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Kassardjian A, Sun E, Sookhoo J, Muthuraman K, Boligan KF, Kucharska I, Rujas E, Jetha A, Branch DR, Babiuk S, Barber B, Julien JP. Modular adjuvant-free pan-HLA-DR-immunotargeting subunit vaccine against SARS-CoV-2 elicits broad sarbecovirus-neutralizing antibody responses. Cell Rep 2023; 42:112391. [PMID: 37053069 PMCID: PMC10067452 DOI: 10.1016/j.celrep.2023.112391] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/14/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023] Open
Abstract
Subunit vaccines typically require co-administration with an adjuvant to elicit protective immunity, adding development hurdles that can impede rapid pandemic responses. To circumvent the need for adjuvant in a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subunit vaccine, we engineer a thermostable immunotargeting vaccine (ITV) that leverages the pan-HLA-DR monoclonal antibody 44H10 to deliver the viral spike protein receptor-binding domain (RBD) to antigen-presenting cells. X-ray crystallography shows that 44H10 binds to a conserved epitope on HLA-DR, providing the basis for its broad HLA-DR reactivity. Adjuvant-free ITV immunization in rabbits and ferrets induces robust anti-RBD antibody responses that neutralize SARS-CoV-2 variants of concern and protect recipients from SARS-CoV-2 challenge. We demonstrate that the modular nature of the ITV scaffold with respect to helper T cell epitopes and diverse RBD antigens facilitates broad sarbecovirus neutralization. Our findings support anti-HLA-DR immunotargeting as an effective means to induce strong antibody responses to subunit antigens without requiring an adjuvant.
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Affiliation(s)
- Audrey Kassardjian
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Eric Sun
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jamie Sookhoo
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB R3E 3M4, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
| | - Krithika Muthuraman
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | | | - Iga Kucharska
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Edurne Rujas
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain; Pharmacokinetic, Nanotechnology and Gene Therapy Group, Faculty of Pharmacy, University of the Basque Country UPV/EHU, 01006 Vitoria, Spain; Bioaraba, Microbiology, Infectious Disease, Antimicrobial Agents, and Gene Therapy, 01006 Vitoria, Spain
| | - Arif Jetha
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada
| | - Donald R Branch
- Canadian Blood Services, Keenan Research Centre, Toronto, ON M5B 1W8, Canada; University of Toronto, Departments of Medicine and Laboratory Medicine and Pathobiology, Toronto, ON M5S 1A8, Canada
| | - Shawn Babiuk
- Canadian Food Inspection Agency, National Centre for Foreign Animal Disease, Winnipeg, MB R3E 3M4, Canada; Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
| | - Brian Barber
- Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jean-Philippe Julien
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON M5G 0A4, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Ho J, MacDonald KS, Barber BH. Construction of recombinant targeting immunogens incorporating an HIV-1 neutralizing epitope into sites of differing conformational constraint. Vaccine 2002; 20:1169-80. [PMID: 11803079 DOI: 10.1016/s0264-410x(01)00441-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
2F5 is one of the very few monoclonal antibodies with the capacity to neutralize a wide spectrum of type 1 human immunodeficiency virus (HIV-1) strains and primary isolates. Constructing an immunogen that contains a conformational mimic of the epitope recognized by 2F5 could provide the means to induce a broadly neutralizing anti-HIV-1 antibody response. Thus, in an effort to create a targeted, adjuvant-independent immunogen able to induce a 2F5-like antibody response, the gp41 sequence recognized by 2F5 (ELDKWAS) was genetically incorporated into different regions of an antibody specific for a framework determinant on human leukocyte antigen (HLA)-DR. All constructs were expressed, secreted from Sf9 insect cells, and found to retain the anti-HLA-DR specificity of the parental antibody. Three of the four constructs in which the ELDKWAS sequence was incorporated into a beta-turn (BT)-like conformational site were recognized by the 2F5 antibody. In contrast, none of the five constructs with the same sequence incorporated into surface-exposed regions of helical turn had any detectable 2F5 reactivity. In addition to demonstrating the significant plasticity of several regions in the antibody molecule in terms of accepting foreign sequences without loss of expression or binding specificity, these results also suggest that the native epitope recognized by the 2F5 antibody may be more beta-turn-like than helical in conformation. Importantly, with respect to vaccine development, the 2F5-reactive antibody constructs represent candidate immunogens for the adjuvant-independent induction of an HIV-1, neutralizing 2F5-like antibody response in humans.
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Affiliation(s)
- Jason Ho
- Department of Immunology, Medical Sciences Building, 1 Kings College Circle, University of Toronto, Ont., M5S 1A8, Toronto, Canada
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Jelley-Gibbs DM, Plitnick LM, Gosselin EJ. Differences in IgG subclass do not effect immune complex-enhanced T cell activation despite differential binding to antigen presenting cells. Hum Immunol 1999; 60:469-78. [PMID: 10408796 DOI: 10.1016/s0198-8859(99)00023-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ag presentation to CD4 T cells is a critical event in the generation of protective immunity. IgG, in the form of IgG-pathogen (Ag) complexes, is capable of mediating FcgammaR-dependent Ag presentation, and thereby enhanced T cell activation. Therefore, it is important to understand the ability of the individual human IgG subclasses to function in enhanced T cell activation. We hypothesized that increased delivery of Ag to monocyte FcgammaR by high affinity human IgG subclasses, IgG1 and IgG3, would lead to increased Ag presentation, as compared to low affinity IgG subclasses, IgG2 and IgG4. To create immune complexes, we linked biotinylated IgG subclasses to biotinylated Ag via an avidin bridge, and examined T cell responses to them. Although IgG2- and IgG4-Ag complexes bound to monocytes at significantly lower levels than those made with IgG1 and IgG3, we observed no significant difference in the ability of the four human IgG subclasses to mediate enhanced T cell activation. Studies suggest the explanation for this dichotomy lies within the first 24 h of Ag processing, and that processing efficiency may vary with IgG subclass. They also suggest the existence of a highly efficient, and selective processing pathway, which is dependent on IgG subclass, and can compensate for low level production and FcgammaR binding of IgG2- and IgG4-Ag complexes.
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Affiliation(s)
- D M Jelley-Gibbs
- Department of Microbiology, Immunology, and Molecular Genetics, Albany Medical College, NY 12208, USA
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