Development of a recombinant truncated nucleocapsid protein based immunoassay for detection of antibodies against human coronavirus OC43.

Human coronaviruses are one of the main causes of upper respiratory tract infections in humans. While more often responsible for mild illness, they have been associated with illnesses that require hospitalization. In this study, an assay for one of the human coronaviruses, OC43, was developed using a truncated recombinant nucleocapsid (N) protein antigen in an enzyme immunosorbent assay (ELISA) and evaluated using serum collected from HCoV-OC43-infected patients, healthy adults, and patients with other respiratory virus infections. Results showed that the diagnostic sensitivity and specificity of the assay were 90.9% (10/11) and 82.9% (39/47), respectively. To evaluate the clinical utility of the ELISA, serum samples collected from patients during an outbreak of HCoV-OC43 infection and previously identified as positive by HCoV-OC43 whole N ELISA were screened resulting in 100% diagnosis agreement between the testing methods. These results suggest that this assay offers a reliable method to detect HCoV-OC43 infection and may be a useful tool in coronavirus seroepidemiological studies.