Enzyme-Linked Immunosorbent Assay Based on a Chimeric Antigen Bearing Antigenic Regions of Structural Proteins E^rns and E2 for Serodiagnosis of Classical Swine Fever Virus Infection

SDS-PAGE and Western blot analysis of the C21E^rnsE2 chimeric protein expressed from pET184-177. The protein bands were stained with Coomassie blue (a) or immunostained with anti-His MAb (b), anti-E^rns M2165 (c), anti-E2 M1655 (d), or nonspecific MAb M1875 (e). Lanes: M, the protein standards with their molecular masses in kilodaltons shown on the left; 1, whole-cell lysates of an E. coli clone (equivalent to 1 ml of culture with an A₅₉₀ of 0.2) harboring pET184-177 in the absence of IPTG (isopropyl-β-d-thiogalactopyranoside); 2, whole-cell lysates of an E. coli clone harboring pET184-177 after induction with IPTG for 3 h; 3, nickel chelate affinity-purified C21E^rnsE2 (5 μg in panel a, 1 μg in all other panels).