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.
Abstract Although cytokine therapies have demonstrated curative effects in some cancer patients, clinical use remains limited due to undesired toxicity profiles accompanying systemic administration. Next generation cytokine approaches include conditional signaling focused on sites of interest, such as the tumor microenvironment or specific immune cell populations. Here, we share a novel approach for generating detuned cytokine therapeutic candidates using the AlphaSeq platform, which involves the re-engineering of yeast agglutination and mating to quantitatively measure protein-protein interactions at a library-on-library scale. Engineering interferon-alpha (IFNα) and interleukin-21 (IL-21), we show how AlphaSeq measures cytokine-receptor interactions and identifies cytokine variants with a broad range of affinities. A saturated mutational library was created for IFNα and IL-21and subsequently screened against a second library consisting of human IFNAR2 or human IL-21R, species orthologs and off-target receptors. AlphaSeq enabled identification of hundreds of detuned IFNα and IL-21 variants against both human and mouse receptors in parallel assays. Cytokine variants with lower affinity than parental IFNα or IL-21 were recombinantly expressed as Fc fusion proteins to orthogonally measure affinity with biolayer interferometry and characterize potency with an in vitro human PBMC phosflow assay, which showed strong correlation with AlphaSeq affinity measurements. Finally, detuned cytokine candidates were fused to anti-CD8 and other localizing antibodies to demonstrate cell population-specific signaling. Candidate molecules showed 1000-fold or greater potency in the targeted cell population than non-targeted populations. Our results show the AlphaSeq platform can accurately quantitate thousands of cytokine variant affinities simultaneously against multiple relevant receptors, enabling the selection of candidate immunocytokine antibody fusion proteins with targeted cell biased signaling. AlphaSeq’s rapid, comprehensive affinity determination is being used to develop clinically relevant IFNα and IL-21 therapeutic immunocytokines with accompanying preclinical data. Citation Format: Charles Lin, Colleen Shikany, Leah Homad, Jessica Fint, Ruchi Bansal, Davis Goodnight, Jeff Adamo, Danielle Van Citters, Ryan Swanson, Randolph Lopez. Selective IL-21 and IFN-alpha immunocytokines engineered using the AlphaSeq platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2477.
Integrating form and function for design Antibodies are broadly used in therapies and as research tools because they can be generated against a wide range of targets. Efficacy can often be increased by clustering antibodies in multivalent assemblies. Divine et al. designed antibody nanocages from two components: One is an antibody-binding homo-oligomic protein and the other is the antibody itself. Computationally designed proteins drive the assembly of antibody nanocages in a range of architectures, allowing control of the symmetry and the antibody valency. The multivalent display enhances antibody-dependent signaling, and nanocages displaying antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein effectively neutralize pseudovirus. Science , this issue p. eabd9994
Abstract 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.
ABSTRACT 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. IN BRIEF SARS-CoV-2 infection leads to expansion of diverse B cells clones against the viral spike glycoprotein (S). The antibodies bind S with high affinity despite being minimally mutated. Thus, the development of neutralizing antibody responses by vaccination will require the activation of certain naïve B cells without requiring extensive somatic mutation. Highlights Analysis of early B cell response to SARS-CoV-2 spike protein Most antibodies target non-neutralizing epitopes Potent neutralizing mAb blocks the interaction of the S protein with ACE2 Neutralizing antibodies are minimally mutated
Epstein-Barr virus (EBV) is a cancer-associated pathogen responsible for 165,000 deaths annually. EBV is also the etiological agent of infectious mononucleosis and is linked to multiple sclerosis and rheumatoid arthritis. Thus, an EBV vaccine would have a significant global health impact. EBV is orally transmitted and has tropism for epithelial and B cells. Therefore, a vaccine would need to prevent infection of both in the oral cavity. Passive transfer of monoclonal antibodies against the gH/gL glycoprotein complex prevent experimental EBV infection in humanized mice and rhesus macaques, suggesting that gH/gL is an attractive vaccine candidate. Here, we evaluate the immunogenicity of several gH/gL nanoparticle vaccines. All display superior immunogenicity relative to monomeric gH/gL. A nanoparticle displaying 60 copies of gH/gL elicits antibodies that protect against lethal EBV challenge in humanized mice, whereas antibodies elicited by monomeric gH/gL do not. These data motivate further development of gH/gL nanoparticle vaccines for EBV.
(Cell Reports 35, 109084-1–109084-15.e1–e8; May 4, 2021) In the originally published version of this paper, an incorrect version of Figure 6 was included. Data from two immunization groups were missing from Figures 6E, 6F, 6H, 6I, and 6J. The corrected version includes the missing data and combines Figures 6I and 6J into a single panel, Figure 6I. The original version appears here, and the corrected version appears here and with the paper online. The authors regret this error.Figure 6The bispecific iv4/iv9 molecule activates iGL-VRC01 B cells in vivo (original)View Large Image Figure ViewerDownload Hi-res image Download (PPT) Development of a VRC01-class germline targeting immunogen derived from anti-idiotypic antibodiesSeydoux et al.Cell ReportsMay 04, 2021In BriefSuccessful engagement of naive B cells that give rise to broadly neutralizing antibodies is thought to be key to a successful HIV-1 vaccine. In this study, Seydoux et al. present the characterization and assessment of anti-idiotypic antibodies targeting VRC01-class B cell precursors. Their results represent an alternative to non-envelope-derived immunogens. Full-Text PDF Open Access
Epstein-Barr virus (EBV) is associated with infectious mononucleosis, cancer, and multiple sclerosis. A vaccine that prevents infection and/or EBV-associated morbidity is an unmet need. The viral gH/gL glycoprotein complex is essential for infectivity, making it an attractive vaccine target. Here, we evaluate the immunogenicity of a gH/gL nanoparticle vaccine adjuvanted with the Sigma Adjuvant System (SAS) or a saponin/monophosphoryl lipid A nanoparticle (SMNP) in rhesus macaques. Formulation with SMNP elicits higher titers of neutralizing antibodies and more vaccine-specific CD4
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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