Immunofluorescence is a traditional diagnostic method for respiratory viruses, allowing rapid, simple and accurate diagnosis, with specific benefits of direct visualization of antigens-of-interest and quality assessment. This study aims to evaluate the potential of indirect immunofluorescence as an in-house diagnostic method for SARS-CoV-2 antigens from nasopharyngeal swabs (NPS). Three primary antibodies raised from mice were used for immunofluorescence staining, including monoclonal antibody against SARS-CoV nucleocapsid protein, and polyclonal antibodies against SARS-CoV-2 nucleocapsid protein and receptor-binding domain of SARS-CoV-2 spike protein. Smears of cells from NPS of 29 COVID-19 patients and 20 non-infected individuals, and cells from viral culture were stained by the three antibodies. Immunofluorescence microscopy was used to identify respiratory epithelial cells with positive signals. Polyclonal antibody against SARS-CoV-2 N protein had the highest sensitivity and specificity among the three antibodies tested, detecting 17 out of 29 RT-PCR-confirmed COVID-19 cases and demonstrating no cross-reactivity with other tested viruses except SARS-CoV. Detection of virus-infected cells targeting SARS-CoV-2 N protein allow identification of infected individuals, although accuracy is limited by sample quality and number of respiratory epithelial cells. The potential of immunofluorescence as a simple diagnostic method was demonstrated, which could be applied by incorporating antibodies targeting SARS-CoV-2 into multiplex immunofluorescence panels used clinically, such as for respiratory viruses, thus allowing additional routine testing for diagnosis and surveillance of SARS-CoV-2 even after the epidemic has ended with low prevalence of COVID-19.
【저자키워드】 COVID-19, nasopharyngeal swabs, immunofluorescence assay, detection of SARS-CoV-2, 【초록키워드】 antibodies, SARS-CoV-2, antibody, SARS-CoV, monoclonal antibody, Diagnosis, detection, virus, nucleocapsid protein, cross-reactivity, respiratory viruses, Nasopharyngeal swab, Protein, Surveillance, Accuracy, Sensitivity and specificity, mice, Microscopy, SARS-CoV-2 spike protein, SARS-CoV-2 N protein, SARS-CoV-2 antigen, immunofluorescence, viral culture, Diagnostic method, COVID-19 patient, polyclonal antibody, COVID-19 case, infected individuals, domain, staining, positive, SARS-CoV-2 nucleocapsid, respiratory epithelial cells, multiplex immunofluorescence, NPs, benefit, Cell, the epidemic, smear, non-infected, primary antibody, highest, tested, identify, was used, evaluate, clinically, raised, were used, demonstrated, against SARS-CoV, individuals, virus-infected cell, respiratory epithelial cell, prevalence of COVID-19, were stained, 【제목키워드】 SARS-CoV-2, detection,