Evaluation of the performance of two commercial SARS-CoV-2 neutralizing antibody test kits

ABSTRACT

Objective To evaluate the performance of two commercial EIA kits for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies. Methods Two commercial SARS-CoV-2 neutralizing antibody ELISA test kits (A and B) were used to detect serum panel consists of the following sera 44 collected before vaccination, 120 collected one month after vaccination and 64 collected six months after recovery from convalescent patients of COVID-19. In the meantime, the above samples were also taken for live virus micro-neutralization test (micro-NT) indicated as the 50% neutralization antibody titer (NT50 ) . The consistency of qualitative and quantitative results between the two commercial kits and live virus neutralization test was analyzed. Results Taking the micro-NT results as the standard, the positive coincidence rates of A and B kits were 97. 40% and 100. 00%, respectively;the negative coincidence rates were 97. 30% and 95. 95%, respectively;the Youden indices were 0. 95 and 0. 96, respectively. Furthermore, quantitative analysis indicated that the correlation coefficients between A and B kits and micro-NT results were 0. 24 (P<0. 05) and 0. 52 (P<0. 000 1) for samples collected after vaccination, respectively;while the correlation coefficients were 0. 81 (P<0. 000 1) and 0. 89 (P<0. 000 1) for convalescent serum samples, respectively. Conclusions The results obtained by the two commercial neutralizing antibody detection kits were in good agreement with the qualitative results of micro-NT. The neutralizing antibody titers in convalescent serum samples detected by the two kits showed a stronger correlation with the micro-NT results. © 2022 Society of Microbiology and Immunology. All rights reserved.