DEVELOPMENT AND VALIDATION OF AN ENZYME-LINKED IMMUNOASSAY KIT FOR DIAGNOSIS AND SURVEILLANCE OF COVID-19

Bagno, F. F.; Sergio, S. A. R.; Figueiredo, M. M.; Godoi, L. C.; Andrade, L. A. F.; Salazar, N. C.; Soares, C. P.; Aguiar, A.; Almeida, F. J.; da Silva, E. D.; Ferreira, A. G. P.; Durigon, E. L.; Gazzinelli, R. T.; Teixeira, S. M. R.; Fernandes, A. P. S. M.; da Fonseca, F. G.

There is a massive demand to identify alternative methods to detect new cases of COVID-19 as well as to investigate the epidemiology of the disease. In many countries, importation of commercial kits poses a significant impact on their testing capacity and increases the costs for the public health system. We have developed an ELISA to detect IgG antibodies against SARS-CoV-2 using a recombinant viral nucleocapsid (rN) protein expressed in E. coli. Using a total of 894 clinical samples we showed that the rN-ELISA was able to detect IgG antibodies against SARS-CoV-2 with high sen-sitivity (97.5%) and specificity (96.3%) when compared to a commercial antibody test. After three external validation studies, we showed that the test accuracy was higher than 90%. The rN-ELISA IgG kit constitutes a convenient and specific method for the large-scale determination of SARS-Cov-2 antibodies in human sera with high reliability.