Publications by authors named "Andrew T McGuire"

54 Publications

Structural basis for broad coronavirus neutralization.

Nat Struct Mol Biol 2021 06 12;28(6):478-486. Epub 2021 May 12.

Department of Biochemistry, University of Washington, Seattle, WA, USA.

Three highly pathogenic β-coronaviruses have crossed the animal-to-human species barrier in the past two decades: SARS-CoV, MERS-CoV and SARS-CoV-2. To evaluate the possibility of identifying antibodies with broad neutralizing activity, we isolated a monoclonal antibody, termed B6, that cross-reacts with eight β-coronavirus spike glycoproteins, including all five human-infecting β-coronaviruses. B6 broadly neutralizes entry of pseudotyped viruses from lineages A and C, but not from lineage B, and the latter includes SARS-CoV and SARS-CoV-2. Cryo-EM, X-ray crystallography and membrane fusion assays reveal that B6 binds to a conserved cryptic epitope located in the fusion machinery. The data indicate that antibody binding sterically interferes with the spike conformational changes leading to membrane fusion. Our data provide a structural framework explaining B6 cross-reactivity with β-coronaviruses from three lineages, along with a proof of concept for antibody-mediated broad coronavirus neutralization elicited through vaccination. This study unveils an unexpected target for next-generation structure-guided design of a pan-β-coronavirus vaccine.
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http://dx.doi.org/10.1038/s41594-021-00596-4DOI Listing
June 2021

Development of a VRC01-class germline targeting immunogen derived from anti-idiotypic antibodies.

Cell Rep 2021 May;35(5):109084

Fred Hutchinson Cancer Research Center, Vaccines and Infectious Diseases Division, Seattle, WA 98109, USA; University of Washington, Department of Global Health, Seattle, WA 98195, USA. Electronic address:

An effective HIV-1 vaccine will likely need to elicit broadly neutralizing antibodies (bNAbs). Broad and potent VRC01-class bNAbs have been isolated from multiple infected individuals, suggesting that they could be reproducibly elicited by vaccination. Several HIV-1 envelope-derived germline-targeting immunogens have been designed to engage naive VRC01-class precursor B cells. However, they also present off-target epitopes that could hinder development of VRC01-class bNAbs. We characterize a panel of anti-idiotypic monoclonal antibodies (ai-mAbs) raised against inferred-germline (iGL) VRC01-class antibodies. By leveraging binding, structural, and B cell sorting data, we engineered a bispecific molecule derived from two ai-mAbs; one specific for VRC01-class heavy chains and one specific for VRC01-class light chains. The bispecific molecule preferentially activates iGL-VRC01 B cells in vitro and induces specific antibody responses in a murine adoptive transfer model with a diverse polyclonal B cell repertoire. This molecule represents an alternative non-envelope-derived germline-targeting immunogen that can selectively activate VRC01-class precursors in vivo.
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http://dx.doi.org/10.1016/j.celrep.2021.109084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127986PMC
May 2021

Protective antibodies against human parainfluenza virus type 3 infection.

MAbs 2021 Jan-Dec;13(1):1912884

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.

Human parainfluenza virus type III (HPIV3) is a common respiratory pathogen that afflicts children and can be fatal in vulnerable populations, including the immunocompromised. There are currently no effective vaccines or therapeutics available, resulting in tens of thousands of hospitalizations per year. In an effort to discover a protective antibody against HPIV3, we screened the B cell repertoires from peripheral blood, tonsils, and spleen from healthy children and adults. These analyses yielded five monoclonal antibodies that potently neutralized HPIV3 . These HPIV3-neutralizing antibodies targeted two non-overlapping epitopes of the HPIV3 F protein, with most targeting the apex. Prophylactic administration of one of these antibodies, PI3-E12, resulted in potent protection against HPIV3 infection in cotton rats. Additionally, PI3-E12 could also be used therapeutically to suppress HPIV3 in immunocompromised animals. These results demonstrate the potential clinical utility of PI3-E12 for the prevention or treatment of HPIV3 in both immunocompetent and immunocompromised individuals.
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http://dx.doi.org/10.1080/19420862.2021.1912884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8078717PMC
April 2021

Designed proteins assemble antibodies into modular nanocages.

Science 2021 04;372(6537)

Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.

Multivalent display of receptor-engaging antibodies or ligands can enhance their activity. Instead of achieving multivalency by attachment to preexisting scaffolds, here we unite form and function by the computational design of nanocages in which one structural component is an antibody or Fc-ligand fusion and the second is a designed antibody-binding homo-oligomer that drives nanocage assembly. Structures of eight nanocages determined by electron microscopy spanning dihedral, tetrahedral, octahedral, and icosahedral architectures with 2, 6, 12, and 30 antibodies per nanocage, respectively, closely match the corresponding computational models. Antibody nanocages targeting cell surface receptors enhance signaling compared with free antibodies or Fc-fusions in death receptor 5 (DR5)-mediated apoptosis, angiopoietin-1 receptor (Tie2)-mediated angiogenesis, CD40 activation, and T cell proliferation. Nanocage assembly also increases severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus neutralization by α-SARS-CoV-2 monoclonal antibodies and Fc-angiotensin-converting enzyme 2 (ACE2) fusion proteins.
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http://dx.doi.org/10.1126/science.abd9994DOI Listing
April 2021

Live imaging of SARS-CoV-2 infection in mice reveals neutralizing antibodies require Fc function for optimal efficacy.

bioRxiv 2021 Mar 22. Epub 2021 Mar 22.

Neutralizing antibodies (NAbs) are effective in treating COVID-19 but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment in prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. We visualized sequential spread of virus from the nasal cavity to the lungs followed by systemic spread to various organs including the brain, culminating in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days of infection. In addition to direct neutralization, efficacy required Fc effector functions of NAbs, with contributions from monocytes, neutrophils and natural killer cells, to dampen inflammatory responses and limit immunopathology. Thus, our study highlights the requirement of both Fab and Fc effector functions for an optimal efficacy afforded by NAbs against SARS-CoV-2.
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http://dx.doi.org/10.1101/2021.03.22.436337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8010726PMC
March 2021

Isolation and Characterization of Cross-Neutralizing Coronavirus Antibodies from COVID-19+ Subjects.

bioRxiv 2021 Mar 24. Epub 2021 Mar 24.

SARS-CoV-2 is one of three coronaviruses that have crossed the animal-to-human barrier in the past two decades. The development of a universal human coronavirus vaccine could prevent future pandemics. We characterized 198 antibodies isolated from four COVID19+ subjects and identified 14 SARS-CoV-2 neutralizing antibodies. One targeted the NTD, one recognized an epitope in S2 and twelve bound the RBD. Three anti-RBD neutralizing antibodies cross-neutralized SARS-CoV-1 by effectively blocking binding of both the SARS-CoV-1 and SARS-CoV-2 RBDs to the ACE2 receptor. Using the K18-hACE transgenic mouse model, we demonstrate that the neutralization potency rather than the antibody epitope specificity regulates the protective potential of anti-SARS-CoV-2 antibodies. The anti-S2 antibody also neutralized SARS-CoV-1 and all four cross-neutralizing antibodies neutralized the B.1.351 mutant strain. Thus, our study reveals that epitopes in S2 can serve as blueprints for the design of immunogens capable of eliciting cross-neutralizing coronavirus antibodies.
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http://dx.doi.org/10.1101/2021.03.23.436684DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8010719PMC
March 2021

mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection.

Science 2021 Mar 25. Epub 2021 Mar 25.

Fred Hutchinson Cancer Research Center, Vaccine and Infectious Disease Division, Seattle, WA, USA.

Emerging SARS-CoV-2 variants have raised concerns about resistance to neutralizing antibodies elicited by previous infection or vaccination. We examined whether sera from recovered and naïve donors collected prior to, and following immunizations with existing mRNA vaccines, could neutralize the Wuhan-Hu-1 and B.1.351 variants. Pre-vaccination sera from recovered donors neutralized Wuhan-Hu-1 and sporadically neutralized B.1.351, but a single immunization boosted neutralizing titers against all variants and SARS-CoV-1 by up to 1000-fold. Neutralization was due to antibodies targeting the receptor binding domain and was not boosted by a second immunization. Immunization of naïve donors also elicited cross-neutralizing responses, but at lower titers. Our study highlights the importance of vaccinating both uninfected and previously infected persons to elicit cross-variant neutralizing antibodies.
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http://dx.doi.org/10.1126/science.abg9175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8139425PMC
March 2021

A single mRNA immunization boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection.

medRxiv 2021 Mar 10. Epub 2021 Mar 10.

Emerging SARS-CoV-2 variants have raised concerns about resistance to neutralizing antibodies elicited by previous infection or vaccination. We examined whether sera from recovered and naïve donors collected prior to, and following immunizations with existing mRNA vaccines, could neutralize the Wuhan-Hu-1 and B.1.351 variants. Pre-vaccination sera from recovered donors neutralized Wuhan-Hu-1 and sporadically neutralized B.1.351, but a single immunization boosted neutralizing titers against all variants and SARS-CoV-1 by up to 1000-fold. Neutralization was due to antibodies targeting the receptor binding domain and was not boosted by a second immunization. Immunization of naïve donors also elicited cross-neutralizing responses, but at lower titers. Our study highlights the importance of vaccinating both uninfected and previously infected persons to elicit cross-variant neutralizing antibodies.
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http://dx.doi.org/10.1101/2021.02.05.21251182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987032PMC
March 2021

A single BNT162b2 mRNA dose elicits antibodies with Fc-mediated effector functions and boost pre-existing humoral and T cell responses.

bioRxiv 2021 Mar 18. Epub 2021 Mar 18.

The standard dosing of the Pfizer/BioNTech BNT162b2 mRNA vaccine validated in clinical trials includes two doses administered three weeks apart. While the decision by some public health authorities to space the doses because of limiting supply has raised concerns about vaccine efficacy, data indicate that a single dose is up to 90% effective starting 14 days after its administration. We analyzed humoral and T cells responses three weeks after a single dose of this mRNA vaccine. Despite the proven efficacy of the vaccine at this time point, no neutralizing activity were elicited in SARS-CoV-2 naïve individuals. However, we detected strong anti-receptor binding domain (RBD) and Spike antibodies with Fc-mediated effector functions and cellular responses dominated by the CD4 T cell component. A single dose of this mRNA vaccine to individuals previously infected by SARS-CoV-2 boosted all humoral and T cell responses measured, with strong correlations between T helper and antibody immunity. Neutralizing responses were increased in both potency and breadth, with distinctive capacity to neutralize emerging variant strains. Our results highlight the importance of vaccinating uninfected and previously-infected individuals and shed new light into the potential role of Fc-mediated effector functions and T cell responses in vaccine efficacy. They also provide support to spacing the doses of two-vaccine regimens to vaccinate a larger pool of the population in the context of vaccine scarcity against SARS-CoV-2.
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http://dx.doi.org/10.1101/2021.03.18.435972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7987016PMC
March 2021

Structural basis for broad coronavirus neutralization.

bioRxiv 2020 Dec 29. Epub 2020 Dec 29.

Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA.

Three highly pathogenic β-coronaviruses crossed the animal-to-human species barrier in the past two decades: SARS-CoV, MERS-CoV and SARS-CoV-2. SARS-CoV-2 has infected more than 64 million people worldwide, claimed over 1.4 million lives and is responsible for the ongoing COVID-19 pandemic. We isolated a monoclonal antibody, termed B6, cross-reacting with eight β-coronavirus spike glycoproteins, including all five human-infecting β-coronaviruses, and broadly inhibiting entry of pseudotyped viruses from two coronavirus lineages. Cryo-electron microscopy and X-ray crystallography characterization reveal that B6 binds to a conserved cryptic epitope located in the fusion machinery and indicate that antibody binding sterically interferes with spike conformational changes leading to membrane fusion. Our data provide a structural framework explaining B6 cross-reactivity with β-coronaviruses from three lineages along with proof-of-concept for antibody-mediated broad coronavirus neutralization elicited through vaccination. This study unveils an unexpected target for next-generation structure-guided design of a pan-coronavirus vaccine.
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http://dx.doi.org/10.1101/2020.12.29.424482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781312PMC
December 2020

Designed proteins assemble antibodies into modular nanocages.

bioRxiv 2020 Dec 1. Epub 2020 Dec 1.

Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.

Antibodies are widely used in biology and medicine, and there has been considerable interest in multivalent antibody formats to increase binding avidity and enhance signaling pathway agonism. However, there are currently no general approaches for forming precisely oriented antibody assemblies with controlled valency. We describe the computational design of two-component nanocages that overcome this limitation by uniting form and function. One structural component is any antibody or Fc fusion and the second is a designed Fc-binding homo-oligomer that drives nanocage assembly. Structures of 8 antibody nanocages determined by electron microscopy spanning dihedral, tetrahedral, octahedral, and icosahedral architectures with 2, 6, 12, and 30 antibodies per nanocage match the corresponding computational models. Antibody nanocages targeting cell-surface receptors enhance signaling compared to free antibodies or Fc-fusions in DR5-mediated apoptosis, Tie2-mediated angiogenesis, CD40 activation, and T cell proliferation; nanocage assembly also increases SARS-CoV-2 pseudovirus neutralization by α-SARS-CoV-2 monoclonal antibodies and Fc-ACE2 fusion proteins. We anticipate that the ability to assemble arbitrary antibodies without need for covalent modification into highly ordered assemblies with different geometries and valencies will have broad impact in biology and medicine.
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http://dx.doi.org/10.1101/2020.12.01.406611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724662PMC
December 2020

Antibody Binding to SARS-CoV-2 S Glycoprotein Correlates with but Does Not Predict Neutralization.

Viruses 2020 10 26;12(11). Epub 2020 Oct 26.

Centre de Recherche du CHUM, Montréal, QC H2X 0A9, Canada.

Convalescent plasma from SARS-CoV-2 infected individuals and monoclonal antibodies were shown to potently neutralize viral and pseudoviral particles carrying the S glycoprotein. However, a non-negligent proportion of plasma samples from infected individuals, as well as S-specific monoclonal antibodies, were reported to be non-neutralizing despite efficient interaction with the S glycoprotein in different biochemical assays using soluble recombinant forms of S or when expressed at the cell surface. How neutralization relates to the binding of S glycoprotein in the context of viral particles remains to be established. Here, we developed a pseudovirus capture assay (VCA) to measure the capacity of plasma samples or antibodies immobilized on ELISA plates to bind to membrane-bound S glycoproteins from SARS-CoV-2 expressed at the surface of lentiviral particles. By performing VCA, ELISA, and neutralization assays, we observed a strong correlation between these parameters. However, while we found that plasma samples unable to capture viral particles did not neutralize, capture did not guarantee neutralization, indicating that the capacity of antibodies to bind to the S glycoprotein at the surface of pseudoviral particles is required but not sufficient to mediate neutralization. Altogether, our results highlight the importance of better understanding the inactivation of S by plasma and neutralizing antibodies.
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http://dx.doi.org/10.3390/v12111214DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7692607PMC
October 2020

Structural basis for potent neutralization of SARS-CoV-2 and role of antibody affinity maturation.

Nat Commun 2020 10 27;11(1):5413. Epub 2020 Oct 27.

Fred Hutchinson Cancer Research Center, Vaccines and Infectious Diseases Division, Seattle, WA, USA.

SARS-CoV-2 is a betacoronavirus virus responsible for the COVID-19 pandemic. Here, we determine the X-ray crystal structure of a potent neutralizing monoclonal antibody, CV30, isolated from a patient infected with SARS-CoV-2, in complex with the receptor binding domain. The structure reveals that CV30 binds to an epitope that overlaps with the human ACE2 receptor binding motif providing a structural basis for its neutralization. CV30 also induces shedding of the S1 subunit, indicating an additional mechanism of neutralization. A germline reversion of CV30 results in a substantial reduction in both binding affinity and neutralization potential indicating the minimal somatic mutation is needed for potently neutralizing antibodies against SARS-CoV-2.
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http://dx.doi.org/10.1038/s41467-020-19231-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7591918PMC
October 2020

Maternal Epstein-Barr Virus-Specific Antibodies and Risk of Infection in Ugandan Infants.

J Infect Dis 2021 Jun;223(11):1897-1904

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.

Background: Epstein-Barr virus (EBV) infection is a major cause of malignancy worldwide. Maternal antibody is thought to prevent EBV infection because it is uncommon in early infancy. Maternal HIV infection is associated with an increased incidence of EBV infection in exposed infants, which we hypothesized results from impaired transfer of EBV-neutralizing maternal antibodies.

Methods: Among Ugandan infants followed for EBV acquisition from birth, we measured antibody binding to EBV glycoproteins (gp350, gH/gL) involved in B-cell and epithelial-cell entry, as well as viral neutralization and antibody-dependent cellular cytotoxicity (ADCC) activity in plasma samples prior to infection. These serologic data were analyzed for differences between HIV-exposed uninfected (HEU) and HIV-unexposed (HUU) infants, and for associations with incident infant EBV infection.

Results: HEU infants had significantly higher titers than HUU infants for all EBV-binding and neutralizing antibodies measured (P < .01) but not ADCC activity, which was similar between groups. No antibody measure was associated with a decreased risk of EBV acquisition in the cohort.

Conclusions: Our findings indicate that in this cohort maternal antibody did not protect infants against EBV infection through viral neutralization. The identification of protective nonneutralizing antibody functions would be invaluable for the development of an EBV vaccine.
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http://dx.doi.org/10.1093/infdis/jiaa654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8176630PMC
June 2021

Generation of a cost-effective cell line for support of high-throughput isolation of primary human B cells and monoclonal neutralizing antibodies.

J Immunol Methods 2021 Jan 15;488:112901. Epub 2020 Oct 15.

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA; Department of Global Health, University of Washington, Seattle, WA, USA; Deparment of Laboratory Medicine and Pahthology, University of Washington, Seattle, WA, USA. Electronic address:

The isolation of human monoclonal antibodies (mAbs) arising from natural infection with human pathogens has proven to be a powerful technology, facilitating the understanding of the host response to infection at a molecular level. mAbs can reveal sites of vulnerability on pathogens and illuminate the biological function of the antigenic targets. Moreover, mAbs have the potential to be used directly for therapeutic applications such as passive delivery to prevent infection in susceptible target populations, and as treatment of established infection. The isolation of antigen-specific B cells from vaccine trials can also assist in deciphering whether the desired B cells are being targeted by a given vaccine. Several different processes have been developed to isolate mAbs, but all are generally labor-intensive and result in varying degrees of efficiency. Here, we describe the development of a cost-effective feeder cell line that stably expresses CD40-ligand, interleukin-2 and interleukin-21. Sorting of single B cells onto a layer of irradiated feeder cells sustained antibody production that permits functional screening of secreted antibodies in a manner that enables subsequent recovery of B cells for recombinant antibody cloning. As a proof of concept, we show that this approach can be used to isolate B cells that secrete antibodies that neutralize human papilloma virus (HPV) from participants of an HPV vaccine study.
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http://dx.doi.org/10.1016/j.jim.2020.112901DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7560121PMC
January 2021

Neutralizing Antibodies Protect against Oral Transmission of Lymphocryptovirus.

Cell Rep Med 2020 Jun;1(3)

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.

Epstein-Barr virus (EBV) is a cancer-associated pathogen for which there is no vaccine. Successful anti-viral vaccines elicit antibodies that neutralize infectivity; however, it is unknown whether neutralizing antibodies prevent EBV acquisition. Here we assessed whether passively delivered AMMO1, a monoclonal antibody that neutralizes EBV in a cell-type-independent manner, could protect against experimental EBV challenge in two animal infection models. When present prior to a high-dose intravenous EBV challenge, AMMO1 prevented viremia and reduced viral loads to nearly undetectable levels in humanized mice. AMMO1 conferred sterilizing immunity to three of four macaques challenged orally with rhesus lymphocryptovirus, the EBV ortholog that infects rhesus macaques. The infected macaque had lower plasma neutralizing activity than the protected animals. These results indicate that a vaccine capable of eliciting adequate titers of neutralizing antibodies targeting the AMMO1 epitope may protect against EBV acquisition and are therefore highly relevant to the design of an effective EBV vaccine.
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http://dx.doi.org/10.1016/j.xcrm.2020.100033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386402PMC
June 2020

Structural basis for potent neutralization of SARS-CoV-2 and role of antibody affinity maturation.

bioRxiv 2020 Jun 12. Epub 2020 Jun 12.

Fred Hutchinson Cancer Research Center, Vaccines and Infectious Diseases Division, Seattle, WA, USA.

SARS-CoV-2 is a betacoronavirus virus responsible for the COVID-19 pandemic. Here, we determined the X-ray crystal structure of a potent neutralizing monoclonal antibody, CV30, isolated from a patient infected with SARS-CoV-2, in complex with the receptor binding domain (RBD). The structure reveals CV30's epitope overlaps with the human ACE2 receptor binding site thus providing the structural basis for its neutralization by preventing ACE2 binding.
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http://dx.doi.org/10.1101/2020.06.12.148692DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301900PMC
June 2020

Analysis of a SARS-CoV-2-Infected Individual Reveals Development of Potent Neutralizing Antibodies with Limited Somatic Mutation.

Immunity 2020 07 8;53(1):98-105.e5. Epub 2020 Jun 8.

Fred Hutchinson Cancer Research Center, Vaccines and Infectious Disease Division, Seattle, WA, USA; University of Washington, Department of Global Health, Seattle, WA, USA. Electronic address:

Antibody responses develop following SARS-CoV-2 infection, but little is known about their epitope specificities, clonality, binding affinities, epitopes, and neutralizing activity. We isolated B cells specific for the SARS-CoV-2 envelope glycoprotein spike (S) from a COVID-19-infected subject 21 days after the onset of clinical disease. 45 S-specific monoclonal antibodies were generated. They had undergone minimal somatic mutation with limited clonal expansion, and three bound the receptor-binding domain (RBD). Two antibodies neutralized SARS-CoV-2. The most potent antibody bound the RBD and prevented binding to the ACE2 receptor, while the other bound outside the RBD. Thus, most anti-S antibodies that were generated in this patient during the first weeks of COVID-19 infection were non-neutralizing and target epitopes outside the RBD. Antibodies that disrupt the SARS-CoV-2 S-ACE2 interaction can potently neutralize the virus without undergoing extensive maturation. Such antibodies have potential preventive and/or therapeutic potential and can serve as templates for vaccine design.
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http://dx.doi.org/10.1016/j.immuni.2020.06.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7276322PMC
July 2020

Characterization of neutralizing antibodies from a SARS-CoV-2 infected individual.

bioRxiv 2020 May 12. Epub 2020 May 12.

Fred Hutchinson Cancer Research Center, Vaccines and Infectious Diseases Division, Seattle, WA, USA.

B cells specific for the SARS-CoV-2 S envelope glycoprotein spike were isolated from a COVID-19-infected subject using a stabilized spike-derived ectodomain (S2P) twenty-one days post-infection. Forty-four S2P-specific monoclonal antibodies were generated, three of which bound to the receptor binding domain (RBD). The antibodies were minimally mutated from germline and were derived from different B cell lineages. Only two antibodies displayed neutralizing activity against SARS-CoV-2 pseudo-virus. The most potent antibody bound the RBD in a manner that prevented binding to the ACE2 receptor, while the other bound outside the RBD. Our study indicates that the majority of antibodies against the viral envelope spike that were generated during the first weeks of COVID-19 infection are non-neutralizing and target epitopes outside the RBD. Antibodies that disrupt the SARS-CoV-2 spike-ACE2 interaction can potently neutralize the virus without undergoing extensive maturation. Such antibodies have potential preventive/therapeutic potential and can serve as templates for vaccine-design.
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http://dx.doi.org/10.1101/2020.05.12.091298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241105PMC
May 2020

Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein.

Cell 2020 04 9;181(2):281-292.e6. Epub 2020 Mar 9.

Department of Biochemistry, University of Washington, Seattle, WA 98195, USA. Electronic address:

The emergence of SARS-CoV-2 has resulted in >90,000 infections and >3,000 deaths. Coronavirus spike (S) glycoproteins promote entry into cells and are the main target of antibodies. We show that SARS-CoV-2 S uses ACE2 to enter cells and that the receptor-binding domains of SARS-CoV-2 S and SARS-CoV S bind with similar affinities to human ACE2, correlating with the efficient spread of SARS-CoV-2 among humans. We found that the SARS-CoV-2 S glycoprotein harbors a furin cleavage site at the boundary between the S/S subunits, which is processed during biogenesis and sets this virus apart from SARS-CoV and SARS-related CoVs. We determined cryo-EM structures of the SARS-CoV-2 S ectodomain trimer, providing a blueprint for the design of vaccines and inhibitors of viral entry. Finally, we demonstrate that SARS-CoV S murine polyclonal antibodies potently inhibited SARS-CoV-2 S mediated entry into cells, indicating that cross-neutralizing antibodies targeting conserved S epitopes can be elicited upon vaccination.
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http://dx.doi.org/10.1016/j.cell.2020.02.058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7102599PMC
April 2020

Anti-idiotypic antibodies elicit anti-HIV-1-specific B cell responses.

J Exp Med 2019 10 25;216(10):2316-2330. Epub 2019 Jul 25.

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA

Human anti-HIV-1 broadly neutralizing antibodies (bNAbs) protect against infection in animal models. However, bNAbs have not been elicited by vaccination in diverse wild-type animals or humans, in part because B cells expressing the precursors of these antibodies do not recognize most HIV-1 envelopes (Envs). Immunogens have been designed that activate these B cell precursors in vivo, but they also activate competing off-target responses. Here we report on a complementary approach to expand specific B cells using an anti-idiotypic antibody, iv8, that selects for naive human B cells expressing immunoglobulin light chains with 5-amino acid complementarity determining region 3s, a key feature of anti-CD4 binding site (CD4bs)-specific VRC01-class antibodies. In mice, iv8 induced target cells to expand and mature in the context of a polyclonal immune system and produced serologic responses targeting the CD4bs on Env. In summary, the results demonstrate that an anti-idiotypic antibody can specifically recognize and expand rare B cells that express VRC01-class antibodies against HIV-1.
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http://dx.doi.org/10.1084/jem.20190446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6780999PMC
October 2019

Detection and activation of HIV broadly neutralizing antibody precursor B cells using anti-idiotypes.

J Exp Med 2019 10 25;216(10):2331-2347. Epub 2019 Jul 25.

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA

Many tested vaccines fail to provide protection against disease despite the induction of antibodies that bind the pathogen of interest. In light of this, there is much interest in rationally designed subunit vaccines that direct the antibody response to protective epitopes. Here, we produced a panel of anti-idiotype antibodies able to specifically recognize the inferred germline version of the human immunodeficiency virus 1 (HIV-1) broadly neutralizing antibody b12 (iglb12). We determined the crystal structure of two anti-idiotypes in complex with iglb12 and used these anti-idiotypes to identify rare naive human B cells expressing B cell receptors with similarity to iglb12. Immunization with a multimerized version of this anti-idiotype induced the proliferation of transgenic murine B cells expressing the iglb12 heavy chain in vivo, despite the presence of deletion and anergy within this population. Together, our data indicate that anti-idiotypes are a valuable tool for the study and induction of potentially protective antibodies.
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http://dx.doi.org/10.1084/jem.20190164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6780997PMC
October 2019

Immunization expands B cells specific to HIV-1 V3 glycan in mice and macaques.

Nature 2019 06 29;570(7762):468-473. Epub 2019 May 29.

Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.

Broadly neutralizing monoclonal antibodies protect against infection with HIV-1 in animal models, suggesting that a vaccine that elicits these antibodies would be protective in humans. However, it has not yet been possible to induce adequate serological responses by vaccination. Here, to activate B cells that express precursors of broadly neutralizing antibodies within polyclonal repertoires, we developed an immunogen, RC1, that facilitates the recognition of the variable loop 3 (V3)-glycan patch on the envelope protein of HIV-1. RC1 conceals non-conserved immunodominant regions by the addition of glycans and/or multimerization on virus-like particles. Immunization of mice, rabbits and rhesus macaques with RC1 elicited serological responses that targeted the V3-glycan patch. Antibody cloning and cryo-electron microscopy structures of antibody-envelope complexes confirmed that immunization with RC1 expands clones of B cells that carry the anti-V3-glycan patch antibodies, which resemble precursors of human broadly neutralizing antibodies. Thus, RC1 may be a suitable priming immunogen for sequential vaccination strategies in the context of polyclonal repertoires.
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http://dx.doi.org/10.1038/s41586-019-1250-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657810PMC
June 2019

HIV-specific humoral immune responses by CRISPR/Cas9-edited B cells.

J Exp Med 2019 06 11;216(6):1301-1310. Epub 2019 Apr 11.

Laboratory of Molecular Immunology, The Rockefeller University, New York, NY

A small number of HIV-1-infected individuals develop broadly neutralizing antibodies to the virus (bNAbs). These antibodies are protective against infection in animal models. However, they only emerge 1-3 yr after infection, and show a number of highly unusual features including exceedingly high levels of somatic mutations. It is therefore not surprising that elicitation of protective immunity to HIV-1 has not yet been possible. Here we show that mature, primary mouse and human B cells can be edited in vitro using CRISPR/Cas9 to express mature bNAbs from the endogenous locus. Moreover, edited B cells retain the ability to participate in humoral immune responses. Immunization with cognate antigen in wild-type mouse recipients of edited B cells elicits bNAb titers that neutralize HIV-1 at levels associated with protection against infection. This approach enables humoral immune responses that may be difficult to elicit by traditional immunization.
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http://dx.doi.org/10.1084/jem.20190287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6547862PMC
June 2019

Targeting broadly neutralizing antibody precursors: a naïve approach to vaccine design.

Authors:
Andrew T McGuire

Curr Opin HIV AIDS 2019 07;14(4):294-301

Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center.

Purpose Of Review: It is believed that broadly neutralizing antibodies (bNAbs) will be an important component of an effective HIV-1 vaccine. Several immunogens have been designed that can target specific precursor B cells as a first step in a vaccine strategy to elicit bNAbs.

Recent Findings: Germline-targeting immunogens have been developed that specifically engage precursors of reproducible classes of anti-HIV antibodies, such as VRC01-class and apex-directed bNAbs. However, these precursors represent only a small portion of the immune repertoire and any antigen will inherently present off-target epitopes to the immune system that may confound bNAb development. Novel animal models are being utilized to understand the competitive fitness of bNAb precursors in the context of immunization with germline-targeting immunogens. In parallel, immunogen design efforts are being pursued to favor the development of bNAb responses over off-target responses following immunization. New studies of bNAb precursor interactions with glycosylated Env variants can inform prime-boost regimens geared towards accelerating bNAb development.

Summary: Germline-targeting immunogens hold promise as a first step in eliciting a bNAb response through vaccination. A better understating of how efficiently germline-targeting immunogens can specifically target rare bNAb precursors is emerging. In addition, a more comprehensive structure-based understanding of critical barriers to bNAb elicitation, as well as commonalities between bNAb classes can further inform vaccine design.
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http://dx.doi.org/10.1097/COH.0000000000000548DOI Listing
July 2019

Inference of the HIV-1 VRC01 Antibody Lineage Unmutated Common Ancestor Reveals Alternative Pathways to Overcome a Key Glycan Barrier.

Immunity 2018 12 11;49(6):1162-1174.e8. Epub 2018 Dec 11.

Duke Human Vaccine Institute, Duke University, Durham, NC, USA; Department of Medicine, Duke University, Durham, NC, USA; Department of Immunology, Duke University, Durham, NC, USA. Electronic address:

Elicitation of VRC01-class broadly neutralizing antibodies (bnAbs) is an appealing approach for a preventative HIV-1 vaccine. Despite extensive investigations, strategies to induce VRC01-class bnAbs and overcome the barrier posed by the envelope N276 glycan have not been successful. Here, we inferred a high-probability unmutated common ancestor (UCA) of the VRC01 lineage and reconstructed the stages of lineage maturation. Env immunogens designed on reverted VRC01-class bnAbs bound to VRC01 UCA with affinity sufficient to activate naive B cells. Early mutations defined maturation pathways toward limited or broad neutralization, suggesting that focusing the immune response is likely required to steer B cell maturation toward the development of neutralization breadth. Finally, VRC01 lineage bnAbs with long CDR H3s overcame the HIV-1 N276 glycan barrier without shortening their CDR L1, revealing a solution for broad neutralization in which the heavy chain, not CDR L1, is the determinant to accommodate the N276 glycan.
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http://dx.doi.org/10.1016/j.immuni.2018.10.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6303191PMC
December 2018

Germline VRC01 antibody recognition of a modified clade C HIV-1 envelope trimer and a glycosylated HIV-1 gp120 core.

Elife 2018 11 7;7. Epub 2018 Nov 7.

Department of Biochemistry, University of Washington, Seattle, United States.

VRC01 broadly neutralizing antibodies (bnAbs) target the CD4-binding site (CD4) of the human immunodeficiency virus-1 (HIV-1) envelope glycoprotein (Env). Unlike mature antibodies, corresponding VRC01 germline precursors poorly bind to Env. Immunogen design has mostly relied on glycan removal from trimeric Env constructs and has had limited success in eliciting mature VRC01 bnAbs. To better understand elicitation of such bnAbs, we characterized the inferred germline precursor of VRC01 in complex with a modified trimeric 426c Env by cryo-electron microscopy and a 426c gp120 core by X-ray crystallography, biolayer interferometry, immunoprecipitation, and glycoproteomics. Our results show VRC01 germline antibodies interacted with a wild-type 426c core lacking variable loops 1-3 in the presence and absence of a glycan at position Asn276, with the latter form binding with higher affinity than the former. Interactions in the presence of an Asn276 oligosaccharide could be enhanced upon carbohydrate shortening, which should be considered for immunogen design.
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http://dx.doi.org/10.7554/eLife.37688DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237438PMC
November 2018

HIV-1 envelope glycan modifications that permit neutralization by germline-reverted VRC01-class broadly neutralizing antibodies.

PLoS Pathog 2018 11 5;14(11):e1007431. Epub 2018 Nov 5.

Department of Surgery, Duke University Medical Center, Durham, NC, United States of America.

Broadly neutralizing antibody (bnAb) induction is a high priority for effective HIV-1 vaccination. VRC01-class bnAbs that target the CD4 binding site (CD4bs) of trimeric HIV-1 envelope (Env) glycoprotein spikes are particularly attractive to elicit because of their extraordinary breadth and potency of neutralization in vitro and their ability to protect against infection in animal models. Glycans bordering the CD4bs impede the binding of germline-reverted forms of VRC01-class bnAbs and therefore constitute a barrier to early events in initiating the correct antibody lineages. Deleting a subset of these glycans permits Env antigen binding but not virus neutralization, suggesting that additional barriers impede germline-reverted VRC01-class antibody binding to functional Env trimers. We investigated the requirements for functional Env trimer engagement of VRC01-class naïve B cell receptors by using virus neutralization and germline-reverted antibodies as surrogates for the interaction. Targeted deletion of a subset of N-glycans bordering the CD4bs, combined with Man5 enrichment of remaining N-linked glycans that are otherwise processed into larger complex-type glycans, rendered HIV-1 426c Env-pseudotyped virus (subtype C, transmitted/founder) highly susceptible to neutralization by near germline forms of VRC01-class bnAbs. Neither glycan modification alone rendered the virus susceptible to neutralization. The potency of neutralization in some cases rivaled the potency of mature VRC01 against wildtype viruses. Neutralization by the germline-reverted antibodies was abrogated by the known VRC01 resistance mutation, D279K. These findings improve our understanding of the restrictions imposed by glycans in eliciting VRC01-class bnAbs and enable a neutralization-based strategy to monitor vaccine-elicited early precursors of this class of bnAbs.
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http://dx.doi.org/10.1371/journal.ppat.1007431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237427PMC
November 2018