EVALUATION OF INTERACTIONS OF SARS-COV-2 STRUCTURAL PROTEINS WITH SPECIFIC ANTIBODIES BY SPR ASSAY

Background: The World Health Organization admitted that the vaccination against Covid 19 limited the deaths, but not the spread of the disease. This requires a method allowing a specific, rapid and accurate diagnosis of the disease. We report a SPR assay that meets the requirements and can be applied no only for SARS Cov-2 diagnosis but as a tool for early diagnosis of otherinfections. Methods: Surface plasmon resonance (SPR) method was used to identify the binding of S/N protein to monoclonal antibodies. N-protein monoclonal antibody (NP mAb), S-protein monoclonal antibody (SP mAb), and receptor bind domain (RBD) antibody were used as recognition molecules. Ligands were deposited by the matrix-assisted laser evaporation (MAPLE) method, which guarantees maximum interaction specificity. Results: We registered S/N protein binding to the corresponding mAbs and S protein to RBD antibody with high sensitivity: the interactions were observed at protein concentration about 130 femtomoles (fM). A very good specificity was observed: the measured S protein binding activity to NP mAb was below the limit of detection (LOD). The same was noticed for N protein binding to SP mAb. Conclusions: The presented SPR assay possesses high sensitivity and selectivity and provides quantitative analysis. This makes it applicable for following the evolution of acute SARS-CoV-2 infection, especially at the early stages of viral replication which can be clinically useful.