scholarly journals Systematic assessment of antiviral potency, breadth, and synergy of triple broadly neutralizing antibody combinations against Simian-Human Immunodeficiency Viruses

2020 ◽  
Author(s):  
Stella J Berendam ◽  
Tiffany M Styles ◽  
Papa K Morgan-Asiedu ◽  
DeAnna Tenney ◽  
Amit Kumar ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Neutralizing Antibodies ◽  
Passive Immunization ◽  
Neutralizing Antibody ◽  
Systematic Assessment ◽  
Effector Functions ◽  
Cd4 Binding Site ◽  
Human Immunodeficiency Viruses ◽  
Antiviral Activities

Daily burden and clinical toxicities associated with antiretroviral therapy (ART) emphasize the need for alternative strategies to induce long-term HIV remission upon ART cessation. Broadly neutralizing antibodies (bNAbs) can both neutralize free virions and mediate effector functions against infected cells and therefore represent a leading immunotherapeutic approach. To increase potency and breadth as well as to limit the development of resistant virus strains, it is likely that bNAbs will need to be administered in combination. It is therefore critical to identify bNAb combinations that can achieve robust polyfunctional antiviral activity against a high number of HIV strains. In this study, we systematically assessed the ability of single bNAbs and triple bNAb combinations to mediate robust polyfunctional antiviral activity against a large panel of cross-clade simian-human immunodeficiency viruses (SHIVs), commonly used as tools for validation of therapeutic strategies targeting the HIV envelope in nonhuman primate models. We demonstrate that most bNAbs are capable of mediating both neutralizing and non-neutralizing effector functions against cross-clade SHIVs, although the susceptibility to V3 glycan-specific bNAbs is highly strain-dependent. Moreover, we observe a strong correlation between the neutralization potencies and non-neutralizing effector functions of bNAbs against the transmitted/founder SHIV CH505. Finally, we identify several triple bNAb combinations comprised of CD4 binding site, V2-glycan, and gp120-gp41 interface targeting bNAbs that are capable of mediating, synergistic polyfunctional antiviral activities against multiple clade A, B, C, and D SHIVs. IMPORTANCE Optimal bNAb immunotherapeutics will need to mediate multiple antiviral functions against a broad range of HIV strains. Our systematic assessment of triple bNAb combinations against SHIVs will identify bNAbs with synergistic, polyfunctional antiviral activity that will inform the selection of candidate bNAbs for optimal combination designs. The identified combinations can be validated in vivo in future passive immunization studies using the SHIV challenge model.

scholarly journals An anti-SARS-CoV-2 non-neutralizing antibody with Fc-effector function defines a new NTD epitope and delays neuroinvasion and death in K18-hACE2 mice

2021 ◽  
Author(s):  
Guillaume Beaudoin-Bussières ◽  
Yaozong Chen ◽  
Irfan Ullah ◽  
Jérémie Prévost ◽  
William D. Tolbert ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Animal Models ◽  
Mouse Model ◽  
Transgenic Mouse ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Transgenic Mouse Model ◽  
Effector Function ◽  
Effector Functions

SummaryEmerging evidence in animal models indicate that both neutralizing activity and Fc- mediated effector functions of neutralizing antibodies contribute to protection against SARS-CoV-2. It is unclear if antibody effector functions alone could protect against SARS-CoV-2. Here we isolated CV3-13, a non-neutralizing antibody from a convalescent individual with potent Fc-mediated effector functions that targeted the N- terminal domain (NTD) of SARS-CoV-2 Spike. The cryo-EM structure of CV3-13 in complex with SAR-CoV-2 spike revealed that the antibody bound from a distinct angle of approach to a novel NTD epitope that partially overlapped with a frequently mutated NTD supersite in SARS-CoV-2 variants. While CV3-13 did not alter the replication dynamics of SARS-CoV-2 in a K18-hACE2 transgenic mouse model, an Fc-enhanced CV3-13 significantly delayed neuroinvasion and death in prophylactic settings. Thus, we demonstrate that efficient Fc-mediated effector functions can contribute to the in vivo efficacy of anti-SARS-CoV-2 monoclonal antibodies in the absence of neutralization.

scholarly journals Design and crystal structure of a native-like HIV-1 envelope trimer that engages multiple broadly neutralizing antibody precursors in vivo

2017 ◽  
Vol 214 (9) ◽  
pp. 2573-2590 ◽  
Author(s):  
Max Medina-Ramírez ◽  
Fernando Garces ◽  
Amelia Escolano ◽  
Patrick Skog ◽  
Steven W. de Taeye ◽  
...  
Keyword(s):  
Crystal Structure ◽  
B Cells ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Effective Vaccine ◽  
Major Advance ◽  
Cd4 Binding Site ◽  
Hiv 1

Induction of broadly neutralizing antibodies (bNAbs) by HIV-1 envelope glycoprotein immunogens would be a major advance toward an effective vaccine. A critical step in this process is the activation of naive B cells expressing germline (gl) antibody precursors that have the potential to evolve into bNAbs. Here, we reengineered the BG505 SOSIP.664 glycoprotein to engage gl precursors of bNAbs that target either the trimer apex or the CD4-binding site. The resulting BG505 SOSIP.v4.1-GT1 trimer binds multiple bNAb gl precursors in vitro. Immunization experiments in knock-in mice expressing gl-VRC01 or gl-PGT121 show that this trimer activates B cells in vivo, resulting in the secretion of specific antibodies into the sera. A crystal structure of the gl-targeting trimer at 3.2-Å resolution in complex with neutralizing antibodies 35O22 and 9H+109L reveals a native-like conformation and the successful incorporation of design features associated with binding of multiple gl-bNAb precursors.

scholarly journals The Fc-mediated effector functions of a potent SARS-CoV-2 neutralizing antibody, SC31, isolated from an early convalescent COVID-19 patient, are essential for the optimal therapeutic efficacy of the antibody

2020 ◽  
Author(s):  
Conrad E.Z. Chan ◽  
Shirley G.K. Seah ◽  
De Hoe Chye ◽  
Shane Massey ◽  
Maricela Torres ◽  
...  
Keyword(s):  
Viral Load ◽  
Therapeutic Efficacy ◽  
Neutralizing Antibodies ◽  
Inflammatory Responses ◽  
Systemic Disease ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Effector Functions ◽  
Igg1 Antibody

AbstractSARS-CoV-2-neutralizing antibodies are promising therapeutics for COVID-19. However, little is known about the mechanisms of action of these antibodies or their effective dosing windows. We report the discovery and development of SC31, a potent SARS-CoV-2 neutralizing IgG1 antibody, originally isolated from a convalescent patient at day 27 after the onset of symptoms. Neutralization occurs via a binding epitope that maps within the ACE2 interface of the SARS-CoV-2 Spike protein, conserved across all common circulating SARS-CoV-2 mutants. In SARS-CoV-2 infected K18-human ACE2 transgenic mice, SC31 demonstrated potent survival benefit by dramatically reducing viral load concomitant with attenuated pro-inflammatory responses linked to severe systemic disease, such as IL-6. Comparison with a Fc-null LALA variant of SC31 demonstrated that optimal therapeutic efficacy of SC31 requires intact Fc-mediated effector functions that can further induce an IFNγ-driven anti-viral immune response. Dose-dependent efficacy for SC31 was observed down to 5mg/kg when dosed before the activation of lung inflammatory responses. Importantly, despite FcγR binding, no evidence of antibody dependent enhancement was observed with the Fc-competent SC31 even at sub-therapeutic doses. Therapeutic efficacy was confirmed in SARS-CoV-2-infected hamsters, where SC31 again significantly reduced viral load, decreased lung lesions and inhibited progression to severe disease manifestations. This study underlines the potential for significant COVID-19 patient benefit for the SC31 antibody that justifies rapid advancement to the clinic, as well as highlighting the importance of appropriate mechanistic and functional studies during development.One Sentence SummaryAnti-SARS-CoV-2 IgG1 antibody SC31 controls infection in vivo by blocking SP:ACE2 binding and triggering a Fc-mediated anti-viral response.

scholarly journals Contribution to HIV Prevention and Treatment by Antibody-Mediated Effector Function and Advances in Broadly Neutralizing Antibody Delivery by Vectored Immunoprophylaxis

2021 ◽  
Vol 12 ◽  
Author(s):  
Meredith Phelps ◽  
Alejandro Benjamin Balazs
Keyword(s):  
Hiv Prevention ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Passive Transfer ◽  
Viral Envelope ◽  
Viral Clearance ◽  
Effector Functions ◽  
Transient Nature ◽  
Antibody Delivery

HIV-1 broadly neutralizing antibodies (bNAbs) targeting the viral envelope have shown significant promise in both HIV prevention and viral clearance, including pivotal results against sensitive strains in the recent Antibody Mediated Prevention (AMP) trial. Studies of bNAb passive transfer in infected patients have demonstrated transient reduction of viral load at high concentrations that rebounds as bNAb is cleared from circulation. While neutralization is a crucial component of therapeutic efficacy, numerous studies have demonstrated that bNAbs can also mediate effector functions, such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and antibody-dependent complement deposition (ADCD). These functions have been shown to contribute towards protection in several models of HIV acquisition and in viral clearance during chronic infection, however the role of target epitope in facilitating these functions, as well as the contribution of individual innate functions in protection and viral clearance remain areas of active investigation. Despite their potential, the transient nature of antibody passive transfer limits the widespread use of bNAbs. To overcome this, we and others have demonstrated vectored antibody delivery capable of yielding long-lasting expression of bNAbs in vivo. Two clinical trials have shown that adeno-associated virus (AAV) delivery of bNAbs is safe and capable of sustained bNAb expression for over 18 months following a single intramuscular administration. Here, we review key concepts of effector functions mediated by bNAbs against HIV infection and the potential for vectored immunoprophylaxis as a means of producing bNAbs in patients.

scholarly journals Validation of a Triplex Pharmacokinetic Assay for Simultaneous Quantitation of HIV-1 Broadly Neutralizing Antibodies PGT121, PGDM1400, and VRC07-523-LS

2021 ◽  
Vol 12 ◽  
Author(s):  
Martina S. Wesley ◽  
Kelvin T. Chiong ◽  
Kelly E. Seaton ◽  
Christine A. Arocena ◽  
Sheetal Sawant ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Broadly Neutralizing Antibodies ◽  
Testing Method ◽  
Cd4 Binding Site ◽  
Broadly Neutralizing Antibody ◽  
Effective Doses ◽  
Pharmacokinetic Assay ◽  
Hiv 1

The outcome of the recent Antibody Mediated Prevention (AMP) trials that tested infusion of the broadly neutralizing antibody (bnAb) VRC01 provides proof of concept for blocking infection from sensitive HIV-1 strains. These results also open up the possibility that triple combinations of bnAbs such as PGT121, PGDM1400, as well as long-lasting LS variants such as VRC07-523 LS, have immunoprophylactic potential. PGT121 and PGDM1400 target the HIV-1 V3 and V2 glycan regions of the gp120 envelope protein, respectively, while VRC07-523LS targets the HIV-1 CD4 binding site. These bnAbs demonstrate neutralization potency and complementary breadth of HIV-1 strain coverage. An important clinical trial outcome is the accurate measurement of in vivo concentrations of passively infused bnAbs to determine effective doses for therapy and/or prevention. Standardization and validation of this testing method is a key element for clinical studies as is the ability to simultaneously detect multiple bnAbs in a specific manner. Here we report the development of a sensitive, specific, accurate, and precise multiplexed microsphere-based assay that simultaneously quantifies the respective physiological concentrations of passively infused bnAbs in human serum to ultimately define the threshold needed for protection from HIV-1 infection.

scholarly journals Screening of potent neutralizing antibodies against SARS-CoV-2 using convalescent patients-derived phage-display libraries

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yongbing Pan ◽  
Jianhui Du ◽  
Jia Liu ◽  
Hai Wu ◽  
Fang Gui ◽  
...  
Keyword(s):  
Phage Display ◽  
Neutralizing Antibodies ◽  
Variable Region ◽  
Neutralizing Antibody ◽  
Chain Gene ◽  
Prophylactic Efficacy ◽  
Heavy Chains ◽  
Effective Interventions ◽  
Phage Display Libraries

AbstractAs the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to threaten public health worldwide, the development of effective interventions is urgently needed. Neutralizing antibodies (nAbs) have great potential for the prevention and treatment of SARS-CoV-2 infection. In this study, ten nAbs were isolated from two phage-display immune libraries constructed from the pooled PBMCs of eight COVID-19 convalescent patients. Eight of them, consisting of heavy chains encoded by the immunoglobulin heavy-chain gene-variable region (IGHV)3-66 or IGHV3-53 genes, recognized the same epitope on the receptor-binding domain (RBD), while the remaining two bound to different epitopes. Among the ten antibodies, 2B11 exhibited the highest affinity and neutralization potency against the original wild-type (WT) SARS-CoV-2 virus (KD = 4.76 nM for the S1 protein, IC50 = 6 ng/mL for pseudoviruses, and IC50 = 1 ng/mL for authentic viruses), and potent neutralizing ability against B.1.1.7 pseudoviruses. Furthermore, 1E10, targeting a distinct epitope on RBD, exhibited different neutralization efficiency against WT SARS-CoV-2 and its variants B.1.1.7, B.1.351, and P.1. The crystal structure of the 2B11–RBD complexes revealed that the epitope of 2B11 highly overlaps with the ACE2-binding site. The in vivo experiment of 2B11 using AdV5-hACE2-transduced mice showed encouraging therapeutic and prophylactic efficacy against SARS-CoV-2. Taken together, our results suggest that the highly potent SARS-CoV-2-neutralizing antibody, 2B11, could be used against the WT SARS-CoV-2 and B.1.1.7 variant, or in combination with a different epitope-targeted neutralizing antibody, such as 1E10, against SARS-CoV-2 variants.

scholarly journals Broadly Neutralizing Hemagglutinin Stalk-Specific Antibodies Induce Potent Phagocytosis of Immune Complexes by Neutrophils in an Fc-Dependent Manner

mBio ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
Caitlin E. Mullarkey ◽  
Mark J. Bailey ◽  
Diana A. Golubeva ◽  
Gene S. Tan ◽  
Raffael Nachbagauer ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Fc Receptor ◽  
Igg Antibodies ◽  
Specific Antibodies ◽  
Effector Functions ◽  
Iga Antibodies ◽  
Specific Igg ◽  
Optimal Protection ◽  
Specific Igg Antibodies

ABSTRACTBroadly neutralizing antibodies that recognize the conserved hemagglutinin (HA) stalk have emerged as exciting new biotherapeutic tools to combat seasonal and pandemic influenza viruses. Our general understanding of the mechanisms by which stalk-specific antibodies achieve protection is rapidly evolving. It has recently been demonstrated that broadly neutralizing HA stalk-specific IgG antibodies require Fc-Fcγ receptor (FcγR) interactions for optimal protectionin vivo. Here we examine the neutrophil effector functions induced by stalk-specific antibodies. As the most abundant subset of blood leukocytes, neutrophils represent a critical innate effector cell population and serve an instrumental role in orchestrating downstream adaptive responses to influenza virus infection. Yet, the interplay of HA stalk-specific IgG, Fc-FcγR engagement, and neutrophils has remained largely uncharacterized. Using anin vitroassay to detect the production of reactive oxygen species (ROS), we show that human and mouse monoclonal HA stalk-specific IgG antibodies are able to induce the production of ROS by neutrophils, while HA head-specific antibodies do not. Furthermore, our results indicate that the production of ROS is dependent on Fc receptor (FcR) engagement and phagocytosis. We went on to assess the ability of monoclonal HA stalk-specific IgA antibodies to induce ROS. Consistent with our findings for monoclonal IgGs, only HA stalk-specific IgA antibodies elicited ROS production by neutrophils. This induction is dependent on the engagement of FcαR1. Taken together, our findings describe a novel FcR-dependent effector function induced by HA stalk-specific IgG and IgA antibodies, and importantly, our studies shed light on the mechanisms by which HA stalk-specific antibodies achieve protection.IMPORTANCEThe present study provides evidence that broadly neutralizing HA stalk-specific antibodies induce downstream Fc-mediated neutrophil effector functions. In addition to their ability to neutralize, this class of antibodies has been shown to rely on Fc-Fc receptor interactions for optimal protectionin vivo. Curiously, neutralizing antibodies that bind the HA head domain do not require such interactions. Our findings build on these previous observations and provide a more complete picture of the relationship between stalk-specific antibodies and cells of the innate immune compartment. Furthermore, our data suggest that the ability of HA stalk-specific antibodies to mediate Fc-Fc receptor engagement is epitope dependent. Overall, this work will inform the rational design of improved influenza virus vaccines and therapeutics.

scholarly journals The Fc-mediated effector functions of a potent SARS-CoV-2 neutralizing antibody, SC31, isolated from an early convalescent COVID-19 patient, are essential for the optimal therapeutic efficacy of the antibody

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253487
Author(s):  
Conrad E. Z. Chan ◽  
Shirley G. K. Seah ◽  
De Hoe Chye ◽  
Shane Massey ◽  
Maricela Torres ◽  
...  
Keyword(s):  
Therapeutic Efficacy ◽  
Neutralizing Antibodies ◽  
Inflammatory Responses ◽  
Therapeutic Potential ◽  
Rhesus Macaques ◽  
Neutralizing Antibody ◽  
Effector Functions ◽  
Viral Loads ◽  
Therapeutic Doses ◽  
Dose Dependent

Although SARS-CoV-2-neutralizing antibodies are promising therapeutics against COVID-19, little is known about their mechanism(s) of action or effective dosing windows. We report the generation and development of SC31, a potent SARS-CoV-2 neutralizing antibody, isolated from a convalescent patient. Antibody-mediated neutralization occurs via an epitope within the receptor-binding domain of the SARS-CoV-2 Spike protein. SC31 exhibited potent anti-SARS-CoV-2 activities in multiple animal models. In SARS-CoV-2 infected K18-human ACE2 transgenic mice, treatment with SC31 greatly reduced viral loads and attenuated pro-inflammatory responses linked to the severity of COVID-19. Importantly, a comparison of the efficacies of SC31 and its Fc-null LALA variant revealed that the optimal therapeutic efficacy of SC31 requires Fc-mediated effector functions that promote IFNγ-driven anti-viral immune responses, in addition to its neutralization ability. A dose-dependent efficacy of SC31 was observed down to 5mg/kg when administered before viral-induced lung inflammatory responses. In addition, antibody-dependent enhancement was not observed even when infected mice were treated with SC31 at sub-therapeutic doses. In SARS-CoV-2-infected hamsters, SC31 treatment significantly prevented weight loss, reduced viral loads, and attenuated the histopathology of the lungs. In rhesus macaques, the therapeutic potential of SC31 was evidenced through the reduction of viral loads in both upper and lower respiratory tracts to undetectable levels. Together, the results of our preclinical studies demonstrated the therapeutic efficacy of SC31 in three different models and its potential as a COVID-19 therapeutic candidate.

scholarly journals Epitope specificity plays a critical role in regulating antibody-dependent cell-mediated cytotoxicity against influenza A virus

2016 ◽  
Vol 113 (42) ◽  
pp. 11931-11936 ◽  
Author(s):  
Wenqian He ◽  
Gene S. Tan ◽  
Caitlin E. Mullarkey ◽  
Amanda J. Lee ◽  
Mannie Man Wai Lam ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Neutralizing Antibodies ◽  
Influenza A ◽  
Critical Role ◽  
Host Cells ◽  
Viral Glycoprotein ◽  
Effector Functions ◽  
Dependent Cell

The generation of strain-specific neutralizing antibodies against influenza A virus is known to confer potent protection against homologous infections. The majority of these antibodies bind to the hemagglutinin (HA) head domain and function by blocking the receptor binding site, preventing infection of host cells. Recently, elicitation of broadly neutralizing antibodies which target the conserved HA stalk domain has become a promising “universal” influenza virus vaccine strategy. The ability of these antibodies to elicit Fc-dependent effector functions has emerged as an important mechanism through which protection is achieved in vivo. However, the way in which Fc-dependent effector functions are regulated by polyclonal influenza virus-binding antibody mixtures in vivo has never been defined. Here, we demonstrate that interactions among viral glycoprotein-binding antibodies of varying specificities regulate the magnitude of antibody-dependent cell-mediated cytotoxicity induction. We show that the mechanism responsible for this phenotype relies upon competition for binding to HA on the surface of infected cells and virus particles. Nonneutralizing antibodies were poor inducers and did not inhibit antibody-dependent cell-mediated cytotoxicity. Interestingly, anti-neuraminidase antibodies weakly induced antibody-dependent cell-mediated cytotoxicity and enhanced induction in the presence of HA stalk-binding antibodies in an additive manner. Our data demonstrate that antibody specificity plays an important role in the regulation of ADCC, and that cross-talk among antibodies of varying specificities determines the magnitude of Fc receptor-mediated effector functions.

scholarly journals Vaccines and Broadly Neutralizing Antibodies for HIV-1 Prevention

2020 ◽  
Vol 38 (1) ◽  
pp. 673-703 ◽  
Author(s):  
Kathryn E. Stephenson ◽  
Kshitij Wagh ◽  
Bette Korber ◽  
Dan H. Barouch
Keyword(s):  
Clinical Trials ◽  
Neutralizing Antibodies ◽  
Passive Immunization ◽  
Neutralizing Antibody ◽  
Broadly Neutralizing Antibodies ◽  
Aids Pandemic ◽  
Broadly Neutralizing Antibody ◽  
Early Phase Clinical Trials ◽  
Hiv 1 ◽  
Review Current

Development of improved approaches for HIV-1 prevention will likely be required for a durable end to the global AIDS pandemic. Recent advances in preclinical studies and early phase clinical trials offer renewed promise for immunologic strategies for blocking acquisition of HIV-1 infection. Clinical trials are currently underway to evaluate the efficacy of two vaccine candidates and a broadly neutralizing antibody (bNAb) to prevent HIV-1 infection in humans. However, the vast diversity of HIV-1 is a major challenge for both active and passive immunization. Here we review current immunologic strategies for HIV-1 prevention, with a focus on current and next-generation vaccines and bNAbs.

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