Preparation and characterization of polyclonal antibody against severe acute respiratory syndrome-associated coronavirus spike protein.

A truncated gene (designated S1) encoding the receptor-binding domain (RBD) in the spike (S) protein of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) was amplified by PCR. The gene was cloned into prokaryotic expression vector pGEX-6P-1, resulting in a recombinant plasmid pGEX-SARS-S1. Subsequently, pGEX-SARS-S1 was transformed into host cells BL21(DE3)pLysS, and the expression of the S1 protein was induced by isopropyl β-D-thiogalactoside (IPTG). Polyclonal antibody against SARS-CoV S1 protein was generated in a rabbit immunized with the purified S1 protein. The reactivity of the antibody to the SARS-CoV S1 protein was confirmed by Western blot analysis. ELISA indicated that the antibody against SARS-CoV S1 protein had no cross reaction with S1 proteins of transmissible gastroenteritis virus, a porcine coronavirus, and infectious bronchitis virus, an avian coronavirus. The SARS-CoV S1 protein and its antibody are valuable reagents for related studies.