The utility of SARS-CoV-2 nucleocapsid protein in laboratory diagnosis

Background The Coronavirus Disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has now become a global pandemic owing to its high transmissibility. The SARS-CoV-2 nucleocapsid protein tests are playing an important role in screening and diagnosing patients with COVID-19, and studies about the utility of SARS-CoV-2 nucleocapsid protein tests are increasing now. Methods In this review, all the relevant original studies were assessed by searching in electronic databases including Scopus, Pubmed, Embase, and Web of Science. "SARS-CoV-2", "COVID-19", "nucleocapsid protein", and "antigen detection" were used as keywords. Results In this review, we summarized the utility of SARS-CoV-2 nucleocapsid protein in laboratory diagnosis. Among the representative researches, this review analyzed, the sensitivity of SARS-CoV-2 nucleocapsid protein detection varies from 13% to 87.9%, while the specificity could almost reach 100% in most studies. As a matter of fact, the sensitivity is around 50% and could be higher or lower due to the influential factors. Conclusion It is well suggested that SARS-CoV-2 nucleocapsid protein is a convenient method with a short turnaround time of about half an hour, and the presence of N antigen is positively related to viral transmissibility, indicating that SARS-CoV-2 N protein immunoassays contribute to finding out those infected people rapidly and segregating them from the uninfected people.