Evaluation of Nucleocapsid and Spike Protein-Based Enzyme-Linked Immunosorbent Assays for Detecting Antibodies against SARS-CoV-2

J Clin Microbiol. 2020 May 26;58(6):e00461-20. doi: 10.1128/JCM.00461-20. Print 2020 May 26.


At present, PCR-based nucleic acid detection cannot meet the demands for coronavirus infectious disease (COVID-19) diagnosis. Two hundred fourteen confirmed COVID-19 patients who were hospitalized in the General Hospital of Central Theater Command of the People's Liberation Army between 18 January and 26 February 2020 were recruited. Two enzyme-linked immunosorbent assay (ELISA) kits based on recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (rN) and spike protein (rS) were used for detecting IgM and IgG antibodies, and their diagnostic feasibility was evaluated. Among the 214 patients, 146 (68.2%) and 150 (70.1%) were successfully diagnosed with the rN-based IgM and IgG ELISAs, respectively; 165 (77.1%) and 159 (74.3%) were successfully diagnosed with the rS-based IgM and IgG ELISAs, respectively. The positive rates of the rN-based and rS-based ELISAs for antibody (IgM and/or IgG) detection were 80.4% and 82.2%, respectively. The sensitivity of the rS-based ELISA for IgM detection was significantly higher than that of the rN-based ELISA. We observed an increase in the positive rate for IgM and IgG with an increasing number of days post-disease onset (d.p.o.), but the positive rate of IgM dropped after 35 d.p.o. The positive rate of rN-based and rS-based IgM and IgG ELISAs was less than 60% during the early stage of the illness, 0 to 10 d.p.o., and that of IgM and IgG was obviously increased after 10 d.p.o. ELISA has a high sensitivity, especially for the detection of serum samples from patients after 10 d.p.o., so it could be an important supplementary method for COVID-19 diagnosis.

Keywords: COVID-19 diagnosis; ELISA; IgG; IgM; antibody; nucleocapsid protein; spike protein.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Betacoronavirus / immunology*
  • COVID-19
  • COVID-19 Testing
  • Clinical Laboratory Techniques / methods*
  • Coronavirus Infections / diagnosis
  • Coronavirus Infections / immunology*
  • Coronavirus Infections / virology*
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Immunoglobulin M / blood
  • Immunoglobulin M / immunology
  • Pandemics
  • Pneumonia, Viral / immunology*
  • Pneumonia, Viral / virology*
  • SARS-CoV-2
  • Spike Glycoprotein, Coronavirus / immunology*


  • Immunoglobulin G
  • Immunoglobulin M
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2