eliciting HIV-cross-reactive oligomannose-specific antibodies and inform on next steps for improving on the elicited response.

scholarly journals Virus-Like Particle Based Vaccines Elicit Neutralizing Antibodies against the HIV-1 Fusion Peptide

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 765
Author(s):  
Alemu Tekewe Mogus ◽  
Lihong Liu ◽  
Manxue Jia ◽  
Diane T. Ajayi ◽  
Kai Xu ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccination Strategy ◽  
Fusion Peptide ◽  
Linear Epitope ◽  
Broadly Neutralizing Antibodies ◽  
Virus Like Particle ◽  
Boost Immunization ◽  
Potential Vaccine ◽  
Hiv Envelope ◽  
Hiv 1

Broadly neutralizing antibodies (bnAbs) isolated from HIV-infected individuals delineate vulnerable sites on the HIV envelope glycoprotein that are potential vaccine targets. A linear epitope within the N-terminal region of the HIV-1 fusion peptide (FP8) is the primary target of VRC34.01, a bnAb that neutralizes ~50% of primary HIV isolates. FP8 has attracted attention as a potential HIV vaccine target because it is a simple linear epitope. Here, platform technologies based on RNA bacteriophage virus-like particles (VLPs) were used to develop multivalent vaccines targeting the FP8 epitope. Both recombinant MS2 VLPs displaying the FP8 peptide and Qβ VLPs displaying chemically conjugated FP8 peptide induced high titers of FP8-specific antibodies in mice. Moreover, a heterologous prime-boost-boost regimen employing the two FP8-VLP vaccines and native envelope trimer was the most effective approach for eliciting HIV-1 neutralizing antibodies. Given the potent immunogenicity of VLP-based vaccines, this vaccination strategy—inspired by bnAb-guided epitope mapping, VLP bioengineering, and prime-boost immunization approaches—may be a useful strategy for eliciting bnAb responses against HIV.

scholarly journals Structural basis for SARS-CoV-2 neutralizing antibodies with novel binding epitopes

PLoS Biology ◽  
2021 ◽  
Vol 19 (5) ◽  
pp. e3001209
Author(s):  
Dan Fu ◽  
Guangshun Zhang ◽  
Yuhui Wang ◽  
Zheng Zhang ◽  
Hengrui Hu ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Therapeutic Interventions ◽  
Structural Basis ◽  
Binding Motif ◽  
Global Public Health ◽  
Variable Regions ◽  
Treatment Groups ◽  
X Ray Crystallography ◽  
Antibody Discovery

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) threatens global public health and economy unprecedentedly, requiring accelerating development of prophylactic and therapeutic interventions. Molecular understanding of neutralizing antibodies (NAbs) would greatly help advance the development of monoclonal antibody (mAb) therapy, as well as the design of next generation recombinant vaccines. Here, we applied H2L2 transgenic mice encoding the human immunoglobulin variable regions, together with a state-of-the-art antibody discovery platform to immunize and isolate NAbs. From a large panel of isolated antibodies, 25 antibodies showed potent neutralizing activities at sub-nanomolar levels by engaging the spike receptor-binding domain (RBD). Importantly, one human NAb, termed PR1077, from the H2L2 platform and 2 humanized NAb, including PR953 and PR961, were further characterized and subjected for subsequent structural analysis. High-resolution X-ray crystallography structures unveiled novel epitopes on the receptor-binding motif (RBM) for PR1077 and PR953, which directly compete with human angiotensin-converting enzyme 2 (hACE2) for binding, and a novel non-blocking epitope on the neighboring site near RBM for PR961. Moreover, we further tested the antiviral efficiency of PR1077 in the Ad5-hACE2 transduction mouse model of COVID-19. A single injection provided potent protection against SARS-CoV-2 infection in either prophylactic or treatment groups. Taken together, these results shed light on the development of mAb-related therapeutic interventions for COVID-19.

scholarly journals Networks of HIV-1 envelope glycans maintain antibody epitopes in the face of glycan additions and deletions

2020 ◽  
Author(s):  
Gemma E. Seabright ◽  
Christopher A. Cottrell ◽  
Marit J. van Gils ◽  
Alessio D’addabbo ◽  
David J. Harvey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutralizing Antibodies ◽  
Broadly Neutralizing Antibodies ◽  
Site Specific ◽  
Glycan Analysis ◽  
Cryo Electron Microscopy ◽  
Immunogen Design ◽  
The Face ◽  
Antibody Epitopes ◽  
Hiv 1

SUMMARYNumerous broadly neutralizing antibodies (bnAbs) have been identified that target the glycans of the HIV-1 envelope spike. Neutralization breadth is notable given that glycan processing can be substantially influenced by the presence or absence of neighboring glycans. Here, using a stabilized recombinant envelope trimer, we investigate the degree to which mutations in the glycan network surrounding an epitope impact the fine glycan processing of antibody targets. Using cryo-electron microscopy and site-specific glycan analysis, we reveal the hierarchy of importance of glycans in the formation of the 2G12 bnAb epitope, and show that the epitope is only subtly impacted by variations in the glycan network. In contrast, we show that the PG9 and PG16 glycan-based epitopes at the trimer apex are dependent on the presence of the highly conserved surrounding glycans. Glycan networks underpin the conservation of bnAb epitopes and are an important parameter in immunogen design.

scholarly journals Neutralizing antibodies induced in immunized macaques recognize the CD4-binding site on an occluded-open HIV-1 envelope trimer

2021 ◽  
Author(s):  
Zhi Yang ◽  
Kim-Marie A. Dam ◽  
Michael D. Bridges ◽  
Magnus A.G. Hoffmann ◽  
Andrew T. DeLaitsch ◽  
...  
Keyword(s):  
Binding Site ◽  
Neutralizing Antibodies ◽  
Resonance Spectroscopy ◽  
Broadly Neutralizing Antibodies ◽  
Receptor Binding Site ◽  
Double Electron ◽  
Immunogen Design ◽  
Cd4 Binding Site ◽  
Double Electron Electron Resonance ◽  
Hiv 1

Broadly-neutralizing antibodies (bNAbs) against HIV-1 Env can protect from infection. We characterized Ab1303 and Ab1573, neutralizing CD4-binding site (CD4bs) antibodies, isolated from sequentially-immunized macaques. Ab1303/Ab1573 binding was observed only when Env trimers were not constrained in the closed, prefusion conformation. Fab-Env cryo-EM structures showed that both antibodies recognized the CD4bs on Env trimer with an occluded-open conformation between closed, as targeted by bNAbs, and fully-open, as recognized by CD4. The occluded-open Env trimer conformation included outwardly-rotated gp120 subunits, but unlike CD4-bound Envs, did not exhibit V1V2 displacement, co-receptor binding site exposure, or a 4-stranded gp120 bridging sheet. Inter-protomer distances within trimers measured by double electron-electron resonance spectroscopy suggested an equilibrium between occluded-open and closed Env conformations, consistent with Ab1303/Ab1573 binding stabilizing an existing conformation. Studies of Ab1303/Ab1573 demonstrate that CD4bs neutralizing antibodies that bind open Env trimers can be raised by immunization, thereby informing immunogen design and antibody therapeutic efforts.

scholarly journals A Structural Update of Neutralizing Epitopes on the HIV Envelope, a Moving Target

Viruses ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1774
Author(s):  
Emma Parker Miller ◽  
Maxwell T. Finkelstein ◽  
Molly C. Erdman ◽  
Paul C. Seth ◽  
Daniela Fera
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Design ◽  
Moving Target ◽  
Resistance Mutations ◽  
Broadly Neutralizing Antibodies ◽  
Spike Analysis ◽  
Hiv Envelope ◽  
Structural Characterizations ◽  
Hiv 1 ◽  
Neutralizing Epitopes

Antibodies that can neutralize diverse HIV-1 strains develop in ~10–20% of HIV-1 infected individuals, and their elicitation is a goal of vaccine design. Such antibodies can also serve as therapeutics for those who have already been infected with the virus. Structural characterizations of broadly reactive antibodies in complex with the HIV-1 spike indicate that there are a limited number of sites of vulnerability on the spike. Analysis of their structures can help reveal commonalities that would be useful in vaccine design and provide insights on combinations of antibodies that can be used to minimize the incidence of viral resistance mutations. In this review, we give an update on recent structures determined of the spike in complex with broadly neutralizing antibodies in the context of all epitopes on the HIV-1 spike identified to date.

scholarly journals A glycoside analog of mammalian oligomannose formulated with a TLR4-stimulating adjuvant elicits HIV-1 cross-reactive antibodies

2021 ◽  
Author(s):  
Jean-Francois Bruxelle ◽  
Tess Kirilenko ◽  
Nino Trattnig ◽  
Yiqiu Yang ◽  
Matteo Cattin ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Envelope Protein ◽  
Protein Sequence ◽  
Neutralizing Antibodies ◽  
Human Antibody ◽  
Broadly Neutralizing Antibodies ◽  
Specific Antibodies ◽  
Strong Binding ◽  
Hiv Envelope ◽  
Hiv 1

Abstract The occurrence of oligomannose-specific broadly neutralizing antibodies (bnAbs) has spurred efforts to develop immunogens that can elicit similar antibodies. Here, we report on the antigenicity and immunogenicity of a CRM197-conjugate of a previously reported oligomannose mimetic. Oligomannose-specific bnAbs that are less dependent on interactions with the HIV envelope protein sequence showed strong binding to the glycoconjugates, with affinities approximating those reported for their cognate epitope. The glycoconjugate is also recognized by germline precursors of oligomannose-specific bnAbs, albeit with the expected low avidity, supporting its potential as an immunogen. Immunization of human-antibody transgenic mice revealed that only a TLR4-stimulating adjuvant formulation evoked antibodies able to bind a panel of recombinant HIV trimers. These antibodies bound at relatively modest levels, likely explaining their inability to neutralize HIV infectivity. Nevertheless, these findings contribute further to understanding conditions for eliciting HIV-cross-reactive oligomannose-specific antibodies and inform on next steps for improving on the elicited response.

scholarly journals Targeted isolation of panels of diverse human broadly neutralizing antibodies against SARS-like viruses

2021 ◽  
Author(s):  
Wan-ting He ◽  
Rami Musharrafieh ◽  
Ge Song ◽  
Katharina Dueker ◽  
Sean Callaghan ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Global Economy ◽  
Selection Strategy ◽  
Broadly Neutralizing Antibodies ◽  
Receptor Binding Site ◽  
Large Panel ◽  
Effective Design ◽  
Original Virus

SUMMARYThe emergence of current SARS-CoV-2 variants of concern (VOCs) and potential future spillovers of SARS-like coronaviruses into humans pose a major threat to human health and the global economy 1–7. Development of broadly effective coronavirus vaccines that can mitigate these threats is needed 8,9. Notably, several recent studies have revealed that vaccination of recovered COVID-19 donors results in enhanced nAb responses compared to SARS-CoV-2 infection or vaccination alone 10–13. Here, we utilized a targeted donor selection strategy to isolate a large panel of broadly neutralizing antibodies (bnAbs) to sarbecoviruses from two such donors. Many of the bnAbs are remarkably effective in neutralization against sarbecoviruses that use ACE2 for viral entry and also show strong binding to non-ACE2-using sarbecoviruses. The bnAbs are equally effective against SARS-CoV-2 VOCs compared to the original virus. Neutralization breadth is achieved by bnAb binding to epitopes on a relatively conserved face of the receptor binding domain (RBD) as opposed to strain-specific nAbs to the receptor binding site that are commonly elicited in SARS-CoV-2 infection and vaccination 14–18. The generation of a large panel of potent bnAbs provides new opportunities and choices for next-generation antibody prophylactic and therapeutic applications and, importantly, provides a basis for effective design of pan-sarbecovirus vaccines.

scholarly journals Nanobody cocktails potently neutralize SARS-CoV-2 D614G N501Y variant and protect mice

2021 ◽  
Vol 118 (19) ◽  
pp. e2101918118
Author(s):  
Phillip Pymm ◽  
Amy Adair ◽  
Li-Jin Chan ◽  
James P. Cooney ◽  
Francesca L. Mordant ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Human Populations ◽  
Wild Type ◽  
Angiotensin Converting Enzyme 2 ◽  
Viral Loads ◽  
X Ray Crystallography ◽  
Binding Domains ◽  
Cryo Electron Microscopy ◽  
Antigenic Sites ◽  
Human Receptor

Neutralizing antibodies are important for immunity against SARS-CoV-2 and as therapeutics for the prevention and treatment of COVID-19. Here, we identified high-affinity nanobodies from alpacas immunized with coronavirus spike and receptor-binding domains (RBD) that disrupted RBD engagement with the human receptor angiotensin-converting enzyme 2 (ACE2) and potently neutralized SARS-CoV-2. Epitope mapping, X-ray crystallography, and cryo-electron microscopy revealed two distinct antigenic sites and showed two neutralizing nanobodies from different epitope classes bound simultaneously to the spike trimer. Nanobody-Fc fusions of the four most potent nanobodies blocked ACE2 engagement with RBD variants present in human populations and potently neutralized both wild-type SARS-CoV-2 and the N501Y D614G variant at concentrations as low as 0.1 nM. Prophylactic administration of either single nanobody-Fc or as mixtures reduced viral loads by up to 104-fold in mice infected with the N501Y D614G SARS-CoV-2 virus. These results suggest a role for nanobody-Fc fusions as prophylactic agents against SARS-CoV-2.

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