Development of an Optical Assay to Detect SARS-CoV-2 Spike Protein Binding Interactions with ACE2 and Disruption of these Interactions Using Electric Current

  1. Mahmoud Al Ahmad
  2. Farah Mustafa
  3. Neena Panicker
  4. Tahir A. Rizvi

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Abstract

This study proposes a novel optical method of detecting and reducing SARS-CoV-2 transmission, the virus responsible for the COVID-19 pandemic that is sweeping the world today. SARS-CoV-2 belongs to the β-coronaviruses characterized by the crown-shaped spike protein that protrudes out of the virus particles, giving the virus a “corona” shape; hence the name coronavirus. This virus is similar to the viruses that caused SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome), the other two coronavirus epidemics that were recently contained within the last ten years. The technique being proposed uses a light source from a smart phone and a mobile spectrophotometer to enable detection of viral proteins in solution or paper as well as protein-protein interactions. The proof-of-concept is shown by detecting soluble preparations of spike protein subunits from SARS-CoV-2, followed by detection of the actual binding potential of the spike protein with its host receptor, the angiotensin-converting enzyme 2 (ACE2). The results are validated by showing that this method can detect antigen-antibody binding using two independent viral protein-antibody pairs. The binding could be detected optically both in solution and on a solid support such as nitrocellulose membrane. Finally, this technique is combined with DC bias to show that introduction of a current into the system can be used to disrupt the antigen-antibody reaction, suggesting that the proposed extended technique can be a potential means of not only detecting the virus, but also reducing virus transmission by disrupting virus-receptor interactions electrically.

Significance

The measured intensity of light can reveal information about different cellular parameters under study. When light passes through a bio-composition, the intensity is associated with its content. The nuclei size, cell shape and the refractive index variation of cells contributes to light intensity. In this work, an optical label-free real time detection method incorporating the smartphone light source and a portable mini spectrometer for SARS-CoV-2 detection was developed based on the ability of its spike protein to interact with the ACE2 receptor. The light interactions with control and viral protein solutions were capable of providing a quick decision regarding whether the sample under test was positive or negative, thus enabling SARS-CoV-2 detection in a rapid manner.

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  1. ScreenIT

    SciScore for 10.1101/2020.11.24.20237628: (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
    Nucleocapsid protein: The SARS-CoV-2 nucleocapsid protein (Sino Biologicals, Cat no. 40588-V08B)61 and its corresponding nucleocapsid antibody (Sino Biologicals Cat no. 40588-T62)61 were used for the binding affinity experiments.
    The SARS-CoV-2 nucleocapsid protein (Sino Biologicals, Cat no. 40588-V08B)61
    suggested: None
    SARS-CoV-2 nucleocapsid protein
    suggested: (Bioss Cat# bsm-41414M, RRID:AB_2848129)

    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: We detected the following sentences addressing limitations in the study:
    To overcome this caveat and have more consistence measurements without constant standardization, advantage was made of the ability of the spectrometer to provide light intensity measurements over time. Hence, after placing the microcentrifuge tube into the holder, the measurement mode would be started and the corresponding “blank” recorded. Then the sample would be added after ∼ 100 mSecond, while keeping the measurement mode on. Figure 3(b) illustrates the corresponding measurement profile for S1B and S2B individual samples suspended in water over time. Initially, a fluctuation in the light intensity was observed with time as each sample was added to the tube, but then it stabilized with time. As expected, the blank exhibited the maximum measured light intensity, while the suspended samples showed lower light intensity than the blank once stabilized. Test of the Spike Proteins Using the Proposed Experimental Set Up: To test the proof-of-principle, initially a mixing experiment was conducted at a light wavelength of 623 nm. Towards this end, 250 μL of S1B protein solution was tested at the same maximum concentration at 5,000 copies/mL followed by addition of same amount of S2B. Figure 3(c) shows the light intensity (as arbitrary units, a.u.) with time as the protein samples were added to the transparent measurement container in a sequential manner. This was followed by addition of 250 μL of ten-fold serial dilutions of the S2 protein at equal time intervals to the S1B + S2B s...

    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 10.1101/2020.11.24.20237628 on medRxiv