Brief Communication: Magnetic Immuno-Detection of SARS-CoV-2 specific Antibodies

  1. Jan Pietschmann
  2. Nadja Vöpel
  3. Holger Spiegel
  4. Hans-Joachim Krause
  5. Florian Schröper

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Abstract

SARS-CoV-2 causes ongoing infections worldwide, and identifying people with immunity is becoming increasingly important. Available point-of-care diagnostic systems as lateral flow assays have high potential for fast and easy on-site antibody testing but are lacking specificity, sensitivity or possibility for quantitative measurements. Here, a new point-of-care approach for SARS-CoV-2 specific antibody detection in human serum based on magnetic immuno-detection is described and compared to standard ELISA. For magnetic immuno-detection, immunofiltration columns were coated with a SARS-CoV-2 spike protein peptide. SARS-CoV-2 peptide reactive antibodies, spiked at different concentrations into PBS and human serum, were rinsed through immunofiltration columns. Specific antibodies were retained within the IFC and labelled with an isotype specific biotinylated antibody. Streptavidin-functionalized magnetic nanoparticles were applied to label the secondary antibodies. Enriched magnetic nanoparticles were then detected by means of frequency magnetic mixing detection technology, using a portable magnetic read-out device. Measuring signals corresponded to the amount of SARS-CoV-2 specific antibodies in the sample. Our preliminary magnetic immuno-detection setup resulted in a higher sensitivity and broader detection range and was four times faster than ELISA. Further optimizations could reduce assay times to that of a typical lateral flow assay, enabling a fast and easy approach, well suited for point-of-care measurements without expensive lab equipment.

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  1. ScreenIT

    SciScore for 10.1101/2020.06.02.131102: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    High-binding 96-well microtiter plates (article number 655061) were purchased form Greiner Bio-One GmbH, Frickenhausen, Germany. 20-aminoacids SARS-CoV-2 spike protein peptide (article number ABIN1382273) derived from the intracellular portion of S2 region of S-protein and corresponding polyclonal rabbit anti-SARS-CoV-2 spike protein peptide specific antibody (article number ABIN1030641) were acquired from antibodies-online GmbH, Aachen, Germany.
    High-binding 96-well microtiter plates (article number 655061)
    suggested: None
    anti-SARS-CoV-2 spike protein peptide specific antibody (article number ABIN1030641) were acquired from antibodies-online GmbH, Aachen, Germany.
    suggested: None
    Biotin-SP (long spacer) AffiniPure Goat Anti-Rabbit IgG (biotinylated GaR secondary antibody), Fc fragment specific (article number 111-065-008) as well as Streptavidin-alkaline phosphatase (streptavidin-AP) (article number 016-050-084) were purchased from Jackson ImmunoResearch Europe Ltd. UK.
    Anti-Rabbit IgG
    suggested: (Jackson ImmunoResearch Labs Cat# 111-065-008, RRID:AB_2337961)
    Streptavidin-alkaline phosphatase (streptavidin-AP) (article number 016-050-084)
    suggested: None
    Streptavidin-functionalized magnetic particles with a hydrodynamic diameter of 70 nm (synomag®-D, article number 104-19-701) were purchased from micromod Partikeltechnologie GmbH, Rostock, Germany. 2.2 ELISA Procedure: For ELISA-based SARS-CoV-2 specific antibody detection, all following incubation steps were performed at room temperature for 60 minutes unless stated otherwise.
    synomag®-D
    suggested: None
    While the sample was flushed through the IFC by gravity flow, SARS-CoV-2 specific antibodies were enriched within the matrix by specific binding to the coated antigen.
    SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    Data Analysis: For ELISA as well as for MInD, data were analyzed using GraphPad Prism 8.0.0, and fitting with a Hill slope was performed.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2020.06.02.131102v1 on bioRxiv