Diagnosis of Acute Respiratory Syndrome Coronavirus 2 Infection by Detection of Nucleocapsid Protein

  1. Bo Diao
  2. Kun Wen
  3. Jian Chen
  4. Yueping Liu
  5. Zilin Yuan
  6. Chao Han
  7. Jiahui Chen
  8. Yuxian Pan
  9. Li Chen
  10. Yunjie Dan
  11. Jing Wang
  12. Yongwen Chen
  13. Guohong Deng
  14. Hongwei Zhou
  15. Yuzhang Wu

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Abstract

BACKGROUND

Nucleic acid test and antibody assay have been employed in the diagnosis for SARS-CoV-2 infection, but the use of viral antigen for diagnosis has not been successfully developed. Theoretically, viral antigen is the specific marker of the virus and precedes antibody appearance within the infected population. There is a clear need of detection of viral antigen for rapid and early diagnosis.

METHODS

We included a cohort of 239 participants with suspected SARS-CoV-2 infection from 7 centers for the study. We measured nucleocapsid protein in nasopharyngeal swab samples in parallel with the nucleic acid test. Nucleic acid test was taken as the reference standard, and statistical evaluation was taken in blind. We detected nucleocapsid protein in 20 urine samples in another center, employing nasopharyngeal swab nucleic acid test as reference standard.

RESULTS

We developed a fluorescence immunochromatographic assay for detecting nucleocapsid protein of SARS-CoV-2 in nasopharyngeal swab sample and urine within 10 minutes. 100% of nucleocapsid protein positive and negative participants accord with nucleic acid test for same samples. Further, earliest participant after 3 days of fever can be identified by the method. In an additional preliminary study, we detected nucleocapsid protein in urine in 73.6% of diagnosed COVID-19 patients.

CONCLUSIONS

Those findings indicate that nucleocapsid protein assay is an accurate, rapid, early and simple method for diagnosis of COVID-19. Appearance of nucleocapsid protein in urine coincides our finding of the SARS-CoV-2 invading kidney and might be of diagnostic value.

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  1. ScreenIT

    SciScore for 10.1101/2020.03.07.20032524: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    BlindingStatistical evaluation was taken in blind based a four-grid table.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The goat anti-rabbit IgG antibodies (2mg/mL) and mouse anti-nucleocapsid protein of SARS-CoV-2 monoclonal antibody (M1,1mg/ml) were dotted on the nitrocellulose membrane at a volume of 0.4 μL to form the control line and test line, respectively.
    anti-rabbit IgG
    suggested: None
    anti-nucleocapsid protein of SARS-CoV-2
    suggested: None
    With the help of the capillarity of the absorbent pad, sample buffer containing SARS-CoV-2 nucleocapsid protein could be combined by III-conjugated M4 antibody and captured by M1 antibody at the test line, while III-conjugated rabbit IgG could be captured on the control line, resulting in a fluorescent band on the test and control lines, respectively.
    M4
    suggested: None
    Software and Algorithms
    SentencesResources
    Data analysis: Statistical analyses were performed blindly with the statistical analysis system software SPSS 19.0.
    SPSS
    suggested: (SPSS, RRID:SCR_002865)

    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 10.1101/2020.03.07.20032524v2 on medRxiv
  3. Version published to 10.1101/2020.03.07.20032524v1 on medRxiv