Application of newly developed SARS-CoV2 serology test along with real-time PCR for early detection in health care workers and on-time plasma donation.

Background: As the daily number of coronavirus infection disease 19 (COVID19) patients increases, the necessity of early diagnosis becomes more obvious. In this respect, we aimed to develop a serological test for specifically detecting anti-SARS-CoV2 antibodies.

Methods: We collected serum and saliva samples from 609 individuals who work at TBZMED affiliated hospitals in Tabriz, Iran, from April to June of 2020. Real-time PCR technique was used to detect SARS-CoV-2 genome using specific primers. An enzyme linked immunosorbent assay (ELISA) test was designed based on virus nucleocapsid (N), spike (S) and its receptor binding domain (RBD) protein, and the collected sera were subjected to IgM and/or IgG analysis.

Result: Real-time PCR results showed that 66 people were infected with the SARS-CoV-2. Our designed ELISA kit showed 93.75% and 98% of sensitivity and specificity, respectively. In this study, 5.74% of participants had specific IgG against RBD, whereas the percentage for IgM positive individuals was 5.58%. Approximately the same results were observed for S protein. The number of positive participants for NP increased further, and the results of this antigen showed 7.38% for IgG and 7.06% for IgM.

Conclusion: The ELISA test beside real-time PCR could provide a reliable serologic profile for the status of the disease progress and early detection of individuals. More importantly, it possesses the potential to identify the best candidates for plasma donation according to the antibody titers.