Borderline and weakly positive antibody levels against the S-protein of SARS-CoV-2 exhibit limited agreement with virus neutralization titres

Alexander E. Egger, Christian Irsara, Barbara Holzer, Christoph Winkler, Rosa Bellmann-Weiler, Günter Weiss, Boris Hartmann, Wolfgang Prokop, Gregor Hoermann, Andrea Griesmacher, Markus Anliker

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The presence of neutralizing antibodies against SARS-CoV-2 in a large number of people is – besides cellular immunity – important to overcome the SARS-CoV-2 pandemic. While determination of neutralizing antibodies via virus neutralization tests are laborious, assays to determine the antibody levels serologically are fully automated and widely available. Correlations between these methodologies were recently given by the manufacturers, however performance in samples close to the cut off value have not yet been fully validated. Thus, we analysed 22 borderline and low positive (<100 BAU/ml) samples and 9 high positive (≥ 100 BAU/ml) from infected and/or vaccinated individuals and compared the SARS-CoV-2 IgG II Quant assay (Abbott), LIAISON SARS-CoV-2 TrimericS IgG (Diasorin), Elecsys Anti-SARS-CoV-2 S (Roche), and SARS-CoV-2 IgG (Siemens) with results obtained from a virus neutralization test. Based on the cut off values given by Abbott, Diasorin, Roche, and Siemens, the positive serologic results were concordant with the virus neutralization test in 100%, 76%, 88%, and 71%, respectively, while in turn, negative ones were in agreement in 29%, 79%, 93%, and 86%, respectively. In conclusion, weakly positive, serologic results are challenging to correctly predict the presence of neutralizing antibodies. Our study suggests, that different cut off values (for positivity vs. presence of neutralizing antibodies) could improve the test's performance, but determination thereof requires more samples to be analysed.

Original languageEnglish
Article number100058
JournalJournal of Clinical Virology Plus
Volume2
Issue number1
DOIs
StatePublished - Feb 2022
Externally publishedYes

Keywords

  • Automated antibody assays
  • Correlation
  • Neutralizing antibodies
  • SARS-CoV-2
  • Serology
  • Virus neutralization test

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