Abstract
For the clinical application of semi-quantitative anti-SARS-CoV-2 antibody tests, the analytical performance and titer correlation of the plaque reduction neutralization test (PRNT) need to be investigated. We evaluated the analytical performance and PRNT titer-correlation of one surrogate virus neutralization test (sVNT) kit and three chemiluminescent assays. We measured the total antibodies for the receptor-binding domain (RBD) of the spike protein, total antibodies for the nucleocapsid protein (NP), and IgG antibodies for the RBD. All three chemiluminescent assays showed high analytical performance for the detection of SARS-CoV-2 infection, with a sensitivity ≥ 98% and specificity ≥ 99%; those of the sVNT were slightly lower. The representativeness of the neutralizing activity of PRNT ND 50 ≥ 20 was comparable among the four immunoassays (Cohen’s kappa ≈ 0.80). Quantitative titer correlation for high PRNT titers of ND 50 ≥ 50, 200, and 1,000 was investigated with new cut-off values; the anti-RBD IgG antibody kit showed the best performance. It also showed the best linear correlation with PRNT titer in both the acute and convalescent phases (Pearson’s R 0.81 and 0.72, respectively). Due to the slowly waning titer of anti-NP antibodies, the correlation with PRNT titer at the convalescent phase was poor. In conclusion, semi-quantitative immunoassay kits targeting the RBD showed neutralizing activity that was correlated by titer; measurement of anti-NP antibodies would be useful for determining past infections.
Keywords: COVID-19; SARS-CoV-2; antibody responses; immunoassay; neutralizing antibody; nucleopcapsid (NP) protein; serology; spike (S) protein.
【저자키워드】 COVID-19, neutralizing antibody, SARS-CoV-2, serology, immunoassay, Antibody responses, spike (S) protein, nucleopcapsid (NP) protein, 【초록키워드】 neutralizing antibody, antibodies, serology, antibody, SARS-COV-2 infection, Spike protein, nucleocapsid protein, Protein, immunoassay, sensitivity, specificity, Neutralizing activity, Antibody responses, infections, IgG antibody, Receptor-binding domain, Plaque reduction neutralization test, anti-SARS-CoV-2 antibody, IgG antibodies, RBD, antibody tests, titer, virus neutralization test, neutralization test, Neutralizing, total antibody, correlation, PRNT, Chemiluminescent assay, Anti-RBD IgG, best, linear correlation, convalescent phase, sVNT, cut-off, total antibodies, Pearson, plaque reduction neutralization, assays, investigated, evaluated, linear, the spike protein, correlated, the RBD, the receptor-binding domain, comparable, semi-quantitative, 【제목키워드】 Effect,