Pig Sera-derived Anti-SARS-CoV-2 Antibodies with Controlled Specificity for Competitive Immunoassay

다국어 초록 (Multilingual Abstract)

Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies against nucleoprotein (NP) were purified from pig sera through two steps: (1) isolation of anti-SARS-CoV-2 NP antibodies using magnetic beads with immobilized SARS-CoV-2 NP and (2) filtration of anti-SARS-CoV-2 spike protein (SP). The binding activities of the isolated antibodies were confirmed using immunoassay and immunostaining. The binding constant (K_d) of the purified anti-SARS-CoV-2 NP antibodies was estimated using a surface plasmon resonance biosensor (SPR) and calculated to be 185 pM. From the dose-response curve, the limit of detection was estimated to be 1.02 pM. Finally, a competitive immunoassay was developed for detecting SARS-CoV-2 NP as well as SARS-CoV-2 in the culture fluid using magnetic beads with immobilized anti-SARS-CoV-2 NP antibodies. The results demonstrated (a) the detection of SARS-CoV-2 in viral fluid and (b) the discrimination of SARS-CoV-2 from SARS-CoV, MERS-CoV, and CoV strain 229E in viral fluids. Additionally, anti-SARS-CoV-2 antibodies against SP were obtained when the isolation process was performed using the magnetic beads with immobilized human SARS-CoV-2 SP.