Abstract
The ongoing COVID-19 pandemic has emphasized the urgent need for rapid, accurate, and large-scale diagnostic tools. Next to this, the significance of serological tests (i.e., detection of SARS-CoV-2 antibodies) also became apparent for studying patients’ immune status and past viral infection. In this work, we present a novel approach for not only measuring antibody levels but also profiling of binding kinetics of the complete polyclonal antibody response against the receptor binding domain (RBD) of SARS-CoV-2 spike protein, an aspect not possible to achieve with traditional serological tests. This fiber optic surface plasmon resonance (FO-SPR)-based label-free method was successfully accomplished in COVID-19 patient serum and, for the first time, directly in undiluted whole blood, omitting the need for any sample preparation. Notably, this bioassay (1) was on par with FO-SPR sandwich bioassays (traditionally regarded as more sensitive) in distinguishing COVID-19 from control samples, irrespective of the type of sample matrix, and (2) had a significantly shorter time-to-result of only 30 min compared to >1 or 4 h for the FO-SPR sandwich bioassay and the conventional ELISA, respectively. Finally, the label-free approach revealed that no direct correlation was present between antibody levels and their kinetic profiling in different COVID-19 patients, as another evidence to support previous hypothesis that antibody-binding kinetics against the antigen in patient blood might play a role in the COVID-19 severity. Taking all this into account, the presented work positions the FO-SPR technology at the forefront of other COVID-19 serological tests, with a huge potential toward other applications in need for quantification and kinetic profiling of antibodies.
Keywords: ELISA; FO-SPR; His6-tagged RBD; SARS-CoV-2; binding kinetics; serological test; serum; whole blood.
【저자키워드】 serological test, SARS-CoV-2, ELISA, serum, Whole blood, FO-SPR, His6-tagged RBD, binding kinetics, 【초록키워드】 COVID-19, serological test, antibodies, viral infection, antibody, COVID-19 pandemic, diagnostic, COVID-19 severity, surface plasmon resonance, ELISA, Spike protein, Receptor binding domain, Antigen, serum, SARS-CoV-2 antibodies, Viral, Serological tests, Whole blood, RBD, SARS-CoV-2 spike protein, Patient, antibody levels, correlation, serological, quantification, COVID-19 patients, Blood, binding kinetics, binding, Immune status, Evidence, Hypothesis, kinetic, polyclonal antibody, Support, surface plasmon, bioassay, aspect, COVID-19 patient serum, Complete, fiber, approach, polyclonal, Taking, antibody response against, significantly shorter, 【제목키워드】 COVID-19, Strategy,