Aim: to evaluate the specificity of the SARS-CoV N protein-based IgG ELISA assay for detection of immunoglobulin G (IgG) in plasma samples obtained from HIV-1 positive and HIV-1 negative intravenous drug users (IDUs). Methods: the SARS-Co V N gene was cloned into pQE-80L vector, and the constructs were transformed into Escherichia coli BL21. The 6 x His-tagged N protein was expressed by induci…