SARS CoV ORF1ab polyprotein (PP1ab) is a 7073 residues long polyprotein which further produces 5 non-structural proteins (NSPs) after processing through virally encoded proteases (NSP12-NSP16) .All these 5 proteins are mainly involved in viral replication, assembly, and immune response modulation.SARS-CoV Plpro/papain-like protease Protein (His) is the recombinant Virus-derived SARS-CoV Plpro/papain-like protease protein, expressed by E.coli , with C-His labeled tag.