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Ebola virus (EBOV) and Bundibugyo virus (BDBV) belong to the family Filoviridae and cause a severe disease in humans. We previously isolated a large panel of monoclonal antibodies from B cells of human survivors from the 2007 Uganda BDBV outbreak, 16 survivors from the 2014 EBOV outbreak in the Democratic Republic of the Congo, and one survivor from the West African 2013-2016 EBOV epidemic. Here, we demonstrate that EBOV and BDBV are capable of spreading to neighboring cells through intercellular connections in a process that depends upon actin and T cell immunoglobulin and mucin 1 protein. We quantify spread through intercellular connections by immunofluorescence microscopy and flow cytometry. One of the antibodies, BDBV223, specific to the membrane-proximal external region, induces virus accumulation at the plasma membrane. The inhibiting activity of BDBV223 depends on BST2/tetherin., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Understanding the human antibody response to emerging viral pathogens is key to epidemic preparedness. As the size of the B cell response to a pathogenic-virus-protective antigen is poorly defined, we perform deep paired heavy- and light-chain sequencing in Ebola virus glycoprotein (EBOV-GP)-specific memory B cells, allowing analysis of the ebolavirus-specific antibody repertoire both genetically and functionally. This approach facilitates investigation of the molecular and genetic basis for the evolution of cross-reactive antibodies by elucidating germline-encoded properties of antibodies to EBOV and identification of the overlap between antibodies in the memory B cell and serum repertoire. We identify 73 public clonotypes of EBOV, 20% of which encode antibodies with neutralization activity and capacity to protect mice in vivo. This comprehensive analysis of the public and private antibody repertoire provides insight into the molecular basis of the humoral immune response to EBOV GP, which informs the design of vaccines and improved therapeutics., Competing Interests: Declaration of interests E.D. and B.J.D. are employees of Integral Molecular, and B.J.D.is a shareholder in that company. J.E.C. has served as a consultant for Luna Labs USA, Merck Sharp & Dohme, Emergent Biosolutions, and GlaxoSmithKline; is a member of the scientific advisory board of Meissa Vaccines; is a former member of the scientific advisory board of Gigagen (Grifols); and is the founder of IDBiologics. The laboratory of J.E.C. received unrelated sponsored research agreements from AstraZeneca, Takeda, and IDBiologics during the conduct of the study., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Despite prolific efforts to characterize the antibody response to human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) mono-infections, the response to chronic co-infection with these two ever-evolving viruses is poorly understood. Here, we investigate the antibody repertoire of a chronically HIV-1/HCV co-infected individual using linking B cell receptor to antigen specificity through sequencing (LIBRA-seq). We identify five HIV-1/HCV cross-reactive antibodies demonstrating binding and functional cross-reactivity between HIV-1 and HCV envelope glycoproteins. All five antibodies show exceptional HCV neutralization breadth and effector functions against both HIV-1 and HCV. One antibody, mAb688, also cross-reacts with influenza and coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We examine the development of these antibodies using next-generation sequencing analysis and lineage tracing and find that somatic hypermutation established and enhanced this reactivity. These antibodies provide a potential future direction for therapeutic and vaccine development against current and emerging infectious diseases. More broadly, chronic co-infection represents a complex immunological challenge that can provide insights into the fundamental rules that underly antibody-antigen specificity., Competing Interests: Declaration of interests K.A.P. and I.S.G. are listed as inventors on patents filed describing the antibodies discovered here. A.R.S. and I.S.G. are co-founders of AbSeek Bio. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Board of Meissa Vaccines, and is founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received sponsored research agreements from Takeda Vaccines, IDBiologics, and AstraZeneca. The Georgiev laboratory at Vanderbilt University Medical Center has received unrelated funding from Takeda Pharmaceuticals., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Dengue is a major public health threat. There are four dengue virus (DENV) serotypes; therefore, efforts are focused on developing safe and effective tetravalent DENV vaccines. While neutralizing antibodies contribute to protective immunity, there are still important gaps in understanding of immune responses elicited by dengue infection and vaccination. To that end, here, we develop a computational modeling framework based on the concept of antibody-virus neutralization fingerprints in order to characterize samples from clinical studies of TAK-003, a tetravalent vaccine candidate currently in phase 3 trials. Our results suggest a similarity of neutralizing antibody specificities in baseline-seronegative individuals. In contrast, amplification of pre-existing neutralizing antibody specificities is predicted for baseline-seropositive individuals, thus quantifying the role of immunologic imprinting in driving antibody responses to DENV vaccines. The neutralization fingerprinting analysis framework presented here can contribute to understanding dengue immune correlates of protection and help guide further vaccine development and optimization., Competing Interests: Declaration of interests This research was supported by Takeda. Serum from DEN-205 trial (30 samples from 20 donors) and funding were provided by Takeda to support Vanderbilt University Medical Center’s evaluation of the NFP algorithm. I.S.G. is a co-founder of AbSeek Bio. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Board of Meissa Vaccines, and is founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received sponsored research agreements from IDBiologics and AstraZeneca. L.K. is an employee of Takeda Vaccines, Inc. S.D. and H.J.D. were employees of Takeda Vaccines, Inc., at the time these studies were performed. H.J.D. is a consultant for Takeda Vaccines, Inc., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The E1 and E2 envelope proteins of hepatitis C virus (HCV) form a heterodimer that drives virus-host membrane fusion. Here, we analyze the role of each amino acid in E1E2 function, expressing 545 individual alanine mutants of E1E2 in human cells, incorporating them into infectious viral pseudoparticles, and testing them against 37 different monoclonal antibodies (MAbs) to ascertain full-length translation, folding, heterodimer assembly, CD81 binding, viral pseudoparticle incorporation, and infectivity. We propose a model describing the role of each critical residue in E1E2 functionality and use it to examine how MAbs neutralize infection by exploiting functionally critical sites of vulnerability on E1E2. Our results suggest that E1E2 is a surprisingly fragile protein complex where even a single alanine mutation at 92% of positions disrupts its function. The amino-acid-level targets identified are highly conserved and functionally critical and can be exploited for improved therapies and vaccines., Competing Interests: Declaration of interests J.M.P.-K., E.D., K.K.-E., M.H., E.R., R.C., and B.J.D. are current or former employees of Integral Molecular. B.J.D. is a shareholder of Integral Molecular. J.E.C., Jr. has served as a consultant for Eli Lilly, GlaxoSmithKline, and Luna Biologics, is a member of the Scientific Advisory Boards of CompuVax and Meissa Vaccines, and is founder of IDBiologics. The J.E.C., Jr. laboratory at Vanderbilt University Medical Center has received sponsored research agreements from Takeda Vaccines, IDBiologics, and AstraZeneca., (Copyright © 2022 Integral Molecular, Inc. Published by Elsevier Inc. All rights reserved.)

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineages that are more transmissible and resistant to currently approved antibody therapies poses a considerable challenge to the clinical treatment of coronavirus disease (COVID-19). Therefore, the need for ongoing discovery efforts to identify broadly reactive monoclonal antibodies to SARS-CoV-2 is of utmost importance. Here, we report a panel of SARS-CoV-2 antibodies isolated using the linking B cell receptor to antigen specificity through sequencing (LIBRA-seq) technology from an individual who recovered from COVID-19. Of these antibodies, 54042-4 shows potent neutralization against authentic SARS-CoV-2 viruses, including variants of concern (VOCs). A cryoelectron microscopy (cryo-EM) structure of 54042-4 in complex with the SARS-CoV-2 spike reveals an epitope composed of residues that are highly conserved in currently circulating SARS-CoV-2 lineages. Further, 54042-4 possesses uncommon genetic and structural characteristics that distinguish it from other potently neutralizing SARS-CoV-2 antibodies. Together, these findings provide motivation for the development of 54042-4 as a lead candidate to counteract current and future SARS-CoV-2 VOCs., Competing Interests: Declarations of interests A.R.S. and I.S.G. are co-founders of AbSeek Bio. K.J.K., A.R.S., N.V.J., I.S.G., J.S.M., R.H.C., and J.E.C. are listed as inventors on patents filed describing the antibodies discovered here. R.H.C. is an inventor on patents related to other SARS-CoV-2 antibodies. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Board of Meissa Vaccines and is Founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received sponsored research agreements from Takeda Vaccines, IDBiologics and AstraZeneca. J.K.W., E.D., and B.J.D. are employees of Integral Molecular. B.J.D. is a shareholder of Integral Molecular. The Georgiev laboratory at Vanderbilt University Medical Center has received unrelated funding from Takeda Pharmaceuticals., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Hendra virus and Nipah virus (NiV), members of the Henipavirus (HNV) genus, are zoonotic paramyxoviruses known to cause severe disease across six mammalian orders, including humans. We isolated a panel of human monoclonal antibodies (mAbs) from the B cells of an individual with prior exposure to equine Hendra virus (HeV) vaccine, targeting distinct antigenic sites. The most potent class of cross-reactive antibodies achieves neutralization by blocking viral attachment to the host cell receptors ephrin-B2 and ephrin-B3, with a second class being enhanced by receptor binding. mAbs from both classes display synergistic activity in vitro. In a stringent hamster model of NiV Bangladesh (NiV B ) infection, antibodies from both classes reduce morbidity and mortality and achieve synergistic protection in combination. These candidate mAbs might be suitable for use in a cocktail therapeutic approach to achieve synergistic potency and reduce the risk of virus escape., Competing Interests: Declaration of interests J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Board of Meissa Vaccines, and is Founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received unrelated sponsored research agreements from Takeda, IDBiologics, and AstraZeneca. E.A.K., Z.A.B., and B.R.W. are employees and shareholders of Mapp. L.Z. is an employee, shareholder, and co-owner of Mapp. C.C.B. is a US federal employee, and C.C.B. and M.A. are co-inventors on US and foreign patents pertaining to Cedar virus and methods of use and recombinant Cedar virus chimeras, whose assignees are the US as represented by the Henry M. Jackson Foundation for the Advancement of Military Medicine (Bethesda, MD, USA). The remaining authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Unrelated individuals can produce genetically similar clones of antibodies, known as public clonotypes, which have been seen in responses to different infectious diseases, as well as healthy individuals. Here we identify 37 public clonotypes in memory B cells from convalescent survivors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or in plasmablasts from an individual after vaccination with mRNA-encoded spike protein. We identify 29 public clonotypes, including clones recognizing the receptor-binding domain (RBD) in the spike protein S1 subunit (including a neutralizing, angiotensin-converting enzyme 2 [ACE2]-blocking clone that protects in vivo) and others recognizing non-RBD epitopes that bind the S2 domain. Germline-revertant forms of some public clonotypes bind efficiently to spike protein, suggesting these common germline-encoded antibodies are preconfigured for avid recognition. Identification of large numbers of public clonotypes provides insight into the molecular basis of efficacy of SARS-CoV-2 vaccines and sheds light on the immune pressures driving the selection of common viral escape mutants., Competing Interests: Declaration of interests E.D., J.K.W., and B.J.D. are employees of Integral Molecular, and B.J.D. is a shareholder in that company. M.S.D. is a consultant for Inbios, Vir Biotechnology, NGM Biopharmaceuticals, and Carnival Corporation and is on the Scientific Advisory Boards of Moderna and Immunome. The Diamond laboratory has received funding support in sponsored research agreements from Moderna, Vir Biotechnology, and Emergent BioSolutions. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Board of Meissa Vaccines and is Founder of IDBiologics. The Crowe laboratory has received funding support in sponsored research agreements from AstraZeneca, IDBiologics, and Takeda., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) variants govern transmissibility, responsiveness to vaccination, and disease severity. In a screen for new models of SARS-CoV-2 infection, we identify human H522 lung adenocarcinoma cells as naturally permissive to SARS-CoV-2 infection despite complete absence of angiotensin-converting enzyme 2 (ACE2) expression. Remarkably, H522 infection requires the E484D S variant; viruses expressing wild-type S are not infectious. Anti-S monoclonal antibodies differentially neutralize SARS-CoV-2 E484D S in H522 cells as compared to ACE2-expressing cells. Sera from vaccinated individuals block this alternative entry mechanism, whereas convalescent sera are less effective. Although the H522 receptor remains unknown, depletion of surface heparan sulfates block H522 infection. Temporally resolved transcriptomic and proteomic profiling reveal alterations in cell cycle and the antiviral host cell response, including MDA5-dependent activation of type I interferon signaling. These findings establish an alternative SARS-CoV-2 host cell receptor for the E484D SARS-CoV-2 variant, which may impact tropism of SARS-CoV-2 and consequently human disease pathogenesis., Competing Interests: Declaration of interests S.P.J.W., P.W.R., and Washington University have filed a patent application for uses of VSV-SARS-CoV-2. S.P.J.W. has received unrelated funding support in sponsored research agreements with Vir Biotechnology, Abbvie, and SAB therapeutics. M.S.D. is a consultant for Inbios, Vir Biotechnology, Fortress Biotech, and Carnival Corporation, and is on the Scientific Advisory Boards of Moderna and Immunome. The Diamond laboratory has received funding support in sponsored research agreements from Moderna, Vir Biotechnology, Kaleido, and Emergent BioSolutions. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Boards of Meissa Vaccines, and is Founder of IDBiologics. The Crowe laboratory has received sponsored research agreements from Takeda, AstraZeneca, and IDBiologics. Vanderbilt University has applied for patents related to antibodies described in this paper. The remaining authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

New World hantaviruses (NWHs) are endemic in North and South America and cause hantavirus cardiopulmonary syndrome (HCPS), with a case fatality rate of up to 40%. Knowledge of the natural humoral immune response to NWH infection is limited. Here, we describe human monoclonal antibodies (mAbs) isolated from individuals previously infected with Sin Nombre virus (SNV) or Andes virus (ANDV). Most SNV-reactive antibodies show broad recognition and cross-neutralization of both New and Old World hantaviruses, while many ANDV-reactive antibodies show activity for ANDV only. mAbs ANDV-44 and SNV-53 compete for binding to a distinct site on the ANDV surface glycoprotein and show potently neutralizing activity to New and Old World hantaviruses. Four mAbs show therapeutic efficacy at clinically relevant doses in hamsters. These studies reveal a convergent and potently neutralizing human antibody response to NWHs and suggest therapeutic potential for human mAbs against HCPS., Competing Interests: Declaration of interests J.E.C. has served as a consultant for Eli Lilly, GlaxoSmithKline, and Luna Biologics; is a member of the Scientific Advisory Boards of CompuVax and Meissa Vaccines; and is Founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received unrelated sponsored research agreements from Takeda Vaccines, IDBiologics, and AstraZeneca. Vanderbilt University has applied for patents concerning hantavirus antibodies that are related to this work. All of the other authors declare no competing interests. Opinions, interpretations, conclusions, and recommendations contained herein are those of the authors and are not necessarily endorsed by the US Department of Defense., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Antibodies that target the glycan cap epitope on the ebolavirus glycoprotein (GP) are common in the adaptive response of survivors. A subset is known to be broadly neutralizing, but the details of their epitopes and basis for neutralization are not well understood. Here, we present cryoelectron microscopy (cryo-EM) structures of diverse glycan cap antibodies that variably synergize with GP base-binding antibodies. These structures describe a conserved site of vulnerability that anchors the mucin-like domains (MLDs) to the glycan cap, which we call the MLD anchor and cradle. Antibodies that bind to the MLD cradle share common features, including use of IGHV1-69 and IGHJ6 germline genes, which exploit hydrophobic residues and form β-hairpin structures to mimic the MLD anchor, disrupt MLD attachment, destabilize GP quaternary structure, and block cleavage events required for receptor binding. Our results provide a molecular basis for ebolavirus neutralization by broadly reactive glycan cap antibodies., Competing Interests: Declaration of interests A.L.B., E.D., and B.J.D. are employees of Integral Molecular. B.J.D. is a shareholder of Integral Molecular. J.E.C. has served as a consultant for Lilly and Luna Biologics, is a member of the Scientific Advisory Boards of CompuVax and Meissa Vaccines, and is the founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received sponsored research agreements from and IDBiologics and AstraZeneca. Vanderbilt University has applied for a patent that is related to antibodies discussed in this work. All other authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

The collection of T cell receptors (TCRs) generated by somatic recombination is large but unknown. We generate large TCR repertoire datasets as a resource to facilitate detailed studies of the role of TCR clonotypes and repertoires in health and disease. We estimate the size of individual human recombined and expressed TCRs by sequence analysis and determine the extent of sharing between individual repertoires. Our experiments reveal that each blood sample contains between 5 million and 21 million TCR clonotypes. Three individuals share 8% of TCRβ- or 11% of TCRα-chain clonotypes. Sorting by T cell phenotypes in four individuals shows that 5% of naive CD4+ and 3.5% of naive CD8+ subsets share their TCRβ clonotypes, whereas memory CD4+ and CD8+ subsets share 2.3% and 0.4% of their clonotypes, respectively. We identify the sequences of these shared TCR clonotypes that are of interest for studies of human T cell biology., Competing Interests: Declaration of Interests J.E.C. has served as a consultant for Takeda Vaccines, Sanofi Pasteur, Pfizer, and Novavax; is on the scientific advisory boards of CompuVax and Meissa Vaccines; and is founder of IDBiologics, Inc., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Spondweni virus (SPOV) is the flavivirus that is most closely related to Zika virus (ZIKV). Although SPOV causes sporadic human infections in Africa, recently it was found in Culex mosquitoes in Haiti. To investigate the pathogenic spectrum of SPOV, we developed infection models in mice. Although two SPOV strains failed to cause disease in immunocompetent mice, each accumulated in the brain, spleen, eye, testis, and kidney when type I interferon signaling was blocked and unexpectedly caused infection, immune cell infiltration, and swelling in the ankle. In pregnant mice, SPOV replicated in the placenta and fetus but did not cause placental insufficiency or microcephaly. We identified human antibodies from ZIKV or DENV immune subjects that neutralized SPOV infection and protected against lethal challenge. Our experiments describe similarities and differences in clinical syndromes between SPOV and ZIKV and suggest that their serological relatedness has implications for antibody therapeutics and flavivirus vaccine development., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

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.)

Some monoclonal antibodies (mAbs) recovered from survivors of filovirus infections can protect against infection. It is currently unknown whether natural infection also induces some antibodies with the capacity for antibody-dependent enhancement (ADE). A panel of mAbs obtained from human survivors of filovirus infection caused by Ebola, Bundibugyo, or Marburg viruses was evaluated for their ability to facilitate ADE. ADE was observed readily with all mAbs examined at sub-neutralizing concentrations, and this effect was not restricted to mAbs with a particular epitope specificity, neutralizing capacity, or subclass. Blocking of specific Fcγ receptors reduced but did not abolish ADE that was associated with high-affinity binding antibodies, suggesting that lower-affinity interactions still cause ADE. Mutations of Fc fragments of an mAb that altered its interaction with Fc receptors rendered the antibody partially protective in vivo at a low dose, suggesting that ADE counteracts antibody-mediated protection and facilitates dissemination of filovirus infections., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Comparative immune response profiling is important for selecting next-generation vaccines. We comprehensively evaluated the antibody responses from a panel of nine respiratory vaccines against Ebola virus (EBOV) derived from human and avian paramyxoviruses expressing EBOV glycoprotein (GP). Most vaccines were protective in guinea pigs but yielded antibody repertoires that differed in proportion targeting key antigenic regions, avidity, neutralizing antibody specificities, and linear epitope preferences. Competition studies with monoclonal antibodies from human survivors revealed that some epitopes in GP targeted for neutralization were vector dependent, while EBOV-neutralizing titers correlated with the response magnitude toward the receptor-binding domain and GP1/GP2 interface epitopes. While an immunogen determines the breadth of antibody response, distinct vaccine vectors can induce qualitatively different responses, affecting protective efficacy. These data suggest that immune correlates of vaccine protection cannot be generalized for all vaccines against the same pathogen, even if they use the exact same immunogen., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Chikungunya virus (CHIKV) and related alphaviruses cause epidemics of acute and chronic musculoskeletal disease. To investigate the mechanisms underlying the failure of immune clearance of CHIKV, we studied mice infected with an attenuated CHIKV strain (181/25) and the pathogenic parental strain (AF15561), which differ by five amino acids. Whereas AF15561 infection of wild-type mice results in viral persistence in joint tissues, 181/25 is cleared. In contrast, 181/25 infection of μMT mice lacking mature B cells results in viral persistence in joint tissues, suggesting that virus-specific antibody is required for clearance of infection. Mapping studies demonstrated that a highly conserved glycine at position 82 in the A domain of the E2 glycoprotein impedes clearance and neutralization of multiple CHIKV strains. Remarkably, murine and human antibodies targeting E2 domain B failed to neutralize pathogenic CHIKV strains efficiently. Our data suggest that pathogenic CHIKV strains evade E2 domain-B-neutralizing antibodies to establish persistence., (Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.)