The C-terminal Domain of S1 Subunit Spike Protein Enhances the Sensitivity of COVID-19 Serological Assay

Evaluating antibody responses against the receptor binding domain (RBD) protein will be essential for determining the antibody response's durability and defining a vaccine-induced antibody response.Consequently, it becomes crucial for the production of innovative RBD antigens to enhance the sensitivity detection of antibody anti-COVID-19.The bottleneck to achieving these targets is the availability of effective RBD antigens construct.This study evaluated the potency RS1, RBD with C-terminal domain (CTD) of Spike S1 domain, to detect antibody anti-spike SARS-CoV-2 in patient sera.Docking simulations with ClusPro have been done to determine how antigens (RBD/RS1) and antibody (Fv) models interact.The RMSD for both complexes is accordingly still in tolerable value.The constructs RBD and RS1 were expressed in Escherichia coli strain Origami under the pET-32b(+) expression vector.The indirect IgG-ELISA of both recombinant proteins could differentiate the presence of negative antibody anti-spike in nave sera and positive sera collected from COVID-19 patients between 2020 and 2022.Furthermore, the degree of detecting antibodies anti-spike utilizing the RS1 protein increased significantly compared to RBD (p = 0.0033).Our results indicate additional CTD in RS1 could access more anti-spike antibodies and enhance the sensitivity detection of antibody anti-spike COVID-19.