Diagnostics (Dec 2022)

Development of in House ELISAs to Detect Antibodies to SARS-CoV-2 in Infected and Vaccinated Humans by Using Recombinant S, S1 and RBD Proteins

  • Aysun Yilmaz,
  • Nuri Turan,
  • Bekir Sami Kocazeybek,
  • Harika Oyku Dinc,
  • Hasan Emre Tali,
  • Ozge Aydin,
  • Hamid Besim Tali,
  • Semaha Gul Yilmaz,
  • Dildar Konukoglu,
  • Sermin Borekci,
  • Dashzeveg Bold,
  • Gleyder Roman Sosa,
  • Nejdiye Gungordu,
  • Ilgim Vardaloglu,
  • Nesrin Gareayaghi,
  • Mine Guzel,
  • Ebru Guner,
  • Jean-Remy Sadeyen,
  • Pengxiang Chang,
  • Munir Iqbal,
  • Juergen A. Richt,
  • Huseyin Yilmaz

DOI
https://doi.org/10.3390/diagnostics12123085
Journal volume & issue
Vol. 12, no. 12
p. 3085

Abstract

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(1) Background: The aim of this study was to produce in-house ELISAs which can be used to determine SARS-CoV-2-specific antibody levels directed against the spike protein (S), the S1 subunit of S and the receptor binding domain (RBD) of S in SARS-CoV-2 vaccinated and infected humans. (2) Methods: Three in-house ELISAs were developed by using recombinant proteins of SARS-CoV-2, namely the S, S1 and RBD proteins. Specificity and sensitivity evaluations of these tests were performed using sera from SARS-CoV-2-infected (n = 70) and SARS-CoV-2-vaccinated (n = 222; CoronaVac vaccine) humans in Istanbul, Turkey. The analyses for the presence of SARS-CoV-2-specific antibodies were performed using the in-house ELISAs, a commercial ELISA (Abbott) and a commercial surrogate virus neutralization test (sVNT). We also analyzed archival human sera (n = 50) collected before the emergence of COVID-19 cases in Turkey. (3) Results: The sensitivity of the in-house S, S1 and RBD ELISAs was found to be 88.44, 90.17 and 95.38%, while the specificity was 72.27, 89.08 and 89.92%, respectively, when compared to the commercial SARS-CoV-2 antibody test kit. The area under curve (AUC) values were 0.777 for the in-house S ELISA, 0.926 for the S1 ELISA, and 0.959 for the RBD ELISA. The kappa values were 0.62, 0.79 and 0.86 for the S, S1 and RBD ELISAs, respectively. (4) Conclusions: The in-house S1 and RBD ELISAs developed in this study have acceptable performance characteristics in terms of sensitivity, specificity, AUC and kappa values. In particular, the RBD ELISA seems viable to determine SARS-CoV-2-specific antibody levels, both in infected and vaccinated people, and help mitigate SARS-CoV-2 outbreaks and spread.

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