▎ 摘　　要

NOVELTY - A protein having an amino acid sequence of SEQ ID NO: 1 (sequence not given in patent specification) , is new. The protein contains antigenic regions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein fused by a flexible glycine-serine linker (Gly-Ser3linker), obtained through recombinant DNA technology using recombinant vector and heterologous expression of Escherichia coli. USE - The protein is useful for performing immunological diagnosis of COVID-19 through indirect ELISA (claimed). ADVANTAGE - The protein ensures immunological diagnosis of COVID-19 with high sensitivity, specificity, accuracy and reproducibility. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a DNA sequence encoding SEQ ID NO: 2 (sequence not given in patent specification), containing codon optimized for expression in E.coliof antigenic regions of SARS-CoV-2 proteins, fused by a flexible glycine-serine linker (Gly-Ser3linker); (2) an indirect enzyme-linked immunosorbent assay (ELISA) for immunological diagnosis of corona virus (COVID)-19 being performed by using 5-500 ng/well protein; and (3) immune diagnostic platform for COVID-19, being performed by using the protein attached or not to a solid support chosen from nitrocellulose, nylon, latex, polypropylene, polystyrene, gold, silver, platinum, mercury, graphene and/or graphite.