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 × 10 6 RNA copies/assay for ultraviolet B-inactivated viruses. We have already shown that the ultrasensitive ELISA for nucleocapsid proteins can detect ultraviolet B-inactivated viruses at the 10 4 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.
【저자키워드】 COVID-19, SARS-CoV-2, Spike protein, antigen test, thio-NAD cycling, ultrasensitive ELISA, 【초록키워드】 coronavirus disease, viruses, coronavirus, SARS-CoV, Infection, Proteins, virus, ELISA, nucleocapsid protein, Antigen, RNA, global pandemic, specificity, Accuracy, ultraviolet, limit of detection, Diagnostic method, Combination, Detection sensitivity, acute respiratory syndrome, Recombinant S1 protein, help, Nucleocapsid proteins, offer, Cycling, enzyme-linked immunosorbent, shown, detect, applied, the spike protein, cause, 【제목키워드】 spike, detection, clinical,