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Several ebolaviruses cause outbreaks of severe disease. Vaccines and monoclonal antibody cocktails are available to treat Ebola virus (EBOV) infections, but not Sudan virus (SUDV) or other ebolaviruses. Current cocktails contain antibodies that cross-react with the secreted soluble glycoprotein (sGP) that absorbs virus-neutralizing antibodies. By sorting memory B cells from EBOV infection survivors, we isolated two broadly reactive anti-GP monoclonal antibodies, 1C3 and 1C11, that potently neutralize, protect rodents from disease, and lack sGP cross-reactivity. Both antibodies recognize quaternary epitopes in trimeric ebolavirus GP. 1C11 bridges adjacent protomers via the fusion loop. 1C3 has a tripartite epitope in the center of the trimer apex. One 1C3 antigen-binding fragment anchors simultaneously to the three receptor-binding sites in the GP trimer, and separate 1C3 paratope regions interact differently with identical residues on the three protomers. A cocktail of both antibodies completely protected nonhuman primates from EBOV and SUDV infections, indicating their potential clinical value. [Display omitted] • Two survivor antibodies provide broad protection, without secreted sGP cross-reactivity • Cryo-EM structure reveals the quaternary epitopes of the antibodies • One, at the chalice center, simultaneously binds all three monomers in the GP trimer • The cocktail of two protects nonhuman primates from Ebola virus and Sudan virus infections Two broadly neutralizing, human survivor antibodies form a therapeutic cocktail that protects nonhuman primates from otherwise lethal Ebola virus and Sudan virus diseases. The cryo-EM structure illustrates mechanism of neutralization by recognition of quaternary epitopes at complementary sites. One antibody, 1C3, simultaneously blocks all three receptor-binding sites in the GP trimer. [ABSTRACT FROM AUTHOR]

Ebola virus (EBOV) remains a public health threat. We performed a longitudinal study of B cell responses to EBOV in four survivors of the 2014 West African outbreak. Infection induced lasting EBOV-specific immunoglobulin G (IgG) antibodies, but their subclass composition changed over time, with IgG1 persisting, IgG3 rapidly declining, and IgG4 appearing late. Striking changes occurred in the immunoglobulin repertoire, with massive recruitment of naive B cells that subsequently underwent hypermutation. We characterized a large panel of EBOV glycoprotein-specific monoclonal antibodies (mAbs). Only a small subset of mAbs that bound glycoprotein by ELISA recognized cell-surface glycoprotein. However, this subset contained all neutralizing mAbs. Several mAbs protected against EBOV disease in animals, including one mAb that targeted an epitope under evolutionary selection during the 2014 outbreak. Convergent antibody evolution was seen across multiple donors, particularly among VH3-13 neutralizing antibodies specific for the GP1 core. Our study provides a benchmark for assessing EBOV vaccine-induced immunity. • Ebola virus infection causes massive recruitment of naive B cells • Virus-specific antibodies continue to class-switch and mutate for months after acute infection • Protective antibodies can be neutralizing or non-neutralizing and can appear early • Convergent, protective antibody rearrangements are seen in multiple donors A longitudinal study of Ebola virus infection survivors maps out the antibody features that confer protection, with potential implications for vaccination. [ABSTRACT FROM AUTHOR]

Summary Protective vaccines elicit high-affinity, neutralizing antibodies by selection of somatically hypermutated B cell antigen receptors (BCR) on immune complexes (ICs). This implicates Fc-Fc receptor (FcR) interactions in affinity maturation, which, in turn, are determined by IgG subclass and Fc glycan composition within ICs. Trivalent influenza virus vaccination elicited regulation of anti-hemagglutinin (HA) IgG subclass and Fc glycans, with abundance of sialylated Fc glycans (sFc) predicting quality of vaccine response. We show that sFcs drive BCR affinity selection by binding the Type-II FcR CD23, thus upregulating the inhibitory FcγRIIB on activated B cells. This elevates the threshold requirement for BCR signaling, resulting in B cell selection for higher affinity BCR. Immunization with sFc HA ICs elicited protective, high-affinity IgGs against the conserved stalk of the HA. These results reveal a novel, endogenous pathway for affinity maturation that can be exploited for eliciting high-affinity, broadly neutralizing antibodies through immunization with sialylated immune complexes. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies against the Ebola virus (EBOV) surface glycoprotein are effective treatments for EBOV disease. Antibodies targeting the EBOV glycoprotein (GP) head epitope have potent neutralization and Fc effector function activity and thus are of high interest as therapeutics and for vaccine design. Here we focus on the head-binding antibodies 1A2 and 1D5, which have been identified previously in a longitudinal study of survivors of EBOV infection. 1A2 and 1D5 have the same heavy- and light-chain germlines despite being isolated from different individuals and at different time points after recovery from infection. Cryoelectron microscopy analysis of each antibody in complex with the EBOV surface GP reveals key amino acid substitutions in 1A2 that contribute to greater affinity, improved neutralization potency, and enhanced breadth as well as two strategies for antibody evolution from a common site., Competing Interests: Declaration of interests R.A., C.D., and E.O.S. are inventors on a patent relating to the antibodies described in this work., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The pairing of antibody genes IGHV2-5/IGLV2-14 is established as a public immune response that potently cross-neutralizes SARS-CoV-2 variants, including Omicron, by targeting class-3/RBD-5 epitopes in the receptor binding domain (RBD). LY-CoV1404 (bebtelovimab) exemplifies this, displaying exceptional potency against Omicron sub-variants up to BA.5. Here, we report a human antibody, 002-S21B10, encoded by the public clonotype IGHV2-5/IGLV2-14. While 002-S21B10 neutralized key SARS-CoV-2 variants, it did not neutralize Omicron, despite sharing >92% sequence similarity with LY-CoV1404. The structure of 002-S21B10 in complex with spike trimer plus structural and sequence comparisons with LY-CoV1404 and other IGHV2-5/IGLV2-14 antibodies revealed significant variations in light-chain orientation, paratope residues, and epitope-paratope interactions that enable some antibodies to neutralize Omicron but not others. Confirming this, replacing the light chain of 002-S21B10 with the light chain of LY-CoV1404 restored 002-S21B10's binding to Omicron. Understanding such Omicron evasion from public response is vital for guiding therapeutics and vaccine design., Competing Interests: Declaration of interests The International Centre for Genetic Engineering and Biotechnology, New Delhi, India; Emory Vaccine Center, Emory University, Atlanta, Georgia, USA; Indian Council of Medical Research, India; and Department of Biotechnology, India, have filed a provisional patent application on human monoclonal antibodies mentioned in this study on which A.C., S.K., K.M.-K., and A.S. are inventors (Indian patent 202111052088). N.C., H.P.V., A.S.N., and J.D.R. are co-inventors on a pending patent related to SARS-CoV-2 WT, Delta, and Omicron spike protein structures and ACE2 interactions from BoAb assay technology filed by Emory University (US Patent Application 63/265,361, filed on December 14, 2021). M.S.S. has previously served as a consultant for Moderna and Ocugen. J.D.R. is a co-founder and consultant for Cambium Medical Technologies. J.D.R. is a consultant for Secure Transfusion Services., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Understanding the molecular features of neutralizing epitopes is important for developing vaccines/therapeutics against emerging SARS-CoV-2 variants. We describe three monoclonal antibodies (mAbs) generated from COVID-19 recovered individuals during the first wave of the pandemic in India. These mAbs had publicly shared near germline gene usage and potently neutralized Alpha and Delta, poorly neutralized Beta, and failed to neutralize Omicron BA.1 SARS-CoV-2 variants. Structural analysis of these mAbs in complex with trimeric spike protein showed that all three mAbs bivalently bind spike with two mAbs targeting class 1 and one targeting a class 4 receptor binding domain epitope. The immunogenetic makeup, structure, and function of these mAbs revealed specific molecular interactions associated with the potent multi-variant binding/neutralization efficacy. This knowledge shows how mutational combinations can affect the binding or neutralization of an antibody, which in turn relates to the efficacy of immune responses to emerging SARS-CoV-2 escape variants., Competing Interests: Declaration of interests The International Center for Genetic Engineering and Biotechnology, New Delhi, India, Emory Vaccine Center, Emory University, Atlanta, USA, Indian Council of Medical Research, India, and Department of Biotechnology, India, have filed a provisional patent application on human monoclonal antibodies mentioned in this study on which A.C., S.K., M.K.K., and A.S. are inventors (Indian patent 202111052088). N.C., H.P.V., A.S.N., and J.D.R. are co-inventors on a pending patent related to SARS-CoV-2 WT, Delta, and Omicron spike protein structures and ACE2 Interactions from BoAb assay technology filed by Emory University (US patent application no. 63/265,361, filed on December 14, 2021). M.S.S. has previously served as a consultant for Moderna and Ocugen. J.D.R. is a co-founder and consultant for Cambium Medical Technologies. J.D.R. is a consultant for Secure Transfusion Services. All other authors declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Ending the COVID-19 pandemic will require long-lived immunity to SARS-CoV-2. Here, we evaluate 254 COVID-19 patients longitudinally up to 8 months and find durable broad-based immune responses. SARS-CoV-2 spike binding and neutralizing antibodies exhibit a bi-phasic decay with an extended half-life of >200 days suggesting the generation of longer-lived plasma cells. SARS-CoV-2 infection also boosts antibody titers to SARS-CoV-1 and common betacoronaviruses. In addition, spike-specific IgG+ memory B cells persist, which bodes well for a rapid antibody response upon virus re-exposure or vaccination. Virus-specific CD4+ and CD8+ T cells are polyfunctional and maintained with an estimated half-life of 200 days. Interestingly, CD4+ T cell responses equally target several SARS-CoV-2 proteins, whereas the CD8+ T cell responses preferentially target the nucleoprotein, highlighting the potential importance of including the nucleoprotein in future vaccines. Taken together, these results suggest that broad and effective immunity may persist long-term in recovered COVID-19 patients., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

SARS-CoV-2, the virus responsible for COVID-19, is causing a devastating worldwide pandemic, and there is a pressing need to understand the development, specificity, and neutralizing potency of humoral immune responses during acute infection. We report a cross-sectional study of antibody responses to the receptor-binding domain (RBD) of the spike protein and virus neutralization activity in a cohort of 44 hospitalized COVID-19 patients. RBD-specific IgG responses are detectable in all patients 6 days after PCR confirmation. Isotype switching to IgG occurs rapidly, primarily to IgG1 and IgG3. Using a clinical SARS-CoV-2 isolate, neutralizing antibody titers are detectable in all patients by 6 days after PCR confirmation and correlate with RBD-specific binding IgG titers. The RBD-specific binding data were further validated in a clinical setting with 231 PCR-confirmed COVID-19 patient samples. These findings have implications for understanding protective immunity against SARS-CoV-2, therapeutic use of immune plasma, and development of much-needed vaccines., Competing Interests: The authors declare no competing interests., (© 2020 The Author(s).)

Synthetically engineered DNA-encoded monoclonal antibodies (DMAbs) are an in vivo platform for evaluation and delivery of human mAb to control against infectious disease. Here, we engineer DMAbs encoding potent anti-Zaire ebolavirus (EBOV) glycoprotein (GP) mAbs isolated from Ebola virus disease survivors. We demonstrate the development of a human IgG1 DMAb platform for in vivo EBOV-GP mAb delivery and evaluation in a mouse model. Using this approach, we show that DMAb-11 and DMAb-34 exhibit functional and molecular profiles comparable to recombinant mAb, have a wide window of expression, and provide rapid protection against lethal mouse-adapted EBOV challenge. The DMAb platform represents a simple, rapid, and reproducible approach for evaluating the activity of mAb during clinical development. DMAbs have the potential to be a mAb delivery system, which may be advantageous for protection against highly pathogenic infectious diseases, like EBOV, in resource-limited and other challenging settings., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Antibodies are promising post-exposure therapies against emerging viruses, but which antibody features and in vitro assays best forecast protection are unclear. Our international consortium systematically evaluated antibodies against Ebola virus (EBOV) using multidisciplinary assays. For each antibody, we evaluated epitopes recognized on the viral surface glycoprotein (GP) and secreted glycoprotein (sGP), readouts of multiple neutralization assays, fraction of virions left un-neutralized, glycan structures, phagocytic and natural killer cell functions elicited, and in vivo protection in a mouse challenge model. Neutralization and induction of multiple immune effector functions (IEFs) correlated most strongly with protection. Neutralization predominantly occurred via epitopes maintained on endosomally cleaved GP, whereas maximal IEF mapped to epitopes farthest from the viral membrane. Unexpectedly, sGP cross-reactivity did not significantly influence in vivo protection. This comprehensive dataset provides a rubric to evaluate novel antibodies and vaccine responses and a roadmap for therapeutic development for EBOV and related viruses., (Copyright © 2018 Elsevier Inc. All rights reserved.)