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Rak A, Matyushenko V, Prokopenko P, Kostromitina A, Polyakov D, Sokolov A, Rudenko L, Isakova-Sivak I. A novel immunofluorescent test system for SARS-CoV-2 detection in infected cells. PLoS One 2024; 19:e0304534. [PMID: 38820303 PMCID: PMC11142482 DOI: 10.1371/journal.pone.0304534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/14/2024] [Indexed: 06/02/2024] Open
Abstract
Highly variable pandemic coronavirus SARS-CoV-2, which causes the hazardous COVID-19 infection, has been persistent in the human population since late 2019. A prompt assessment of individual and herd immunity against the infection can be accomplished by using rapid tests to determine antiviral antibody levels. The microneutralization assay (MN) is one of the most widely used diagnostic methods that has been proposed to assess the qualitative and quantitative characteristics of virus-specific humoral immunity in COVID-19 convalescents or vaccine recipients. However, some aspects of the assay, such as sensitivity and time cost, need improvement. Here, we developed an express test, which may be potentially used in clinical practice for the assessment of serum-caused SARS-CoV-2 inhibition in infected cell cultures. It implies the detection and counting of coronaviral fluorescent-forming units (FFU) and includes two sequentially used developing components: biotinylated mouse monoclonal antibodies against the recombinant N protein of SARS-CoV-2 (B.1) and the recombinant EGFP-streptavidin fusion protein. Due to the universal specificity of the antibodies, our analytical tool is suitable for the detection of various strains of SARS-CoV-2 when determining both the infectious titer of viruses and the titer of serum virus-neutralizing antibodies. The developed two-component test system is characterized by high sensitivity, a reduced number of analytic stages and low assay cost, as well as by flexibility, since it may be modified for detection of other pathogens using the appropriate antibodies.
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Affiliation(s)
- Alexandra Rak
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Victoria Matyushenko
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Polina Prokopenko
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Arina Kostromitina
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Dmitry Polyakov
- Department of Molecular Genetics, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Alexey Sokolov
- Department of Molecular Genetics, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Larisa Rudenko
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
| | - Irina Isakova-Sivak
- Department of Virology, Institute of Experimental Medicine, St. Petersburg, Russian Federation
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2
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Sun Y, Huang W, Xiang H, Nie J. SARS-CoV-2 Neutralization Assays Used in Clinical Trials: A Narrative Review. Vaccines (Basel) 2024; 12:554. [PMID: 38793805 PMCID: PMC11125816 DOI: 10.3390/vaccines12050554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/09/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Since the emergence of COVID-19, extensive research efforts have been undertaken to accelerate the development of multiple types of vaccines to combat the pandemic. These include inactivated, recombinant subunit, viral vector, and nucleic acid vaccines. In the development of these diverse vaccines, appropriate methods to assess vaccine immunogenicity are essential in both preclinical and clinical studies. Among the biomarkers used in vaccine evaluation, the neutralizing antibody level serves as a pivotal indicator for assessing vaccine efficacy. Neutralizing antibody detection methods can mainly be classified into three types: the conventional virus neutralization test, pseudovirus neutralization test, and surrogate virus neutralization test. Importantly, standardization of these assays is critical for their application to yield results that are comparable across different laboratories. The development and use of international or regional standards would facilitate assay standardization and facilitate comparisons of the immune responses induced by different vaccines. In this comprehensive review, we discuss the principles, advantages, limitations, and application of different SARS-CoV-2 neutralization assays in vaccine clinical trials. This will provide guidance for the development and evaluation of COVID-19 vaccines.
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Affiliation(s)
- Yeqing Sun
- School of Life Sciences, Jilin University, Changchun 130012, China;
- Division of HIV/AIDS and Sex-Transmitted Virus Vaccines, National Institutes for Food and Drug Control, State Key Laboratory of Drug Regulatory Science, NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Beijing 102629, China;
| | - Weijin Huang
- Division of HIV/AIDS and Sex-Transmitted Virus Vaccines, National Institutes for Food and Drug Control, State Key Laboratory of Drug Regulatory Science, NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Beijing 102629, China;
| | - Hongyu Xiang
- School of Life Sciences, Jilin University, Changchun 130012, China;
| | - Jianhui Nie
- Division of HIV/AIDS and Sex-Transmitted Virus Vaccines, National Institutes for Food and Drug Control, State Key Laboratory of Drug Regulatory Science, NHC Key Laboratory of Research on Quality and Standardization of Biotech Products, NMPA Key Laboratory for Quality Research and Evaluation of Biological Products, Beijing 102629, China;
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3
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O’Reilly S, Kenny G, Alrawahneh T, Francois N, Gu L, Angeliadis M, de Masson d’Autume V, Garcia Leon A, Feeney ER, Yousif O, Cotter A, de Barra E, Horgan M, Mallon PWG, Gautier V. Development of a novel medium throughput flow-cytometry based micro-neutralisation test for SARS-CoV-2 with applications in clinical vaccine trials and antibody screening. PLoS One 2023; 18:e0294262. [PMID: 38033116 PMCID: PMC10688860 DOI: 10.1371/journal.pone.0294262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
Quantifying neutralising capacity of circulating SARS-COV-2 antibodies is critical in evaluating protective humoral immune responses generated post-infection/post-vaccination. Here we describe a novel medium-throughput flow cytometry-based micro-neutralisation test to evaluate Neutralising Antibody (NAb) responses against live SARS-CoV-2 Wild Type and Variants of Concern (VOC) in convalescent/vaccinated populations. Flow Cytometry-Based Micro-Neutralisation Test (Micro-NT) was performed in 96-well plates using clinical isolates WT-B, WT-B.1.177.18 and/or VOCs Beta and Omicron. Plasma samples (All Ireland Infectious Diseases (AIID) Cohort) were serially diluted (8 points, half-log) from 1:20 and pre-incubated with SARS-CoV-2 (1h, 37°C). Virus-plasma mixture were added onto Vero E6 or Vero E6/TMPRSS2 cells for 18h. Percentage infected cells was analysed by automated flow cytometry following trypsinisation, fixation and SARS-CoV-2 Nucleoprotein intracellular staining. Half-maximal Neutralisation Titres (NT50) were determined using non-linear regression. Our assay was compared to Plaque Reduction Neutralisation Test (PRNT) and validated against the First WHO International Standard for anti-SARS-CoV-2 immunoglobulin. Both Micro-NT and PRNT achieved comparable NT50 values. Further validation showed adequate correlation with PRNT using a panel of secondary standards of clinical convalescent and vaccinated plasma samples. We found the assay to be reproducible through measuring both repeatability and intermediate precision. Screening 190 convalescent samples and 11 COVID-19 naive controls (AIID cohort) we demonstrated that Micro-NT has broad dynamic range differentiating NT50s <1/20 to >1/5000. We could also characterise immune-escape VOC Beta and Omicron BA.5, achieving fold-reductions in neutralising capacity similar to those published. Our flow cytometry-based Micro-NT is a robust and reliable assay to quantify NAb titres, and has been selected as an endpoint in clinical trials.
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Affiliation(s)
- Sophie O’Reilly
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Grace Kenny
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
- Department of Infectious Diseases, St Vincent’s University Hospital, Elm Park, Dublin, Ireland
| | - Tamara Alrawahneh
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Nathan Francois
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Lili Gu
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Matthew Angeliadis
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Valentin de Masson d’Autume
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Alejandro Garcia Leon
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
| | - Eoin R. Feeney
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
- Department of Infectious Diseases, St Vincent’s University Hospital, Elm Park, Dublin, Ireland
| | - Obada Yousif
- Endocrinology Department, Wexford General Hospital, Carricklawn, Wexford, Ireland
| | - Aoife Cotter
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
- Department of Infectious Diseases, Mater Misericordiae University Hospital, Eccles St, Dublin, Ireland
| | - Eoghan de Barra
- Department of Infectious Diseases, Beaumont Hospital, Beaumont, Dublin, Ireland
- Department of International Health and Tropical Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Mary Horgan
- Department of Infectious Diseases, Cork University Hospital, Wilton, Cork, Ireland
| | - Patrick W. G. Mallon
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
- Department of Infectious Diseases, St Vincent’s University Hospital, Elm Park, Dublin, Ireland
| | - Virginie Gautier
- Centre for Experimental Pathogen Host Research (CEPHR), University College Dublin, Belfield, Dublin, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin, Ireland
- Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Belfield, Dublin 4, Ireland
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Hansen LG, Larsen LE, Rasmussen TB, Miar Y, Lassuniére R, Jørgensen CS, Ryt-Hansen P. Investigation of the SARS-CoV-2 post-vaccination antibody response in Canadian farmed mink. Vaccine 2023; 41:7387-7394. [PMID: 37932134 DOI: 10.1016/j.vaccine.2023.10.073] [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: 08/10/2023] [Revised: 10/28/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023]
Abstract
Currently, SARS-CoV-2 have been detected in farmed mink in 13 different countries. Due to the high susceptibility and transmissibility among mink, great concerns of mink serving as a reservoir to generate novel variants with unknown virulence and antigenic properties arose. These concerns have consequently resulted in entire mink productions being culled and banned. This study investigates the post-vaccination antibody response in the Canadian farmed mink vaccinated with a commercial Index spike protein-based vaccine, approved for use in cats, and compares the antibody response to that observed post infection in Danish farmed mink. Blood samples were obtained from 50 mink at the Canadian Centre for Fur Animal Research (CCFAR), Dalhousie University (Truro, Canada). The sera were initially analyzed for antibodies by enzyme-linked immunosorbent assay (ELISA), and selected sera was subsequently tested in a virus neutralization tests. The levels of neutralizing antibodies were evaluated for an ancestral D614G strain and a recent circulating SARS-CoV-2 variant of concern (Omicron BA.4). The results revealed that the vaccine induced a strong antibody response in mink by reaching antibody titer levels of up to 1:12800 in the ELISA. Moreover, high levels of neutralizing antibodies were obtained, and despite the great level of genetic differences between the ancestral and Omicron BA.4 strains, the vaccinated mink showed high levels of cross-reacting neutralizing antibodies. Interestingly, the antibody levels towards SARS-CoV-2 in the Canadian vaccinated mink were significantly higher than observed in recently SARS-CoV-2 infected Danish mink and equal to anamnestic responses following re-infection. In conclusion, the vaccine used in the Canadian farmed mink was able to induce a strong and broad-reacting antibody response in mink, which could limit the spread of SARS-CoV-2 in farmed mink and thereby reduce the risk of mink serving as a SARS-CoV-2 reservoir for human infections.
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Affiliation(s)
- Line Gram Hansen
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark.
| | - Lars Erik Larsen
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark.
| | | | - Younes Miar
- Haley Institute of Animal Science and Aquaculture 100-A, Dalhousie University, Faculty of Agriculture, 58 Sipu Awti, Truro, NS, Canada.
| | - Ria Lassuniére
- Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
| | | | - Pia Ryt-Hansen
- Dpt. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 2, DK-1870 Frederiksberg C, Denmark.
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Lassaunière R, Polacek C, Linnea Tingstedt J, Fomsgaard A. Preclinical evaluation of a SARS-CoV-2 variant B.1.351-based candidate DNA vaccine. Vaccine 2023; 41:6505-6513. [PMID: 37726179 DOI: 10.1016/j.vaccine.2023.09.021] [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: 03/29/2023] [Revised: 07/22/2023] [Accepted: 09/12/2023] [Indexed: 09/21/2023]
Abstract
The SARS-CoV-2 pandemic revealed the critical shortfalls of global vaccine availability for emergent pathogens and the need for exploring additional vaccine platforms with rapid update potential in response to new variants. Thus, it remains essential, for the present evolving SARS-CoV-2/Covid-19 and future pandemics, to continuously develop and characterize new and different vaccine platforms. Here, we describe an expression-optimized DNA vaccine candidate based on the SARS-CoV-2 spike protein of the Beta variant (B.1.351), pNTC-Spike.351, and, in animal models, compare its immunogenicity with a similar DNA vaccine encoding the ancestral index strain spike protein, pNTC-Spike. Both DNA vaccines induced neutralizing antibodies and a Th1 biased immune response. In contrast to the index-specific vaccine, the Beta-specific DNA vaccine induced antibodies in mice and rabbits that, even at low levels, efficiently neutralize the otherwise antibody resistant Beta variant. It similarly neutralized unrelated variants bearing the neutralization resistant E484K spike mutation. Intensive priming using two vaccinations with pNTC-Spike and a single booster immunization with the pNTC-Spike.351 induced a more robust neutralizing antibody response with comparable magnitude against different variants of concern. Thus, DNA vaccine technology with heterologous spike protein prime-boost should be explored further using the Beta derived pNTC-Spike.351 to broaden neutralizing antibody responses against emerging variants of concern.
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Affiliation(s)
- Ria Lassaunière
- Department of Virus and Microbiological Special Diagnostic, Statens Serum Institut, Copenhagen, Denmark
| | - Charlotta Polacek
- Department of Virus and Microbiological Special Diagnostic, Statens Serum Institut, Copenhagen, Denmark
| | - Jeanette Linnea Tingstedt
- Department of Virus and Microbiological Special Diagnostic, Statens Serum Institut, Copenhagen, Denmark
| | - Anders Fomsgaard
- Department of Virus and Microbiological Special Diagnostic, Statens Serum Institut, Copenhagen, Denmark; Infectious Disease Research Unit, Clinical Institute, University of Southern Denmark, Odense, Denmark.
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6
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Frische A, Gunalan V, Krogfelt KA, Fomsgaard A, Lassaunière R. A Candidate DNA Vaccine Encoding the Native SARS-CoV-2 Spike Protein Induces Anti-Subdomain 1 Antibodies. Vaccines (Basel) 2023; 11:1451. [PMID: 37766128 PMCID: PMC10535225 DOI: 10.3390/vaccines11091451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/25/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023] Open
Abstract
The ideal vaccine against viral infections should elicit antibody responses that protect against divergent strains. Designing broadly protective vaccines against SARS-CoV-2 and other divergent viruses requires insight into the specific targets of cross-protective antibodies on the viral surface protein(s). However, unlike therapeutic monoclonal antibodies, the B-cell epitopes of vaccine-induced polyclonal antibody responses remain poorly defined. Here we show that, through the combination of neutralizing antibody functional responses with B-cell epitope mapping, it is possible to identify unique antibody targets associated with neutralization breadth. The polyclonal antibody profiles of SARS-CoV-2 index-strain-vaccinated rabbits that demonstrated a low, intermediate, or high neutralization efficiency of different SARS-CoV-2 variants of concern (VOCs) were distinctly different. Animals with an intermediate and high cross-neutralization of VOCs targeted fewer antigenic sites on the spike protein and targeted one particular epitope, subdomain 1 (SD1), situated outside the receptor binding domain (RBD). Our results indicate that a targeted functional antibody response and an additional focus on non-RBD epitopes could be effective for broad protection against different SARS-CoV-2 variants. We anticipate that the approach taken in this study can be applied to other viral vaccines for identifying future epitopes that confer cross-neutralizing antibody responses, and that our findings will inform a rational vaccine design for SARS-CoV-2.
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Affiliation(s)
- Anders Frische
- Department of Virus & Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen, Denmark; (A.F.); (V.G.); (K.A.K.); (A.F.)
- Section of Molecular and Medicinal Biology, Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Vithiagaran Gunalan
- Department of Virus & Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen, Denmark; (A.F.); (V.G.); (K.A.K.); (A.F.)
| | - Karen Angeliki Krogfelt
- Department of Virus & Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen, Denmark; (A.F.); (V.G.); (K.A.K.); (A.F.)
- Section of Molecular and Medicinal Biology, Department of Science and Environment, Roskilde University, 4000 Roskilde, Denmark
| | - Anders Fomsgaard
- Department of Virus & Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen, Denmark; (A.F.); (V.G.); (K.A.K.); (A.F.)
- Infectious Diseases Unit, Clinical Institute, University of Southern Denmark, 5230 Odense, Denmark
| | - Ria Lassaunière
- Department of Virus & Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen, Denmark; (A.F.); (V.G.); (K.A.K.); (A.F.)
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High titers of neutralizing SARS-CoV-2 antibodies six months after symptom onset are associated with increased severity in COVID-19 hospitalized patients. Virol J 2023; 20:14. [PMID: 36698135 PMCID: PMC9875770 DOI: 10.1186/s12985-023-01974-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 01/20/2023] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Viral shedding and neutralizing antibody (NAb) dynamics among patients hospitalized with severe coronavirus disease 2019 (COVID-19) and immune correlates of protection have been key questions throughout the pandemic. We investigated the duration of reverse transcriptase-polymerase chain reaction (RT-PCR) positivity, infectious viral shedding and NAb titers as well as the association between NAb titers and disease severity in hospitalized COVID-19 patients in Denmark 2020-2021. MATERIALS AND METHODS Prospective single-center observational cohort study of 47 hospitalized COVID-19 patients. Oropharyngeal swabs were collected at eight time points during the initial 30 days of inclusion. Serum samples were collected after a median time of 7 (IQR 5 - 10), 37 (IQR 35 - 38), 97 (IQR 95 - 100), and 187 (IQR 185 - 190) days after symptom onset. NAb titers were determined by an in-house live virus microneutralization assay. Viral culturing was performed in Vero E6 cells. RESULTS Patients with high disease severity had higher mean log2 NAb titers at day 37 (1.58, 95% CI [0.34 -2.81]), 97 (2.07, 95% CI [0.53-3.62]) and 187 (2.49, 95% CI [0.20- 4.78]) after symptom onset, compared to patients with low disease severity. Peak viral load (0.072, 95% CI [- 0.627 - 0.728]), expressed as log10 SARS-CoV-2 copies/ml, was not associated with disease severity. Virus cultivation attempts were unsuccessful in almost all (60/61) oropharyngeal samples collected shortly after hospital admission. CONCLUSIONS We document an association between high disease severity and high mean NAb titers at days 37, 97 and 187 after symptom onset. However, peak viral load during admission was not associated with disease severity. TRIAL REGISTRATION The study is registered at https://clinicaltrials.gov/ (NCT05274373).
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Valdovino-Navarro BJ, Dueñas S, Flores-Acosta GI, Gasperin-Bulbarela J, Bernaldez-Sarabia J, Cabanillas-Bernal O, Cervantes-Luevano KE, Licea-Navarro AF. Neutralizing Ability of a Single Domain VNAR Antibody: In Vitro Neutralization of SARS-CoV-2 Variants of Concern. Int J Mol Sci 2022; 23:ijms232012267. [PMID: 36293124 PMCID: PMC9603574 DOI: 10.3390/ijms232012267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
Severe Acute Respiratory Syndrome Coronavirus 2 is the causal pathogen of coronavirus disease 2019 (COVID-19). The emergence of new variants with different mutational patterns has limited the therapeutic options available and complicated the development of effective neutralizing antibodies targeting the spike (S) protein. Variable New Antigen Receptors (VNARs) constitute a neutralizing antibody technology that has been introduced into the list of possible therapeutic options against SARS-CoV-2. The unique qualities of VNARs, such as high affinities for target molecules, capacity for paratope reformatting, and relatively high stability, make them attractive molecules to counteract the emerging SARS-CoV-2 variants. In this study, we characterized a VNAR antibody (SP240) that was isolated from a synthetic phage library of VNAR domains. In the phage display, a plasma with high antibody titers against SARS-CoV-2 was used to selectively displace the VNAR antibodies bound to the antigen SARS-CoV-2 receptor binding domain (RBD). In silico data suggested that the SP240 binding epitopes are located within the ACE2 binding interface. The neutralizing ability of SP240 was tested against live Delta and Omicron SARS-CoV-2 variants and was found to clear the infection of both variants in the lung cell line A549-ACE2-TMPRSS2. This study highlights the potential of VNARs to act as neutralizing antibodies against emerging SARS-CoV-2 variants.
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