Used in research and diagnostic applications to detect the spike protein's receptor-binding domain (RBD) of SARS-CoV-2. Helps in studying virus neutralization mechanisms and evaluating immune response in infected or vaccinated individuals. Commonly applied in ELISA, Western blot, and immunofluorescence assays. Supports development of therapeutic antibodies and vaccine efficacy testing by specifically binding to the RBD region involved in host cell entry.