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Stocks BB, Thibeault MP, L'Abbé D, Umer M, Liu Y, Stuible M, Durocher Y, Melanson JE. Characterization of biotinylated human ACE2 and SARS-CoV-2 Omicron BA.4/5 spike protein reference materials. Anal Bioanal Chem 2024:10.1007/s00216-024-05413-7. [PMID: 38942955 DOI: 10.1007/s00216-024-05413-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/14/2024] [Accepted: 06/18/2024] [Indexed: 06/30/2024]
Abstract
Accurate diagnostic and serology assays are required for the continued management of the COVID-19 pandemic yet spike protein mutations and intellectual property concerns with antigens and antibodies used in various test kits render comparability assessments difficult. As the use of common, well-characterized reagents can help address this lack of standardization, the National Research Council Canada has produced two protein reference materials (RMs) for use in SARS-CoV-2 serology assays: biotinylated human angiotensin-converting enzyme 2 RM, ACE2-1, and SARS-CoV-2 Omicron BA.4/5 spike protein RM, OMIC-1. Reference values were assigned through a combination of amino acid analysis via isotope dilution liquid chromatography tandem mass spectrometry following acid hydrolysis, and ultraviolet-visible (UV-Vis) spectrophotometry at 280 nm. Vial-to-vial homogeneity was established using UV-Vis measurements, and protein oligomeric status, monitored by size exclusion liquid chromatography (LC-SEC), was used to evaluate transportation, storage, and freeze-thaw stabilities. The molar protein concentration in ACE2-1 was 25.3 ± 1.7 µmol L-1 (k = 2, 95% CI) and consisted almost exclusively (98%) of monomeric ACE2, while OMIC-1 contained 5.4 ± 0.5 µmol L-1 (k = 2) spike protein in a mostly (82%) trimeric form. Glycoprotein molar mass determination by LC-SEC with multi-angle light scattering detection facilitated calculation of corresponding mass concentrations. To confirm protein functionality, the binding of OMIC-1 to immobilized ACE2-1 was investigated with surface plasmon resonance and the resulting dissociation constant, KD ~ 4.4 nM, was consistent with literature values.
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Affiliation(s)
- Bradley B Stocks
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada.
| | - Marie-Pier Thibeault
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Denis L'Abbé
- Human Health Therapeutics, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Muhammad Umer
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Yali Liu
- Human Health Therapeutics, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Matthew Stuible
- Human Health Therapeutics, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Yves Durocher
- Human Health Therapeutics, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Jeremy E Melanson
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
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2
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Stuible M, Schrag JD, Sheff J, Zoubchenok D, Lord-Dufour S, Cass B, L'Abbé D, Pelletier A, Rossotti MA, Tanha J, Gervais C, Maurice R, El Bakkouri M, Acchione M, Durocher Y. Influence of variant-specific mutations, temperature and pH on conformations of a large set of SARS-CoV-2 spike trimer vaccine antigen candidates. Sci Rep 2023; 13:16498. [PMID: 37779126 PMCID: PMC10543594 DOI: 10.1038/s41598-023-43661-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 09/27/2023] [Indexed: 10/03/2023] Open
Abstract
SARS-CoV-2 subunit vaccines continue to be the focus of intense clinical development worldwide. Protein antigens in these vaccines most commonly consist of the spike ectodomain fused to a heterologous trimerization sequence, designed to mimic the compact, prefusion conformation of the spike on the virus surface. Since 2020, we have produced dozens of such constructs in CHO cells, consisting of spike variants with different mutations fused to different trimerization sequences. This set of constructs displayed notable conformational heterogeneity, with two distinct trimer species consistently detected by analytical size exclusion chromatography. A recent report showed that spike ectodomain fusion constructs can adopt an alternative trimer conformation consisting of loosely associated ectodomain protomers. Here, we applied multiple biophysical and immunological techniques to demonstrate that this alternative conformation is formed to a significant extent by several SARS-CoV-2 variant spike proteins. We have also examined the influence of temperature and pH, which can induce inter-conversion of the two forms. The substantial structural differences between these trimer types may impact their performance as vaccine antigens.
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Affiliation(s)
- Matthew Stuible
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Joseph D Schrag
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Joey Sheff
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Daria Zoubchenok
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Simon Lord-Dufour
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Brian Cass
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Denis L'Abbé
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Alex Pelletier
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Martin A Rossotti
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Jamshid Tanha
- Human Health Therapeutics Research Centre, National Research Council Canada, Ottawa, ON, Canada
| | - Christian Gervais
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Roger Maurice
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Majida El Bakkouri
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Mauro Acchione
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Yves Durocher
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada.
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3
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Pflumm D, Seidel A, Klein F, Groß R, Krutzke L, Kochanek S, Kroschel J, Münch J, Stifter K, Schirmbeck R. Heterologous DNA-prime/protein-boost immunization with a monomeric SARS-CoV-2 spike antigen redundantizes the trimeric receptor-binding domain structure to induce neutralizing antibodies in old mice. Front Immunol 2023; 14:1231274. [PMID: 37753087 PMCID: PMC10518615 DOI: 10.3389/fimmu.2023.1231274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/09/2023] [Indexed: 09/28/2023] Open
Abstract
A multitude of alterations in the old immune system impair its functional integrity. Closely related, older individuals show, for example, a reduced responsiveness to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccines. However, systematic strategies to specifically improve the efficacy of vaccines in the old are missing or limited to simple approaches like increasing the antigen concentration or injection frequencies. We here asked whether the intrinsic, trimeric structure of the SARS-CoV-2 spike (S) antigen and/or a DNA- or protein-based antigen delivery platform affects priming of functional antibody responses particularly in old mice. The used S-antigens were primarily defined by the presence/absence of the membrane-anchoring TM domain and the closely interlinked formation/non-formation of a trimeric structure of the receptor binding domain (S-RBD). Among others, we generated vectors expressing prefusion-stabilized, cell-associated (TM+) trimeric "S2-P" or secreted (TM-) monomeric "S6-PΔTM" antigens. These proteins were produced from vector-transfected HEK-293T cells under mild conditions by Strep-tag purification, revealing that cell-associated but not secreted S proteins tightly bound Hsp73 and Grp78 chaperones. We showed that both, TM-deficient S6-PΔTM and full-length S2-P antigens elicited very similar S-RBD-specific antibody titers and pseudovirus neutralization activities in young (2-3 months) mice through homologous DNA-prime/DNA-boost or protein-prime/protein-boost vaccination. The trimeric S2-P antigen induced high S-RBD-specific antibody responses in old (23-24 months) mice through DNA-prime/DNA-boost vaccination. Unexpectedly, the monomeric S6-PΔTM antigen induced very low S-RBD-specific antibody titers in old mice through homologous DNA-prime/DNA-boost or protein-prime/protein-boost vaccination. However, old mice efficiently elicited an S-RBD-specific antibody response after heterologous DNA-prime/protein-boost immunization with the S6-PΔTM antigen, and antibody titers even reached similar levels and neutralizing activities as in young mice and also cross-reacted with different S-variants of concern. The old immune system thus distinguished between trimeric and monomeric S protein conformations: it remained antigen responsive to the trimeric S2-P antigen, and a simple change in the vaccine delivery regimen was sufficient to unleash its reactivity to the monomeric S6-PΔTM antigen. This clearly shows that both the antigen structure and the delivery platform are crucial to efficiently prime humoral immune responses in old mice and might be relevant for designing "age-adapted" vaccine strategies.
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Affiliation(s)
- Dominik Pflumm
- Department of Internal Medicine I, University Hospital of Ulm, Ulm, Germany
| | - Alina Seidel
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Fabrice Klein
- Department of Gene Therapy, University Hospital of Ulm, Ulm, Germany
| | - Rüdiger Groß
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Lea Krutzke
- Department of Gene Therapy, University Hospital of Ulm, Ulm, Germany
| | - Stefan Kochanek
- Department of Gene Therapy, University Hospital of Ulm, Ulm, Germany
| | - Joris Kroschel
- Institute of Clinical Chemistry, Ulm University Medical Center, Ulm, Germany
| | - Jan Münch
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Katja Stifter
- Department of Internal Medicine I, University Hospital of Ulm, Ulm, Germany
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4
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Alpuche-Lazcano SP, Stuible M, Akache B, Tran A, Kelly J, Hrapovic S, Robotham A, Haqqani A, Star A, Renner TM, Blouin J, Maltais JS, Cass B, Cui K, Cho JY, Wang X, Zoubchenok D, Dudani R, Duque D, McCluskie MJ, Durocher Y. Preclinical evaluation of manufacturable SARS-CoV-2 spike virus-like particles produced in Chinese Hamster Ovary cells. COMMUNICATIONS MEDICINE 2023; 3:116. [PMID: 37612423 PMCID: PMC10447459 DOI: 10.1038/s43856-023-00340-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 07/25/2023] [Indexed: 08/25/2023] Open
Abstract
BACKGROUND As the COVID-19 pandemic continues to evolve, novel vaccines need to be developed that are readily manufacturable and provide clinical efficacy against emerging SARS-CoV-2 variants. Virus-like particles (VLPs) presenting the spike antigen at their surface offer remarkable benefits over other vaccine antigen formats; however, current SARS-CoV-2 VLP vaccines candidates in clinical development suffer from challenges including low volumetric productivity, poor spike antigen density, expression platform-driven divergent protein glycosylation and complex upstream/downstream processing requirements. Despite their extensive use for therapeutic protein manufacturing and proven ability to produce enveloped VLPs, Chinese Hamster Ovary (CHO) cells are rarely used for the commercial production of VLP-based vaccines. METHODS Using CHO cells, we aimed to produce VLPs displaying the full-length SARS-CoV-2 spike. Affinity chromatography was used to capture VLPs released in the culture medium from engineered CHO cells expressing spike. The structure, protein content, and glycosylation of spikes in VLPs were characterized by several biochemical and biophysical methods. In vivo, the generation of neutralizing antibodies and protection against SARS-CoV-2 infection was tested in mouse and hamster models. RESULTS We demonstrate that spike overexpression in CHO cells is sufficient by itself to generate high VLP titers. These VLPs are evocative of the native virus but with at least three-fold higher spike density. In vivo, purified VLPs elicit strong humoral and cellular immunity at nanogram dose levels which grant protection against SARS-CoV-2 infection. CONCLUSIONS Our results show that CHO cells are amenable to efficient manufacturing of high titers of a potently immunogenic spike protein-based VLP vaccine antigen.
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Affiliation(s)
- Sergio P Alpuche-Lazcano
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Matthew Stuible
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Bassel Akache
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Anh Tran
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - John Kelly
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Dr, Ottawa, ON, K1A 0R6, Canada
| | - Sabahudin Hrapovic
- Aquatic and Crop Resources Development Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Anna Robotham
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Dr, Ottawa, ON, K1A 0R6, Canada
| | - Arsalan Haqqani
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Dr, Ottawa, ON, K1A 0R6, Canada
| | - Alexandra Star
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Dr, Ottawa, ON, K1A 0R6, Canada
| | - Tyler M Renner
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Julie Blouin
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Jean-Sébastien Maltais
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Brian Cass
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Kai Cui
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9, Canada
| | - Jae-Young Cho
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9, Canada
| | - Xinyu Wang
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9, Canada
| | - Daria Zoubchenok
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada
| | - Renu Dudani
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Diana Duque
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Michael J McCluskie
- Human Health Therapeutics Research Centre, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Yves Durocher
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC, H4P 2R2, Canada.
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5
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Stocks BB, Thibeault MP, L’Abbé D, Stuible M, Durocher Y, Melanson JE. Production and Characterization of a SARS-CoV-2 Nucleocapsid Protein Reference Material. ACS MEASUREMENT SCIENCE AU 2022; 2:620-628. [PMID: 36785774 PMCID: PMC9662649 DOI: 10.1021/acsmeasuresciau.2c00050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 05/02/2023]
Abstract
Rapid antigen tests have become a widely used COVID-19 diagnostic tool with demand accelerating in response to the highly contagious SARS-CoV-2 Omicron variant. Hundreds of such test kits are approved for use worldwide, predominantly reporting on the presence of the viral nucleocapsid (N) protein, yet the comparability among manufacturers remains unclear and the need for reference standards is recognized. To address this lack of standardization, the National Research Council Canada has developed a SARS-CoV-2 nucleocapsid protein reference material solution, NCAP-1. Reference value determination for N protein content was realized by amino acid analysis (AAA) via double isotope dilution liquid chromatography-tandem mass spectrometry (LC-ID-MS/MS) following acid hydrolysis of the protein, in conjunction with UV spectrophotometry based on tryptophan and tyrosine absorbance at 280 nm. The homogeneity of the material was established through spectrophotometric absorbance readings at 280 nm. The molar concentration of the N protein in NCAP-1 was 10.0 ± 1.9 μmol L-1 (k = 2, 95% confidence interval). Reference mass concentration and mass fraction values were subsequently calculated using the protein molecular weight and density of the NCAP-1 solution. Changes to protein higher-order structure, probed by size-exclusion liquid chromatography (LC-SEC) with UV detection, were used to evaluate transportation and storage stabilities. LC-SEC revealed nearly 90% of the N protein in the material is present as a mixture of hexamers and tetramers. The remaining low molecular weight species (<30 kDa) were interrogated by top-down mass spectrometry and determined to be autolysis products homologous to those previously documented for N protein of the original SARS-CoV [Biochem. Biophys. Res. Commun.2008t, 377, 429-433].
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Affiliation(s)
- Bradley B. Stocks
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
| | - Marie-Pier Thibeault
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
| | - Denis L’Abbé
- Human
Health Therapeutics, National Research Council
Canada, 6100 Royalmount
Avenue, Montreal, QC H4P 2R2, Canada
| | - Matthew Stuible
- Human
Health Therapeutics, National Research Council
Canada, 6100 Royalmount
Avenue, Montreal, QC H4P 2R2, Canada
| | - Yves Durocher
- Human
Health Therapeutics, National Research Council
Canada, 6100 Royalmount
Avenue, Montreal, QC H4P 2R2, Canada
| | - Jeremy E. Melanson
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
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