Ultrasensitive detection of SARS-CoV-2 spike proteins using the thio-NAD cycling reaction: A preliminary study before clinical trials

Yuta Kyosei, Mayuri Namba, Daiki Makioka, Ayumi Kokubun, Satoshi Watabe, Teruki Yoshimura, Tadahiro Sasaki, Tatsuo Shioda, Etsuro Ito*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

To help control the global pandemic of coronavirus disease 2019 (COVID-19), we developed a diagnostic method targeting the spike protein of the virus that causes the infection, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We applied an ultrasensitive method by combining a sandwich enzyme-linked immunosorbent assay (ELISA) and the thio-nicotinamide adenine dinucleotide (thio-NAD) cycling reaction to quantify spike S1 proteins. The limit of detection (LOD) was 2.62 × 10−19 moles/assay for recombinant S1 proteins and 2.6 × 106 RNA copies/assay for ultraviolet B-inactivated viruses. We have already shown that the ultrasensitive ELISA for nu-cleocapsid proteins can detect ultraviolet B-inactivated viruses at the 104 RNA copies/assay level, whereas the nucleocapsid proteins of SARS-CoV-2 are difficult to distinguish from those in conventional coronaviruses and SARS-CoV. Thus, an antigen test for only the nucleocapsid proteins is insufficient for virus specificity. Therefore, the use of a combination of tests against both spike and nucleocapsid proteins is recommended to increase both the detection sensitivity and testing accuracy of the COVID-19 antigen test. Taken together, our present study, in which we incorporate S1 detection by combining the ultrasensitive ELISA for nucleocapsid proteins, offers an ultrasensitive, antigen-specific test for COVID-19.

Original languageEnglish
Article number2214
JournalMicroorganisms
Volume9
Issue number11
DOIs
Publication statusPublished - 2021 Nov

Keywords

  • Antigen test
  • COVID-19
  • SARS-CoV-2
  • Spike protein
  • Thio-NAD cycling
  • Ultrasensi-tive ELISA

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)
  • Virology

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