A1 Journal article – refereed

A Combination of N and S Antigens With IgA and IgG Measurement Strengthens the Accuracy of SARS-CoV-2 Serodiagnostics

List of Authors: Jalkanen P, Pasternack A, Maljanen S, Melén K, Kolehmainen P, Huttunen M, Lundberg R, Tripathi L, Khan H, Ritvos MA, Naves R, Haveri A, Österlund P, Kuivanen S, Jääskeläinen AJ, Kurkela S, Lappalainen M, Rantasärkkä K, Vuorinen T, Hytönen J, Waris M, Tauriainen S, Ritvos O, Kakkola L, Julkunen I

Publication year: 2021

Journal: Journal of Infectious Diseases

Journal name in source: The Journal of infectious diseases

Journal acronym: J Infect Dis

Volume number: 224

Issue number: 2

ISSN: 0022-1899

eISSN: 1537-6613

DOI: http://dx.doi.org/10.1093/infdis/jiab222

URL: https://academic.oup.com/jid/article/224/2/218/6255671


Background: Primary diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is based on detection of virus RNA in nasopharyngeal swab samples. In addition, analysis of humoral immunity against SARS-CoV-2 has an important role in viral diagnostics and seroprevalence estimates.

Methods: We developed and optimized an enzyme immunoassays (EIA) using SARS-CoV-2 nucleoprotein (N), S1 and receptor binding domain (RBD) of the viral spike protein, and N proteins from SARS, Middle East respiratory syndrome (MERS), and 4 low-pathogenic human CoVs. Neutralizing antibody activity was compared with SARS-CoV-2 IgG, IgA, and IgM EIA results.

Results: The sensitivity of EIA for detecting immune response in COVID-19 patients (n = 101) was 77% in the acute phase and 100% in the convalescent phase of SARS-CoV-2 infection when N and RBD were used as antigens in IgG and IgA specific EIAs. SARS-CoV-2 infection significantly increased humoral immune responses against the 229E and NL63 N proteins. S1 and RBD-based EIA results had a strong correlation with microneutralization test results.

Conclusions: The data indicate a combination of SARS-CoV-2 S1 or RBD and N proteins and analysis of IgG and IgA immunoglobulin classes in sera provide an excellent basis for specific and sensitive serological diagnostics of COVID-19.

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Last updated on 2021-30-09 at 14:32